NTSB Final Report on US Airways 1549
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I'm often amazed how a CO or FO's innocuous statement in the CVR transcript often presages the coming emergency. Sullenberger blithely states, 30 seconds before the bird strike - "uh beautiful view of the Hudson today.." - perhaps this view spring-loaded him for ditching and helped focus his energies. An attempt to return to LGA would surely have failed.
Fate is the hunter - often the prophetic remark has a darker ending. (UAL 585, AAL 587). -drl |
Thanks for the link, some interesting weekend reading in there, and some wry smiles:
... an Evacuation checklist, which included the following procedures for the captain: select parking brake ON, turn engine master switches 1 and 2 to OFF ... The captain stated that he considered completing his part of the checklist but that he realized that the items would not help the situation On a more serious note:
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PilotS (plural)
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6% of pax got themselves a life jacket http://jetsmoke.com/crash.jpg :} |
A fair and eye opening report to all in aviation.
Three pages of checklist to be completed in 2,500' whilst manipulating switches and providing support to the PF. Also some procedural steps of the stand alone Ditching Checklist missing, i.e. switching off nuisance warnings, i.e. GPWS.
Also, one would hope that there will be a similar change like that that occurred after the SWR 111 fire. If at any stage a Ditching or Forced landing is imminent go straight to the BOXED PRIORITY PROCEDURAL ITEMS, only resume the original checklist if time avails. |
wetbehind the ear
I would use the term : maintain a flare reserve. sadly, I can't open the PDF to read the report...but early on in the discussion, sully mentioned throughout that he just kept the stick back for optimum glide...but didn't have anything left in terms of energy to arrest the descent. |
If a non-pilot might be permitted to make an observation, from what I've read, accurately judging height above water can be difficult, so maintaining excess speed to flare may be of doubtful benefit - a misjudgement could make the resulting impact worse than a steady rate of descent. Imagine the situation in poor visibility. I'd say an 'optimum glide' approach should be all that can reasonably be allowed for...
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someguyonthedeck
in the above post, the test pilot used the raido altimeter/radar altimeter to help judge his height above the water. while on open water, away from other visual references, without the radio altimeter, it would be more difficult. but in New York, with many common things nearby to compare heights, it shouldn't have been too hard. |
SomeGuyOnTheDeck,
And to second what protectthehornet wrote: Basic floatplane skills Calm conditions known as glassy water are the most deceptive phenomenon known to the float pilot. It is an outright dangerous surface to land on if not completely comfortable with the procedures. The height above the water surface is impossible to estimate correctly, making it extremely difficult to judge the final few feet. Many experienced float pilots have been caught up in the deception. The most dangerous glassy water condition is when the water surface is clear. The pilot will be looking at the bottom of the river or lake and not at the surface of the water. |
Protectthehornet, I can see the merit of using a radio altimeter if it is working, but is it necessarily wise to assume it will?
I'm not suggesting that in the case of flight 1549 allowing sufficient excess speed to flare would have been wrong - with hindsight it might have reduced damage and injuries - but as a more general observation, expecting an accurate flare might be unrealistic, and if a plane is to be expected to survive a ditching, a flare should not be assumed. It can't be realistic to assume everything the pilots do in such circumstances is optimal, instead one should assume they are competent, and do what would be reasonably expected. I'd say that those on flight 1549 far exceeded this... |
some guyon the deck
why wouldn't the radio altimeter work? lack of electrical power? hitting the thing with a spanner? the radio altimeter is probably as reliable as the radio (and they used it to call ATC), and the flight controls. And of course, if they had been without a radio altimeter, and on a glassy surface, I too would just set up a min descent and hope for the best but they weren't. quite frankly, I might have gone for interstate 80...but I wonder what the bridge toll would have been. ;-) |
Wasn't Sully just holding the a/c on alpha prot? So the a/c was just flying it's own pitch. I guess it was also trying to action alpha floor to no avail. Amazing it stayed in normal law. Like others he was lucky & the flying technique was not found wanting.
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other way around ...
None of my business really because I'm SLF but I really prefer that the other way around ... the flying technique was not found wanting which gave him the chance to get lucky ....
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About twice as important as sink rate: they hit wings level. The structure took the decel load straight down the fuselage.
One wingtip or nacelle hitting a wave first and it would have been massive yaw, impact loads to the side of the fuse and a broken up airplane, on the bottom in seconds... |
Protectthehornet said:
quite frankly, I might have gone for interstate 80...but I wonder what the bridge toll would have been. As far as luck goes, he was "lucky" in that
But given all of luck elements, both pilots still had decisions to make and actions to take that were all dependent upon their skill levels and years of experience. Would a CRJ jockey on a regional airline fared as well.?? Maybe, but I sort of doubt it. |
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patricakl
thanks for the info on the bridge toll. I'm on the other end of interstate 80 out west. sully minizmied risk to those on the ground by landing on the river. |
Quote: Would a CRJ jockey on a regional airline fared as well.?? Pinnacle 3701. Interesting seeing the transcript that they had a TCAS RA during the final descent. I somehow doubt they would have even heard it. |
i once heard that (especially) Canadian float plane pilots
carry a house brick to chuck out of the window when landing on flat calm water. Perhaps a future modification for the Airbus ?? |
Bridge Toll
PTH
Bridge toll wouldn't have been very high. They charge by axle:D I flew floats in Canada for awhile. On glassy water, we set up a shallow descent in touchdown attitude and waited. As for the brick, that only works if you have power to go around and make another approach to the newly disturbed water. |
I flew floats in Canada for awhile. On glassy water, we set up a shallow descent in touchdown attitude and waited. I cant help thinking that expecting a ditching aircraft to be able to accurately flare is unrealistic in most circumstances - that was the only point I was trying to make. Given the (fortunately) minor injuries received in this incident, it seems that a 'best glide' descent is entirely survivable, and working on this assumption has got to be the starting point for any changes sought as a result. |
Think you make your own luck.
These guys had three and a half minutes in which to diagnose and attempt to rectify an emergency, select an area to land, run the checklist as far as it would take them, inform ATC and pax and then successfully ditch an aircraft at an almost MAUW of 150,000 lbs. |
This is not a "best glide" landing. L/D was over 200 kts(220 KIAS +/-?).
The report says they were 15-19 knots below 'V sub LS' (Vls) and at AOA limit and touchdown was at 750 FPM (12.6 fps). Having some energy to flare might have reduced the impact damage. |
Originally Posted by wetbehindear
In 1 of these 12 runs, a -0.2° touchdown flightpath angle was achieved by an Airbus test pilot who used a technique that involved approaching the water at a high speed, leveling the airplane a few feet above the water with the help of the radar altimeter, and then bleeding off airspeed in ground effect until the airplane settled into the water. Nice one to note.( Can we call it a dive and drive mindset rather than continous descend ? )
Originally Posted by IcePack
Wasn't Sully just holding the a/c on alpha prot? So the a/c was just flying it's own pitch. I guess it was also trying to action alpha floor to no avail. Amazing it stayed in normal law. Like others he was lucky & the flying technique was not found wanting.
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air rabbit
wouldn't the plane allow a flare in a normal landing? is this change in law dependent upon gear down as well as radio altitude????? |
Originally Posted by protectthehornet
wouldn't the plane allow a flare in a normal landing? is this change in law dependent upon gear down as well as radio altitude?????
The "law" that is operational at any given time is related to the status of the computers and the malfunctions or combination of malfunctions existing at any given time. Even though the aircraft OEM cites the probability of a complete computer failure being less than 10, raised to the -9 power, the FAA still requires the pilots to be trained on certain tasks when operating in Direct Law (i.e., without envelope protection), and the simulators used for training must be tested in a representative number of those conditions. There are several sets of circumstances that will put the airplane into operation without envelope protection - "direct law" - notice, I said "sets" of circumstances - that means a combination of circumstances - and I think there are about 10 - 12 such combinations. Unfortunately, some of those combinations can be reached quite quickly in some cases. Sorry for the "ramble." But I think it important that those who are interested should know ALL the available facts. I think Sully and his FO did a wonderful job of maintaining control of the airplane - but, in my estimation, the most significant thing he did was, make a reasonable decision, and he stuck to it - even when others were offering other alternatives. My hat was off to him and his first officer - and will stay that way - particularly knowing the predilictions of the airplane under the conditions that crew was facing - and that just makes that hat position more appropriate. |
thanks rabbit
yes, the right thing to do is stick with your plan, as other options are constantly getting worse while the plan you are on increasingly becomes the only choice. certainly, if a giant aircraft carrier with a mile long flight deck had risen from the hudson, sully could rightly have changed his mind. ;-) I don't care for the airbus and its control laws. I actually could have been captain on the A320 series (for more money) but elected to fly the 737 instead ( also a POS). but that's that. I do think he would have been better off at speed plus 10 to give a better flare (note speed at stick full aft, add ten knots and hold that till flare regime) |
Originally Posted by AirRabbit
While one engine was inoperative, the other one was still operating although not producing much, if any, thrust. It was the continued operation of that engine that prevented reversion to direct law – and thereby prevented any last minute “flare” capability.
That's the early start of the APU by the captain that kept the aircraft in normal law.
Originally Posted by IcePack
I guess it was also trying to action alpha floor to no avail.
Originally Posted by AirRabbit
the computers were still "in control," and alpha floor could not be exceeded
What is surprising is that absolutely no graph from the FDR has been published. Technically speaking Alpha Max has not even been approached during the flare despite the full back stick action by the captain. Finding 24 remains pretty vague : Training pilots that sidestick inputs may be attenuated when the airplane is in the alpha-protection mode would provide them with a better understanding of how entering the alpha-protection mode may affect the pitch response of the airplane. |
:oh:
Sorry about using the wrong term - I'm not a "bus" guy - just under the impression that AFloor was driven by an AoA that when approached disallowed any further increase in AoA and would command an increase in thrust (to TOGA - regardless of throttle position) and a retraction of any speed brake extended. In that there were no speed brakes deployed and (virtually) zero thrust available, the only thing that was accomplished was the disallowance to further increase AoA - regardless of the sidestick position. |
A comment , if I may, from a private pilot. I fly an amphibian and note that being unable to flare more forcefully may have been a saving grace. Aircraft that land in water nose high and in stall tend to touch down tail first and then the nose drops suddenly and forcefully enough to submarine. Note that the fulcrum point for a stall on , U/c up is not around the main U/c position (just aft of the CG,) but further back at the tail. Aft end touch downs cause a strong rotational moment.
Float planes have narrow pontoons with pronounced V which penetrate the surface and act as a cushion. If I stall on my plane, a rather flat hull, it causes pronounced and rather scary porpoising even though the step is only about three feet behind the CG. Just my very humble opinion but attitude is more important that 10 to 20 knots of speed at this point. |
I just read 'Fly by Wire' by William Langewiesche, and can thoroughly recommend it. He describes in a very balanced way what happened not just during the flight but also during the hearings.
He makes clear his view that the crew did a great job and he argues compellingly that the design of the plane also helped. Interestingly there are very few differences between his version of events written last year and the official report just published. |
no one is advocating a full stall landing in this case, but a descent rate of less than 750 fpm would have been better.
lederhosen, as I mentioned a long time ago...other comparable airplanes have done better water landings without any electronic gadgets. |
Are we sure this '750fpm' is correct at 'touchdown'? What I recall of the actual video did not look like a full blown, no arrest ILS rate of descent!
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Protectthehornet I gather we are both 'if its not Boeing I'm not going' captains. I have no axe to grind about Airbus aircraft. The gist of my post was to recommend Langewiesche's book.
Have you read it? It is available in e-book format. If I have any criticism it is that it is a little short. But then again I guess that shows I would have enjoyed reading more. Not being funny but can you list some examples of more successful comparable aircraft ditchings? |
lederhosen, check out Tu-124 on the Neva in 1963. The landing itself was even more successful than Sully's, but yeah — they had more time for pondering the situation. On the other hand, the Neva is more of a slalom course than the straight and wide Hudson.
Tupolev 124 ditching in Neva River - Wikipedia, the free encyclopedia |
Let's see:
PITCH ATTITUDE PROTECTION Pitch attitude is limited to : 30° nose up in conf 0 to 3 (progressively reduced to 25° at low speed). 25° nose up in conf FULL (progressively reduced to 20° at low speed). 15° nose down (indicated by green symbols "=" on the PFD's pitch scale). The flight director bars disappear from the PFD when the pitch attitude exceeds 25° up or 13° down. They return to the display when the pitch angle returns to the region between 22° up and 10° down. HIGH ANGLE OF ATTACK PROTECTION Under normal law, when the angle of attack becomes greater than prot, the system switches elevator control from normal mode to a protection mode, in which the angle of attack is proportional to sidestick deflection. That is, in the prot range, from prot to max, the sidestick commands directly. However, the angle of attack will not exceed max, even if the pilot gently pulls the sidestick all the way back. If the pilot releases the sidestick, the angle of attack returns to prot and stays there. This protection against stall and windshear has priority over all other protections. The autopilot disconnects at prot + 1°. V prot, V floor, V max vary according to the weight and the configuration. To deactivate the angle of attack protection, the pilot must push the sidestick : More than 8° forward, or More than 0.5° forward for at least 0.5 seconds, when < max. In addition, below 200 feet, the angle of attack protection is also deactivated, when : Sidestick deflection is less than half nose-up, and Actual is less than prot – 2°. Note : At takeoff, prot is equal to max for 5 seconds. floor is activated through the A/THR system, when : is greater than floor (9.5° in configuration 0; 15° in configuration 1, 2; 14° in configuration 3 ; 13° in configuration FULL), or Sidestick deflection is greater than 14° nose up, with either the pitch attitude or the angle of attack protection active. The floor function is available from lift-off to 100 feet RA before landing. FLARE MODE The flight mode changes to flare mode when the aircraft passes 50 feet RA as it descends to land. The system memorizes the attitude at 50 feet, and that attitude becomes the initial reference for pitch attitude control. As the aircraft descends through 30 feet, the system begins to reduce the pitch attitude, reducing it to 2° nose down over a period of 8 seconds. This means that it takes gentle nose-up action by the pilot to flare the aircraft. Since the aircraft was in "Normal Law" (one engine is enough to keep it in that mode) it should have behaved as designed, i.e., when crossing 50', it progressively must have changed into Flare Mode, therefore allowing a further increase of the AoA, during those few seconds from 100', (protections lost) till ditching. IMHO - (and this is not to say that Sully made a bad landing, there is still room for proving that there is a better way to ditch an A320) - the best way to glide a FBW aircraft into a ditching, is to fly it stick neutral, once you were able to set-up a glide speed (as we usually do for a landing), in order to allow for (further stick movement) to flare. |
lederhosen
I am thinking of a JAL DC8 at San Francisco, CA USA late 1960's or so...landed in the bay...gear down! plane was recovered and started flying again after repairs. |
Lederhosen - PTH
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Don't remember that one. But I can remember the JAL DC8 with the unstable captain who deliberately crashed into the bay short of Haneda. The poor flight engineer who was trying to restrain the suicidal captain was sadly killed. I don't think the airplane was reusable on that occasion, at least in part due to the interaction with the approach lights. However I think we can all agree that Douglas built strong airplanes.
The successful examples from nearly fifty years ago show this is an unusual enough occurance for airlines to have been seriously considering if they could save weight by ditching the survival gear. The regulators thank heavens saw things differently. I personally was unconvinced up to the Hudson event that a landing on water might be a survivable option, particular given that apart from a non normal checklist in the QRH this is not something normally covered in training. In open waters I still think a happy outcome is not very likely. I was aware of the Russian ditching, again in sheltered waters, the Neva is actually pretty wide for at least a couple of kilometres either side of the Hermitage. You might want to avoid the bridges though! Again they built solid machines. |
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