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(Video) NTSB Chairman's Thursday Briefing on Asiana 214

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On Thursday afternoon, the NTSB Chairman discussed the status of the investigation and provided in-depth information on the accident flight. (www.youtube.com) Daha Fazlası...

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bravowren
bravowren 2
One question I have that the NTSB briefings have not answered yet. I know there were two separate crew call outs for a go-around very late in the botched approach (1.5 and 3 sec before impact), but was the go-around sequence actually initiated, and if so, at what point after impact were the throttles retarded and engines shut down?

From passenger accounts we do know that there was rapid advancement of the throttles right before impact, and video shows a very high nose-up attitude on short final. One has to wonder if the gear would have cleared the seawall if PF had kept the nose down in those last few seconds instead of pulling up. When that slow, he must have been in the "area of reverse command", where pulling up actually increases your angle of descent. It takes some stick and rudder skills learned in emergency training to fight that human instinct to pull.
PhotoFinish
PhotoFinish 1
" One has to wonder if the gear would have cleared the seawall if PF had kept the nose down in those last few seconds instead of pulling up."

Actually been wondering this all week.

It would be good to know what the optimal attitude should be for a large jet (777) with minimal attitude and ridiculously low near-stall speed to get the highest altitude possible.

Nose up - hail mary attempt in hope that trust will spool up in time.
Level - to increase lift quickly and minimize altitude loss
Pointing slightly down - to increase lift as quickly as possible, with some continued loss of altitude but in a more controlled way.

Would it have have aerodynamically possible to actually land the aircraft at the last minute when they first spotted the decreased airspeed? If so, which of the above options in attitude would have been most likely to get them the best chance of 1) entirely clearing the sea wall and then 2) having the closest to a non-disruptive landing, no matter how rough.

Completely clearing the seawall at near stall speed with engines that are just beginning to be spooled up could lead to a quite unremarkable landing (apart from the underwear change) with the entirety of a quite long runway to cone to a stop.
Steve1822
Steve1822 1
PhotoFinish, if you read the few posts below your above questions are answered.
PhotoFinish
PhotoFinish 1
Thanks, Steve.

I did read the posts below. I may have even read yours twice. It was quite dense with information.

The issues you raised in your post reawakened my curiosity in the issue.

I have since read a post elsewhere by a glider pilot that suggests that:
1. When slow and trying to avoid an obstacle, aim for a point just above your obstacle and give it all you've got (75%+ power). You want to use build up as much speed and lift as possible. Let gravity help you. Certainly don't fight gravity. Turning your nose up before attaining speed would actually cause you to lose altitude faster, as doing so would put you into a stall.

2. Then lift your nose at the last second for an extra bump up after you've built up as much speed as possible.

Notes:
Of course, a 777 has a large mass and momentum.

Your point about An attitude with a pitch up not necessarily resulting in decreased rate if descent is noted. However, my concerns are: the stick shook meaning they had 10 knots before stalling before pitching up, but probably entering a stall immediately upon pitching up.

They increased airspeed 4 knots with a putch up, buy may have gotten a more significant increase with a more optimal attitude.

And the concern about deck angle is a real concern. If only the rear gear and tail struck the seawall, then it seems that the plane may have entirely cleared the seawall with a less sever deck angle. The nose would've certainly been lower but the tail and gear would've been higher.

The landing would've still been a mess and would almost certainly still be considered a crash landing into the stop zone.

However, the forces applied to the aircraft and the passengers would've been significantly less, resulting in less damage to the aircraft and less severe injuries.

So sad to realize that 5 seconds was probably the only difference between crashing into the seawall and getting up to full thrust and just missing the seawall to then climb up into a go around procedure, hopefully to be followed by a successful landing.

It is not clear that the increase in altitude from the increased pitch up was greater than the increased loss of altitude from the more aggressive pitch.

Also, the engines only powered up to 50% so they were late to that party as well.

It is possible that they executed the only option they had (being they were in the last seconds before impact when the initiated corrective action).

And we are entirely in speculative territory.

And it would've been best had they monitored airspeed and altitude, and started corrective action sooner, which is the real moral of the story.

But it is fun to hypothesize about what might've been. Monday morning quarterbacking (or in this case piloting).
Steve1822
Steve1822 1
The 4 knot increase in airspeed(update from 103 knots) right before impact and pitch up, was a result of engine thrust increasing......but as the saying goes. Too little, too late.
Steve1822
Steve1822 1
LOL. Yes, from the CVR, passenger testimony and video the go-around was actually initiated...just too late. Engine power was increasing and at aproximately 50% at time of impact. No information on power lever angle (PLA) after impact. The engines clearly shut down by impact. It was a crash and I seriously doubt the crew was concerned with the engine shutdown checklist. Initial engine inspection showed signs of high rotational force damage....meaning the engines were generating thrust at time of impact and stoppage.
bbabis
bbabis 1
Good point bravowren. Not just reverse command but because the gear are behind the center of lift, pitching up actually moved the gear lower. If he had held what he had or even pitched down they may have cleared the seawall and had a very very hard landing probably still bending if not breaking the airplane.
Steve1822
Steve1822 1
Bravowren, at least your are thinking in the right direction. Keep in mind that when flying in the region of reverse command (behind the power curve) pitching up will not always increase your angle of descent (IF) accompanied by thrust (prop or jet)that is in excess of thrust (required) to mainain level flight. However, from video we see the B777 was already low in altitude, nose high deck angle, FDR data shows decreasing airspeed and engines at a low power setting. I cannot think of a worse position to be in at such a low altiude. Babis is correct by stating increasing deck angle actually lowered actual height of the landing gear in the horizontal plane above the surface. You wonder if the PF had kept the nose down the aircraft might have cleared the sea wall. Look at both together. Based on video and FDR data we know the aircraft was too low and descending when approaching the sea wall and needed to arrest that descent RIGHT NOW. Without the last seconds pitch up they were going landing in the water right before the sea wall or on the seawall. Therefore holding what they had and the angle of descent going would have impact at or just before the sea wall. Babis, lowering the nose to (clear) the sea wall would have put them in the water at the indicated rate and angle of descent. The PF final seconds pitch up before the sea wall and command for go around power did one thing with the very little energy (airspeed) he had left, level off snag the sea wall with gear and tail section. The engines were spooling up but the guy was so far back in the region of reverse command at the point the last seconds increase in pitch only exacerbated the situation with only 50% power and now approaching a high alpha scenario even though FDR showed a 4 knot increase in airpseed just prior to impact.......it wasn't enough considering the stick shaker normally activates 10 knots before a stall. The bottomline Bravowren is never, ever allow the aircraft to get into that conidtion so close to the ground. Excess airspeed or more altitude would have given this crew options. They had neither.
bbabis
bbabis 2
After listening to all the briefings there is still much missing but a couple of things are clearer. All though I don't think it was said, the stick shaker was probably this crew's first realization that things weren't right and this happened around 100' or less. I don't know what sink rate and other parameters were, but can a 777 person tell me if a successful recovery to go-around or landing could be made from this point? Secondly, on an earlier post, I stated that what the crew did do when they knew they were in trouble probably added to the seriousness of the accident. This is probably not true. Even though they did everything they could wrong, if they succeeded in moving the impact point from in front of the main gear to the main gear, they saved 100+ lives. I would not give them great credit for this because they were so far detached from flying the airplane that this thought was not on their radar.
Steve1822
Steve1822 2
Any pro pilot, be it a B777 pilot down to a lighter business jet pilot, will tell you based on the facts we now know that commanding a go-around that low to the surface and that low on airspeed 1.5 seconds before impact is not going to have a positive outcome. Keep in mind the surface (open water) he was flying over just prior to impact was at sea level, not to mention RA altitude. At 4 seconds prior to impact the stick shaker activates and the aircraft is approaching a 13 MSL rock embankment rising up into the pilots descending glide path at the same time. The last few seconds pitch up and power up clearly didn't cut it. The PF in testimony mentioned that after being (distracted) by a bright light he looked at the PAPI at 500 feet and notice 3 red and 1 white. This is below the glide path. Plenty of time to take corrective action. This accident investigation is going center more around positional/situational awareness issues and human factors/performance. Inspite of all the automation, as you know, we are still trained to monitor what the aircraft is actually doing and where are we in relation to the touchdown point. This aircraft impacted 1,000 feet short of its intended touchdown point. As some have said, this crew was way behind the airplane........why?
bbabis
bbabis 1
Thanks Steve. I'm very familiar with what you say since all my experience is in biz-jets. What I will add is that in almost all biz-jets if you are on speed you can instantly stop decent with pitch and then power gets you up and outa there. If you are at stick shaker speed, you probably wont have enough pitch left and engine spool up time will determine if you crash or dash. I would still like to hear what the actual 777 go around capability is.

As far as this crew goes, they weren't behind the airplane. You have to know where it is before you can get behind it. Their only idea of where they were was wrote actions and assumptions.
Steve1822
Steve1822 1
Totally agree Babis. I don't think this crew knew they were behind the plane. And we both know from jet sim training on stalls, micro burst recovery or balked landings etc, that after initiating recovery or go around the aircraft is stilling descending another 50-100 feet after reaction time and commencing a positive climb. At the time of awakening (go around) from photo's/video that aircraft was barely 30 feet above the surface. I still marvel that 305 survived and that Boeing builds tough aircraft.
bbabis
bbabis 1
Ahmen to that.
Pileits
Pileits 1
Speculation and/or guessing is wasted brain energy. No need to drain your brains wondering, wait for the final NTSB crash report next year or some time after that and you will have ALL your questions answered.
bravowren
bravowren 1
Pileits, this is not just idle armchair speculation and wasted energy. Discussions like these give us the opportunity to share ideas, and reflect on critical issues related to flight.
Think about the pilot who is set up perfectly on final approach while carrying no power, and he is unexpectedly hit with a downdraft 200' off the deck. A discussion like this could make him rethink the physics of pulling up at the last minute, which could result in averting an accident.
I consider myself a fairly seasoned pilot, but I am always learning, questioning other viewpoints, and sometimes revising my thinking.
For a pilot starting out, who wants a thorough grasp of the mechanics of flight, a book that was a real eye-opener to me in my early flying days was "Emergency Maneuver Training" by Rich Stowell. I also ended up taking his EMT course. Too much knowledge can never be a bad thing in aviation. Never stop analyzing and thinking.
bbabis
bbabis 1
Well said. Plus, absolutely nothing guarantees that the NTSB gets this right.

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