Jump to content

A Crash Landing Technique?


Recommended Posts

Imagine that you have the misfortune to be flying along on a cross-country jaunt when your airplane suffers engine failure which means that you will soon be back on the ground, BUT the terrain you are flying over presents no suitable, cleared landing patch - just trees or rock-strewn paddocks. You know that your arrival at ground level will result in the airplane being severely damaged. How do you handle the landing??

 

Old advice is that you have to fly the airplane as far into the crash as you can. So the first requirement is to decide that the approach to landing will be the sort that would result in a 'greaser' in front of the Sunday crowd at your home field. All that remains is to decide how to fly the last two feet.

 

In my opinion, the airplane should be side-slipped to the ground, trying to make the wingtip furthest from you hit first. Obviously, every attempt should be made to reduce ground speed to a minimum.

 

What's my reasoning? Well your moving airplane has Momentum, which is dependent on speed and weight.

 

M = mass x velocity

 

(Not quite the correct scientific words to use, but clear enough for this post). Momentum is a form of Energy, and this energy has to be dissipated before the airplane will stop. One way to dissipate the energy is to distort structures. That's why modern cars have front and rear 'crumple zones'. In a collision, the car's momentum distorts the material in the crumple zones so that the total momentum of the car is reduced before the cabin area starts to distort.

 

If the airplane is flown with the nose leading the motion, this sequence will happen.The front of an airplane usually contains a big mass of heavy metal (the engine) supported by relatively soft metal (engine bearers). In a front-on impact, the first parts of the airframe to bend and break are the bearers. This allows the cabin to collided with the rear of the engine, without much of a reduction in momentum. The next thing which can dissipate energy is the instrument panel, and then when it crumples, the occupants are next in line to get rid of the momentum. Have a look at some photos of WWl flying crashes. The pilot is usually slumped over the front of the cockpit, and the engine has been pushed back. Note that the wings are often only slightly damaged.

 

What I am suggesting is that by side-slipping to the ground and trying to have the wingtip furthest from you hit first, it will be the wing spar that will start collapsing first, and there are quite a number of feet of strong material to break up before the force exerted by the ground reaches the fuselage (Remember Newton's Second). The airplane may rotate around the collapsing wingtip, but this will have the advantage of making the engine collide with the ground at an angle to the longitudinal axis of the airplane, and may cause the engine to rotate away from the cabin, where you are sitting. This rotation with force you to the rear and centre of the cabin away from the collapsing instrument panel. However when it is your turn to do some momentum dissipating, you will stop your rearward motion and start to move forward, but towards the side of the cabin which is going to be a lot softer that the instrument panel and engine.

 

So my suggestion for surviving a crash landing onto unforgiving terrain is to:

 

1: Fly the airplane into the crash as slowly as possible, while still maintaining directional control.

 

2: Side-slip your approach to the impact point, with the wing tip furthest from you leading the motion.

 

3: Prepare for the impact of your body with the side of the cabin on the opposite side of the airplane to the wingtip that hit first.

 

There is one thing that will affect your decision as to which wingtip hits first - if you are flying with a passenger in a side-by-side, you have a moral and legal Duty of Care, to place your passenger's welfare above your own. In that case, you land on the wingtip on your side. "Greater love hath no man ..."

 

I'd suggest that as an exercise in airplane control, you shoot some circuits on a calm day and make each landing a power off, side-slip approach, so that you get a feeling for what the situation looks like.

 

WARNING and DISCLAIMER

 

Before conducting side slip manoeuvres in landing configuration with flaps, consult your airplane's Operator's manual to see if such manoeuvres are permitted.

 

Old Man Emu

 

 

  • Like 2
  • Caution 2
Link to comment
Share on other sites

The prang-a-wingtip-first theory might sound OK but in practice I think it's likely to be a showstopper.

 

For one thing I doubt you could get sufficient slip angle and wing-down angle to plant the wingtip of a high-wing plane so the theory might only apply to a low-winger with minimal dihedral and I think the tip might just be deflected off the ground, hard ground in any case, and the next thing to contact would be the gear leg which might not produce any great benefit.

 

Further - if you stop one wingtip suddenly the other wingtip will double its speed in an instant and rather than cause a flat rotation, when the similar event occurs with a float-plane or floating hull plane that dips a wingtip inadvertently, the opposite wing's doubled airspeed lifts it to the vertical and cartwheels the plane tip over tip. That's bad enough in water but would slam the nose of the plane into the ground much harder than might result from most other crash-landing methods. This is not an uncommon scenario in gliders/sailplanes when tip-stalled near the ground and they dig a wingtip in, and frequently fatal.

 

I'd also imagine that it'd be harder to get the high slip/bank angle that you seek at the slowest possible speed. In my experience the biggest slips are achieved at quite high speed and I wouldn't really fancy flying myself into the ground that fast ...

 

 

Link to comment
Share on other sites

One problem with this theory is that the body can tolerate much greater forces in a fore-aft direction than sideways. Sideways or twisting forces are much more likely to do internal damage.

 

Landing into the wind is very important. The likelihood of death/injury goes up VERY quickly with increasing speed of impact.

 

 

Link to comment
Share on other sites

You may very well be correct to a point, however when the engine stops the damn thing belongs to the insurance company so the primary focus is all getting out with the least injury as possible. For my money it would be to take the wings off between two trees if possible and hang on!!

 

 

  • Agree 4
Link to comment
Share on other sites

I reckon clipping one wing would pivot the plane pretty hard into the ground. I say go straight and shallow, make your priority to maintain enough speed so you don't stall or are mushing when you hit the ground.

 

 

  • Agree 1
Link to comment
Share on other sites

I Agree with FT.

 

Seems to me (I'm no expert) that we are getting some advice here which would be similar to someone saying "if your brakes in your car fail, remove your seatbelt and pull the handbrake on so that you hit boot first."

 

I think the risk when hitting one wing first is (as was mentioned by HITC) the risk of it turning into a perpendicular impact for the cockpit, which would be devastating.

 

I think it would be much more diligent to have the shallowest straight arrival that you can without stalling it in.

 

It would be nice to have some extra speed BEFORE your flare to ensure adequate elevator authority but you also have to take into account the danger of a long flare missing your targeted softest patch in the rough, this of course will vary greatly from machine to machine.

 

Thinking of how much it will cost to repair the plane will in no way profit you while you are still on descent.

 

At the end of the day I am sure we are told to fly as far into the crash as we can for a VERY good reason, the longer we can keep the plane straight without obviously hitting a tree trunk or cliff the slower we will be getting and the less it will hurt. Doing something that could turn our shallow arrival into a vertical impact is adding danger that we wouldn't need.

 

And finally I think side slips are a VERY VERY useful tool to have and they are something I enjoy practicing but just don't like the idea of arriving that way:thumb up:

 

And finally finally I don't mean to offend anyone and enjoy the fact that this is so far a friendly discussion:spot on:

 

 

  • Agree 1
Link to comment
Share on other sites

I landed a Chinook ultralight on one wing to avoid hitting a ditch one time. This resulted in one complete cartwheel and the plane came to rest facing the direction it had been travelling. There was a fair bit of damage to the plane but I did not get a scratch.

 

 

  • Informative 1
Link to comment
Share on other sites

Which part of your aircraft can absorb most energy? The undercarriage can soak up lots, so your least-worst option may be getting your approach speed back to the ragged edge so that you stalling a metre of two above the ground.

 

 

Link to comment
Share on other sites

Or, just pop the BRS. Problem solved.

Maybe... It's a last resort and by pulling that handle you surrender control. You still decend at 7m/sec. or more.

Maybe flying into the "crash" and launching the 'chute about four seconds before impact would be a good compromise. As long as the rocket puts the canopy somewhere behind you it has time to open enough to arrest most forward motion.

 

 

Link to comment
Share on other sites

I am with TP on this one exclamation.gif.7a55ce2d2271ca43a14cd3ca0997ad91.gif 014_spot_on.gif.1f3bdf64e5eb969e67a583c9d350cd1f.gif

 

In a side slip your rate of descent is higher (that's what we do them for) and your stall speed is also probably higher. 054_no_no_no.gif.950345b863e0f6a5a1b13784a465a8c4.gif

 

 

 

For me it would be into wind, as straight as possible, between the trees/obstructions to use the wings to absorb the initial impact.

 

Hope I never have to try the theory out though. 041_helmet.gif.78baac70954ea905d688a02676ee110c.gif

 

 

 

DWF 080_plane.gif.36548049f8f1bc4c332462aa4f981ffb.gif

 

 

  • Agree 1
Link to comment
Share on other sites

If you are slipping you will not be travelling at the slowest possible speed. When you hit there will be a sideways movement ent that heavy lump on your shoulders is going to accelerate towards the canopy or whatever is alongside it.

 

I would rather go in forwards at the slowest possible speed and flattest glide. I don't mean do a long slow glide, but make the last few feet very flat.

 

The trees round here are not inviting, they are very hard and there are lots of stags siting up there. Not what you want to hit first. The wings would be demolished while you were still 10 metres up in the air, so regardless of forward speed you will hit the ground hard.

 

What does look inviting from the air is the mud flats along the coast, but I would imagine the wheels would stop and the fuse carry on to inverted. Not a good idea. Most beaches would be fairly good, but there would have to be a bit of room above the tide level.

 

Best idea is to always travel where there will be an option to put down safely. Easier said than done. One trip I have done a few times would let me land on in inshore island, but what then, it is uninhabited and the water around it, while only a few hundred metres wide would possibly have sharks or crocs waiting for a feed.

 

 

Link to comment
Share on other sites

Guest ozzie

Was it Bob Hoover that said, "Keep flying the aircraft as far into the crash as possible or until the dust settles"?

 

 

Link to comment
Share on other sites

full flaps? you want to be going as slow as possible

There are a few things to consider with flaps, firstly full flaps in most planes will drasticly reduce your glide range so shouldn't be used until right at the end also remember without prop wash some planes might not have enough elevator authority to flare effectively if full flap and slow speeds are combined. Also be mindful of stopping once on the ground we often hear of the practice of dumping flaps to help braking effectiveness (but I guess in the trees time rolling on the ground would be minimum anyway).

Full flaps in some planes would be a good idea but we need to be mindful of different characteristics in different rigs.

 

 

  • Agree 1
Link to comment
Share on other sites

Don't think the sideslip theory is too inviting. A mission pilot in PNG tried it in a Dornier 27 and hit so hard that he killed himself, although his pax survived. I met other PNG F/L pilots who had successfully made it by landing up a relatively steep slope to shorten the run. Others had literally taken off the wings,(and fuel tanks), by arriving between tree trunks. Others had landed 'onto a sandbar' in a narrow river/stream. Most of Oz has better opportunities. These days I am usually prepared to take extra time to avoid bad stuff....a sign of age I guess. happy days,

 

 

  • Like 2
  • Informative 1
Link to comment
Share on other sites

Imagine that you have the misfortune to be flying along on a cross-country jaunt when your airplane suffers engine failure which means that you will soon be back on the ground, BUT the terrain you are flying over presents no suitable, cleared landing patch - just trees or rock-strewn paddocks. You know that your arrival at ground level will result in the airplane being severely damaged. How do you handle the landing??Old advice is that you have to fly the airplane as far into the crash as you can. So the first requirement is to decide that the approach to landing will be the sort that would result in a 'greaser' in front of the Sunday crowd at your home field. All that remains is to decide how to fly the last two feet.

 

In my opinion, the airplane should be side-slipped to the ground, trying to make the wingtip furthest from you hit first. Obviously, every attempt should be made to reduce ground speed to a minimum.

 

What's my reasoning? Well your moving airplane has Momentum, which is dependent on speed and weight.

 

M = mass x velocity

 

(Not quite the correct scientific words to use, but clear enough for this post). Momentum is a form of Energy, and this energy has to be dissipated before the airplane will stop. One way to dissipate the energy is to distort structures. That's why modern cars have front and rear 'crumple zones'. In a collision, the car's momentum distorts the material in the crumple zones so that the total momentum of the car is reduced before the cabin area starts to distort.

 

If the airplane is flown with the nose leading the motion, this sequence will happen.The front of an airplane usually contains a big mass of heavy metal (the engine) supported by relatively soft metal (engine bearers). In a front-on impact, the first parts of the airframe to bend and break are the bearers. This allows the cabin to collided with the rear of the engine, without much of a reduction in momentum. The next thing which can dissipate energy is the instrument panel, and then when it crumples, the occupants are next in line to get rid of the momentum. Have a look at some photos of WWl flying crashes. The pilot is usually slumped over the front of the cockpit, and the engine has been pushed back. Note that the wings are often only slightly damaged.

 

What I am suggesting is that by side-slipping to the ground and trying to have the wingtip furthest from you hit first, it will be the wing spar that will start collapsing first, and there are quite a number of feet of strong material to break up before the force exerted by the ground reaches the fuselage (Remember Newton's Second). The airplane may rotate around the collapsing wingtip, but this will have the advantage of making the engine collide with the ground at an angle to the longitudinal axis of the airplane, and may cause the engine to rotate away from the cabin, where you are sitting. This rotation with force you to the rear and centre of the cabin away from the collapsing instrument panel. However when it is your turn to do some momentum dissipating, you will stop your rearward motion and start to move forward, but towards the side of the cabin which is going to be a lot softer that the instrument panel and engine.

 

So my suggestion for surviving a crash landing onto unforgiving terrain is to:

 

1: Fly the airplane into the crash as slowly as possible, while still maintaining directional control.

 

2: Side-slip your approach to the impact point, with the wing tip furthest from you leading the motion.

 

3: Prepare for the impact of your body with the side of the cabin on the opposite side of the airplane to the wingtip that hit first.

 

There is one thing that will affect your decision as to which wingtip hits first - if you are flying with a passenger in a side-by-side, you have a moral and legal Duty of Care, to place your passenger's welfare above your own. In that case, you land on the wingtip on your side. "Greater love hath no man ..."

 

I'd suggest that as an exercise in airplane control, you shoot some circuits on a calm day and make each landing a power off, side-slip approach, so that you get a feeling for what the situation looks like.

 

WARNING and DISCLAIMER

 

Before conducting side slip manoeuvres in landing configuration with flaps, consult your airplane's Operator's manual to see if such manoeuvres are permitted.

 

Old Man Emu

Nice APRIL FOOLS JOKE

 

Got a good thread going though , well done .

 

Ill refrain from my encounter with " the tree " story , its in an earlier post.

 

Cheers .

 

 

  • Haha 1
Link to comment
Share on other sites

My very good friend Paul W. said that he tried a similar trick ( not on April 1st though ) in an aircraft called an Avid Flyer. . .if you don't heave the type in Oz,. . it's a bit of a Denney Kitfox lookalike, ie, two seat side by side seating Microlight ( 450 Kgs ) high wing taildragger with doped fabric covering. It has a slightly smaller wingspan than the marque 2 and 3 kitfox types, and a 582 Rotax 2 stroke engine. Paul had agreed to check fly the aircraft following it's successful permit inspection ( LAA ) why, I don't know, as he'd never flown one . . .which was why I had declined. ( sensible coward ? ) If you have zero time in a type, then you have no business check flying it for quite a large number of reasons which should be obvious. ( especially if you have only recently converted to fixed wing from a PPL(H).

 

On takeoff, the attachment bolt connecting the left support strut to the trailing edge area of the wing - broke. Fortunately for him, the front attachment to the other strut didn't. But this allowed the wing to twist slightly upward at the trailing edge, producing an uncontrolleable left turn moment.

 

The aircraft came down into a deeply ploughed field adjacent to the airstrip' striking the field in a shallow angle with the left wingtip, which took most of the impact, but forced the wing spar tube left to right through the cockpit, over Paul's head, and into the right side of the cabin.

 

He said he'd deliberately done this, but . . .weeeeeell. . . .I don't see how, with virtually no roll authority. Had there been anyone in the right seat, they would almost certainly have had their head removed by the spar tube. I have ribbed him mercilessly about this every time he starts a bragging excercise about his latest flying escapade. . . . I'm amazed he still pays for my curries on a Wednesday night ! ! ! *** Incidentally, some of you will remember I've posted this story before,. . . so I'm not losing me marbles,. . .it just seemed apt, with regard to OMEs post !

 

 

Link to comment
Share on other sites

Aircraft and environment characteristics are so variable, it would be hard to perfect the sideslip crash.

 

Save the brain power for finding the best spot and slowest approach to target rather than think about the sideslip.

 

Lots going on in your head and in the aircraft at the time I imagine.

 

I agree with SD about the flaps. Need to be careful about them.

 

I have flaperons and full flap gives a very pitch down attitude which requires significant elevator.

 

I normally land at one stage so would probably fly into a crash with this, atleast until the last minute.

 

I would be vary wary of putting the aircraft into an unfamiliar flight configuration.

 

Alot of advantages in knowing how your aircraft will perform right upto and into the crash over a theoretical and unfamiliar setup.

 

 

  • Agree 4
Link to comment
Share on other sites

Guest ozzie

book i read once suggested some of the following.

 

chose a hedge instead of a brick fence.

 

aim between the trees or fence posts.

 

land with the furrows in a plowed field

 

land near the bank of river or dam.

 

Ground looping can shorten your roll out.

 

Stall into the tree tops and hope to get caught in the branches, try and avoid arriving in between the tops of trees it may be a long fall to the ground.

 

Also surly this is a subject that you discuss with your instructor during training?

 

 

Link to comment
Share on other sites

I think in a lot of cases it is Ozzie, the main trouble I see with people discussing this (and I am surprised and pleased that it hasn't gone there too much in this thread) is the 'do gooders' (just using that as a descriptive word, I don't mean to offend those that it is describing) jump in and just keep repeating 'if you can't land don't fly over it' which IMHO is simplifying it too far. YES that is a good idea obviously but I don't think a conversation of options for tiger country should be quashed because of that. I'll ignore the fact that some strips and some locations don't give options, but in some cases if you are say 2 or 3 thousand feet above ground level flying over open looking ground then things go quiet, the close inspection you have of that nice clear paddock may be vastly different to the view from up high and having thought/talked over options regarding boulders/shrubs ect beforehand will greatly reduce your mental load at that moment where mental overload is already high.

 

It's a bit like refusing low level training because of a lack of 'true need'. IMHO the more constructive discussion (especially when it brings out real world examples from the participants) about such situations the better

 

 

  • Agree 3
Link to comment
Share on other sites

Aircraft and environment characteristics are so variable, it would be hard to perfect the sideslip crash.Save the brain power for finding the best spot and slowest approach to target rather than think about the sideslip.

Lots going on in your head and in the aircraft at the time I imagine.

 

I agree with SD about the flaps. Need to be careful about them.

 

I have flaperons and full flap gives a very pitch down attitude which requires significant elevator.

 

I normally land at one stage so would probably fly into a crash with this, atleast until the last minute.

 

I would be vary wary of putting the aircraft into an unfamiliar flight configuration.

 

Alot of advantages in knowing how your aircraft will perform right upto and into the crash over a theoretical and unfamiliar setup.

Generally speaking, it would depend on the aircrafts design factors. My J230 for instance with full flaps glides hands off with full rear trim. I do a reasonable amount of slideslip Practice to the point that it is an instantaneous decision in changing X wind situations.

 

So, maybe if I was flying into a crash, this option would be available immediately to me to align myself with the chosen site and lose some height quickly if needed.

 

By chosen site, I mean perhaps between the big trees or better still a less forested area if available.

 

Just my thoughts.

 

Phil

 

 

Link to comment
Share on other sites

Into the wind, slow as possible, aim for the soft stuff that will dissipate force over time....

 

Side slip to make a paddock, but No side slip at impact as vertical impact forces are lethal when sitting, with no leg bending to absorb impact.

 

 

  • Agree 1
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...