Try maximizing a window on a mac. Minimize a window, then alt-tab back to that app. You get the app, with no window! You then get the 'pleasure' of moving the mouse to the menu bar, selecting the window menu, and hopefully finding the window you wanted.
You probably don't know the following keyboard short-cut. When you said 'Alt-Tab', I'm assuming you mean 'Command-Tab', since that's the app switcher on Macs. AFTER you let go of the Tab (because you've switched to the right app), but BEFORE you let go of the Command key, PRESS AND HOLD the alt/option key, and THEN let go of the Command key. Any hidden or minimized windows will restore themselves to visibility. It's a fantastic trick which saves a lot of trips to the mouse. I hope it helps you!
Let's get real. On average, about 1 customer in 50, despite all the electronic device speeches, leaves their cell phone on inadvertently. You can hear the sounds of 'new voicemail' in the cabin when the aircraft gets within a few thousand feet of the ground for landing. This is a world-wide phenomenon. Passengers world-wide use their laptops, CD players, DVD players, electric shavers, etc. on board aircraft in flight. All these devices broadcast EM. There are something like 50,000 departures a DAY. Tons of other airlines fly the Airbus A330. Yet, only on Qantas airplanes in the last 6 months does this alleged interference occur? Give me a break.
This is a distraction technique. This may just be bad luck, it may be something specific to Qantas, it may be something with the Airbus A330, but pinning it on EM emissions by mobile devices seems like a quick way to assure that a real investigation is not done.
In addition, TFA said:
The ATSB said the pilots received messages about "some irregularity with the aircraft's elevator control system", before the plane climbed 300 feet and then nosedived.
I'm not typed on the Airbus A330. Does anyone who is care to chime in on what 'messages' the A330 could possibly deliver regarding 'irregularities' with the elevator control system?
I know nothing about their master caution/warning system.
All time can be universal (UTC). Noon can be "When the sun is directly overhead." which will locally be different. Start time for work can be Noon-3 Hours (3 hours before noon) to Noon+5 Hours (5 Hours after noon). No DST necessary and no leap-seconds necessary. Why do they want to overcomplicate things here?
...and so how do I know when to be at work? Look at my UTC watch? Consult my portable sundial?
Your system was tried and in widespread use until the 1800's with the spread of railroads. With increasingly fast and common transportation (and nowadays, communication), the 'every town has it's own time' system made it almost impossible to schedule trains, business, meetings, armies, etc. - so the train companies came up with the time zone system. It was such a vast improvement and massive success that essentially the entire world adopted it.
Who gives a damn about the sun being overhead at 12PM? China operates in a single timezone, despite spanning something like five, and they do just fine.
They did that because Eastern China, containing 95% of their population, is at +8 UTC 'naturally'. The fact that Western China, containing such pesky places as Tibet has their typical sunrise at 0830 and sunset at 2030 and has a jump of 2.5 to 3 hours when you cross over into India or Pakistan, doesn't bother the Chinese government much. I'm not so sure the people living there feel the same way. Or, to put it differently - I live in NYC. I think the US should have one time zone, and it should be based on NYC time. -5/-4 UTC for everybody! Who cares if California would have the sunset at 2230 today? Forget about Alaska and Hawaii....
Perhaps you live in a different world, but most people like to be awake and work roughly when the sun is up. Many places in the world are a little too poor to have the luxury of cheap nighttime lighting, and have large agrarian communities, all of which make the hours of daylight supremely important.
If you find timezones and the sun too tedious, why don't you set your own personal watch to TAI, and schedule your life that way? Nothing is stopping you... other than the fact that I've never seen a watch display TAI, and you might have to meet other people from time to time, thus requiring a translation. Oh well, it sounded good.
What I meant was that, in actual fact, there should be leap nanoseconds and atomic clocks handle those adjustments, but we don't record them per se.
That sounds great, until you want to compute the DIFFERENCE in two times. How can you do that with any accuracy if you don't know how many leap nanoseconds have been inserted (because no record was kept) between them?
As to changing time, the Sumerians didn't even agree as to the precise definition, and many cultures have accurately kept time using wheels and water clocks using other measurements - China, Aztecs, Toltecs, etc.
We really only keep clock seconds - changing the names of the units above it shouldn't matter.
They did not ACCURATELY keep time by any stretch of the imagination. All those clocks you mentioned had to constantly be resynced with more authoritative sources on a constant basis - those authoritative sources being the position of the sun, moon, etc. Being able to create a device that could even take a stab at a unit of time as short as a second with any accuracy (if your second was 88,000 per day one day and 66,000 the next, it's not very useful!) had to wait until the invention of the pendulum clock in the late 1600's by Huygens. If by clock seconds, you mean track solar time, we have a clock that does that - it's called UT1. It can only be determined by measurement, so no devices that present a time readout independently use it. We instead keep UTC within a second of UT1 by inserting leap seconds from time to time.
Besides, humans have a natural 25 hour clock, so it seems the earth may have rotated much faster originally, so our current "hours" are probably not correct.
Actually, the 25 hour circadian rythum argues for the Earth rotating SLOWER in the past, not faster - but, in fact, it did rotate FASTER in the past. Or, if you are a fan of intellegent creation or whatever it's called, when the Earth's rotation period slows to 25 hours (and presuming that an hour == 86,400 SI seconds) in however many millions of years, the time is right for ponies! Or something.
More to the point, it appears to average out, so we could be inserting them just to have to remove them a decade later.
No, they don't. The Earth's rotation rate is slowing due to tidal friction (and slowly pushing the moon away in the process, since angular momentum doesn't just vanish). The SI second was set based off of the average solar day back in the 1700's or so, and the Earth's average rotational period has slowed measurably since then. We have only added leap seconds, never subtracted them, and likely never will, despite a significant variation in the rate of slowing.
The problem is that we want to measure different periodic processes via the same unit - the second. The second was originally based off of the average length of the solar day, but then was redefined in terms of atomic standards. The average solar day, according to atomic standards, has been lengthening somewhat erratically. Either we give up using the second as a fundamental unit in the SI system, suitable for meausring times vast and small, or we give up having our clocks based on the second but choose some other 'variable' unit, synced to the sun (such as UT1 time), or we compromise and stick a leap second in from time to time to assure that UTC and UT1 remain within a second of each other - which is what is currently done. There really isn't an easy way out since the periodic processes of nature that matter to us are not neatly in ratios. Do we really want a 'science' time, and a 'civilian' time?
As you say, one day, programmers will wrap these difficulties up in libraries nicely and neatly so that it just 'works', but it will be based on an arbitrary table of leap seconds, much like we have an arbitrary table of time zone rules in our zoneinfo files. Part of the problem was due to the POSIX standard for time NOT being done properly. UTC actually specifies that the 'extra' second means that there are 61 seconds in a particular minute - i.e. 23:59:60 is a valid UTC time when a leap second is inserted. Unfortunately, POSIX time 'repeats' a second instead. POSIX time goes.... 23:59:57....23:59:58.... 23:59:59.....(zip! leap second!) 23:59:59.... 00:00:00.... 00:00:01... etc.
There are some complex tradeoffs associated with this. It simplifies the numerical calculation of traslating POSIX time (since POSIX time really is represented as the integer number of seconds since 1970-Jan-01 00:00:00, and the leap seconds are ignored) to 'clockface' time (i.e. The year, month, date, hour, minute and second). On the other hand, it yields incorrect answers when two POSIX times are naively subtracted to figure out the time delta between the time marks; one has to modify the 'obvious' subtraction algorithm with a somewhat complex lookup table procedure to get an accurate delta. UTC is more complex because the occassional 61 second minute requires that you consult a lookup table to translate UTC seconds to year-month-date-hour-minute-second form, but subtraction easily yields the correct delta between the time marks. If we want to stick with SI seconds and schedule ourselves with the sun, there will always be some messiness!
We rotate the same way we orbit, so the Earth rotates (from the point of view of the distant stars - the sidereal day) one more time in a year (366.24) than the number of solar days (365.24) - the number of times the sun circuts the sky. The length of the sidereal day is 23:56:04.1 long, and the solar day is 24:00:00 (roughly!). That extra 4 minutes is the Earth rotating 'a little extra' to put the sun in the same place in the sky since it's moved around it a little since the last noon.
If you have ever tried the coin rotation trick, that might help you out visualizing it. Glue one coin to a piece of paper with the 'head' up. Align another coin above the first, with the head also up. Now, rotate the second coin around the first, keeping the edges in contact (no slipping). How many times does the second coin rotate?
Most people will guess once, because the circumferences of the coins are the same. However, because the second coin 'orbits' the first as well as rotating on its own axis, it actually rotates TWICE. In our simplified coin scenario, there are 2 sidereal days, but only one solar day in a year. Look at how many times the bottom of the rotating coin 'sees a noon', and you'll be convinced.
First, please forgive my tone. It was quite late for me at the time. I still do not find the meme in any way amusing, and I actually find it disrespectful, whether done to me or to others, and the basic sentiment stands -- I'd rather my words not be edited to change their meaning. But I was too harsh in the wording.
Accepted, and understood - thank you for taking the time to consider my point.
I have a rather jaundiced view of it, because I work for a major airline, and daily see the silliness of it.
As you point out, ID verifications consist of a stern staring at an easily fakeable picture ID. The metal detector scan is almost useless, as many bags have metal frames that can be repurposed, many explosives and weapons do not have any metallic components, etc. The liquid restriction is a similar joke. Frankly, the only way to increase the security of carry-on baggage is not to allow it, and make everyone check all bags - i.e. subject it to the same standards as checked luggage, which now does have significant inspections applied to it. Passengers would probably revolt.
Banning all non-flying folk from significant areas of the airport is also presently toothless, since you can print out boarding passes, and probably useless, but definitely annoying.
I go and sit at the gate for a little while, then board the plane, which has a reinforced cockpit door. This is good, though a little regretful for kids these days who cannot see the cockpit. But again, there are enough people who would like to cause problems that it's a reasonable solution.
Sadly, the door is quite solid, but the surrounding superstructure is not. To really make it solid, the entire partition needs to be built to the same standard, and there needs to be two partitions/doors; an airlock system. But, this would cost money... so the reinforced door alone will have to do. Tip if you have kids; come after the flight is at the gate, and we'll usually be quite happy to show them the cockpit - most pilots as kids were shown a cockpit - it's usually a vivid memory - and we like to pass that on.
So, we basically agree - reinforced cockpit doors are pretty much the main improvement in security. There are other small improvements - mandatory and complete screening of checked bags, increased number of air marshals, allowing a Federal Flight Deck Officer program thus arming a significant percentage of airline pilots (although Schneier disagrees and considers the increased risk of access to guns inside the security area as outweighing the gain)... but probably the biggest improvement is that passengers would now instantly know what was up, and move to prevent it.
But legally speaking, you do not have a right to fly. You have a choice, and that choice is contingent upon you accepting certain requirements. You also have no right to drive -- this is made clear upon getting one's license. If you don't want to drive safely, then you choose not to drive (or else risk tickets or arrest, depending on the violation).
I understand the present legal situation. I was pointing out that it is highly inconsistent in balancing the public good with individual privacy when I compared the two cases. I think that such large inconsistency in the legal landscape breeds disrespect for the law in general. The lawmakers then make sillier laws, the enforcers exceed their given powers under the law more easily and its citizens ignore the law more when its convenient. This kind of environment has often lead to dictatorships and corruption. I don't like that, and I don't want to see it here.
I hope you are correct that the courts will eventually correct some of this nonsense, but after seven years, I'm getting a bit impatient. I had a sincere hope after 9-11, that finally after such a horror, we might get serious about security for the airlines. We all knew it was a joke before then. Instead, we were (literally) not allowed to laugh at the joke anymore.
If you want to voice an opinion that I should have used different phrasing, please do so. If you're going to quote me, then quote my words faithfully. "Fixing" it, even in jest, is altering the quote of my words.
Actually, I'll do as I see fit - thanks for the marching orders, though. Do you always order people around when you disagree with how they do things?
The meme isn't funny or clever, and never has been.
Strangely, I do think it's funny, and an effecient way to provide commentary to the clueful. You have a habit of stating your opinions as facts; hence my making fun of that habit.
But since you need an opinion clearly stated, here is one - the security at our airports is a big, expensive, ineffective, intrusive show. Flying is apparently a fun choice for you, and you don't seem to object to either the waste of resources or the invasion of privacy heaped upon it. Many people do, and you answer their objections by stating, (wouldn't want to misquote you here!):
It's not unreasonable search. This has been addressed before by the courts and many times here on Slashdot. Flying is a choice. If you choose not to go through the security measures, that means you choose not to fly (at least commercially). You are free to take other routes that do not have the same level of security.
This dismisses the fact that the searches provide little practical value in deterring hijackings, but are highly invasive, and an excuse for all sorts of legal fishing expeditions.
Let me put it to you like this - 40,000 USA folk are killed in driving accidents, the vast majority due to driver error, typically exacerbated by drunk driving. This exceeds the number of USA folk killed by aircraft-caused security failures by many orders of magnitude. Driving should, logically, have much more severe security measures applied - for instance, authorized drivers for each car, backed up with a biometric sensor that refuses to let an engine start for non-authorised drivers. A built-in breathalizer that you need to blow into to let the engine start. Built in GPS in every car that police can call up based on a licence plate number so that drunk driving reports can be more effeciently tracked. I'm sure you could think of additional measures that would reduce the death toll, like governers built into every engine that prohibited speeding, etc.
Perhaps you would object to this. I'm guessing here. But I could dismiss those arguments with the same, handwavy dismissal: (not an exact quote! Warning!) "Driving is a choice. If you choose not to go through the security measures, that means you choose not to drive. You are free to take other routes that do not have the same level of security." (end of non-exact quoting)
At least the above measures would probably drastically reduce driving deaths. The current measures at airports have probably done nothing to enhance airline security. So on a practical level, your argument dismissing people's concerns is even weaker.
But rather than spell this all out in nauseating detail, I thought a pithy little addition to your quote would make the point. My mistake.
Flying is a choice. If you choose not to go through the security measures, that means you choose not to fly (at least commercially). You are free to take other routes that do not have the same level of security theatre.
I taught them nothing. I didn't understand what it was at the end. I wasn't a pid tutor, but I was know as the helpful guy, and someone that was stumped on something asked for my help, wanted it even though I told them I didn't know what they were talking about, and I tutored them in learning skills (applied immediately) as opposed to tutoring them in the subject. I don't recall what the subject was, but it's something I didn't know and I don't think I learned any about while tutoring them. It was a matter of seeing what they were hung up on, and directing them to other ways of getting around that block.
That was nice of you, and I have no doubts that you helped. But when you are trying to figure out standards for teaching professionals, you want to aim a bit higher than just a general idea about how to learn, no?
Someone walks up. "I don't understand this." They walk away later. "Now I understand this." Not that someone couldn't have done better, but I know for a fact that someone can facilitate learning without knowledge in the subject.
As you point out - it could be done better. If you are coming up with standards for an education system, shouldn't we be aiming for better?
Well, if you think that advanced math skills are needed for teachers to hand out photocopies of worksheets with multiplication tables and such and answer all questsions with "because I said so" then feel free to press for that. However, until high school, that's about all that's done these days.
And that is the problem, and it is self-feeding. If we have teachers in elementary school who are incapable of teaching anything more than rote memorization of tables, then it becomes that much harder to raise the standards for what is taught there, doesn't it? Elementary school students are perfectly capable of learning algebra, geometry, and other basic mathematical topics IF they have a good grounding in math up to that point and they have a good teacher who knows the subject and can explain it well. If we really want to improve our mathematics education, we need to take standards for teachers seriously at all levels of the system.
If algebra was actually introduced when the students could learn it, rather than the "all children left behind" system that the Republicans have been pressing for to cause a self-destruct of the public education system and get their vouchers through, then you'd have a point. Oh, and yes, I actually believe that Republicans are willing to purposefully destroy the education system in an effort to have the richest 1% of the country save another $2k per year.
Unfortunately, you have me right there. And unfortunately, I think you are correct in your assesment of the present day Republican Party. Forgive me if I responded too heatedly - I used to make my living teaching, and it is frustrating on many levels that being an elementary or high school teacher in the U.S. is just not a good career path if you care about a) teaching, and b) making a good living. I spent a good deal of time correcting the mistakes of public school teachers improperly grading exams and assignments of my students, so I have a particular dislike of professional teachers who don't know their subject.
And what I'm hearing from you is that a bad teacher with a math degree is better at nurturing a learning spirit than a good teacher with a decent math background and a degree in education, because I stated the opposite, and you disagreed.
IMHO - I think BOTH components are necessary for an excellent teacher, and I don't think its unreasonable to insist on both for our professional teachers. Of course, this means we have to pay and respect people who choose to become teachers like professionals in other fields. I don't know if a majority of people in the U.S. are willing to do that, even if you and I would. I hope that we (as a country) wise up as to the value of a good education while we can afford it...
Which is why you need a person at the front of the class that connects, and their knowledge of the material is secondary.
Whenever I see this bit of folk wisdom trotted out, I have to roll my eyes at yet another amateur 'tutor' who is bright enough to be able to figure out things on the fly (or faster than his student). Being able to connect with the student is important. But if you just figure out things as you go along about the subject you are teaching, you are shortchanging that student, even if they don't notice it because you have 'connected'.
I know from personal experience tutoring, that I've actually tutored someone successfully in a subject I had no knowledge of. I talked them through, asked them questions, and they were able to learn what they needed with direction, but not someone just giving them answers.
And I tutored adults and kids full time for four years. I tutored in math, physics, engineering, and lots of other topics which I wasn't qualified for. Yes, you can get away with it, quite successfully. Then you run into someone who actually studied the topic in depth and who knows the connections between what you have taught and what lies ahead, and it occurs to you that you didn't do as good a job as you thought.
Math teachers eed to be teachers first, and mathmaticians low on the list, at least until up until the last coule years of high school and beyond, where the math gets more complicated.
Why not forget high school? They really don't need to know the tough math until they are in a college. And heck, while we're pushing forward the boundaries of ignorance, if you are an undergraduate student, you really don't need to be taught by 'real' math professors; save them for the graduate students only.
You are correct - to teach well, you need to make a connection with your student, have an inquisitive mind and be ahead of your student as much as you can so you can lead them. But to say that is more important that having a deep understanding of what you are teaching is to condemn your potential students to a more enjoyable second-rate education. The sooner talent and inquisitiveness can be nurtured and fed, the better.
My first worry upon reading the idea would be that some dim bulb would propose that we need to reduce the number of heavy tear-down inspections to look for fatigue damage, since they 'self-repair'. But the article proposes using not only a resin that flows out to repair broken fibers, but putting dye in the resin so that fatigue cracks (and the subsequent self-repair) are much more obvious to inspectors....
To quote the article:
"This approach can deal with small-scale damage that's not obvious to the naked eye but which might lead to serious failures in structural integrity if it escapes attention," says Dr Ian Bond, who has led the project. "It's intended to complement rather than replace conventional inspection and maintenance routines, which can readily pick up larger-scale damage, caused by a bird strike, for example."
Nice idea... I hope we see it deployed in production aircraft someday.
They always give these projects double-speak names such as "Golden Shield", "Happy Fun Safety Blanket" or "Patriot Act" instead of something like "Citizen Surveillance System".
Kinda like the Democratic People's Republic of Korea vs. the Republic of Korea... guess which one's the Northern one?
I remember a psychological test done on lab rats with such a scenario where they shocked one rat with electricity at regular intervals and then shocked the other at random. Even though the one at regular intervals was shocked more often, the rat that was shocked at random ate less and slept less and could not adapt to the situation.
Actually, the experiment was more interesting than that. There were two cages, filled with 12 rats each. The shocking would start at random times during the day, but the first key is that the shocks would be applied identically to the rats in both cages. However, in one cage, there was a bar that the rats in that cage could slap. When the rats in the one cage slapped the bar, the shocking stopped in both cages. This way, both sets of rats would experience identical durations and amounts of shocking - yet, the rats in the cage with the bar were far healthier. The control they could exert over their environment, not the environment itself, led to them being healthier - or, put another way, the rats who did not have control became physically, measurably worse than ones who did - even if the outcome was the same.
The illusion of control is an important one for the rats' wellbeing, and I would bet it's the same for us.
If this result holds up, all sorts of interesting questions come up. For instance:
They claim it's half-life is about 10e8 years. Since our solar system is very roughly 1e10 years old, that's about 100 half-lives, or a decrease by a factor of 2^100 or about 1e30. Since its atomic weight is 292, that suggests that an original sample of about 292e7 grams should have decayed to 1e7 moles * 6e23 at/mol / 1e30 = 6 atoms left. In other words, an original chunk of this stuff of mass 2,920,000 kilos would have decayed to 6 atoms. But when you condsider how much mass of all sorts of elements exist on the earth, and take into account chemical concentration, one would think more of this stuff would be around.... maybe. Does anyone know about the frequency of discovery of naturally radioactive isotopes with a similar half-life that are not part of the decay path of other longer lived radioactive isotopes? In other words, is it reasonable to expect to find significant quantities of something with a half-life of around 1e8 years that isn't being formed from other decay products any more?
Also, if the reason it is so rare is because so little was formed, perhaps that indicates it is extremely hard, even in a supernova, to create this element? What does that suggest about our ability to artificially synthesise this element?
Oh yeah, I remember a band with the same name putting out some good stuff, in the 80's. Then an album called 'Load' came out... and I really didn't bother paying attention any more.
I guess they want some free publicity, since nobody wants to buy the crap they put out since then. I have to admit, after getting in bed with the RIAA I really don't feel inclined to help them in the slightest, even if they do manage to make some nice sounds again - which remains to be seen.
There is a lot of good music, new and old to listen to besides them.
I have noticed that serious math people who lean toward theory will almost always say 'discovered', and those who lean toward the applied side or have little native mathematical ability will say 'invented'.
I suspect this has to do with the problem solving bias one has - if you are a theoretician, you are trying to prove theorems. They are either true or false (yes, I'm ignoring the posibility they are indeterminate), and the fact that you haven't figured out which doesn't mean the answer is some wishy-washy thing - the theorem is TRUE or it is FALSE, we just don't know which yet. This sense of the answer being there but not being found yet is like a process of discovery, seeking something that already exists, but we just don't quite know where.
Applied people, OTOH, are rarely interested in proving a theorem for it's own sake, but usually are hunting down algorithims for determining answers to well modeled problems, perhaps proving some bounds on how rapidly their solution converges. There are frequently many different ways of calculating something, and when we come up with a faster converging, more computationally convenient method, it seems a clever invention, something new created. We don't think of methods and algorithims as being discovered, because they seem more like plans of action rather than a claim about a static thing.
People who have no feel for numbers tend to be in the 'invented' camp, but that's because they view mathematics as a bunch of arbitrary rules - the connections and underlying consistency is invisible to them, so they conclude it's all just made up - i.e. invented.
I personally like Ivar Peterson's interpetation; mathematics is like a vast jungle, of which we have only cleared out the tiniest areas. We have made many forays into the jungle, cleared a few spots, blazed many trails, and quite frequently find that many different trails wind up at the same place; the peaks of mountains, the waterfalls at the edge of a cliff.... Those who focus on the meeting spots and large cleared areas see them as being there already, and think of mathematics as a process of discovery of these common meeting points. Those who focus on the multiple trails, all the random and winding ways they go, watching how old, treacherous ones get replaced by shorter and eaiser ones, in a somewhat arbitrary fashion and with an apparent degree of luck, see mathematics as being invented.
Actually, something very similiar to that is already done at many airlines. The data is downloaded at various intervals, and examined for any 'unusual' events - the pilots involved are contacted in a 'non-jeopardy' fashion and asked to explain why something occurred. It has already led to significant improvements in maintainance replacements, and highlighted a few non-optimal procedures that tend to put a crew in a worse place than they started.
The key is that it is non-jeopardy, otherwise the pilots wouldn't speak candidly about the situation and what led them into it, and you might get little or no clue as to what was actually occurring. We call it FOQA, and I'm sure various others have thier own names...
Sailplanes fly their final approach with an excess of altitude and rely on drag brakes to guide them to the end of the runway. A drag brake which is stuck on could make them land short but these control surfaces are usually fail safe to off.
Airliners rely on engine power modulation to keep them on the glide path. An engine failure will make them land short. So why not land like a sailplane? The descent will be slightly steeper and possibly less comfortable for the passengers but it guarantees that an engine failure in the last minute won't be as fatal.
A nice idea, but commercial airliners have several characteristics that would make that unworkable. First off, in the landing configuration (flaps 30 and gear down), the descent angle would probably be close to 6 or 7 degrees rather than the normal 3 - leading to a descent rate of 2000 fpm or more. In a sailplane (with a very low moment of inertia around the lateral axis), when you command pitch up, the lag between your pulling back on the stick and the airplane rotating to a different angle of attack and increasing lift is almost zero - i.e. near instantaneous response in vertical speed to pitch commands. In a commerical jet, the moment of inertia is much greater, so it takes a few seconds for the plane to rotate to a different angle of attack and thus generate more lift. If you didn't time your flare perfectly, you would smash into the ground quite smartly.
Secondly, if you instead had the airliner attempt to land in a much 'cleaner' configuration with a better glide ratio, closer to 3 degrees, your landing speeds would probably be 50% faster, probably near 200 knots. The required landing distance is proportional to the square of the velocity, so you would need to double the size of existing runways. Not likely....
Third, jet engines have relatively slow response characteristics, particularly from idle (much better than a decade or two ago, but they are still slow compared to piston powered engines); this caused several crashes back in the late 50's and early 60's - pilots would be doing idle thrust approaches, then circumstances called for a go around, and when they advanced the thrust levers, it took a good 10 seconds (or more... DC-9s particularly sucked in that area, from what I remember) for full thrust to be developed... and they didn't have 10 seconds to wait. So, it was decided that jets should approach in a 'thrusted-up' configuration; one where the engines were developing much more than idle thrust throughout the final approach - if go around was required, the time to full power was much smaller. But, to maintain such a 'thrusted-up' configuration, the approach slope had to be shallow (a good idea as I mentioned above), and the airplane had to have a very draggy configuration. The amount of extra lift at a given speed from flaps 15 to 30 is very small, but the additional drag is quite large... that's the reason airplanes take off with very small flap settings (typically 5 degrees), for maximum additional lift with little additional drag, but put out full flaps, with lots of drag, for landing, so the engines stay spooled up until about touchdown.
The simple "running out of fuel" hypothesis is very unlikely. All aircraft are supposed to carry reserves to divert to another airport (not far in this case) plus ninety minutes flying. While cheapo airlines might short-cut on this, I cannot imagine BA doing so. There is no indication that the aircraft had been "stacked" for any length of time, so it shoudl have landed with two hours worth of fuel on board. There have been cases of aircraft being misfueled, but on a regular run between two sophisticated endpoints, this seems unlikely.
Your numbers for the fuel reserves are not quite correct. For most domestic flights, the reserve above and beyond alternate requirements is 45 minutes, not 90. For flag ops (international), the numbers can be slimmer; they are usually based on a percentage - 10% above estimated burn - which is not that much.
In addition, that is simply PLANNED fuel calculations. The winds you actually run into, the actual weight of the people & baggage & cargo on board (affecting burn rate, particularly on ultra-long range flights), all can significantly deviate from planned, and frequently in the same direction. It is not uncommon for airliners to land with 30 flying minutes in the tanks - that is not much at all. I HOPE that no fellow pilots would ever attempt something so stupid as to 'push' to make a destination rather than make a (rather expensive) stop for fuel - but when I saw not a trace of fire and the wing tanks torn open by the landing gear.... it does make one think seriously about the idea there was no fuel to ignite in there.
I've heard a few reports that fuel was pouring out of the plane after impact - meaning they just got really, really lucky that it didn't ignite. Does anyone have a link to an article that reports such? It would be nice to hear.
That was my very first thought when I saw the mains punched right through the wing tanks, yet not a single bit of fire or flame or carbon stains from such. That generally happens only when there is no fuel to ignite, such as the Avianca crash on Long Island many years ago. I still have not heard this definitively ruled out, but if the pilots were dumbasses and ran out of fuel, I think that would have come to the fore by now. It looks like something far more subtle... and probably common to many other flying 777s right now.
Then I will quit coding. You think pilots want to wear that stuff? Well, not all of us. Some night freight companies (you know who you are) insist on those fake epaulets too.
True story. When I took my commercial checkride the examiner commented that not all of my logbook entries were in black ink. "So what?" "Well, the airlines like to see black ink."
I have no idea if the airlines care or not, since I have never interviewed for an airline. My only point is the social filters for airline pilot are arbitrary and mighty.
You may appreciate this, from someone with a major carrier. A long, long time ago, I went in for an interview with a regional airline. This was back in the mid 1990's, where they put you through pysch evals and various other annoying tests before they gave you the 'personality' interview just so you could start flying ATRs for $13k a year (after you paid for your own training, of course). I heard the same damn story about the logbook ink colors... 5 minutes before my interview. My logbook, of course, was filled in pretty much in every color under the sun, so there wasn't anything I could do about it - not to mention the various 'remarks' (hey, the column said remarks - I took it literally) regarding which FBO had the cutest counter girls. Anyway, I managed to quash the rising panic about my rainbow colored logbook, and aced the interview. We had second interviews at the end of the day, and they offered me a position - I was the only one to get one that day, out of thirteen interviewees. On the ride back to the hotel, with some rather glum fellow prospects who kinda knew they didn't get it, one knew why he had failed.... 'They said my logbook was horrible! It had entries in black AND blue! He said I'd never make it in an airline with that kinda sloppiness.'
Moral of the story - the interviewers want to see if they would like to fly next to you in the cockpit. If they bust your balls about ink colors or suit fashions or FARs or other nonsense, they are either stress testing you or are looking for a reason to bounce you.
The hat thing is my pet peeve. Hats stopped being cool around 1950. But they still want you to wear them, along with the fry-your-leg-in-the-sun black polyester. Rrrrrr.
The fact that these simple truths can be irreversibly concealed through the one-way hash known as legalese, is just evidence that the legal system is broken beyond repair. At least you can brute-force RSA:/
You can brute-force the legal system as well, but the relevant metric is dollars instead of processor cycles.
Slashdot Mirror
Try maximizing a window on a mac. Minimize a window, then alt-tab back to that app. You get the app, with no window! You then get the 'pleasure' of moving the mouse to the menu bar, selecting the window menu, and hopefully finding the window you wanted.
You probably don't know the following keyboard short-cut. When you said 'Alt-Tab', I'm assuming you mean 'Command-Tab', since that's the app switcher on Macs. AFTER you let go of the Tab (because you've switched to the right app), but BEFORE you let go of the Command key, PRESS AND HOLD the alt/option key, and THEN let go of the Command key. Any hidden or minimized windows will restore themselves to visibility. It's a fantastic trick which saves a lot of trips to the mouse. I hope it helps you!
This is a distraction technique. This may just be bad luck, it may be something specific to Qantas, it may be something with the Airbus A330, but pinning it on EM emissions by mobile devices seems like a quick way to assure that a real investigation is not done.
In addition, TFA said:
I'm not typed on the Airbus A330. Does anyone who is care to chime in on what 'messages' the A330 could possibly deliver regarding 'irregularities' with the elevator control system? I know nothing about their master caution/warning system.
All time can be universal (UTC). Noon can be "When the sun is directly overhead." which will locally be different. Start time for work can be Noon-3 Hours (3 hours before noon) to Noon+5 Hours (5 Hours after noon). No DST necessary and no leap-seconds necessary. Why do they want to overcomplicate things here?
Your system was tried and in widespread use until the 1800's with the spread of railroads. With increasingly fast and common transportation (and nowadays, communication), the 'every town has it's own time' system made it almost impossible to schedule trains, business, meetings, armies, etc. - so the train companies came up with the time zone system. It was such a vast improvement and massive success that essentially the entire world adopted it.
They did that because Eastern China, containing 95% of their population, is at +8 UTC 'naturally'. The fact that Western China, containing such pesky places as Tibet has their typical sunrise at 0830 and sunset at 2030 and has a jump of 2.5 to 3 hours when you cross over into India or Pakistan, doesn't bother the Chinese government much. I'm not so sure the people living there feel the same way. Or, to put it differently - I live in NYC. I think the US should have one time zone, and it should be based on NYC time. -5/-4 UTC for everybody! Who cares if California would have the sunset at 2230 today? Forget about Alaska and Hawaii....
Perhaps you live in a different world, but most people like to be awake and work roughly when the sun is up. Many places in the world are a little too poor to have the luxury of cheap nighttime lighting, and have large agrarian communities, all of which make the hours of daylight supremely important.
If you find timezones and the sun too tedious, why don't you set your own personal watch to TAI, and schedule your life that way? Nothing is stopping you... other than the fact that I've never seen a watch display TAI, and you might have to meet other people from time to time, thus requiring a translation. Oh well, it sounded good.
That sounds great, until you want to compute the DIFFERENCE in two times. How can you do that with any accuracy if you don't know how many leap nanoseconds have been inserted (because no record was kept) between them?
They did not ACCURATELY keep time by any stretch of the imagination. All those clocks you mentioned had to constantly be resynced with more authoritative sources on a constant basis - those authoritative sources being the position of the sun, moon, etc. Being able to create a device that could even take a stab at a unit of time as short as a second with any accuracy (if your second was 88,000 per day one day and 66,000 the next, it's not very useful!) had to wait until the invention of the pendulum clock in the late 1600's by Huygens. If by clock seconds, you mean track solar time, we have a clock that does that - it's called UT1. It can only be determined by measurement, so no devices that present a time readout independently use it. We instead keep UTC within a second of UT1 by inserting leap seconds from time to time.
Actually, the 25 hour circadian rythum argues for the Earth rotating SLOWER in the past, not faster - but, in fact, it did rotate FASTER in the past. Or, if you are a fan of intellegent creation or whatever it's called, when the Earth's rotation period slows to 25 hours (and presuming that an hour == 86,400 SI seconds) in however many millions of years, the time is right for ponies! Or something.
No, they don't. The Earth's rotation rate is slowing due to tidal friction (and slowly pushing the moon away in the process, since angular momentum doesn't just vanish). The SI second was set based off of the average solar day back in the 1700's or so, and the Earth's average rotational period has slowed measurably since then. We have only added leap seconds, never subtracted them, and likely never will, despite a significant variation in the rate of slowing.
The problem is that we want to measure different periodic processes via the same unit - the second. The second was originally based off of the average length of the solar day, but then was redefined in terms of atomic standards. The average solar day, according to atomic standards, has been lengthening somewhat erratically. Either we give up using the second as a fundamental unit in the SI system, suitable for meausring times vast and small, or we give up having our clocks based on the second but choose some other 'variable' unit, synced to the sun (such as UT1 time), or we compromise and stick a leap second in from time to time to assure that UTC and UT1 remain within a second of each other - which is what is currently done. There really isn't an easy way out since the periodic processes of nature that matter to us are not neatly in ratios. Do we really want a 'science' time, and a 'civilian' time?
As you say, one day, programmers will wrap these difficulties up in libraries nicely and neatly so that it just 'works', but it will be based on an arbitrary table of leap seconds, much like we have an arbitrary table of time zone rules in our zoneinfo files. Part of the problem was due to the POSIX standard for time NOT being done properly. UTC actually specifies that the 'extra' second means that there are 61 seconds in a particular minute - i.e. 23:59:60 is a valid UTC time when a leap second is inserted. Unfortunately, POSIX time 'repeats' a second instead. POSIX time goes.... 23:59:57....23:59:58.... 23:59:59.....(zip! leap second!) 23:59:59.... 00:00:00.... 00:00:01... etc.
There are some complex tradeoffs associated with this. It simplifies the numerical calculation of traslating POSIX time (since POSIX time really is represented as the integer number of seconds since 1970-Jan-01 00:00:00, and the leap seconds are ignored) to 'clockface' time (i.e. The year, month, date, hour, minute and second). On the other hand, it yields incorrect answers when two POSIX times are naively subtracted to figure out the time delta between the time marks; one has to modify the 'obvious' subtraction algorithm with a somewhat complex lookup table procedure to get an accurate delta. UTC is more complex because the occassional 61 second minute requires that you consult a lookup table to translate UTC seconds to year-month-date-hour-minute-second form, but subtraction easily yields the correct delta between the time marks. If we want to stick with SI seconds and schedule ourselves with the sun, there will always be some messiness!
We rotate the same way we orbit, so the Earth rotates (from the point of view of the distant stars - the sidereal day) one more time in a year (366.24) than the number of solar days (365.24) - the number of times the sun circuts the sky. The length of the sidereal day is 23:56:04.1 long, and the solar day is 24:00:00 (roughly!). That extra 4 minutes is the Earth rotating 'a little extra' to put the sun in the same place in the sky since it's moved around it a little since the last noon.
If you have ever tried the coin rotation trick, that might help you out visualizing it. Glue one coin to a piece of paper with the 'head' up. Align another coin above the first, with the head also up. Now, rotate the second coin around the first, keeping the edges in contact (no slipping). How many times does the second coin rotate?
Most people will guess once, because the circumferences of the coins are the same. However, because the second coin 'orbits' the first as well as rotating on its own axis, it actually rotates TWICE. In our simplified coin scenario, there are 2 sidereal days, but only one solar day in a year. Look at how many times the bottom of the rotating coin 'sees a noon', and you'll be convinced.
You know you can do that right now with strategically placed aluminum foil in a flat area of your bag? I like a big Smiley Face myself.... ;-)
Accepted, and understood - thank you for taking the time to consider my point.
I have a rather jaundiced view of it, because I work for a major airline, and daily see the silliness of it.
As you point out, ID verifications consist of a stern staring at an easily fakeable picture ID. The metal detector scan is almost useless, as many bags have metal frames that can be repurposed, many explosives and weapons do not have any metallic components, etc. The liquid restriction is a similar joke. Frankly, the only way to increase the security of carry-on baggage is not to allow it, and make everyone check all bags - i.e. subject it to the same standards as checked luggage, which now does have significant inspections applied to it. Passengers would probably revolt.
Banning all non-flying folk from significant areas of the airport is also presently toothless, since you can print out boarding passes, and probably useless, but definitely annoying.
Sadly, the door is quite solid, but the surrounding superstructure is not. To really make it solid, the entire partition needs to be built to the same standard, and there needs to be two partitions/doors; an airlock system. But, this would cost money... so the reinforced door alone will have to do. Tip if you have kids; come after the flight is at the gate, and we'll usually be quite happy to show them the cockpit - most pilots as kids were shown a cockpit - it's usually a vivid memory - and we like to pass that on.
So, we basically agree - reinforced cockpit doors are pretty much the main improvement in security. There are other small improvements - mandatory and complete screening of checked bags, increased number of air marshals, allowing a Federal Flight Deck Officer program thus arming a significant percentage of airline pilots (although Schneier disagrees and considers the increased risk of access to guns inside the security area as outweighing the gain)... but probably the biggest improvement is that passengers would now instantly know what was up, and move to prevent it.
I understand the present legal situation. I was pointing out that it is highly inconsistent in balancing the public good with individual privacy when I compared the two cases. I think that such large inconsistency in the legal landscape breeds disrespect for the law in general. The lawmakers then make sillier laws, the enforcers exceed their given powers under the law more easily and its citizens ignore the law more when its convenient. This kind of environment has often lead to dictatorships and corruption. I don't like that, and I don't want to see it here.
I hope you are correct that the courts will eventually correct some of this nonsense, but after seven years, I'm getting a bit impatient. I had a sincere hope after 9-11, that finally after such a horror, we might get serious about security for the airlines. We all knew it was a joke before then. Instead, we were (literally) not allowed to laugh at the joke anymore.
Actually, I'll do as I see fit - thanks for the marching orders, though. Do you always order people around when you disagree with how they do things?
Strangely, I do think it's funny, and an effecient way to provide commentary to the clueful. You have a habit of stating your opinions as facts; hence my making fun of that habit.
But since you need an opinion clearly stated, here is one - the security at our airports is a big, expensive, ineffective, intrusive show. Flying is apparently a fun choice for you, and you don't seem to object to either the waste of resources or the invasion of privacy heaped upon it. Many people do, and you answer their objections by stating, (wouldn't want to misquote you here!):
This dismisses the fact that the searches provide little practical value in deterring hijackings, but are highly invasive, and an excuse for all sorts of legal fishing expeditions.
Let me put it to you like this - 40,000 USA folk are killed in driving accidents, the vast majority due to driver error, typically exacerbated by drunk driving. This exceeds the number of USA folk killed by aircraft-caused security failures by many orders of magnitude. Driving should, logically, have much more severe security measures applied - for instance, authorized drivers for each car, backed up with a biometric sensor that refuses to let an engine start for non-authorised drivers. A built-in breathalizer that you need to blow into to let the engine start. Built in GPS in every car that police can call up based on a licence plate number so that drunk driving reports can be more effeciently tracked. I'm sure you could think of additional measures that would reduce the death toll, like governers built into every engine that prohibited speeding, etc.
Perhaps you would object to this. I'm guessing here. But I could dismiss those arguments with the same, handwavy dismissal: (not an exact quote! Warning!) "Driving is a choice. If you choose not to go through the security measures, that means you choose not to drive. You are free to take other routes that do not have the same level of security." (end of non-exact quoting)
At least the above measures would probably drastically reduce driving deaths. The current measures at airports have probably done nothing to enhance airline security. So on a practical level, your argument dismissing people's concerns is even weaker.
But rather than spell this all out in nauseating detail, I thought a pithy little addition to your quote would make the point. My mistake.
Fixed that for ya'.
That was nice of you, and I have no doubts that you helped. But when you are trying to figure out standards for teaching professionals, you want to aim a bit higher than just a general idea about how to learn, no?
As you point out - it could be done better. If you are coming up with standards for an education system, shouldn't we be aiming for better?
And that is the problem, and it is self-feeding. If we have teachers in elementary school who are incapable of teaching anything more than rote memorization of tables, then it becomes that much harder to raise the standards for what is taught there, doesn't it? Elementary school students are perfectly capable of learning algebra, geometry, and other basic mathematical topics IF they have a good grounding in math up to that point and they have a good teacher who knows the subject and can explain it well. If we really want to improve our mathematics education, we need to take standards for teachers seriously at all levels of the system.
Unfortunately, you have me right there. And unfortunately, I think you are correct in your assesment of the present day Republican Party. Forgive me if I responded too heatedly - I used to make my living teaching, and it is frustrating on many levels that being an elementary or high school teacher in the U.S. is just not a good career path if you care about a) teaching, and b) making a good living. I spent a good deal of time correcting the mistakes of public school teachers improperly grading exams and assignments of my students, so I have a particular dislike of professional teachers who don't know their subject.
IMHO - I think BOTH components are necessary for an excellent teacher, and I don't think its unreasonable to insist on both for our professional teachers. Of course, this means we have to pay and respect people who choose to become teachers like professionals in other fields. I don't know if a majority of people in the U.S. are willing to do that, even if you and I would. I hope that we (as a country) wise up as to the value of a good education while we can afford it...
Whenever I see this bit of folk wisdom trotted out, I have to roll my eyes at yet another amateur 'tutor' who is bright enough to be able to figure out things on the fly (or faster than his student). Being able to connect with the student is important. But if you just figure out things as you go along about the subject you are teaching, you are shortchanging that student, even if they don't notice it because you have 'connected'.
And I tutored adults and kids full time for four years. I tutored in math, physics, engineering, and lots of other topics which I wasn't qualified for. Yes, you can get away with it, quite successfully. Then you run into someone who actually studied the topic in depth and who knows the connections between what you have taught and what lies ahead, and it occurs to you that you didn't do as good a job as you thought.
Why not forget high school? They really don't need to know the tough math until they are in a college. And heck, while we're pushing forward the boundaries of ignorance, if you are an undergraduate student, you really don't need to be taught by 'real' math professors; save them for the graduate students only.
You are correct - to teach well, you need to make a connection with your student, have an inquisitive mind and be ahead of your student as much as you can so you can lead them. But to say that is more important that having a deep understanding of what you are teaching is to condemn your potential students to a more enjoyable second-rate education. The sooner talent and inquisitiveness can be nurtured and fed, the better.
Actually, the experiment was more interesting than that. There were two cages, filled with 12 rats each. The shocking would start at random times during the day, but the first key is that the shocks would be applied identically to the rats in both cages. However, in one cage, there was a bar that the rats in that cage could slap. When the rats in the one cage slapped the bar, the shocking stopped in both cages. This way, both sets of rats would experience identical durations and amounts of shocking - yet, the rats in the cage with the bar were far healthier. The control they could exert over their environment, not the environment itself, led to them being healthier - or, put another way, the rats who did not have control became physically, measurably worse than ones who did - even if the outcome was the same.
The illusion of control is an important one for the rats' wellbeing, and I would bet it's the same for us.
They claim it's half-life is about 10e8 years. Since our solar system is very roughly 1e10 years old, that's about 100 half-lives, or a decrease by a factor of 2^100 or about 1e30. Since its atomic weight is 292, that suggests that an original sample of about 292e7 grams should have decayed to 1e7 moles * 6e23 at/mol / 1e30 = 6 atoms left. In other words, an original chunk of this stuff of mass 2,920,000 kilos would have decayed to 6 atoms. But when you condsider how much mass of all sorts of elements exist on the earth, and take into account chemical concentration, one would think more of this stuff would be around.... maybe. Does anyone know about the frequency of discovery of naturally radioactive isotopes with a similar half-life that are not part of the decay path of other longer lived radioactive isotopes? In other words, is it reasonable to expect to find significant quantities of something with a half-life of around 1e8 years that isn't being formed from other decay products any more?
Also, if the reason it is so rare is because so little was formed, perhaps that indicates it is extremely hard, even in a supernova, to create this element? What does that suggest about our ability to artificially synthesise this element?
Very interestng....
Oh yeah, I remember a band with the same name putting out some good stuff, in the 80's. Then an album called 'Load' came out... and I really didn't bother paying attention any more.
I guess they want some free publicity, since nobody wants to buy the crap they put out since then. I have to admit, after getting in bed with the RIAA I really don't feel inclined to help them in the slightest, even if they do manage to make some nice sounds again - which remains to be seen.
There is a lot of good music, new and old to listen to besides them.
I suspect this has to do with the problem solving bias one has - if you are a theoretician, you are trying to prove theorems. They are either true or false (yes, I'm ignoring the posibility they are indeterminate), and the fact that you haven't figured out which doesn't mean the answer is some wishy-washy thing - the theorem is TRUE or it is FALSE, we just don't know which yet. This sense of the answer being there but not being found yet is like a process of discovery, seeking something that already exists, but we just don't quite know where.
Applied people, OTOH, are rarely interested in proving a theorem for it's own sake, but usually are hunting down algorithims for determining answers to well modeled problems, perhaps proving some bounds on how rapidly their solution converges. There are frequently many different ways of calculating something, and when we come up with a faster converging, more computationally convenient method, it seems a clever invention, something new created. We don't think of methods and algorithims as being discovered, because they seem more like plans of action rather than a claim about a static thing.
People who have no feel for numbers tend to be in the 'invented' camp, but that's because they view mathematics as a bunch of arbitrary rules - the connections and underlying consistency is invisible to them, so they conclude it's all just made up - i.e. invented.
I personally like Ivar Peterson's interpetation; mathematics is like a vast jungle, of which we have only cleared out the tiniest areas. We have made many forays into the jungle, cleared a few spots, blazed many trails, and quite frequently find that many different trails wind up at the same place; the peaks of mountains, the waterfalls at the edge of a cliff.... Those who focus on the meeting spots and large cleared areas see them as being there already, and think of mathematics as a process of discovery of these common meeting points. Those who focus on the multiple trails, all the random and winding ways they go, watching how old, treacherous ones get replaced by shorter and eaiser ones, in a somewhat arbitrary fashion and with an apparent degree of luck, see mathematics as being invented.
But it is discovered, you know.... ;-)
Actually, something very similiar to that is already done at many airlines. The data is downloaded at various intervals, and examined for any 'unusual' events - the pilots involved are contacted in a 'non-jeopardy' fashion and asked to explain why something occurred. It has already led to significant improvements in maintainance replacements, and highlighted a few non-optimal procedures that tend to put a crew in a worse place than they started.
The key is that it is non-jeopardy, otherwise the pilots wouldn't speak candidly about the situation and what led them into it, and you might get little or no clue as to what was actually occurring. We call it FOQA, and I'm sure various others have thier own names...
A nice idea, but commercial airliners have several characteristics that would make that unworkable. First off, in the landing configuration (flaps 30 and gear down), the descent angle would probably be close to 6 or 7 degrees rather than the normal 3 - leading to a descent rate of 2000 fpm or more. In a sailplane (with a very low moment of inertia around the lateral axis), when you command pitch up, the lag between your pulling back on the stick and the airplane rotating to a different angle of attack and increasing lift is almost zero - i.e. near instantaneous response in vertical speed to pitch commands. In a commerical jet, the moment of inertia is much greater, so it takes a few seconds for the plane to rotate to a different angle of attack and thus generate more lift. If you didn't time your flare perfectly, you would smash into the ground quite smartly.
Secondly, if you instead had the airliner attempt to land in a much 'cleaner' configuration with a better glide ratio, closer to 3 degrees, your landing speeds would probably be 50% faster, probably near 200 knots. The required landing distance is proportional to the square of the velocity, so you would need to double the size of existing runways. Not likely....
Third, jet engines have relatively slow response characteristics, particularly from idle (much better than a decade or two ago, but they are still slow compared to piston powered engines); this caused several crashes back in the late 50's and early 60's - pilots would be doing idle thrust approaches, then circumstances called for a go around, and when they advanced the thrust levers, it took a good 10 seconds (or more... DC-9s particularly sucked in that area, from what I remember) for full thrust to be developed... and they didn't have 10 seconds to wait. So, it was decided that jets should approach in a 'thrusted-up' configuration; one where the engines were developing much more than idle thrust throughout the final approach - if go around was required, the time to full power was much smaller. But, to maintain such a 'thrusted-up' configuration, the approach slope had to be shallow (a good idea as I mentioned above), and the airplane had to have a very draggy configuration. The amount of extra lift at a given speed from flaps 15 to 30 is very small, but the additional drag is quite large... that's the reason airplanes take off with very small flap settings (typically 5 degrees), for maximum additional lift with little additional drag, but put out full flaps, with lots of drag, for landing, so the engines stay spooled up until about touchdown.
Your numbers for the fuel reserves are not quite correct. For most domestic flights, the reserve above and beyond alternate requirements is 45 minutes, not 90. For flag ops (international), the numbers can be slimmer; they are usually based on a percentage - 10% above estimated burn - which is not that much.
In addition, that is simply PLANNED fuel calculations. The winds you actually run into, the actual weight of the people & baggage & cargo on board (affecting burn rate, particularly on ultra-long range flights), all can significantly deviate from planned, and frequently in the same direction. It is not uncommon for airliners to land with 30 flying minutes in the tanks - that is not much at all. I HOPE that no fellow pilots would ever attempt something so stupid as to 'push' to make a destination rather than make a (rather expensive) stop for fuel - but when I saw not a trace of fire and the wing tanks torn open by the landing gear.... it does make one think seriously about the idea there was no fuel to ignite in there.
I've heard a few reports that fuel was pouring out of the plane after impact - meaning they just got really, really lucky that it didn't ignite. Does anyone have a link to an article that reports such? It would be nice to hear.
That was my very first thought when I saw the mains punched right through the wing tanks, yet not a single bit of fire or flame or carbon stains from such. That generally happens only when there is no fuel to ignite, such as the Avianca crash on Long Island many years ago. I still have not heard this definitively ruled out, but if the pilots were dumbasses and ran out of fuel, I think that would have come to the fore by now. It looks like something far more subtle... and probably common to many other flying 777s right now.
You may appreciate this, from someone with a major carrier. A long, long time ago, I went in for an interview with a regional airline. This was back in the mid 1990's, where they put you through pysch evals and various other annoying tests before they gave you the 'personality' interview just so you could start flying ATRs for $13k a year (after you paid for your own training, of course). I heard the same damn story about the logbook ink colors... 5 minutes before my interview. My logbook, of course, was filled in pretty much in every color under the sun, so there wasn't anything I could do about it - not to mention the various 'remarks' (hey, the column said remarks - I took it literally) regarding which FBO had the cutest counter girls. Anyway, I managed to quash the rising panic about my rainbow colored logbook, and aced the interview. We had second interviews at the end of the day, and they offered me a position - I was the only one to get one that day, out of thirteen interviewees. On the ride back to the hotel, with some rather glum fellow prospects who kinda knew they didn't get it, one knew why he had failed.... 'They said my logbook was horrible! It had entries in black AND blue! He said I'd never make it in an airline with that kinda sloppiness.'
Moral of the story - the interviewers want to see if they would like to fly next to you in the cockpit. If they bust your balls about ink colors or suit fashions or FARs or other nonsense, they are either stress testing you or are looking for a reason to bounce you.
The hat thing is my pet peeve. Hats stopped being cool around 1950. But they still want you to wear them, along with the fry-your-leg-in-the-sun black polyester. Rrrrrr.
You can brute-force the legal system as well, but the relevant metric is dollars instead of processor cycles.