rheinwaldner
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Ditching With A High-wing Plane. Possible?

Tue Jan 20, 2009 12:44 pm

Regarding the recent ditching of an A320 I wondered whether an Avro RJ type of aircraft with high wings would have a chance too.

Points to discuss:
- Having the engines and the wing not in the water the fuselage probably would sink much deeper.
- All buoyancy had to come from the fuselage
- The landing probably would be easier, because the fuselage alone would hit the water.
- Being formed like a boat the fuselage probably would behave well on the water.
- The chances that the body remain intact are almost better
- After evacuation the wings can not be used to put people on

Because of instability in the longitudinal axis the aircraft would probably tilt to one side. Maybe this would allow to evacuate the plane easily on the side that "looks out of the water" (while the other side would be completely under water) -> a good strategy could be to open the doors not before the plane came to rest and the leave the doors which go under the waterline closed.

Are there events of high-wing planes which ditched in the past?
 
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SEPilot
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RE: Ditching With A High-wing Plane. Possible?

Tue Jan 20, 2009 12:47 pm

My experience with high winged aircraft is with Cessnas, which usually have fixed gear. The problem with ditching them is that they almost always flip over. This may improve bouyancy, but makes survival and exiting the aircraft much more problematic.

[Edited 2009-01-20 05:17:39]
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
 
rheinwaldner
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RE: Ditching With A High-wing Plane. Possible?

Tue Jan 20, 2009 1:08 pm



Quoting SEPilot (Reply 1):
which usually have fixed gear

I assume fixed gear are quite difficult to handle in all cases. Worse than the engines on a low-wing plane.
 
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SEPilot
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RE: Ditching With A High-wing Plane. Possible?

Tue Jan 20, 2009 1:17 pm



Quoting Rheinwaldner (Reply 2):
I assume fixed gear are quite difficult to handle in all cases. Worse than the engines on a low-wing plane.

True; but a low-winged fixed gear plane may be easier to handle. If it does flip, however, you would be in much worse shape.
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
 
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Scooter01
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RE: Ditching With A High-wing Plane. Possible?

Tue Jan 20, 2009 6:10 pm

What happened to the Tunisair ATR-72 comes to mind,
-empty fueltanks and all...

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Dogbreath
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RE: Ditching With A High-wing Plane. Possible?

Tue Jan 20, 2009 9:51 pm

Yep it happened to a Columbian C-130 that ditched in the Atlantic Ocean in 55kt winds after running out of fuel en route Azores-Bermuda due to a navigation system failure; the Hercules remained afloat for 2 days in Oct 1982.
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acabgd
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RE: Ditching With A High-wing Plane. Possible?

Wed Jan 21, 2009 1:32 am



Quoting Scooter01 (Reply 4):
What happened to the Tunisair ATR-72 comes to mind,
-empty fueltanks and all...

Yes, that's interesting. I never actually learned if they ditched properly or cartwheeled or...?
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speedygonzales
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RE: Ditching With A High-wing Plane. Possible?

Wed Jan 21, 2009 2:02 am

IIRC (been a while since I last flew with them), Widerøes Dash-8 safety cards show that only the front exits should be used after a ditching. Presumably the plane will float with the nose high enough to keep both exits above water.
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Alessandro
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RE: Ditching With A High-wing Plane. Possible?

Wed Jan 21, 2009 11:54 am

If you look upon all seaplanes without floats (well floats on the wingtip doesn´t count)
you´ll see that most are high wing, Be-103 one exception which is low wing. So ditching is definitly possible.
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OldAeroGuy
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RE: Ditching With A High-wing Plane. Possible?

Wed Jan 21, 2009 7:15 pm



Quoting Alessandro (Reply 8):
If you look upon all seaplanes without floats (well floats on the wingtip doesn´t count)
you´ll see that most are high wing

Their fuselages are also designed to withstand the impact of landing on water at a controlled sink.

Power off sink rates with normal fuselages are more likely to have skin failures so the hull doesn't act like a boat any longer.
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
rheinwaldner
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RE: Ditching With A High-wing Plane. Possible?

Thu Jan 22, 2009 12:12 pm



Quoting OldAeroGuy (Reply 9):
Power off sink rates with normal fuselages are more likely to have skin failures so the hull doesn't act like a boat any longer.

If you build up speed before you can achieve later any desirable sink rate. I don't see the problem.
 
OldAeroGuy
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RE: Ditching With A High-wing Plane. Possible?

Thu Jan 22, 2009 5:42 pm



Quoting Rheinwaldner (Reply 10):
Quoting OldAeroGuy (Reply 9):
Power off sink rates with normal fuselages are more likely to have skin failures so the hull doesn't act like a boat any longer.

If you build up speed before you can achieve later any desirable sink rate. I don't see the problem.

The difficulty with any water landing is judging how far you are off the water. As a result, sea/float planes generally do no flare landings and are flown onto the water under power at low sink rates.

If you're doing an unpowered landing like the US Air - Hudson event, you only get one chance at hitting the water with a low sink rate. If you miss judge with either an early flare or a late one, fuselage damage will be the likely result.

On a low wing airplane, the wings will give you another chance at useful flotation that isn't there for a high wing airplane.
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
prebennorholm
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RE: Ditching With A High-wing Plane. Possible?

Thu Jan 22, 2009 10:55 pm

By careful study of those very unclear pictures, which have been released of the US 1549 ditching, it seems to me (mostly from the water spray) that the plane was initiately "waterskiing" on the engines. Do any others see the same?

If that theory is correct, then it was really a masterpiece of a "landing". That way it can have bled off considerable speed before it fell lower into the water, breaking off only one engine.

That stunt cannot be made with a high wing plane.

This very lucky US 1549 event - just like the safety cards - makes us assume that ditching with a modern jet airliner is generally surviveable. Luck is needed as well.

Imagine just one of the following situations during the US 1549 ditcing:
- dark night
- low visibility
- moderate wind and consequently waves on the river
- it had happened a couple of days later when ice had drifted down the river.

When things go bad, then extreme forces are at play. Forced which the fuselage is not designed to cope with.

That said, ditching after running out of fuel is a lot more fortunate and surviveable than US 1549 which carried a heavy load of fuel. US 1549 was probably way heavier than certified max landing weight making the landing speed pretty high. The forces at play increases with the square of the landing speed increase. Also the wing is the strongest part of the plane. With empty wing tanks it will keep the plane floating even if the fuselage fails badly and fills with water.

On the Tunisair ATR, which ran out of fuel, the fuselage broke in three pieces because there were waves on the sea. The middle section, connected to the wing, kept floating and would have floated forever. But it was of course submerged. The two other sections sank.

Because it was summer, and the water was nice and warm, only 14 out of 39 souls perished. Also the ATR landing speed is a good deal lower than an ordinary jet plane, making the whole thing more surviveable.

If I should ever be on a ditcing plane, then I think that I would prefer a low wing plane. And I wouldn't mind having Sully in control in the front office. Anyway, for an average ditcing without extreme luck I wouldn't give myself a 50% chance of survival.

It looks so simple on those safety cards. "Just tighten that seat belt when we land on the water, then take on your life vest, inflate it, and swim ashore. And finally claim a partial refund of your ticket because we didn't bring you all way to destination". Reality is much tougher. Those planes are not made for that sort of stunt.

It isn't all that easy even wtith planes which are made for it. I once knew a captain who back in the 50'es lost a Royal Danish Air Force PBY-5A Catalina while landing on a completely calm sea. Because the sea was absolutely like a mirror he misjudged the flaring. Consequently he made a rough landing, the hull broke, and the plane sank to the bottom of the sea. No injuries, however, but sure that plane didn't fly again. Of course the crew were all fit military men who had trained for that stunt. If grandma had been on board the story might have had a less happy end.
Always keep your number of landings equal to your number of take-offs
 
rheinwaldner
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RE: Ditching With A High-wing Plane. Possible?

Fri Jan 23, 2009 11:15 am



Quoting Prebennorholm (Reply 12):
Imagine just one of the following situations during the US 1549 ditcing:
- dark night
- low visibility
- moderate wind and consequently waves on the river
- it had happened a couple of days later when ice had drifted down the river.

+ it would have been a pilotless aircraft as discussed last year in this forum! Ferryships had to be equiped with TCAS!  Wink
 
MD-90
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RE: Ditching With A High-wing Plane. Possible?

Sun Jan 25, 2009 9:54 am



Quoting SEPilot (Reply 1):
My experience with high winged aircraft is with Cessnas, which usually have fixed gear. The problem with ditching them is that they almost always flip over.

Hmmm....while Cessnas with amphibious floats that land with the gear extended are notoriously prone for flipping, I'm don't think you can say that they almost always flip over. And it appears (form Doug Ritter's excellent Equipped to Survive website:

Myth 2: If I Have to Ditch, I'm Better Off in a Low Wing Than a High Wing Airplane

You won't convince us of that. Of the 179 ditchings, 87 involved high wing airplanes (49 percent), 73 were low wings (41 percent), and the rest were helicopters.

Yet, in the subgroup that involved fatalities, high wing airplanes were noticeably underepresented: Although they were involved in 49 percent of all the ditchings, they represent only 27 percent of the fatalities. On the other hand, low wing airplanes represent 41 percent of the total ditchings, but accounted for 68 percent of the fatalities.

We don't make a great deal of this finding due to the small actual numbers involved, other than to note that it doesn't at all support the widely held notion that high wing airplanes sink to their struts and trap the occupants. If high wing airplanes are more difficult to get out of in the water--and we think that's debatable--it certainly doesn't keep people from getting out of them. Which leads directly to myth number 3…


(the above data was extrapolated from NTSB files from 1985-1990 and 1994-1996 involving 179 intentional ditchings--the survival rate for the occupants was 92%)
 
Alessandro
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RE: Ditching With A High-wing Plane. Possible?

Sun Jan 25, 2009 2:43 pm



Quoting OldAeroGuy (Reply 9):
Their fuselages are also designed to withstand the impact of landing on water at a controlled sink.

Power off sink rates with normal fuselages are more likely to have skin failures so the hull doesn't act like a boat any longer.

Sure it´s never good to ditch a plane compared with seaplane.
Thank´s MD-90, interesting stats.
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phatty3374
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RE: Ditching With A High-wing Plane. Possible?

Thu Feb 05, 2009 2:08 am



Quoting MD-90 (Reply 14):
Yet, in the subgroup that involved fatalities, high wing airplanes were noticeably underepresented: Although they were involved in 49 percent of all the ditchings, they represent only 27 percent of the fatalities. On the other hand, low wing airplanes represent 41 percent of the total ditchings, but accounted for 68 percent of the fatalities.

Well I will bet you that the low wing airplanes that had to ditch carried far more passengers than the high winged airplanes which would make up the statistical discrepancy. How many people can the largest high wing airplane (that has ditched) carry vs. the largest low wing airplane that has ditched?
 
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SEPilot
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RE: Ditching With A High-wing Plane. Possible?

Thu Mar 19, 2009 6:25 pm



Quoting MD-90 (Reply 14):
And it appears (form Doug Ritter's excellent Equipped to Survive website:

Thanks for posting that; it was very informative. As is usually the case, "what everyone knows" seems to be far from reality. I must admit that most of my knowledge about ditching comes from general pilot's lore; I have never known anyone who has actually experienced it. I do have friends (non-pilots) who witnessed a couple of friends of theirs attempt to ditch a plane, and they did not survive. But I don't know any of the details.
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler

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