Northwest727
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Emergency: When To Land Gear Up Or Not

Mon Feb 21, 2011 6:11 pm

Lets say an aircraft has an emergency. When would a pilot decide to land with the gear up vs. gear down if a partial main landing gear extension has occurred (one of the gear is up while the others are down?

In addition, what about ditching the aircraft, other than water? Example, if a pilot of a PA28R should need to ditch the airplane, is there any terrain that would affect this choice of gear up vs. gear down? Example, corn fields vs. soybean fields, marshland vs. grass (prairie or a golf course),. pine trees vs. hardwood trees, rugged terrain vs. swamp vs. beach?
 
unattendedbag
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RE: Emergency: When To Land Gear Up Or Not

Mon Feb 21, 2011 6:14 pm

Quoting Northwest727 (Thread starter):
When would a pilot decide to land with the gear up vs. gear down if a partial main landing gear extension has occurred (one of the gear is up while the others are down?

I would say, he/she should make that decision at least 3 minutes before touchdown.
Slower traffic, keep right
 
Northwest727
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RE: Emergency: When To Land Gear Up Or Not

Mon Feb 21, 2011 6:39 pm

Quoting unattendedbag (Reply 1):

I would say, he/she should make that decision at least 3 minutes before touchdown.

Appreciate the response, however, I was looking more for along the lines of short runway vs. long runway, runway material, weather, etc. Anything that would effect control-ability upon touchdown and survivability for the passengers. Maybe factor in airframe survivability as well, although that always takes back seat to passengers' lives.
 
wilco737
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RE: Emergency: When To Land Gear Up Or Not

Mon Feb 21, 2011 6:43 pm

Quoting Northwest727 (Thread starter):

There are many many different opinions about that out there. Even in our manuals we only have guidelines what to do.
For a water landing it would be better to have gear up to achieve a smooth touchdown with the aft fuselage. Partial gear would make sense on a normal runway. Keep it 'in the air' as long as possible until some parts of the airplane touches the runway. A full gear up landing on a runway can be bad as well if the belly touches down and you basically cannot control the airplane to weer off to the left or right...
But this is all very theoretical and I hope I never have to make that decision.

wilco737
  
 
Viscount724
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RE: Emergency: When To Land Gear Up Or Not

Tue Feb 22, 2011 2:25 am

Quoting Wilco737 (Reply 3):
A full gear up landing on a runway can be bad as well if the belly touches down and you basically cannot control the airplane to veer off to the left or right...

Reminds me of the PIA 742 that landed gear up at ISB in 1986 (crew forgot to lower the gear). It stayed on the runway. Aircraft was repaired and returned to service.

 
musang
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RE: Emergency: When To Land Gear Up Or Not

Tue Feb 22, 2011 4:47 pm

I would add to Wilco737's post by saying the guideline on the 737 is basically that you land with whatever gear combination you have. I would think the worst case scenario is only one main leg, but one main plus the nose didn't look too dramatic in the USAir landing at Greensboro.

The other basic philosophy is that even if landing on rough ground, use the gear because it will act as an initial shock absorber. The gear will either survive and help protect the fuselage from damage, or if the stresses are too high, it will rip off with minimal colateral damage.

As far as I'm aware, the only emergency landing 737s would be advised to do with the gear UP is on water.

Regards - musang
 
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RE: Emergency: When To Land Gear Up Or Not

Tue Feb 22, 2011 6:58 pm

Landing gear up very seldom causes serious injury to passengers; every gear up accident I have read about that had serious consequences happened because the pilot did something stupid. If the pilot just treats it as a normal landing until the actual impact it almost always comes out OK.
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
 
HaveBlue
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RE: Emergency: When To Land Gear Up Or Not

Wed Feb 23, 2011 3:28 am

An example of the decision your talking about happened a few miles from my house at New Smyrna Beach (EVB) airport. An F-4U Corsair, owned by Collins Foundation and newly restored was being test flown by veteran airshow pilot Dale Snodgrass. The right main gear refused to extend. Dale tried maneuvers in the air and additionally bouncing the plane off of the left gear to try to get the gear to extend. After exhausting all options, he retracted the left gear and opted for a belly landing. Because he shut down the engine prior to touchdown, and because of the Corsairs unique gull wing, little damage was done to the aircraft and it was repaired.

As a side note, and ironically, a pilot was forced to ditch that same F-4U back in '97 after running out of fuel. It was after years of restoration that Dale was taking it up for its first flights when the gear incident happened.
Here Here for Severe Clear!
 
Inbound
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RE: Emergency: When To Land Gear Up Or Not

Wed Feb 23, 2011 4:56 am

practiced partial gear up landing in 738 sim recently with right main not extended.

approach on one engine. good engine had to be shut down prior to touchdown. no speed brake or reversers available.

worked out fine. held off on left main, then eventually rested on right pod.
even with 15Kt xwind, was able to hold centre line and stop within reason....dry conditions this time.
Maintain own separation with terrain!
 
bjorn14
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RE: Emergency: When To Land Gear Up Or Not

Wed Feb 23, 2011 9:08 am

I was told its always best to try to land on a solid suface because what can happen is that the plane will dig into the ground and possibly flip over.
"I want to know the voice of God the rest is just details" --A. Einstein
 
Klaus
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RE: Emergency: When To Land Gear Up Or Not

Wed Feb 23, 2011 2:10 pm

I would guess that landing with whatever gear legs you manage to extend has to do with being able to slow down as far as possible before the unsupported wing ultimately loses too much lift and scrapes the ground. But by that point you should already be well below touchdown speed and the damage should be reduced that way, right?

It would seem plausible that spoilers might not be deployed to keep the unsupported wing afloat as long as possible.

And do I remember correctly that both the 747 and A380 should be able to land safely with at least one main landing gear leg per side extended (and the nose landing gear, of course) provided it is light enough (minimal fuel)?

[Edited 2011-02-23 06:11:02]
 
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RE: Emergency: When To Land Gear Up Or Not

Wed Feb 23, 2011 2:19 pm

Quoting bjorn14 (Reply 9):
I was told its always best to try to land on a solid suface because what can happen is that the plane will dig into the ground and possibly flip over.

Correct. Also, even if the plane doesn't flip the irregular soft surface and chance of rocks are likely to do more damage to the plane than a hard, smooth runway does. I have seen a couple of aftermaths of belly landings on small planes; it's really surprising how little damage it does (except to the prop and engine.)
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
 
113312
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RE: Emergency: When To Land Gear Up Or Not

Fri Feb 25, 2011 1:51 am

I would say that there isn't a cut and dry set of rules for this. In some cases, attempts to lower landing gear may make it impossible to raise it again. So landing with partial gear results and is not an option. It is almost always suggested that landing on water should be done with the landing gear retracted. Landing on a solid surface should be done with landing gear extended. The thought behind this is to absorb energy even if this means the landing gear will be sheared off. However, the aircraft has to be able to get to the point of the intended landing. When making an emergency landing off airport or on a runway, the pilot has to determine if the plane will reach the intended and safest point of touchdown with the landing gear extended. If that cannot be achieved, the only option might be to make the approach with the landing gear retracted and land in that state.

I was once faced with an engine failure, in a single engine plane, at night over mountainous terrain. I made a successful forced landing with the landing gear retracted and am convinced that the outcome would have been different had I attempted to land with the gear extended.

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