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Flying below VAPP - What to do ?

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Flying below VAPP - What to do ?

Old 18th Aug 2015, 22:01
  #81 (permalink)  
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MANY newer cars have electronic throttles, but the foot pedals still move. AFAIK, most brake pedals are still mechanically connected to the booster unit.
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Old 19th Aug 2015, 12:35
  #82 (permalink)  
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Not FBW but By Wire already exists in cars like speedometer etc. Brake by wire is there in formula1 cars. I am not sure about aircrafts.
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Old 19th Aug 2015, 13:32
  #83 (permalink)  
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Actually the 2014/2015 Infiniti Q50 sedan is already drive-by-wire ("steer-by-wire"). Toyota / Lexus has sold brake-by-wire cars for over 10 years, starting with the Toyota Estima hybrid in 2001.

On the Infiniti Q50 there is no mechanical linkage between the steering wheel and the tires. The Q50's "Active Lane Control" can make corrections to your driving input to help you stay in the lane in case of strong crosswind, poor road conditions, etc.

Closer on topic, coupled with the car's Auto-Throttle (aka cruise control) the Q50 can completely drive the car for you:

Infiniti Q50 Active Lane control is scarily self-driving

(Notice however the poor auto-pilot disconnect warning at the end)

The Infinity Q50 A/T will adaptively adjust to the speed of the cars ahead of you and maintain appropriate distance (or applying emergency braking if needed). Sensors track, detect and anticipate two cars ahead -- the car in front of you, plus the next car ahead of it.

The controls are intuitive. The A/T below Vspeed-limit? Just hid the "accelerator pedal". If it's going too fast, there is a "brake pedal" provided.

There have been a lot of innovations on the car side which will eventually be brought back to the aviation in the form of NextGen, e.g., for sequencing flights on approach to land.

Starting at $37,150 at a dealer near you.
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Old 21st Aug 2015, 05:20
  #84 (permalink)  
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From BEA Cautions Authorities On Legacy Airbus A320 Guidance Computers | MRO content from Aviation Week I note the priority button features again, or lack of use thereof.
The French civil aviation investigative authority, BEA, is asking EASA and Airbus to consider issuing an airworthiness directive that would force operators of hundreds of Airbus A320-family aircraft to replace legacy flight management guidance computer (FMGC) with an updated version.

For aircraft equipped with those systems, the auto throttle will incorrectly increase thrust when approach speeds are too high at 50-150 ft. above the ground, exacerbating the speed problem. Airbus learned of the problem in 1996 and introduced an improved FMGC in 2001, but airlines have to pay for the new equipment. To date, the change-out has been voluntary.

The auto throttle issue gained renewed prominence in a July 2013 accident involving an Hermes Airlines A321 that overran the runway at Lyon Saint-Exupery in instrument weather conditions after a too-fast, unstable approach. The aircraft, operating as a charter for Air Mediterranee, touched down 5,300 ft. past the threshold and exited the runway 1,000 ft. past the opposite threshold, damaging the engines but injuring none of the 174 passengers or five crew members.

BEA, in a final report issued on the incident, named a number of causes for the accident, including the inexperience and training of the first officer (the pilot–flying), the failure of both crew members to abort the unstable approach while in the air or during the extended flare above the runway, the fatigue potential of a 15-hour workday and the pilots’ lack of understanding of the control sticks.

During the flare both pilots were attempting to control the aircraft, with the sum of the inputs sent to the elevator control, rather than the captain taking over.

An analysis of the autothrottle revealed that the improper increase in thrust just before landing could have added as much as 1,600 ft. to the distance the aircraft traveled before touching down. BEA says none of the previous operators of the aircraft—Swissair and Air Mediterranee—had opted for FMGC replacement, and Hermes has been unaware of the issues when it purchased the A321.

Following the Lyon overrun, Airbus issued a special bulletin to alert operators equipped with the legacy FMGC of the issue. In June 2014, Airbus told the BEA that “operators were studying the proposed replacement. This concerned about 250 aircraft, and 36 of the aircraft were modified.”

BEA is asking EASA and Airbus to “define a period following which it determines” the effectiveness of replacement actions taken by airlines. “Without feedback from operators on their decision to replace the FMGCs concerned, it could then consider issuing an airworthiness directive,” BEA said.
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Old 21st Aug 2015, 12:24
  #85 (permalink)  
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Very interesting. I wonder if that applies to the A330 as well?

The quoted report talks of a thrust increase just before landing, and I wonder if perhaps the F/O - who sounds inexperienced - did not retard the thrust levers in the flare? If the thrust levers are left in the CLB gate too long, there will be a power increase as the A/THR tries to maintain Vapp, and this can cause a long float.
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Old 21st Aug 2015, 18:05
  #86 (permalink)  
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The quoted report talks of a thrust increase just before landing, and I wonder if perhaps the F/O - who sounds inexperienced - did not retard the thrust levers in the flare?
The A/THR applied thrust increase long before the flare (at around 150ft AGL).

The plane was already at least 10 kts over the 141 kts Vapp at the time and the A/THR bug accelerated the plane even further, to 163 kts by the threshold according to the report. Plus there was a +7 kts tail wind.

But lots of other things went wrong on that flight. The plane was never stabilized (Vapp+47 kts at 1,000ft), the crew contradicted each other (even though the Captain was a CRM instructor), both were manipulating the sidesticks after the flare, the thrust levers were retarded late (only after the RETARD annunciator), etc.

The plane ended up touching down 1,600 meters (!) past the runway threshold at 154 kts ground speed.

The crew training was also shockingly poor. The F/O reportedly didn't know what the airline's stabilization criteria was, and couldn't explain the meaning of the characteristic speeds (green dot, F, S).

Similarly the Captain allegedly didn't really know the stabilization criteria, missed approach requirements, proper emergency evac procedures, etc.
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