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Discussion in 'Hangar Talk' started by ARFlyer, Jul 6, 2013.
Can't the FMS make a glideslope?
80lbs.......ho lee fuk!!!
missed the word 'virtual?'
Yes - like usAA notes - you can program the FMS to create a virtual GS and then fly it like a real one. . . .
Yes, but first, you have to know how to use it.
And then you need understand the limitations enough that you don't end up......in the trees in Birmingham.
They didn't disable it exactly. It sounds like they were descending in FLCH mode, and this is also independent of whether the A/P is on or not, the Autothrottles do not provide low speed protection in FLCH mode.
Your understanding is sadly mistaken...and it isn't the first time.
Can the 777 go around from 200' agl without the wheels touching?
There is some fuzzyness about why one of the flight directors was on and the other off and whether that was the reason for the inactivated AT. Whatever the reason, the PF thought he had autothrottles but with the autopilot mode selected and the settings of the flight directors, he did not.
If I understood the information in the report correctly, the AT system in the A320 (which he flew previously) would provide low-speed/high AOA protection regardless of the AP mode selected when some of the Boeing planes dont have that logic.
It should with no problem under normal circumstances, meaning configured and on speed. In fact, you'd lose less than 30-50' normally. But they weren't anywhere on speed/stabilized. They also had idle thrust, which takes longer to spool up than when the engines are around 55-60%, as they are normally.
I didn't realize one was on and off. Who had the FD off?
You're correct about the A320/30/40/50/80. Even in an open descent (FLCH in the bus), the low speed protection works. They would have slowed to the low speed and the engines would have gone to full power automatically. If they held the back pressure (which they were doing), they would have climbed out in a spectacular fashion.
Boeing designs their FBW planes to allow pilots to put them into positions outside the flight envelope. It looks like in this case the pilots did just that and the plane did exactly what it was designed to do.
The IP switched them both off then switched his FD back on again. The way I read through this is the IP just ****ed the trainee captain.
When he changed the AP mode, apparently following company manual, one of them turned both FDs off and back on (I assume that creates some sort of re-set). I dont remember which way around it was, but he only turned one of them off and left it off, the FDR doesn't show that the other one was ever cycled. What this left was one FD on and one FD off. The repeat interviews with the PF harped on that for pages and somehow it seems to play into the function of the AT system.
I only had little time to skim through the interviews, one of them is with a FAA test-pilot who was involved in certification of the 787 A350 and many other types. They went into those differences in programming philosophy between the two companies. He had written up a post-test report on the 787 where during test-flights he had to arrest a descent due to a RA. The throttles didn't 'wake up' and he flew the plane into a under-speed condition.
I am glad that in relative terms, this accident ended with as little loss of life as it did and that they were able to talk to the different people in the cockpit. None of the issues raised :
- cultural deference,
- FBW programming algorithms
are particularly novel, having all of them in one accident is quite instructive. I hope some things are learned out of this accident, a shame that two people had to die to gain that insight .
Well, I can't help you there!
Which one of these is Doctor Bruce's Ten Causes of Airplane Accidents?
I'll take 'fly the plane' for $500 Alex
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"What can you do to avoid a crash?"
answer: ________ is critical for a safe landing
question "what is airspeed?"
Correct, here is more info how they were descending, what emerges is a scary picture of two captains not understanding the consequences of pushing some buttons (copy and pasted):
During hearings on December 11, National Transportation Safety Board officials described the final approach sequence of Asiana Airlines Flight 214, scannerwhich crashed at San Francisco International Airport on July 6. The Boeing 777 was cleared for a visual approach to Runway 28 Left where, as per a Notam, the glideslope was inactive. The left-seat pilot flying had logged fewer than 45 hours in the 777, while the right-seat instructor had 3,200 hours of time on the widebody. On a 15 mile final approach, the Boeing’s airspeed was at 210 knots as it descended with autopilot and flight-level change (FLCH) engaged. Descent altitude was set at 1,800 feet. The aircraft was high on final approach and switching to vertical speed mode did not help this situation. Final approach reference speed was calculated at 137 knots. On a five-mile final the altitude was reset to 3,000 feet in case of a go-around. At 1,600 feet and 3.5 miles from the runway, the FLCH switch was again activated, which changed the auto-throttle mode. [Boeing does not recommend using FLCH inside the final approach fix—Ed.]. When the FLCH was engaged, the autopilot tried to climb the aircraft to 3,000 feet. The pilot reacted by pulling the thrust to idle and disconnecting the autopilot. This put the autothrottles in hold mode at idle. At 1.4 miles from the runway and at 500 feet above the water the aircraft was still descending. With the thrust at idle, the left-seat pilot began to add backpressure to the control wheel to stop the descent and get back on the visual glideslope from the precision approach path indicator. The airspeed continued to decay–now slowing through 120 knots–although neither pilot mentioned it. Eleven seconds before impact a low-speed alert was heard in the cockpit. At eight seconds from impact and with the aircraft 100 feet above the water, the pilots moved the throttles full forward to initiate a go-around. Four seconds later the stick shaker activated and someone in the cockpit called for a go-around. The action was too late and the main gear and aft fuselage struck the seawall. The lowest recorded airspeed was 103 knots, 34 knots below the calculated safe reference speed.
Good find. I'm not excusing the Asiana pilots at all, but I highlighted this portion to show how fast this happened. Remember, in the landing configuration at 777 is producing a LOT of drag. If the pilot pitched up to remain on glidepath and the autothrottles don't respond, they will be bleeding speed off very rapidly. It only took a few seconds to "get slow", then from the time the alert to went off to the application of go around thrust was another 3 seconds. Even with that, another 8 seconds go by, but it was too late. The engines would take too long to spool up and they hit the seawall.
The cues were there before the alert went off. I'm guessing the sound of the seat moving on the CVR recording is one of the pilots adjusting their seat up because the runway is low in the windshield when it should be about dead center.
In any case, they screwed themselves from farther out than most would realize. It takes time for the plane to react and once they got slow and realized it, it was too late. The events just happened too fast.
Good analysis, I also noticed and was a bit perplexed that at 8 seconds before impact they seemingly could not save themselves - was too late but your explanation about speed bleeding very quickly at abnormally high angle of attack makes perfect sense.
What is a Pilot In Command?
I spent a year running a training range in Korea, and got to know the Koreans pretty well. There were only two American officers in a 50 mile radius of our range.
Koreans are very, very, status conscious. They will risk their lives rather than cause a 'senior' person to lose face. I've seen this happen more than once.
If you read the pilot interviews, it's pretty obvious that Korean culture caused this accident, because the two pilots in the front row were not sure who was 'senior' in the Korean culture sense.
The pilot flying knew he had to go around pretty early on, but since he perceived the instructor to be senior to him (in the Korean sense) he found it almost impossible to call for a go around, he was waiting for the instructor to say the word.
The instructor appears to have perceived the pilot flying as senior, and so didn't want to say anything either.
So they both sat there waiting for the other to say 'go around', as the PAPI's all turned red.
And the rest is history.....
Well, guess we know now it was all Boeing's fault.
The lawsuit alleges that some equipment on the plane was improperly installed or defective, resulting in inadequate warnings for the pilots about low airspeed.
"Boeing was aware that its low airspeed warning system was inadequate," the suit states.
More than 80 of the plane's 291 passengers are named as plaintiffs in the lawsuit
Knowing how the US legal system works, I am not suprised at all.
Boeing has much deeper pockets than Asiana.