A comment on ensuring landing gear down if forced landing a retractable gear aircraft
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A comment on ensuring landing gear down if forced landing a retractable gear aircraft
Issue No. 18 of ATSB Aviation Short Investigation Bulletin contains a report on the apparent double engine failure in cruise of a PA-39 Twin Commanche VH-RMA.
The following excerpt makes interesting reading:
Concerned about the aircraft’s proximity to the critical V
mca3 airspeed (70 kt), the pilot maintained about 90 kt, while searching for a suitable landing site. He commenced an approach and broadcast the aircraft’s position and his intentions on the Melbourne Centre frequency. On final approach, he turned off the fuel pumps. During the round-out, he decided to extend the landing gear, as the surface looked more suitable than first thought. He pulled back on the control column to gain height and selected the landing gear down. The aircraft stall warning briefly sounded, so the pilot lowered the aircraft nose. Moments later, the propellers contacted the ground and the aircraft skidded to a halt.
............................................................ ...............................
In the old days of predominately tail-wheel aircraft, it was considered safer to land wheels up in a forced landing to prevent the aircraft from nosing over on touch-down. This was vital in the cases of fighter aircraft such as the Spitfire, Hurricane and Hawker Typhoons and Tempests -all of which were retractable main landing gear types with tail wheels.
When the North American Sabre jet fighter was introduced into the United States Air Force it had a tricycle landing gear with a nosewheel. Initially pilots would continue with the then policy of landing with the wheels retracted on a forced landing. The higher landing speed associated with jet types often resulted in severe back injury to the pilot in a forced landing gear up as there was no energy transfer to the landing gear on impact and the force of impact often caused spinal injuries.
Because of this danger, it became standard procedure to land wheels down in event of a forced landing in a tricycle landing gear type. Impact forces through the spine were reduced because the landing gear absorbed most of the energy; especially if a high rate of descent was occurring at the flare. Also it may be possible to reduce the landing run by use of the wheel brakes if they are available. Of course this did not apply to ditching, where wheels up applied to all types.
It took many years for the civilian training community to accept the military recommendation to lower the landing gear in a forced landing in a tricycle landing gear aircraft. Even now it is doubtful if the word has been passed down to flying school instructors and I wonder if this was the reason for the pilot of the afore-mentioned Twin Commanche to plan for a gear up belly landing in his aircraft after both engines played up and a forced landing became necessary.
The ATSB report indicated he tried to lower the landing gear just before he flared when he saw the field was suitable for a gear down landing. The point could have been made in the ATSB report that experience has shown a wheels down forced landing has its advantages over a belly landing, almost regardless of the surface (apart from ditching). Even with a rocky surface, it would almost certainly be safer wheels down because of the energy transfer to the wheels rather than the bottom of the fuselage and directly to the pilot's seat and spine.
I wonder if this sort of airmanship consideration is actively taught at todays flying schools whether on single engine or twin engine retractable landing gear types?
The following excerpt makes interesting reading:
Concerned about the aircraft’s proximity to the critical V
mca3 airspeed (70 kt), the pilot maintained about 90 kt, while searching for a suitable landing site. He commenced an approach and broadcast the aircraft’s position and his intentions on the Melbourne Centre frequency. On final approach, he turned off the fuel pumps. During the round-out, he decided to extend the landing gear, as the surface looked more suitable than first thought. He pulled back on the control column to gain height and selected the landing gear down. The aircraft stall warning briefly sounded, so the pilot lowered the aircraft nose. Moments later, the propellers contacted the ground and the aircraft skidded to a halt.
............................................................ ...............................
In the old days of predominately tail-wheel aircraft, it was considered safer to land wheels up in a forced landing to prevent the aircraft from nosing over on touch-down. This was vital in the cases of fighter aircraft such as the Spitfire, Hurricane and Hawker Typhoons and Tempests -all of which were retractable main landing gear types with tail wheels.
When the North American Sabre jet fighter was introduced into the United States Air Force it had a tricycle landing gear with a nosewheel. Initially pilots would continue with the then policy of landing with the wheels retracted on a forced landing. The higher landing speed associated with jet types often resulted in severe back injury to the pilot in a forced landing gear up as there was no energy transfer to the landing gear on impact and the force of impact often caused spinal injuries.
Because of this danger, it became standard procedure to land wheels down in event of a forced landing in a tricycle landing gear type. Impact forces through the spine were reduced because the landing gear absorbed most of the energy; especially if a high rate of descent was occurring at the flare. Also it may be possible to reduce the landing run by use of the wheel brakes if they are available. Of course this did not apply to ditching, where wheels up applied to all types.
It took many years for the civilian training community to accept the military recommendation to lower the landing gear in a forced landing in a tricycle landing gear aircraft. Even now it is doubtful if the word has been passed down to flying school instructors and I wonder if this was the reason for the pilot of the afore-mentioned Twin Commanche to plan for a gear up belly landing in his aircraft after both engines played up and a forced landing became necessary.
The ATSB report indicated he tried to lower the landing gear just before he flared when he saw the field was suitable for a gear down landing. The point could have been made in the ATSB report that experience has shown a wheels down forced landing has its advantages over a belly landing, almost regardless of the surface (apart from ditching). Even with a rocky surface, it would almost certainly be safer wheels down because of the energy transfer to the wheels rather than the bottom of the fuselage and directly to the pilot's seat and spine.
I wonder if this sort of airmanship consideration is actively taught at todays flying schools whether on single engine or twin engine retractable landing gear types?
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Tee Emm - Have you read the other short reports released today? Specifically this one: Investigation: AO-2013-023 - Engine failure involving a Cessna 182R, VH-OWZ, Kununurra Airport, WA, 22 January 2013
I am a believer in gear up forced landings, unless absolutely sure of landing surface.
After extending the landing gear and selecting full flap, the main landing gear touched down in long grass and the aircraft decelerated rapidly. When the nose gear touched down, it dug into boggy ground and the aircraft flipped over, coming to rest inverted. The pilot and passenger received minor injuries and the aircraft sustained substantial damage.
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Protecting the occupants is paramount.
Except in a case where rolling over is very likely then protecting the spine by having the gear down is best.
In Gliders this should always be done, even on water landings ( to break the surface tension and reduce submarining as well as protecting against hitting the bottom in shallow water).
In the case mentioned the problem seems to have been the late change of plan.
Except in a case where rolling over is very likely then protecting the spine by having the gear down is best.
In Gliders this should always be done, even on water landings ( to break the surface tension and reduce submarining as well as protecting against hitting the bottom in shallow water).
In the case mentioned the problem seems to have been the late change of plan.
In the aircraft I fly (Bonanza, C210) if the engine fails my focus is on walking away from the forced landing. That being the case, its going in wheels up - no ifs, buts or maybes! I can think of NO good reason to do otherwise.
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This sort of airmanship consideration is still discussed at flying schools, but there is no consensus.
Many general aviation pilots claim it is safer to land wheels-up on an unprepared surface. It seems many pilots think that an aircraft nosing-over scenario is a catastrophic scenario. I don't think it is, in most cases.
ForkTailed - why do you think you are safer landing on (for example) a rough surface wheels up than down? I guess you're more concerned with nose-over than with fuselage impact damage, but you haven't said.
Personally, I'm with the OP on this one. The landing gear is designed to absorb a lot of kinetic energy, so I'm going to put it down. If the aircraft does nose over, it's not a disaster provided my seatbelt is fastened firmly (and fuel off, etc etc).
Many general aviation pilots claim it is safer to land wheels-up on an unprepared surface. It seems many pilots think that an aircraft nosing-over scenario is a catastrophic scenario. I don't think it is, in most cases.
ForkTailed - why do you think you are safer landing on (for example) a rough surface wheels up than down? I guess you're more concerned with nose-over than with fuselage impact damage, but you haven't said.
Personally, I'm with the OP on this one. The landing gear is designed to absorb a lot of kinetic energy, so I'm going to put it down. If the aircraft does nose over, it's not a disaster provided my seatbelt is fastened firmly (and fuel off, etc etc).
Last edited by Oktas8; 17th May 2013 at 05:03. Reason: to address FTDK's post
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FTDK, you've obviously given the matter some serious thought.
I'd just like to know how you came up with that answer.
I'd have thought it reasonable if you were to take a look out the window and make a decision on the circumstances as they were at the time.
edit
Both Boeing and Airbus stress the importance of leaving the gear down to absorb impact forces in the event of likely ground contact in take-off/go around windshear events at the expense of additional climb performance with the gear retracted.
regards.
I'd just like to know how you came up with that answer.
I'd have thought it reasonable if you were to take a look out the window and make a decision on the circumstances as they were at the time.
edit
Both Boeing and Airbus stress the importance of leaving the gear down to absorb impact forces in the event of likely ground contact in take-off/go around windshear events at the expense of additional climb performance with the gear retracted.
regards.
Last edited by Trent 972; 17th May 2013 at 05:13. Reason: get the tenses correct
My thoughts would be that it is more about managing the deceleration rate rather than a concern about tipping over. On a wet boggy field or a really rocky one, gear down is more likely to lead to a sudden stop, whereas gear up will skip along the top for a gentler landing.
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I do think it's a type specific thing. Eg. In one of the aircraft I fly, Yak 52, the book says gear up. Short nose, long gear and nil structure above the pilots head means ending up on you lid is more likely and highly undesirable. Couple this with the gear still being exposed when retracted means I'm going in gear up unless I'm very certain of the surface.
I don't know the Twin Comanche, but at first glance gear down seems the choice to make. Short gear and long nose indicates that you're unlikely to end up blue side down.
I don't know the Twin Comanche, but at first glance gear down seems the choice to make. Short gear and long nose indicates that you're unlikely to end up blue side down.
Last edited by Wanderin_dave; 17th May 2013 at 05:39.
You've got to love this comment from the ATSB in the C182R report:
Doh!
An engine tear down was not performed and the reason for the engine failure could not be determined.
Last edited by Old Akro; 17th May 2013 at 05:35.
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A short selection of flight manuals
A36 - gear down or up depending on terrain
Chieftain - nothing mentioned
Cessna 404 - gear down if field is smooth and hard, if terrain is rough or soft plan on a wheels up landing
T-28 - gear up for unprepared surface
Mate deadsticked an A36 with gear down in a wheat paddock and tore the nose wheel out. Damage would have been far less if he had bellied it in.
A36 - gear down or up depending on terrain
Chieftain - nothing mentioned
Cessna 404 - gear down if field is smooth and hard, if terrain is rough or soft plan on a wheels up landing
T-28 - gear up for unprepared surface
Mate deadsticked an A36 with gear down in a wheat paddock and tore the nose wheel out. Damage would have been far less if he had bellied it in.
Personally who gives a rats about the damage caused gear up or down, yr life is far more important besides what's that saying........you no longer own the A/C in such instances the Ins Co does:-)
Do as the Flt Man says or make an informed decision (terrain etc) & stick to it.
I've got a few hrs in the old 'twin can', gear down every time (unless water landing) due low stance as those old birds where tuff as an old FC Holden
Same for the old Beech machines, gear down as they too are built like tanks:-)
C210? Diff story, they feel like they are made out of tissue paper & sticks:-)
And this if for you 'Jabba', don't fly SE planes (or low powered twins) & reduce the chances
Wmk2
Do as the Flt Man says or make an informed decision (terrain etc) & stick to it.
I've got a few hrs in the old 'twin can', gear down every time (unless water landing) due low stance as those old birds where tuff as an old FC Holden
Same for the old Beech machines, gear down as they too are built like tanks:-)
C210? Diff story, they feel like they are made out of tissue paper & sticks:-)
And this if for you 'Jabba', don't fly SE planes (or low powered twins) & reduce the chances
Wmk2
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Wheels up on water, no if's or but's!
As for the rest, RTFM!
As for the rest, RTFM!
FTDK, you've obviously given the matter some serious thought.
I'd just like to know how you came up with that answer.
I'd just like to know how you came up with that answer.
Unless I am sure of the surface and length, its wheels up for me!
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FTDK, appreciate the reply.
I also appreciate the qualification in your reply.
Your initial post indicated that it would be gear-up no matter what.
I was a little surprised.
My concern is for the newbies that read these forums and take away that a very experienced 'Bonza' pilot such as yourself, had such a hard and fast rule.
Your experience is what you have to rely on when it turns to sh!t.
regards
I also appreciate the qualification in your reply.
Your initial post indicated that it would be gear-up no matter what.
I was a little surprised.
My concern is for the newbies that read these forums and take away that a very experienced 'Bonza' pilot such as yourself, had such a hard and fast rule.
Your experience is what you have to rely on when it turns to sh!t.
regards
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It depends an the aircraft.
In a glider ( and I have >30 " forced landings") then it is wheel down,
Even in water! - no ifs or buts!
Your spine is too fragile to trust the belly.
In a glider ( and I have >30 " forced landings") then it is wheel down,
Even in water! - no ifs or buts!
Your spine is too fragile to trust the belly.
Unless I am sure of the surface and length, its wheels up for me!
Does the Owners Manual provide any guidance?
Mate deadsticked an A36 with gear down in a wheat paddock and tore the nose wheel out. Damage would have been far less if he had bellied it in.
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Numerous paddock retrieves in a long ago prior life towing gliders. Even with the extensive time spent checking out the proposed site from the air ... never did one just wing it in ... good way to kill yourself stone dead real quick .. the hidden rocks in the grass were always my fear once I'd got past the hidden power and phone lines.
The certification standards for singles .. and light twins (and that's the more likely scenario for a forced landing, I suggest) envisage a maximum stall speed of 61 kts .. see, for instance, FAR 23.49(c). Why 61 kts may well you ask ? Originally this was 70 mph in the olden days. Where did that come from ? Finger in the wind WAG. According to an old chap who was an instructor on a course I sat 20 odd years ago .. and who, as a young chap, himself, had been an office boy engineer in the very early days of the original US regulatory body .. a lot of rules had to be made up simply because they were needed and there was no rule book to look up and get the information to formulate the rule.
Energy to get rid of once you are on the ground is related to speed squared and you need to get rid of this one way or another. Low speed touch down is your friend.
If you have a nice firm, smooth surface ... why wouldn't you land wheels down ?
If you have a rough surface with lots of hard things scattered around .. why wouldn't you land wheels down ? Putting aside the case where the aircraft hits a big, immovable object, the wheel assembly is going to crack and break during the impact .. reducing the loads which your body has to react in the cabin.
In between there is a range of variations, some of which might suggest a wheels up if there is negligible risk of personel injury. About the only case I can bring to mind might be an off runway landing onto a mown, extremely sodden, grass/dirt surface.
A couple of considerations to support landing wheels down ..
(a) motor vehicle Standards run at around 20 odd G for the impact requirements and emphasis collapsible structure and a survival volume via the cabin to get the occupants through most minor impacts without too much damage. Keep in mind that 30-35G is a reasonable guesstimate for a survivable impact without encroachment into the survival volume.
(b) when the aircraft dynamic seat standards come into vogue, FAA's CAMI did a bunch of sled tests using real world fuselage sections. End result was that the typical widebody with an underfloor baggage compartment full of stuff ... resulted in the occupants experiencing comparatively low decelerations. By comparison, a hard airframe with a high ROD during the impact sequence (otherwise known as a helicopter) occupant experienced VERY high loads .. so much so that a helicopter seat needs to have a long stroking mechanism to achieve the dynamic design Standards requirements.
For the above, read "spread the impact over a few metres to survive". The alternative of hitting a brick wall is not a successful life strategy.
What does this mean for an outfield landing unless you absolutely know that there exist NO obstacles littering the grass ? You really want to have some structural stuff available to bend and break instead of having that energy taken up by your body. Undercarriage is real beaut for doing this.
Of course, wheels up or wheels down some impacts will be unsurvivable. What you should be doing is loading the dice in your favour.
Me ? Hang the aircraft .. it's wheels down just about every time and fly the machine as far into the prang as is practicable with a view to delaying hitting anything hard until the speed is right down there in the low numbers.
The certification standards for singles .. and light twins (and that's the more likely scenario for a forced landing, I suggest) envisage a maximum stall speed of 61 kts .. see, for instance, FAR 23.49(c). Why 61 kts may well you ask ? Originally this was 70 mph in the olden days. Where did that come from ? Finger in the wind WAG. According to an old chap who was an instructor on a course I sat 20 odd years ago .. and who, as a young chap, himself, had been an office boy engineer in the very early days of the original US regulatory body .. a lot of rules had to be made up simply because they were needed and there was no rule book to look up and get the information to formulate the rule.
Energy to get rid of once you are on the ground is related to speed squared and you need to get rid of this one way or another. Low speed touch down is your friend.
If you have a nice firm, smooth surface ... why wouldn't you land wheels down ?
If you have a rough surface with lots of hard things scattered around .. why wouldn't you land wheels down ? Putting aside the case where the aircraft hits a big, immovable object, the wheel assembly is going to crack and break during the impact .. reducing the loads which your body has to react in the cabin.
In between there is a range of variations, some of which might suggest a wheels up if there is negligible risk of personel injury. About the only case I can bring to mind might be an off runway landing onto a mown, extremely sodden, grass/dirt surface.
A couple of considerations to support landing wheels down ..
(a) motor vehicle Standards run at around 20 odd G for the impact requirements and emphasis collapsible structure and a survival volume via the cabin to get the occupants through most minor impacts without too much damage. Keep in mind that 30-35G is a reasonable guesstimate for a survivable impact without encroachment into the survival volume.
(b) when the aircraft dynamic seat standards come into vogue, FAA's CAMI did a bunch of sled tests using real world fuselage sections. End result was that the typical widebody with an underfloor baggage compartment full of stuff ... resulted in the occupants experiencing comparatively low decelerations. By comparison, a hard airframe with a high ROD during the impact sequence (otherwise known as a helicopter) occupant experienced VERY high loads .. so much so that a helicopter seat needs to have a long stroking mechanism to achieve the dynamic design Standards requirements.
For the above, read "spread the impact over a few metres to survive". The alternative of hitting a brick wall is not a successful life strategy.
What does this mean for an outfield landing unless you absolutely know that there exist NO obstacles littering the grass ? You really want to have some structural stuff available to bend and break instead of having that energy taken up by your body. Undercarriage is real beaut for doing this.
Of course, wheels up or wheels down some impacts will be unsurvivable. What you should be doing is loading the dice in your favour.
Me ? Hang the aircraft .. it's wheels down just about every time and fly the machine as far into the prang as is practicable with a view to delaying hitting anything hard until the speed is right down there in the low numbers.
Putting aside the case where the aircraft hits a big, immovable object, the wheel assembly is going to crack and break during the impact ..
Perhaps some landing gear systems are built to be quite strong e.g. to practise carrier landings, and may not break as conveniently as assumed.
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It all comes back to stats and damned lies as well as peak acceleration loading on the body.
What you need is any means to have your body go from goa to whoa over a reasonably long distance. How you achieve that is a moot point and up to the boy or girl in the driver's seat at the time.
Reduce that distance and the deceleration loads go up. Experience too high a G and nasty things start to occur .. aorta rips out, stuff like that .. this assumes that your survival volume is not breached. If you get hard things coming into your survival space then you have the problem of significant direct trauma to the body.
I'd still prefer the chance of bending, breaking, and ripping off any structure that's not real close to my bits and pieces rather than taking my chances with a comparatively thin keel surface. So, as an almost invariable rule .. it's gear down for me.
What you need is any means to have your body go from goa to whoa over a reasonably long distance. How you achieve that is a moot point and up to the boy or girl in the driver's seat at the time.
Reduce that distance and the deceleration loads go up. Experience too high a G and nasty things start to occur .. aorta rips out, stuff like that .. this assumes that your survival volume is not breached. If you get hard things coming into your survival space then you have the problem of significant direct trauma to the body.
I'd still prefer the chance of bending, breaking, and ripping off any structure that's not real close to my bits and pieces rather than taking my chances with a comparatively thin keel surface. So, as an almost invariable rule .. it's gear down for me.