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737 'Tailstrike' Caused By Typo On a Tablet (arstechnica.com)
An anonymous reader writes: In August of last year, a Boeing 737 operated by Qantas experienced a tailstrike while taking off — the thrust wasn't great enough for the tail to clear the runway, so it clipped the ground. The investigation into the incident (PDF) has finally been completed, and it found the cause of the accident: the co-pilot accidentally entered the wrong plane weight data into the iPad used to make calculations about the takeoff thrust. "First, when working out the plane's takeoff weight on a notepad, the captain forgot to carry the "1," resulting in an erroneous weight of 66,400kg rather than 76,400kg. Second, the co-pilot made a "transposition error" when carrying out the same calculation on the Qantas on-board performance tool (OPT)—an iPad app for calculating takeoff speed, amongst other things. "Transposition error" is an investigatory euphemism for "he accidentally hit 6 on the keyboard rather than 7." This caused the problem: "For a weight of 76,400kg and temperature of 35C, the engine thrust should've been set at 93.1 percent with a takeoff speed of 157 knots; instead, due to the errors, the thrust was set to 88.4 percent and takeoff speed was 146 knots."
It still boggles my mind how we live in the Information Age and this data was not automatically uploaded and calculated. I'm not saying it dosent require a human to sign off on, but it's mildly insane it isn't all automatically calculated and simply checked.
So somebody entered bad data into the Flight Management Controller.
Happens all the time with Qantas, which has been caught out for having extremely lax protocols.
Search the ATSB database, there have been more than a dozen incidents in the past decade which by pure luck didn't result in mass casualties.
Then read the BS excuses Qantas gives. Such as "the ladder wasn't tall enough to check the engine cowling was locked".
As if the co-pilot couldn't have made the exact same mistake with a calculator or even paper.
They could have just as easily mistyped the weight using the on-board flight management system's keyboard.
That'll make for some angry birds.
They did both do the calculation. The pilot did the arithmetic wrong and the copilot typed in his result wrong, and the upshot was that the numbers they entered independently agreed with each other... and were both wrong.
On a recent flight from SYD to MEL our Qantas pilot ranted on the PA about how evil the ATSB was because they wouldn't let the plane take off, because Qantas engineering accidentally put an incorrect black box into our plane. He said that Qantas maintenance made mistakes like that all the time, and that, since it wasn't a safety issue to fly without a black box, the ATSB were just being pricks.
I will never set foot on a Qantas plane ever agin.
Headwinds are helpful for takeoff. Tailwinds are detrimental.
"Lack of speed can be overcome. In the worst case by patience." --Znork
Because if an automatic system fails in an "obvious" way and causes an accident, people here would be posting "why wasn't a human in the loop?"
In an ideal world, both automatic systems and people would complement each other with a person manually checking the automatic results. But in the real world, once you automate the system, people tend to get lazy and stop double-checking the automated system's calculations. NASA ran across the same problem - in the post-Challenger investigation they discovered that having multiple inspections actually decreased safety. Each inspector assumed the other was doing his job, so became more lax and sometimes didn't check things thoroughly or sometimes even skipped checks. Even in this incident, the pilot using the iPad didn't bother checking to make sure the number he entered into the iPad was the number he thought he typed. He just assumed the input method worked, despite everyone who's tried to type an email on a touch interface knowing that errors occur frequently.
So you end up with an either/or situation. Either the system has to be completely automated with the engineers trying to think up every possible scenario during design, and it'll still occasionally fail in ways you never thought of which will lead people to question why humans were left out of the loop. Or it has to be reliant on humans doing everything by hand, to ensure they take their job seriously and actually do it. Unless an automatic system has a track record showing decades of reliability (this is why computers on aircraft are usually more than a decade old), aerospace usually relies on humans.
Umm...Tail Strikes on take off are caused by over rotation.
Regardless, seems to me that pilots calculating the take off weight is anachronistic. Manufacturers can easily incorporate weight sensing devices into the gear. Or, weight sensors could be incorporated into a Wheel Chock device. There is no reason for guesstimates.
When Fascism comes to America, it will call itself Anti-Fascism, and tell you to give up your guns.
I suspect, sadly, that your bias against unions is an indicator that your mind is made up already.
Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac?
...but then the stupidity of taking off at less than 100% throttle to save a little bit of fuel at the expense of increasing risk is also a pretty dumb thing to do, engineering wise.
Taking off at less than 100% throttle means reduced acceleration, which reduces stress on the airframe (and passengers). It reduces wear on the engines and - more important - reduces the risk of turbine failure. It makes the aircraft easier to control (less unbalanced thrust) if it does lose an engine immediately before or after takeoff.
So...not just to save fuel.
~Idarubicin
First of all, tail strikes on take-off are obviously the result of overrotation, but this usually happens because the pilot rotates at the wrong speed. You pull back, expecting the plane to leave the ground, but instead the plane remains on the ground while the nose keeps going up. Also, you may be running out of runway if the calculations were off, so you'll pull back regardless.
About the weight sensors: good idea, but this is aviation, where everything has to work reliably in pretty difficult environmental circumstances. Even something as simple as a proximity switch to determine whether or not the gear is down, fails from time to time. We often deal with incorrect tire pressure indications, temperature indications, etcetera. Measuring the weight of a plane with sufficient precision is quite a bit more complex than a simple tire pressure reading, so I can't see any manufacturer trusting that kind of system enough to let it determine take-off settings by itself. Maybe as an extra crosscheck for the data from the loadsheet, sure, but not as the primary source of information.
People always go "we should replace the pilots with automated systems because pilots make too many mistakes", but they have no idea how many mechanical failures we deal with as part of the routine of our job. We make mistakes, sure. But so does automation.