Southwest Captain Reduced Power Before NYC Crash Landing
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Southwest Captain Reduced Power Before NYC Crash Landing
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Reading the group chairman's factual report she reduced thrust to idle at flaps 40, took control and decided the nose was too low for flaps 40 so pulled back to raise nose and added thrust as they impacted the runway.
When landing flaps 40 on a B737 reducing to idle before descent is stopped is always an absolute disaster unless you have a lot of excess airspeed.
When landing flaps 40 on a B737 reducing to idle before descent is stopped is always an absolute disaster unless you have a lot of excess airspeed.
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When landing flaps 40 on a B737 reducing to idle before descent is stopped is always an absolute disaster unless you have a lot of excess airspeed.
The main difference between flap 30 & 40 is that the flare needs to be more positive with flap 40 to get the nose high. To do that you need to have the power off & airspeed reducing towards Vref in order to prevent ballooning.
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If you look at the FDR plots you'll see that 5 secs before touchdown/impact, with the co-pilot flying at nominal speed and slightly above GS, the captain calls out "I got it" and reduces thrust to idle but both pilots abandon the control columns !! and the pitch goes from +2 to -4 degrees pitch until touchdown/impact.
No movement in the 2 control columns: forwards, backwards, turning right, or left are recorded i.e. no motion !!
After impact the left engine throttle almost goes to full thrust for over 5 secs.
There seems to be no captain-side GS data on the plots.
No movement in the 2 control columns: forwards, backwards, turning right, or left are recorded i.e. no motion !!
After impact the left engine throttle almost goes to full thrust for over 5 secs.
There seems to be no captain-side GS data on the plots.
flare needs to be more positive with flap 40 to get the nose high. To do that you need to have the power off & airspeed reducing towards Vref in order to prevent ballooning.
Having read the various reports and interviews I can't understand,as a layman, why the captain took control at this point.
If the plane hadn't touched down within the TDZ then a call of "go around" would surely be the procedure, assuming that the PF hadn't already commenced a GA.
Even a touchdown slightly beyond the last marker would still give approx 4000ft to stop, plenty for a 73G on a dry runway.
If the plane hadn't touched down within the TDZ then a call of "go around" would surely be the procedure, assuming that the PF hadn't already commenced a GA.
Even a touchdown slightly beyond the last marker would still give approx 4000ft to stop, plenty for a 73G on a dry runway.
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Only the Captain can really answer that.
My totally unfair speculations (but based on available NTSB data):
1. Prior to the approach, the Captain fixates on landing distances. This was due to some weather expected in the area (rain, tail winds during approach). The crew enters "wet" runway for their landing distance computations, and saw that the standard "Autobrake 2" setting isn't going to cut it. They set Autobrake 3, and the Captain also elects Flaps 40 for extra margin. This is her mindset coming in.
2. Near touchdown, the FO hand flies by reference to PAPI, while the Captain looks through her Heads-up Display (HUD) -- probably in IMC Mode, with ILS RWY 4 showing on the display.
3. The problem is, at LGA RWY 4, the ILS glideslope and the PAPI are not coincident. The PAPI is set "further down" the runway, so even if you fly perfectly down the PAPI, you would show increasingly high on the ILS GS. At the threshold, the airplane would be 54' high if on the ILS, but would be 76' high if on the PAPI. And we all know that the ILS by design gets really sensitive near the runway.
4. On short final the FO goes a touch high on the PAPI and is slow to correct it. He maintains the required descent angle (3.10 degrees), but on the Captain's HUD ILS it looks like the plane is "ballooning" when in fact it is not -- causing a type of spatial disorientation. In fact, from the HUD perspective, the plane looks like it's going to fly "well past" the TDZ -- where the ILS GS intersects the ground. (Which it was, since the PAPI is set further down the runway).
5. On the HUD ILS the plane looks like it's increasingly high and the Captain overreacts. She chops the throttle and takes over the controls from the FO, at less than 75' AGL. The ILS glideslope is now at full deflection too high (5-dots) -- even though the approach is fine on the PAPI. The Captain wants "to get down now", so she relaxes on the control column and lets the nose drop... and drop... and drop... chasing the already-past ILS glideslope.
6. Two seconds to impact, the Captain realizes her mistake. She starts to apply full-throttle but changes her mind -- and chops the throttles again to idle. BUT, she makes another mistake: the left engine throttle was not pulled back all the way. This creates a little asymmetric thrust.
7. The Captain thinks about pulling the nose up, but its already too late. Impact occurs with aircraft nose-down, no flare, and the nose wheel collapses. The plane is now sliding on the ground. Due to #6 above the plane starts to veer to the right of centerline. The Captain tries to adjust with rudder. Well into the slide someone notices the left throttle was still open and pulls it down to idle.
8. The plane finally comes to a stop. The Captain orders everyone to stay in their seats, but the flight attendants and jump-seat pilot notice smoke in the cabin. The Captain orders evac, but does not use the evac checklist.
My totally unfair speculations (but based on available NTSB data):
1. Prior to the approach, the Captain fixates on landing distances. This was due to some weather expected in the area (rain, tail winds during approach). The crew enters "wet" runway for their landing distance computations, and saw that the standard "Autobrake 2" setting isn't going to cut it. They set Autobrake 3, and the Captain also elects Flaps 40 for extra margin. This is her mindset coming in.
2. Near touchdown, the FO hand flies by reference to PAPI, while the Captain looks through her Heads-up Display (HUD) -- probably in IMC Mode, with ILS RWY 4 showing on the display.
3. The problem is, at LGA RWY 4, the ILS glideslope and the PAPI are not coincident. The PAPI is set "further down" the runway, so even if you fly perfectly down the PAPI, you would show increasingly high on the ILS GS. At the threshold, the airplane would be 54' high if on the ILS, but would be 76' high if on the PAPI. And we all know that the ILS by design gets really sensitive near the runway.
4. On short final the FO goes a touch high on the PAPI and is slow to correct it. He maintains the required descent angle (3.10 degrees), but on the Captain's HUD ILS it looks like the plane is "ballooning" when in fact it is not -- causing a type of spatial disorientation. In fact, from the HUD perspective, the plane looks like it's going to fly "well past" the TDZ -- where the ILS GS intersects the ground. (Which it was, since the PAPI is set further down the runway).
5. On the HUD ILS the plane looks like it's increasingly high and the Captain overreacts. She chops the throttle and takes over the controls from the FO, at less than 75' AGL. The ILS glideslope is now at full deflection too high (5-dots) -- even though the approach is fine on the PAPI. The Captain wants "to get down now", so she relaxes on the control column and lets the nose drop... and drop... and drop... chasing the already-past ILS glideslope.
6. Two seconds to impact, the Captain realizes her mistake. She starts to apply full-throttle but changes her mind -- and chops the throttles again to idle. BUT, she makes another mistake: the left engine throttle was not pulled back all the way. This creates a little asymmetric thrust.
7. The Captain thinks about pulling the nose up, but its already too late. Impact occurs with aircraft nose-down, no flare, and the nose wheel collapses. The plane is now sliding on the ground. Due to #6 above the plane starts to veer to the right of centerline. The Captain tries to adjust with rudder. Well into the slide someone notices the left throttle was still open and pulls it down to idle.
8. The plane finally comes to a stop. The Captain orders everyone to stay in their seats, but the flight attendants and jump-seat pilot notice smoke in the cabin. The Captain orders evac, but does not use the evac checklist.
Last edited by peekay4; 1st Nov 2014 at 18:28.
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My totally unfair speculations (but based on available NTSB data):
Like other cases of TMI (too much information) either path guidance will probably be fine to the touchdown zone on an ILS. And, often there is plenty of runway to land a little long or go around, but not enough to indecisively do parts of both maneuvers.
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Good video. Notice how the nose pitches down before impact with descent rate not arrested first. The winglet trailing edge shows it best.
I never flew with a pilot that relied on papi, GS and HUD to flare so have a hard time understanding why just looking out the window and landing like we all did in my career isn't the norm for some pilots now. I'm sure it works in all aircraft still, no matter how many computers it has.
I never flew with a pilot that relied on papi, GS and HUD to flare so have a hard time understanding why just looking out the window and landing like we all did in my career isn't the norm for some pilots now. I'm sure it works in all aircraft still, no matter how many computers it has.
Peekay4 - your excellent analysis does shed more light on what went on.
I would be interested to know if crews would brief (at TOD) for any anomalies between the locations of the PAPI and the glide path transmitter.
Also if there is full deflection on the ILS (even if intentional) and PNF not happy at or near decision then surely a GA call is the most prudent course of action?
I would be interested to know if crews would brief (at TOD) for any anomalies between the locations of the PAPI and the glide path transmitter.
Also if there is full deflection on the ILS (even if intentional) and PNF not happy at or near decision then surely a GA call is the most prudent course of action?
Video
There was another video posted in the original thread, however, the link has gone bad.
It showed the actual touchdown on the nose from a different angle than all the ones of the plane skidding down the runway.
If I can find it again, I will post. It shows the pitch down in the last moments.
Maybe someone here knows where that video is located?
It showed the actual touchdown on the nose from a different angle than all the ones of the plane skidding down the runway.
If I can find it again, I will post. It shows the pitch down in the last moments.
Maybe someone here knows where that video is located?
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I would be interested to know if crews would brief (at TOD) for any anomalies between the locations of the PAPI and the glide path transmitter.
Is it common on US charts for this information to be published? In EU it is normally the ILS TCH. Once again we might be having the debate about which glide path indicator is primary; ILS or PAPI. My own philosophy is if in doubt ILS. That's what an autopilot would fly on an auto land and it is checked/maintained to a higher fidelity; or so I've always been told/believed.
I remember BALPA Tech chap pies having a discuss over the use of HUD's. One point raised was how the non-HUD pilot could monitor what the HUD flying pilot was seeing and responding to. I assumed that a HUD displaying an ILS G.S. would match the basic PFD ILS G.S. Thus monitoring that parameter should be possible. Not so easy on a visual final with HUD displaying FPV to touchdown. The PM might have to use Mk.1 eyeball or PAPI; and therein lies a hole in the cheese. Thus are HUD's on a 2 crew civilian airliner necessarily a better/safer item?
Is it common on US charts for this information to be published? In EU it is normally the ILS TCH. Once again we might be having the debate about which glide path indicator is primary; ILS or PAPI. My own philosophy is if in doubt ILS. That's what an autopilot would fly on an auto land and it is checked/maintained to a higher fidelity; or so I've always been told/believed.
I remember BALPA Tech chap pies having a discuss over the use of HUD's. One point raised was how the non-HUD pilot could monitor what the HUD flying pilot was seeing and responding to. I assumed that a HUD displaying an ILS G.S. would match the basic PFD ILS G.S. Thus monitoring that parameter should be possible. Not so easy on a visual final with HUD displaying FPV to touchdown. The PM might have to use Mk.1 eyeball or PAPI; and therein lies a hole in the cheese. Thus are HUD's on a 2 crew civilian airliner necessarily a better/safer item?
ILS 4
The approach plate for the ILS 4 at KLGA has a statement that the VGSI and the ILS are not coincident. (VGSI angle 3.10 and TCH 76) The GS angle is 3.1 and the TCH is 54.
As an aside its a nice change to read an article that makes sense! Normally aviation issues are written about in terms that make no sense, but this one was quite good. Well done Bloomberg!
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we might be having the debate about which glide path indicator is primary; ILS or PAPI. My own philosophy is if in doubt ILS.
If the ILS and PAPIs are mismatched accept the picture delivered by the ILS at DH and hold it until the flare, it then wouldn't matter if the ILS and PAPIs both failed the approach angle would stay the same.
Last edited by Schnowzer; 2nd Nov 2014 at 02:53. Reason: English