US Air Plane down in the Hudson River in NYC

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Sir Gallivant
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Re: US Air Plane down in the Hudson River in NYC

Postby Sir Gallivant » Tue Feb 10, 2009 9:20 am

All this mapping of actual positions and altitudes is interesting as an academic exercise. I would sit down and do it if I had the time. However, it doesn't change the choices available to the pilot at the time of engine failure. He asked himself "where can I go and put the aircraft down with minimal damage". He chose the relative safe (at least with regards to innocent bystanders) option of the Hudson that he was sure to make and he discarded the options that he might be able to make. I think ITS made some comments to this decision making earlier in the thread.
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Re: US Air Plane down in the Hudson River in NYC

Postby Gabriel » Tue Feb 10, 2009 1:49 pm

Sir Gallivant wrote:All this mapping of actual positions and altitudes is interesting as an academic exercise. I would sit down and do it if I had the time. However, it doesn't change the choices available to the pilot at the time of engine failure. He asked himself "where can I go and put the aircraft down with minimal damage". He chose the relative safe (at least with regards to innocent bystanders) option of the Hudson that he was sure to make and he discarded the options that he might be able to make. I think ITS made some comments to this decision making earlier in the thread.

I fully agree.

In fact, it was another forum member (not ITS) who first brought that line of thought into this thread several pages earlier:
It looks from the flight tracks that the airplane would have been able to reach and land both in Teterboro or La Guardia [...]. However, this is what it "looks" now, not what the flight crew "knew" then. Unless it's by a large margin, it's very hard to tell whether an airplane will be able to glide and reach some specific point or not. [...]. If you know for sure that you can easily reach a river with calm waters and are not almost 100% sure that you can reach reach an airport after overflying dense population and high buildings, it looks like the right decision, though a very tough one, is to choose the river.


Then ITS corrected (?) that, saying more or less the same.
ITS wrote:Actually Gabriel it is very easy to tell how well an aircraft glides and where you will end up. What the crew knew was not to stretch a glide. If it is marginal you take another option. It is the premise of every forced landing a pilot practices from his very first training.
Last edited by Gabriel on Tue Feb 10, 2009 1:51 pm, edited 1 time in total.

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Re: US Air Plane down in the Hudson River in NYC

Postby Putt4Par » Tue Feb 10, 2009 1:50 pm

I guess this is a question for DP, ITS, Flyboy, RCL......or some informed parlour talker :mrgreen:

It caught my attention that Sully was flying the airplane and also talking to ATC. Wasn't that the job of the co-pilot or do things change in case of an emergency? I imagine Skiles was going through the ditch checklist. I figured it would have been easier for Sully to leave the communications to his copilot.

And another question: when you ditch I imagine you need to go as slow as possible. Does that mean you get flaps and slats out to the max or is the procedure to keep them retracted for ditching?

I apologize in advance if the answers to my questions are obvious.

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Re: US Air Plane down in the Hudson River in NYC

Postby flyboy2548m » Tue Feb 10, 2009 2:03 pm

Putt4Par wrote:I guess this is a question for DP, ITS, Flyboy, RCL......or some informed parlour talker :mrgreen:

It caught my attention that Sully was flying the airplane and also talking to ATC. Wasn't that the job of the co-pilot or do things change in case of an emergency?


No. In case of an emergency, here's what we're trained to do. The flying pilot states (clearly and loudly) to the PNF "I have the aircraft and the radios, please perform the xxxx checklist/memory items".
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Gabriel
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Re: US Air Plane down in the Hudson River in NYC

Postby Gabriel » Tue Feb 10, 2009 2:06 pm

Putt4Par wrote:I guess this is a question for DP, ITS, Flyboy, RCL......or some informed parlour talker :mrgreen:

It caught my attention that Sully was flying the airplane and also talking to ATC. Wasn't that the job of the co-pilot or do things change in case of an emergency? I imagine Skiles was going through the ditch checklist. I figured it would have been easier for Sully to leave the communications to his copilot.

And another question: when you ditch I imagine you need to go as slow as possible. Does that mean you get flaps and slats out to the max or is the procedure to keep them retracted for ditching?

I apologize in advance if the answers to my questions are obvious.

Informed parlour talker here:

In an emergency the flying pilot handles the radio, the non-flying pilot has a high workload running the checklists.
In this case the flying pilot was originally the copilot, and the captain (the non-flying pilot) was handling the radios.
When the emergency emerged, the captain decided to swap roles and assume the flying pilot duties (which during the emergency include handling the radio).

About the flaps, I have read one airliner ditching checklist (I think it was the A-320 but I don't remember for sure) that calls for max flaps available. [EDIT to add, but I doubt that they ever got tht far in the checklists]

In theory, you want the slowest speed possible, but at some point adding more flaps add a lot more of drag (that when you don't have power to overcome that drag it translates into a much steeper approach) with minimum reduction in the stall speed.

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Re: US Air Plane down in the Hudson River in NYC

Postby Procede » Tue Feb 10, 2009 2:35 pm

Gabriel wrote:About the flaps, I have read one airliner ditching checklist (I think it was the A-320 but I don't remember for sure) that calls for max flaps available. [EDIT to add, but I doubt that they ever got tht far in the checklists]

In theory, you want the slowest speed possible, but at some point adding more flaps add a lot more of drag (that when you don't have power to overcome that drag it translates into a much steeper approach) with minimum reduction in the stall speed.


More important is that higher flap settings give the aircraft a much lower angle of attack and thus nose down attitude when hitting the water.

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Re: US Air Plane down in the Hudson River in NYC

Postby Dmmoore » Tue Feb 10, 2009 5:46 pm

A some points.
1. The ditching was 100% successful. All passengers and crew survived.
2. By choosing the river as the landing area the crew had use of the largest clear area in NYC.
3. It's obvious they could have reached an airport. A direct course would place the aircraft over Teterborough airport but not aligned with a runway. A turn back to LaGuardia would require another 90 degree turn from a point where Flight aware has them at 1200 feet, 5 miles from the runway. The aircraft lost 1600 feet making the turn to align with he Hudson. Returning to LaGuardia was possible but at the limit of the aircraft's performance.
4. Aligning the aircraft with a runway at Teterborough requires a 60 (+or-) degree change of heading and places the aircraft over populated areas for the entire time the aircraft is airborne. The aircraft would have to be aligned with the runway some distance away from the touchdown end lengthening the distance the aircraft has to cover.
5. See point 1.
A pilots first responsibility is to safely operate the aircraft. When during emergencies the pilots responsibility shift to protecting the passengers and crew. Sacrifice the aircraft if necessary to protect human life.
Could ah - Would ah - Should ah be damned. This crew did the job for which they were hired. And they were 100% successful. End of story.
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Re: US Air Plane down in the Hudson River in NYC

Postby Dmmoore » Tue Feb 10, 2009 6:00 pm

Procede wrote:
Gabriel wrote:About the flaps, I have read one airliner ditching checklist (I think it was the A-320 but I don't remember for sure) that calls for max flaps available. [EDIT to add, but I doubt that they ever got tht far in the checklists]

In theory, you want the slowest speed possible, but at some point adding more flaps add a lot more of drag (that when you don't have power to overcome that drag it translates into a much steeper approach) with minimum reduction in the stall speed.


More important is that higher flap settings give the aircraft a much lower angle of attack and thus nose down attitude when hitting the water.


The difference between stall speed with takeoff flaps set and full flaps isn't that much (<10 knots). The increased drag steepens the approach angle, shortens the glide and takes times to set and stabilize. Moving the flaps changes the aircrafts trim and as noted, attitude. Most pilots will land with what they have rather than reconfigure the aircraft at the last minute.
Don't forget, it worked. If it had resulted in disaster, we would have something to talk about.
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Re: US Air Plane down in the Hudson River in NYC

Postby Dmmoore » Tue Feb 10, 2009 6:04 pm

aardvark2zz wrote:
David Hilditch wrote:Re: aardvaark's chart/map, I am not sure how accurate this is. Is it each spot supposed to repesent the aircraft's track and height above ground ? If so, it's not correct, since the 300 feet marker is well to the south of where it actually ditched, so the 300 feet arc would have been further north, I think. The ditching took place a little to the north of the Intrepid carrier, which is at 46th Street - so let's say 48-50th Street. However, the 300 feet marker, at its most generous, cannot be north of around the 23rd-24th Street area. The point of impact, in my judgment, was about one third of the distance south from the 400 feet marker to the 300 feet marker. For reference, the street at the southerly base of Central Park is 59th.

Also, why did he climb 100 feet from 1200 to 1300 feet ? Just equipment readout inaccuracy ?


The data is from flightaware.

Around the time of your post I finally found the location of the touch down pt which is near the Intrepid.

That means it's closer to the 400ft pt like u wrote. But it looks like the 2 airports can still be reached; even with the same flap schedule as actually flown (but gear up).

I wonder if all or some of the data points just need to be shifted north (maybe) by the error which is around 2000 ft horiz, including the 2000ft ASL pt. In that case the 17.77 km "glide" possibly remains the same.


It would appear the accuracy of the GPS reporting points displayed on Flightaware are not 100% accurate.
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Re: US Air Plane down in the Hudson River in NYC

Postby AndyToop » Tue Feb 10, 2009 7:11 pm

aardvark2zz wrote:AWE1549 US AIRWAYS RADIUS OF GLIDE WITHIN LAGUARDIA AND TETERBORO. Glide down to 300 ft ASL from 2000 ft ASL turn point. 17.77km "glide".


aardvark2zz what are you using as the glide ratio?
the consensus on best glide ratio from the quotes I have found put it at 17, which would give you 34000ft from 2000ftASL, or a little over 10km.

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Re: US Air Plane down in the Hudson River in NYC

Postby AndyToop » Tue Feb 10, 2009 7:27 pm

Just checked on google earth. From 40.88 -73.90 the 2000ft point, to the threshold of RWY 24 at Teterboro is 43,400 ft.
I'm not sure he could have made it.

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Re: US Air Plane down in the Hudson River in NYC

Postby aardvark2zz » Tue Feb 10, 2009 10:05 pm

Remember, the plane still had some thrust. I used the flightaware data of the actual flight and not from a handbook, for better or for worst. If you have better data pls do post it. One suggestion is to try to figure out the error in the radar data pts; filter/process them. Maybe some of the radar data points are from far away radars and some are from close by. Maybe consider radar beam tilt and angular errors in your calcs. Maybe, use data from one radar only. See Dmmoore's data.

I'm happy they ditched in the water. Future flights now know that a proper ditching is possible.

It's too bad that the crew didn't mention, to my knowledge, that it was great that the plane didn't break up, and congratulate the A320 plane, it's designers, and government specs.

Apparently the back door was opened by a hysterical female passenger, in front of the stewardess*, which allowed the quick flooding of the tail.

* The "blonde" one that now refuses to wear her uniform to interviews.

see cbs 60 minutes interviews (5 parts) http://www.youtube.com/profile?user=nypdcar1&view=videos
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Re: US Air Plane down in the Hudson River in NYC

Postby 3WE » Wed Feb 11, 2009 12:39 am

aardvark2zz wrote:...Remember, the plane still had some thrust. I used the flightaware data of the actual flight...


On the other hand, we have to remember that the knowedge of just how much thrust they had and the knowledge of how far they could actually make it (based on actual flightaware data) is something that was not available until after they splashed down, got hauled to shore, went on the internet, and went through Ardvark2zz's steps.

And- mega parlor talk: Practicing dead stick landings in an average light plane at 800 ft AGL on an extreeeemly tight traffic pattern (compared to an airliner) at a small airport.....you can't pull the throttle at mid-field downwind or you'll wind up short....extrapolating that to 2000 ft and several miles from the airport just doesn't seem to add up to getting back.
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Re: US Air Plane down in the Hudson River in NYC

Postby Giles » Wed Feb 11, 2009 2:04 am

aardvark2zz wrote:Remember, the plane still had some thrust.

hmmmmm..... idle is considered thrust?

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Re: US Air Plane down in the Hudson River in NYC

Postby aardvark2zz » Wed Feb 11, 2009 4:53 am

Where did you get that they were at idle thrust ? There was some talk earlier on that there was some thrust, can't remember where, here or pprune, certainly not jetphotos ;)

Assuming the levers were placed high enough - the engine's computers will give the max thrust that the engines can deliver.

Anyone know if an undamaged core can deliver full rpm (and serious low-bypass thrust) even though the fan is seriously damaged ?
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Re: US Air Plane down in the Hudson River in NYC

Postby aardvark2zz » Wed Feb 11, 2009 5:12 am

This co-pilot and his smile and mustache makes me laugh. All he needs is a leather cap and he'll look right at home in the 1920's or in the movie The Great Waldo Pepper.
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Re: US Air Plane down in the Hudson River in NYC

Postby Giles » Wed Feb 11, 2009 11:08 am

aardvark2zz wrote:Where did you get that they were at idle thrust ?

see my post page 11and see don's post regarding n2 speed.

also, if the fo was attempting to restart both engines i ould think that the engines were dead.

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Re: US Air Plane down in the Hudson River in NYC

Postby aardvark2zz » Wed Feb 11, 2009 4:25 pm

Then explain the 17.77 km* or 29:1 "glide" from the 2000 ft ASL turn. (note 17.8 km = 58,400 ft).

* Or whatever "glide" distance.
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Re: US Air Plane down in the Hudson River in NYC

Postby Giles » Wed Feb 11, 2009 4:50 pm

aardvark2zz wrote:Then explain the 17.77 km* or 29:1 "glide" from the 2000 ft ASL turn. (note 17.8 km = 58,400 ft).

why?
the engines were not producing thrust. thats it.
your graphic makes no sense.

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Re: US Air Plane down in the Hudson River in NYC

Postby Dmmoore » Wed Feb 11, 2009 5:35 pm

Al Weaver has produced a 20 minute video / audio presentation of the event using real time communications between the aircraft, ATC and ground personnel.

http://fromtheflightdeck.com/Al/USAIR1549%20ATC-1.mpg
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Re: US Air Plane down in the Hudson River in NYC

Postby aardvark2zz » Wed Feb 11, 2009 6:53 pm

Giles wrote:
aardvark2zz wrote:Then explain the 17.77 km* or 29:1 "glide" from the 2000 ft ASL turn. (note 17.8 km = 58,400 ft).

why?
the engines were not producing thrust. thats it.
your graphic makes no sense.


To you, not us.
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Re: US Air Plane down in the Hudson River in NYC

Postby Giles » Wed Feb 11, 2009 7:10 pm

aardvark2zz wrote:
Giles wrote:
aardvark2zz wrote:Then explain the 17.77 km* or 29:1 "glide" from the 2000 ft ASL turn. (note 17.8 km = 58,400 ft).

why?
the engines were not producing thrust. thats it.
your graphic makes no sense.


To you, not us.
.

who is "us" ?

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Re: US Air Plane down in the Hudson River in NYC

Postby aardvark2zz » Wed Feb 11, 2009 7:39 pm

Skiles on Charlie Rose said that a senior training pilot at the airline simulated the flight and failed 25 times to reach LaGuardia. No mention at what point along the "glide" they tried to turn back to LaGuardia.

http://www.charlierose.com/view/interview/10069
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Re: US Air Plane down in the Hudson River in NYC

Postby aardvark2zz » Wed Feb 11, 2009 7:43 pm

Giles wrote:who is "us" ?


As said at http://www.airdisaster.info/forums/viewtopic.php?f=6&t=1945&p=26466#p26428

If you have better data pls do post it. Or if you have other engine EPR, RPM, etc. data pls do post it.
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Re: US Air Plane down in the Hudson River in NYC

Postby Giles » Wed Feb 11, 2009 7:55 pm

aardvark2zz wrote:
Giles wrote:who is "us" ?


As said at http://www.airdisaster.info/forums/viewtopic.php?f=6&t=1945&p=26466#p26428

i dont think there is one person on here who believes the accuracy of your graphic.
so, please tell me, who is "us" that you refer to.

If you have better data pls do post it. Or if you have other engine EPR, RPM, etc. data pls do post it.


Dmmoore wrote:Normal idle N-2 should be in the 55 -60% range.
Normal idle N-1 should be in the 25 - 30% range.


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