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> So you're claiming that Airbus knowingly leaves a critical defect in their planes, which may cause the loss of flight controls and which they refreain from fi

by mopsi 7y ago

> So you're claiming that Airbus knowingly leaves a critical defect in their planes, which may cause the loss of flight controls and which they refreain from fixing for almost 30 years? A320's computers monitor gear for uncompression of 1 second or longer. Computers are not in sync. If landing gear decompresses due to bouncing for long enough to be seen for 1 second by one computer, but short enough to get missed by the other, computers will produce different outputs and the system will shut down, freezing important flight control at a dangerous phase of flight and leaving pilots in a situation they have not been trained for. Given the very obviously flawed and incredibly poor design that's easy to understand even for laymen, I would have very hard time believing that no-one at Airbus ever noticed, no-one ever spoke up. I think this would reflect even more poorly on Airbus. Especially so considering that there have been multiple hull-loss accidents with fatalities (LH2904, TAM3054), where air/ground detection has been a contributing factor. Throughout the years, the aircraft has been unable to tell whether it's on the ground or in the air.

inferiorhuman 7y ago
Especially so considering that there have been multiple hull-loss accidents with fatalities (LH2904, TAM3054), where air/ground detection has been a contributing factor. Throughout the years, the aircraft has been unable to tell whether it's on the ground or in the air. With the Lufthansa flight the problem was not the aircraft design but rather that the pilot remained on only one main gear for too long. The Airbus design requires weight on both wheels (this had nothing to do with computers being out of sync) in order to prevent things like the Lauda Air (Boeing 767-300ER) crash where the thrust reversers deployed in flight causing the plane to drop out of the sky, killing everyone. Same deal with the TAM flight. For whatever reason the pilots didn't properly position the thrust lever on one engine. That had nothing to do with computers being out of sync and had absolutely nothing to do with ground detection. Meanwhile with the Boeing 737, a single (unreliable) radar altimeter (RA) is used as part of the ground detection and a single failed RA caused a Westjet 737 to start pulling back on the throttles. http://avherald.com/h?article=41e84cb5 http://avherald.com/h?article=41e84cb5 As far a the Turkish 737 crash: http://avherald.com/h?article=41595ec3 http://avherald.com/h?article=41595ec3 During the accident flight, while executing the approach by means of the instrument landing system with the right autopilot engaged, the left radio altimeter system showed an incorrect height of -8 feet on the left primary flight display. This incorrect value of -8 feet resulted in activation of the ‘retard flare’ mode of the autothrottle, whereby the thrust of both engines was reduced to a minimal value (approach idle) in preparation for the last phase of the landing. ... The problems with radio altimeter systems in the Boeing 737-800 fleet had been affecting several airlines, including Turkish Airlines, for many years and were known to Boeing and the Federal Aviation Administration of the United States of America. ... Despite the fact that Boeing and the Federal Aviation Administration of the United States of America had been aware for many years that the radio altimeter system was causing many problems and was affecting the operation of other systems, this situation was not designated as a safety risk. Reports of problems with the radio altimeter system that could not be resolved by Boeing justified an effort to analyse the radio altimeter system and other related systems. Boeing and the Federal Aviation Administration of the United States of America could have recognised the fact that the problems caused by the radio altimeter system, especially the potential for activating the autothrottle retard flare mode, posed a safety risk. That sounds a lot like the engineering that went into MCAS - using only one input for something safety critical.
- mopsi 7y ago
  In TAM and LH cases, pilots were locked out of using full braking capabilities of the aircraft because they found themselves in a situation that didn't satisfy the conditions defined as "landing" by aircraft designers. The had wheels on the ground, but program logic evaluated to onground = FALSE. Westjet and Turkish incidents are irrelevant. Westjet malfunctioned, pilot took control and landed safely - that's what pilots are there for. Turkish airplane also malfunctioned and gave multiple warnings over several minutes, but pilots didn't pay attention to what the aircraft was doing until stall warning activated at 460 feet, by which time it was too late. Had they paid attention, they would've also recovered and landed safely. In contrast, Airbuses systems didn't malfunction. They worked as designed and made the already difficult situation (landing in bad weather) deadly due to not responding like a pilot would expect. The design was deeply flawed, just like MCAS.
  - inferiorhuman 7y ago
    The had wheels on the ground, but program logic evaluated to onground = FALSE. Nope. The Lufthansa bird had one bogie on the ground and one off. With the TAM flight the pilots left one thrust lever at climb power and one at idle, pure pilot error. The Westjet and Turkish incidents are irrelevant. Westjet malfunctioned, pilot took control and landed safely - that's what pilots are there for. Turkish airplane also malfunctioned and gave multiple warnings over several minutes, but pilots didn't pay attention to what the aircraft was doing until stall warning activated at 460 feet, by which time it was too late. Had they paid attention, they would've also recovered and landed safely. Unfortunately the 737s were functioning as designed, the computers took invalid input and ran with it instead of cross checking it.
    - mopsi 7y ago
      > Nope. The Lufthansa bird had one bogie on the ground and one off. Which is to be expected from a crosswind landing (especially with a lot of lift from higher-than-usual speed), but it took 900 m of runway before enough weight was detected on both of them to activate thrust reversers and spoilers. And even after all wheels were on the ground, it took another 300 m before wheel brakes became active. The accident investigation report recommended introduction of emergency override to cover the whole range of conditions in which airplanes fly. > With the TAM flight the pilots left one thrust lever at climb power and one at idle, pure pilot error. The aircraft was firmly on the ground, with one thrust lever in reverse position. Spoilers and auto-brake did not activate because position of the other lever lever was prioritized over actual condition of the aircraft. Critical data was derived from a thrust lever, which has no safety features to prevent inadvertent wrong positioning. Furthermore, lever positioning suppressed aural reminders to bring thrust levers to idle (the famous "RETARD"). > Unfortunately the 737s were functioning as designed, the computers took invalid input and ran with it instead of cross checking it. Which is irrelevant on the 737, because its design philosophy expects pilots to monitor and (if necessary) override automation, which hundreds of attentive crews successfully did before the Turkish crash. A320, on the other hand, lacks emergency override, as the LH2904 investigators noted in their report. It cannot reliably tell whether the aircraft is on the ground or not, and stops pilots from taking the correct action.

by mopsi 7y ago

inferiorhuman 7y ago

Especially so considering that there have been multiple hull-loss accidents with fatalities (LH2904, TAM3054), where air/ground detection has been a contributing factor. Throughout the years, the aircraft has been unable to tell whether it's on the ground or in the air. With the Lufthansa flight the problem was not the aircraft design but rather that the pilot remained on only one main gear for too long. The Airbus design requires weight on both wheels (this had nothing to do with computers being out of sync) in order to prevent things like the Lauda Air (Boeing 767-300ER) crash where the thrust reversers deployed in flight causing the plane to drop out of the sky, killing everyone. Same deal with the TAM flight. For whatever reason the pilots didn't properly position the thrust lever on one engine. That had nothing to do with computers being out of sync and had absolutely nothing to do with ground detection. Meanwhile with the Boeing 737, a single (unreliable) radar altimeter (RA) is used as part of the ground detection and a single failed RA caused a Westjet 737 to start pulling back on the throttles. http://avherald.com/h?article=41e84cb5 http://avherald.com/h?article=41e84cb5 As far a the Turkish 737 crash: http://avherald.com/h?article=41595ec3 http://avherald.com/h?article=41595ec3 During the accident flight, while executing the approach by means of the instrument landing system with the right autopilot engaged, the left radio altimeter system showed an incorrect height of -8 feet on the left primary flight display. This incorrect value of -8 feet resulted in activation of the ‘retard flare’ mode of the autothrottle, whereby the thrust of both engines was reduced to a minimal value (approach idle) in preparation for the last phase of the landing. ... The problems with radio altimeter systems in the Boeing 737-800 fleet had been affecting several airlines, including Turkish Airlines, for many years and were known to Boeing and the Federal Aviation Administration of the United States of America. ... Despite the fact that Boeing and the Federal Aviation Administration of the United States of America had been aware for many years that the radio altimeter system was causing many problems and was affecting the operation of other systems, this situation was not designated as a safety risk. Reports of problems with the radio altimeter system that could not be resolved by Boeing justified an effort to analyse the radio altimeter system and other related systems. Boeing and the Federal Aviation Administration of the United States of America could have recognised the fact that the problems caused by the radio altimeter system, especially the potential for activating the autothrottle retard flare mode, posed a safety risk. That sounds a lot like the engineering that went into MCAS - using only one input for something safety critical.

mopsi 7y ago
In TAM and LH cases, pilots were locked out of using full braking capabilities of the aircraft because they found themselves in a situation that didn't satisfy the conditions defined as "landing" by aircraft designers. The had wheels on the ground, but program logic evaluated to onground = FALSE. Westjet and Turkish incidents are irrelevant. Westjet malfunctioned, pilot took control and landed safely - that's what pilots are there for. Turkish airplane also malfunctioned and gave multiple warnings over several minutes, but pilots didn't pay attention to what the aircraft was doing until stall warning activated at 460 feet, by which time it was too late. Had they paid attention, they would've also recovered and landed safely. In contrast, Airbuses systems didn't malfunction. They worked as designed and made the already difficult situation (landing in bad weather) deadly due to not responding like a pilot would expect. The design was deeply flawed, just like MCAS.
- inferiorhuman 7y ago
  The had wheels on the ground, but program logic evaluated to onground = FALSE. Nope. The Lufthansa bird had one bogie on the ground and one off. With the TAM flight the pilots left one thrust lever at climb power and one at idle, pure pilot error. The Westjet and Turkish incidents are irrelevant. Westjet malfunctioned, pilot took control and landed safely - that's what pilots are there for. Turkish airplane also malfunctioned and gave multiple warnings over several minutes, but pilots didn't pay attention to what the aircraft was doing until stall warning activated at 460 feet, by which time it was too late. Had they paid attention, they would've also recovered and landed safely. Unfortunately the 737s were functioning as designed, the computers took invalid input and ran with it instead of cross checking it.
  - mopsi 7y ago
    > Nope. The Lufthansa bird had one bogie on the ground and one off. Which is to be expected from a crosswind landing (especially with a lot of lift from higher-than-usual speed), but it took 900 m of runway before enough weight was detected on both of them to activate thrust reversers and spoilers. And even after all wheels were on the ground, it took another 300 m before wheel brakes became active. The accident investigation report recommended introduction of emergency override to cover the whole range of conditions in which airplanes fly. > With the TAM flight the pilots left one thrust lever at climb power and one at idle, pure pilot error. The aircraft was firmly on the ground, with one thrust lever in reverse position. Spoilers and auto-brake did not activate because position of the other lever lever was prioritized over actual condition of the aircraft. Critical data was derived from a thrust lever, which has no safety features to prevent inadvertent wrong positioning. Furthermore, lever positioning suppressed aural reminders to bring thrust levers to idle (the famous "RETARD"). > Unfortunately the 737s were functioning as designed, the computers took invalid input and ran with it instead of cross checking it. Which is irrelevant on the 737, because its design philosophy expects pilots to monitor and (if necessary) override automation, which hundreds of attentive crews successfully did before the Turkish crash. A320, on the other hand, lacks emergency override, as the LH2904 investigators noted in their report. It cannot reliably tell whether the aircraft is on the ground or not, and stops pilots from taking the correct action.