Slashdot Mirror
Electronics In Flight — Danger Or Distraction?
another similar writes "IEEE Spectrum has a blog post revisiting the debate on whether electronic devices pose a risk to flight avionics spurred by a NY Post article about Arianna Huffington's refusal to power down her Blackberry during takeoff. The post points out the EU's removal of their own ban on cell phone use in 2007 and the likelihood of significant non-compliance daily in the US — and curiously, planes haven't been falling from the sky at a similar rate. While the potential exists for there to be a problem, it would appear the risk is low. Ever bent the rules? Is an app for landing commercial jets somewhere in our future?"
Over the last few months I have been on a few EU carriers and they have the same restriction of no personnal electronics during take off and landing, same as when I was on the US carriers.
A few seasons back, Mythbusters did some tests and found that none of their phones were able to affect even remotely the instruments of a plane. It makes sense after all - we're not exactly seeing terrorists trying to sneak twelve cell phones on board and try to text each other into crashing the plane.
Rubbish. While an ILS system CAN land an aircraft today pilots do not wait until the aircraft is 300 feet off the ground to turn off the autopilot. The autopilot is not very good at coping with any of a number of unexpected situations (the most frequent being sudden gusts of wind) that can arise on short final.
Seven puppies were harmed during the making of this post.
The ban on cellphone usage during takeoff and landing is for your safety. The ban on cellphone usage during cruise is due to weaknesses in the cell network and your sanity.
The reason we tell you not to use your phone for takeoff and landing is because those are the point during the flight when the aircraft is most likely to encounter problems and also when our navaid usage and workload is at its highest. We are trained to assume that the airplane will crash on every flight and act accordingly - Complacency Kills! You should be in the same mindset. First, there's the matter of the crash. When the aircraft goes from flying speed to nothing in a few seconds, the G-forces are going to make that iphone/laptop/whatever that you are holding in your hands suddenly weigh several times its normal weight. You WILL NOT be able to keep ahold of it. It's going to become a projectile and injure or kill the people sitting near you. Next is longer-term survival. The fact is, most deaths in air crashes happen not during the impact sequence, but in the post-crash environment. People panic and stampede. They don't know which way is out. The aircraft is dark and possibly filling with smoke or water. Situational awareness and decision-making ability are KEY to both your survival and that of your fellow passengers. Having to get your headphones off or figure out where your laptop went is not going to help. If you weren't paying attention to things before the crash you won't know where you are now and what direction you need to go. You probably ignored the safety briefing too. See where this is going? Finally, if you are alert and paying attention, the amount of information you will be able to provide to the crash investigators after the crash will be of higher quality. Those of us at the pointy end of the aircraft probably died in the impact. Being able to give information to the investigators could uncover flaws in the aircraft or our procedures, and by correcting those save hundreds of lives. We take this flying stuff seriously. You should too.
I've heard that cell usage during cruise overloads the cell network by switching cells too often - I'm not an expert on the cell system so I'll defer to a cell tech on that. In my eyes, the ban on cell usage during cruise is for reasons of everyone's sanity. Do you really want to hear the guy in the next seat shouting into his phone about the BIG IMPORTANT EXECUTIVE THINGS BIG IMPORTANT EXECUTIVES LIKE HIM DO, or THIS THING ON MY NECK IS GETTING BIGGER, or whatever other inane thing he wants to rattle on about at maximum volume? It's bad enough everywhere else, why must we suffer too? (Misery loves company?)
Anyway, that's the score. I've repeated this I don't know how many times now and it never sticks. STICK, DAMMIT!
Ah sure, there are pretty strict limits on autoland (such as crosswind etc) - and it's not a "pilots read the newspaper while an iPhone lands the plane" affair, but Cat III autoland is equipped on the large commercial jets, and many of the large airports have a Cat III autoland certified runway, allowing for, well, autoland. Go google for it, it's pretty well described out there on the intertubes.
While the odds of a crash are minimal - if it's about to happen (and during takeoff and landing the timescales involved can be very short), you can drastically improve your odds if you pay attention.
One that hath name thou can not otter
Your car is touching the ground. Shielding is easy when you have a solid ground. How, exactly, do you get an effective ground when you're in the air?
Your car is insulated from the ground by rubber tires, which is why it's standard to get shocked if you touch a car on a dry, windy day, and why Asians sometimes install ground straps on their cars (well, I've never seen anyone else do it, anyway.) The PCM in the car is shielded by being wrapped in a bunch of metal, just like your PC has a metal case to prevent RFI intrusion... if it is worth a crap. Or at least a metal coating on the plastic parts, for the same purpose.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
Have you ever actually left your phone on during a flight?
I have. It doesn't connect to multiple cell towers - it doesn't connect at all, even when you're over a fairly large city.
Posting AC because I broke federal law, and will continue to do so, because cell phones aren't a threat to airplanes, and I don't give a fuck what the law says.
I'm an airline pilot, and a colleague of mine (on a Boeing 737/300) once saw his fuel quantity indicators suddenly jump to zero. He asked a cabin attendant to check if anyone was using electronic equipment in the cabin. One passenger, sitting next to the wing, was using a portable CD player. He was asked to turn it off, and fuel quantity indication returned to normal. Switched it back on again... indications went back to zero. The cause of the interference was later determined to be the motor of the CD player, which is rapidly switched on and off to keep a variable speed necessary for reading data at different distances from the center.
Personally, while flying in the cockpit myself, I have forgotten to turn off my cell phone many times. This usually just resulted in a drained battery but no ill effects on the airplane. On a few occasions, it even started ringing during final approach. I never saw any fluctuations in the instrument indications. However, I have heard the typical noise on the radio "trrrrrrrr tkt tkt tkt tkt", which I'm sure pretty much anyone has already heard when a phone was about to ring and it was close to a radio. The instrument landing system receives signals on frequencies pretty close to those of ordinary radio, so I can imagine it being affected in the same way. But I haven't actually seen the needles jump as a result.
In any case, this interference is VERY unlikely to affect the flight controls. Most landings are done manually, so interference should not actually be able to bring down an airplane. However, in foggy weather, the plane is landed automatically and in this case, it's probably safest to just keep all electronics off just in case the autopilot suddenly behaves in some weird way. Planes have crashed because of relatively minor errors in input, for example the radio altimeter reading an altitude that is much too low, and the plane thinking it's above the runway and bringing the power back to idle while in fact it's still at a few hundred feet. That sort of thing. Yes, it can happen, and planes have crashed as a result.
>pilots do not wait until the aircraft is 300 feet off
Actually your REQUIRED TO perform full autolands every 90 days in each aircraft in order to keep it certified to perform such landings when you 'really' need its help.
(work for airline, wrote the system that keeps track of the compliance)
Also have been in aircraft cockpit several times during autolands and even performed one myself in the full SIM. It's pretty amazing.
-- Given enough time and money, Microsoft will eventualy invent UNIX.
add a ferrite bead (round lump near the cable end) and it will be fixed.
EASY.
next one, please.
--
"It is now safe to switch off your computer."
This is definitely wrong.
First of all regulation make it mandatory to perform Cat. 3 precision landing on autopilot. If the autopilot is not operational you are not authorized for Cat. 3
(Cat. 3 is the one which has the lowest minima, up to Cat. 3 C, which has 0/0 for minima...meaning no minima, you land and stop blind).
Said that yes,. small, light single prop autopilots are just a little more than toys and can't land safely a plane ether in ideal conditions. Big planes do have very sophisticated autoland systems which are in fact able to react to wind shears and other hazards much faster than any human being.
Please study some basic instrumental flight test or have a chat with an airline pilot before saying such nonsense.
Grounding straps on the back of cars are fairly common to see here in Australia too. Not just Asians. Increasingly rare these days but during the 80s and 90s you saw em everywhere.
I should point out that most of Australia has very low humidity for most of the year. So you get shocked by your car far more often than in many other places. It's summer here at the moment and I can tell you, I've been zapped every single time I get in or out of mine in the last few months. Not so much in winter when the humidity is higher.
The AC is absolutely correct. The average commenter on this thread really doesn't understand E&M.
Every radio antenna has a defined radiation pattern. Cell phone towers incorporate directional antennas and have very focused radiation patterns to extend the horizontal range of the tower. If the tower were radiating vertically into the sky, it would be wasted power, and the ground range of the tower would be reduced.
Since the strength of a radio signal decreases with the square of its distance from the transmitter, and neglecting the information I gave about radiation patterns with respect to directional antennas, a cell phone radio one *foot* from a wire on an airplane poses a greater risk of interference than its transmitter one *mile* away, despite the fact that the transmitter is a couple orders of magnitude more powerful than the phone.
However, here's the best story:
A Piper PA-32R aircraft equipped with a GNS-430W was reporting loss of GPS fix when the VHF comm was in use on certain frequencies. The VHF antenna is on the bottom of the fuselage, and the GPS antennas are located on the top. It was determined that the frequencies this occurred on were were between 121.0 and 122.0 MHz. This is nowhere near GPS frequencies, which are at 1.57 and 1.23 GHz. So what causes a complete loss of fix when the VHF transmits? The ELT (emergency location transponder) transmits at 121.5MHz. The ELT is off in flight and only activated when an aircraft crashes, or manually by a pilot in distress. The VHF comm transmissions *near* 121.5 energized the ELT's transmitter, which had a wire running very near the GPS antenna wires. The resultant interference on the GPS antenna wires caused the avionics to lose the fix. For a pilot shooting a GPS/WAAS approach in IMC, activating the comm would cause GPS failure, and force the pilot to execute a missed approach. Ultimately, this could make safely landing the aircraft at an airport impossible.
So if someone were to ask me if I thought a cell phone had the potential to interfere with avionics, I would say yes, and I would back it up with experimental evidence backed by hard physics. And if they wanted to keep challenging the concept, I would politely remind them that I toiled for years to become an aerospace engineer and a pilot, and have spent many years in the aerospace and consumer electronics industries. Unless someone has a credible basis of knowledge and experience in these fields, their arguments on this topic usually are without merit.