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pontifex
23rd Jan 2008, 22:08
This topic was touched on in the 777 discussions but I didn't bite as it would have been blatant thread creep. However, now that we can expect to be able to access PPrune again it might be worth raising the subject to promote discussion. Not sure if Rumours and News is the right place for it but it can always be moved.

There is an old adage "If you are going to have a crash, have it with the wings level" and I feel no-one will argue with that. But there has always been discussion on whether to crash land on concrete or grass and whether to do so gear up or down. It seems that the biggest difference of opinion is grass or concrete. I feel strongly that it should be hard surface. As it is said "It's not the falling that hurts, it the stopping". Deceleration on concrete will be much less and, although there will be sparks, earth and stuff will not be ripping the structure apart (causing sparks) and rupturing fuel tanks whilst atomizing the fuel. If you analyze the Sioux City crash, the aircraft seemed to be sliding right side up until it went into the corn at which time it started to cartwheel, somersault and break up.

Gear or no gear. Unless it is a ditching, I believe this is a no-brainer. Even if it gets ripped off during the initial impact, it has done its job by taking the first shock, and this is relevant on soft or hard surfaces. In my opinion the 777 would have been a tragedy had it touched down gear up. It may be that most will think this is stating the blindingly obvious but I had quite a full, frank and free discussion with a fellow tp when we were flying the prototype Tucano with a flame out and no electrics (no gear indication). I was set up to land on the runway but agitated stick movement from the rear with accompanying gestures made it plain he wanted the grass. Since he had signed for I complied. The gear was down and it was a non event, but it does illustrate that opinions differ between even quite experienced pilots. This is why I am starting this thread because I believe it is a subject that deserves an airing.

ChristiaanJ
23rd Jan 2008, 23:02
pontifex,
One will not always have the option "grass or runway", or "gear up or down".
I won't interfere in the discussion, just want to follow it.

groper
23rd Jan 2008, 23:25
Gear up or down? Gear down if possible - I want as much distance as possible from me and the hard stuff (i.e. planet earth). It also has things like wheels and brakes on it to help control the crash phase and perhaps absorb some energy.

Rwy or grass? Hmmm, depends on many unknowns and variables. The consistent thing about runways is that they are generally straight, smooth and hard (unless it's a grass runway) and may have arrestor systems if applicable. Grass areas alongside rwys can be straight, smooth and soft, but can also hide objects, ditches, holes, very soft patches etc. etc. that could be a big gotcha. I'd always go for a rwy as first choice.

I stress that the above are my thoughts only and that I never (thankfully) had to face such a situation in 30 years of flying.

Pugilistic Animus
23rd Jan 2008, 23:25
Survival in any plane crash in most terrain depends not only on speed attitude, wing loading, fuel state, prepartaion time Met conditions etc---- but also on a willingness to use expendable structures wings /engines/ gear/ to expend the energy and decelerate rapidly and aggressive use of any means of directional control available---also DON'T STALL, and never try to achieve to too low a touch down speed because sink can become intolerable---also selection of surfaces is important -----like a large grove of trees in mountainous terrain---- or a body of water---the BA crash is an excellent example of energy mangement and control in an extreme situation Kudos to the PF and CREW:D


Following up a bit on ChristiaanJs sentiments ---luck be a lady:uhoh:

MidgetBoy
23rd Jan 2008, 23:58
ditching in a puddle?

alexpc
24th Jan 2008, 01:14
Gear up or down?

OK, to widen the scope a little...

Failure of one main gear leg: land on the other, or both up? Likely to depend on a/c type of course.

The Sandman
24th Jan 2008, 03:22
Give me 10,000' of grass any day....

Intruder
24th Jan 2008, 04:15
Only one way: In a REAL airplane on a steel (or wood) deck somewhere out at sea.

Meatball, lineup, angle of attack...

Fredairstair
24th Jan 2008, 09:29
Someone (Bob Hoover?) once said "fly it as far into the crash as possible"

Makes sense to me!

DozyWannabe
24th Jan 2008, 10:02
If you analyze the Sioux City crash, the aircraft seemed to be sliding right side up until it went into the corn at which time it started to cartwheel, somersault and break up.

I'm not a pilot, so I can't answer the question in a relevant manner, but I don't think it was the simply the transfer from runway to grass that caused the aircraft to dig in and flip, so much as they'd lost the right wing and right MLG very early in the crash sequence which pulled the aircraft violently to the left and introduced a rotational moment about the yaw axis. I personally believe that even if the whole area was paved the aircraft still would have flipped over simply because of the amount of kinetic energy they had at touchdown, as both their approach speed and sink rate were way in excess of what the aircraft was designed to take.

Obviously leaving the paved area did have an effect, but if you're going onto concrete with an excessive sink rate then it's not likely to matter what your horizontal deceleration rate is.

Albert Driver
24th Jan 2008, 12:09
Flying often involves doing counter-intuitive things. That's why the path to safe aviation has been so long and costly in lives. We learn to trust the instruments, not our feelings. We learn to trust our instructors, even when they tell us to do things that seem instinctively wrong.

"Crash-landing is a counter-intuitive exercise. Fly fast enough to fully control the areoplane. Land with as much landing gear down as possible. Land on a hard prepared smooth surface if possible. Stay strapped in until it stops completely"...

......Not my words - advice I was given forty years ago.

I doubted it then but everything I have seen and experienced since confirms it was absolutely the correct advice - and remains so today.

barit1
24th Jan 2008, 13:11
Gear up or down? Gear down if possible

If a taildragger, landing on unprepared (soft or rough) surface, your odds are better gear up, to avoid noseover.

I once had to land a C172 with suspected frozen brakes (slush frozen in the wheel pants). Fortunately part of the runway was still unplowed, with liquid slush - so I chose that as my touchdown zone, reasoning that a messy slip-slide was better than overturning. The owner made me wash the aeroplane afterwards, but no problems otherwise. :ouch:

Captain Planet
24th Jan 2008, 13:16
But isn't every LANDING a "controlled" crash??

Essentially you're plunging the nose into the ground and at the last second pulling back.

CP.:ok:

Erwin Schroedinger
24th Jan 2008, 15:03
How does one crash 'nicely'?


Softly spoken "I say", "Oh bother" or "Dearie me" are suggested.

white44
24th Jan 2008, 17:46
Having had to plant an old Herald (What's that I hear) without nose gear, I would definitely prefer somewhere long, and smooth(ish) - sorry about the centreline lights Cardiff.

Also, in any emergency give yourself a second or so to think. It's better to do the right thing calmly but not too slowly, than the wrong thing very quickly, as any pilot who has shut down the only remaining (ie good) engine like greased lightning will agree!!

A good expletive sometimes helps, even if only to give yourself the aforementioned thinking time

ChristiaanJ
24th Jan 2008, 18:48
Having had to plant an old Herald (What's that I hear) without nose gear, I would definitely prefer somewhere long, and smooth(ish) - sorry about the centreline lights Cardiff.I was thinking F27, but same difference, really.

Also, in any emergency give yourself a second or so to think. It's better to do the right thing calmly but not too slowly, than the wrong thing very quickly, as any pilot who has shut down the only remaining (ie good) engine like greased lightning will agree!!BA038 had only about 50 secs, and they must have used up several of those to figure out what was happening.

I agree, "Houston, we have a problem" was a bit verbose. But then they DID have more than 50 seconds to sort it out.

llanfairpg
24th Jan 2008, 18:55
How does one crash 'nicely'?

By not taking control from the FO, after all it was his leg!

sevenstrokeroll
24th Jan 2008, 19:27
Does anyone recall a JAL DC8 that landed short of the runway at KSFO? Gear down, stable approach, right into the bay.

the plane was salvaged and off it flew.

I would take a paved runway over grass. and usually gear down over gear up. a real ditching at sea, gear up, outflow valve closed.

barit1
24th Jan 2008, 19:38
Yes I recall (http://aviation-safety.net/database/record.php?id=19681122-0).

Rule #1: Aviate. :ugh:

white44
24th Jan 2008, 20:08
A bit like "take off power!". I much preferred "power for takeoff", or a specific TIT or torque figure.

A bit off thread but I was never too happy with the standard takeoff brief part "Once attaining V1 we will continue and sort out any problems when airborne". My feeling was that if a catastrophic failure occurred involving structural damage just above V1, but before liftoff, I would rather go through the far hedge than fall out of the sky.

go-si
24th Jan 2008, 20:15
The plan must be to dump as much energy as possible and then concentrate on survival ... though apart from that i suppose there can't be much advice as every crash is bound to be different.

Computer George
24th Jan 2008, 20:39
I always wondered: if you had to ditch your plane with engines mounted under the wings, would it be better to pull the plane up very fast, as to lose the engines? This would make the chance of flipping nose over less. Of course, engines breaking lose also has impact on the wings, the force of pulling up can have 'some side effect' and if you not lose all engines, the plane may be out of balance. But still wondering...

ChristiaanJ
24th Jan 2008, 21:21
... so as to lose the engines?...On Concorde, we never had that option...
Tank trials showed it was not totally impossible to ditch a Concorde, but in practice I think everybody was happy we never had to demonstrate it in real life.

clmixon
25th Jan 2008, 03:27
My first post....

I always thought the rule was,

When a prang (crash) seems inevitable, endeavor to strike the softest, cheapest object inthe vicinity as slowly and gently as possible.

Chris

Heli-phile
25th Jan 2008, 03:57
Dont start that up again!! please God
Stick to the SOP's or we are all in a world of hurt.

(But I know what you mean!!);)

SYYHerring
28th Jan 2008, 00:41
A great man one said "fly it as far into the crash as possible".

lomapaseo
28th Jan 2008, 15:51
A great man one said "fly it as far into the crash as possible".

From my read and listen to CVRs of survivable crashes that's exactly what they do. I have never yet heard anything like "Oh look there's an orphanage let's try and miss it"

PlasticPilot
29th Jan 2008, 10:06
From an airport worker and PPL point of view, if I had a long runway with a long parallel grass area, I would chose the runway for a very simple reason: firemen will have access there easily.

By any emergency the position themselves along the runway, and follow the plane, entering runway using the taxiways.

I don't know how good would the firetrucks be in an unprepared grass area, particularly if wet and muddy.

nosefirsteverytime
1st Feb 2008, 12:32
Odd, I was sure I'd made a post here before, to confirm that large Airport fire tenders are run from hard surfaces unless absolutely necessary, because once stopped, they will not be able to be moved from the grass without assistance. Twas said to me by a firefighter on a visit across the ramp from work.

Anyway, that's all I can say on the matter.