Plane Down in Hudson River - NYC
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From: alameda
I think along time ago in this thread, I mentioned the concept of flare reserve.
I don't think he had much left in that area and that a higher glide speed would have resulted in an additional flare reserve to cushion the touchdown.
oh well. what is done is done and everything worked out ok for most of the people.
I don't think he had much left in that area and that a higher glide speed would have resulted in an additional flare reserve to cushion the touchdown.
oh well. what is done is done and everything worked out ok for most of the people.
Joined: Dec 1998
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From: England
But is anybody qualified to answer the question asked
........4 posts above
.
.
"This action kept electricals (and hydraulics?) and retained(?) the FBW mode as NORMAL Law (????).
What if he hadn't started the APU? Would sufficient busses have been powered and would battery power for the 5 min flight have been enough? Would the crew have had their full FBW or have been reverted to a lesser law? "
What if he hadn't started the APU? Would sufficient busses have been powered and would battery power for the 5 min flight have been enough? Would the crew have had their full FBW or have been reverted to a lesser law? "
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From: BC
OVERTALK:
The APU supplies only pneumatics and electrical power generation on ground and in the air. (On heavy takeoffs, one can run the packs off the APU to reduce engine bleed and slightly increase power while keeping temperatures slightly lower.) Starting the APU is a standard procedure when an engine is lost so the reaction was a good one given the circumstances.
Here, the engines were still rotating slightly - 35% and 17% if I recall from earlier in the thread but I may be wrong on the numbers - the point is, both hydraulic and electrical power generation can occur at these N2 speeds.
The RAT would not deploy under these conditions as at least one if not both of the two AC buses was powered.
The RAT only powers the "Blue" hydraulic system which would power only the slats. The minimum RAT operating speed is 140kts, so there is another consideration in terms of control and available hydraulic power; they got Flaps to Config 2 so there had to be "Green" and/or "Yellow", (vice 1, 2 or3, or left/center/right), hydraulic system power.
With the RAT extended, an emergency generator driven by a hydraulic motor powered by the blue system can supply limited electrical power. The airplane would be in Alternate Law and there would be limited instrumentation. The possibility of it dropping to Direct Law exists as speed is reduced and hydraulic power lost. At this point it gets a bit messy.
Under the circumstances experienced by this flight, with electrical power the flight control system would have remained in Normal Law and the APU would be providing backup "just in case", rather than powering the aircraft electrical system but in the time available and priorities considered, the crew would almost certainly not make a decision to rely upon windmilling engines.
If the engine(s) had not been supplying electrical power and the emergency generator was unable to supply electrical power, the batteries would supply sufficient power to support the flight control system. The RAT would power sufficient hydraulics to move the necessary surfaces but the flaps could not be extended, only the slats, as described above. It might have turned out slightly differently - bit faster; I believe touchdown was around 107kts, but again that's just from recollection - someone else will surely know and help out.
Further info: On battery-only flight, the battery is certified for 30 minutes but I would not trust that length of time. On an A320 series aircraft, if the APU or the APU generator is u/s and one loses an engine or engine generator in my opinion as a captain that is an emergency and a landing at the nearest suitable airport. The ECAM - LAND ASAP would be an amber, not red message.
The A320 is emminently flyable in Alternate or Direct Law. It becomes a "WYSIWYG" airplane without any of the autoflight system protections. It is not a problem to land in either mode.
If the APU hadn't been started, the degree of controllability that led to a "sufficient" flare (although not optimal - NTSB Report) and subsequent benign ditching might well have been characterised as a crash.... with a significant loss of life due to a greater loss of airframe integrity.
Here, the engines were still rotating slightly - 35% and 17% if I recall from earlier in the thread but I may be wrong on the numbers - the point is, both hydraulic and electrical power generation can occur at these N2 speeds.
The RAT would not deploy under these conditions as at least one if not both of the two AC buses was powered.
The RAT only powers the "Blue" hydraulic system which would power only the slats. The minimum RAT operating speed is 140kts, so there is another consideration in terms of control and available hydraulic power; they got Flaps to Config 2 so there had to be "Green" and/or "Yellow", (vice 1, 2 or3, or left/center/right), hydraulic system power.
With the RAT extended, an emergency generator driven by a hydraulic motor powered by the blue system can supply limited electrical power. The airplane would be in Alternate Law and there would be limited instrumentation. The possibility of it dropping to Direct Law exists as speed is reduced and hydraulic power lost. At this point it gets a bit messy.
Under the circumstances experienced by this flight, with electrical power the flight control system would have remained in Normal Law and the APU would be providing backup "just in case", rather than powering the aircraft electrical system but in the time available and priorities considered, the crew would almost certainly not make a decision to rely upon windmilling engines.
If the engine(s) had not been supplying electrical power and the emergency generator was unable to supply electrical power, the batteries would supply sufficient power to support the flight control system. The RAT would power sufficient hydraulics to move the necessary surfaces but the flaps could not be extended, only the slats, as described above. It might have turned out slightly differently - bit faster; I believe touchdown was around 107kts, but again that's just from recollection - someone else will surely know and help out.
Further info: On battery-only flight, the battery is certified for 30 minutes but I would not trust that length of time. On an A320 series aircraft, if the APU or the APU generator is u/s and one loses an engine or engine generator in my opinion as a captain that is an emergency and a landing at the nearest suitable airport. The ECAM - LAND ASAP would be an amber, not red message.
The A320 is emminently flyable in Alternate or Direct Law. It becomes a "WYSIWYG" airplane without any of the autoflight system protections. It is not a problem to land in either mode.
Per Ardua ad Astraeus
Joined: Mar 2000
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From: UK
Way back in 'history'- around #1768 - Cosmo, I, JW and downin3 took a fair bit of flak ('not SOP' etc etc) for suggesting that it might be a good idea to keep it running for a while after take-off. I still think so. I reckon 3000'/after take-off checks would do me nicely. Stuff the fuel burn!
Joined: Mar 2002
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From: EU
When the A320 went into the Hudson River, the Captain deviated from the checklist cadence and quite appropriately fired up the APU, more or less immediately after the birds hit.
This action kept electricals (and hydraulics?) and retained(?) the FBW mode as NORMAL Law (????)
This action kept electricals (and hydraulics?) and retained(?) the FBW mode as NORMAL Law (????)
all aircraft I flew have enough hydraulic output from a windmilling engine at clean speeds. Below speeds of typically 160-180 hydraulics are lost. You notice every time with an engine out that once reducing below those speeds, the hyd "low press" lights (Boeing) or secondary HYD/FCTL failures (Airbus) will kick in. Also battery power is sufficient for flight controls and primary instruments.
APU start is still important, especially to keep your position awareness as navigation displays (moving map) remain displayed
BTW Airbus goes to alternate law as a result of the "both engines out" condition, regardless of whether hydraulics and electrics are retained.
Not relevant here as flare mode is the same for alternate laws 1 or 2 or normal law.
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From: US
The term "flair reserve" would be what I would use to make a gentle touchdown as Sully did. Airliners are not designed to land in rivers so obviously the aft fuselage had damage but was minor. He did a great job and whoever said he hit the Hudson at over 700 FPM was wrong. We would all try to touch down with a negligable descent rate and it was obvious he did. We all know we would have to maintain over 700 FPM to do what he did to have the energy to flair and stop the descent. Why couldn't the NTSB? If I wasn't so old I would like to work for them but the fun stuff is probably done by the senior guys. I would be pulling up their last physical dates.
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From: Ceduna
Sully did a good job under the circumstances but he had to thank his lucky stars that he had heroes/heroines on the Hudson coming over to effect a quick rescue. Had this been in a remote airport or open seas without the ferries and boats nearby, then any lost of lives or injuries would have caused a VERY DIFFERENT outcome. Then the very difficult questions would have come about the " ditching " switch. The insurance lawyers would be asking very very difficult questions.
The whole episode was caught on camera and the media had made Sully a hero...........Americans love heroes and I am sure this has made the FAA and NTSB shy away from very difficult questions. Make no mistake, Sully's navigational situation awareness was superb and he deserve the accolades for his piloting skills BUT THERE ARE DIFFICULT QUESTIONS!
In other countries the nit pickers in the regulatory and safety bodies may not be so kind.
The whole episode was caught on camera and the media had made Sully a hero...........Americans love heroes and I am sure this has made the FAA and NTSB shy away from very difficult questions. Make no mistake, Sully's navigational situation awareness was superb and he deserve the accolades for his piloting skills BUT THERE ARE DIFFICULT QUESTIONS!
In other countries the nit pickers in the regulatory and safety bodies may not be so kind.
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From: South Africa
I guess the " scooping " motion ad the bottom of the aft empennage contacted water can cause the fuselage to rip apart. Had the outflow valve been close, it would have sealed off the hole and reduced resistance which cause the bottom aft fuselage to rip. Also the ditching switch closes other apertures as well. I must agree, the Americans love heroes and are definitely not going to take this one down like BA did to Captain Burkill. Remember, they also manufacture heroes and heroines out of Iraq and Afghanistan.
With the incident caught on tape and no loss of life, Sully is indeed the perfect poster boy! And deservedly so!
With the incident caught on tape and no loss of life, Sully is indeed the perfect poster boy! And deservedly so!
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From: Feriton
the aft fuselage had damage but was minor
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From: BC
Diamond Bob;
That is correct. The engines never actually failed, they just couldn't accelerate due to blade damage. Full hydraulics and electrical power were available until splashdown at about 130kts.
The NTSB Docket of all available materials associated with the investigation can be found here. Detailed photographs of the fuselage damage are available here. I understand the NTSB will release the full report on May 10th.
PJ2
I believe it was posted in this thread that Airbus announced the plane was in normal law for the entire flight.
The NTSB Docket of all available materials associated with the investigation can be found here. Detailed photographs of the fuselage damage are available here. I understand the NTSB will release the full report on May 10th.
PJ2
Joined: Sep 2007
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From: USA
Wrt the post that had the ditching switch been activated, it would have sealed of the outflow valves, ram inlets etc to prevent water ingestion. Does the switch really do all that ( sorry, not A320 rated )? If it does, I would agree with the poster that sealing off the orifices will help prevent drag forces from ripping open the bottom aft fuselage.
Last edited by woodyspooney; 9th May 2010 at 00:22.
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From: fl
What drag forces? The last three pages of this thread are not readable. I don't think hitting that switch would have made any difference. They did the part of the ditching checklist they had time for and they ditched. Perfect.
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From: Newcastle
In other countries the nit pickers in the regulatory and safety bodies may not be so kind.
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From: India
I suppose it all boils down to Situational Awareness and Decision Making - a classic example of excellent airmanship!
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From: London
Tipsy
Which competent aviation lawyers on the other side would have had no difficulty answering.
Captain Sullenberger's book is worth reading.
FL
The insurance lawyers would be asking very very difficult questions.
Captain Sullenberger's book is worth reading.
FL