Wycombe air park - accident
Fair points - although doing those calculations isn't hard, and even if AAIB might be best advised not to publish such things (and I'm willing to bet that they spent a lot of time debating whether they should or not) most of us are quite capable of doing the sums.
The message however is pretty clear! Stay in weight and balance, and don't try to take off where there's less runway than you need.
G
The message however is pretty clear! Stay in weight and balance, and don't try to take off where there's less runway than you need.
G
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While I compleatly agree with the post above I thing the root of this accident was the C of G position not the weight.
If the aircraft had behaved as the pilot was expecting the chances are he would have cleared the hedge by a narrow margin and we would be reading A confession about this in the back pages of Pilot.
The control difficultys put the aircraft into a high drag situation that the aircraft did not have the performance to recover from.
The bottom line is that a marginally overloaded aircraft will fly badly, a marginally mis-loaded aircraft may not fly at all.
If the aircraft had behaved as the pilot was expecting the chances are he would have cleared the hedge by a narrow margin and we would be reading A confession about this in the back pages of Pilot.
The control difficultys put the aircraft into a high drag situation that the aircraft did not have the performance to recover from.
The bottom line is that a marginally overloaded aircraft will fly badly, a marginally mis-loaded aircraft may not fly at all.
Except that neither the overloading, nor the misloading, were marginal!
About 5% over MTOW, and 3" out of what I imagine was about a 9" CG range, is a hell of a lot.
But yes, knowing more than most about aeroplane design, I know well that there are large margins on weight, but basically none on CG.
G
About 5% over MTOW, and 3" out of what I imagine was about a 9" CG range, is a hell of a lot.
But yes, knowing more than most about aeroplane design, I know well that there are large margins on weight, but basically none on CG.
G
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This thread serves as an interesting case study for those who would quell any speculation following an accident. Early speculation got this one exactly right and served well as lessons to us all to make sure we check W&B and take off distance required accurately.
On another issue, it's often stated insurance would be invalid following pilot error such as this - is that really true and was it in this case?
On another issue, it's often stated insurance would be invalid following pilot error such as this - is that really true and was it in this case?
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About 5% over MTOW, and 3" out of what I imagine was about a 9" CG range, is a hell of a lot.
But yes, knowing more than most about aeroplane design, I know well that there are large margins on weight, but basically none on CG.
But yes, knowing more than most about aeroplane design, I know well that there are large margins on weight, but basically none on CG.
5% overweight means you need 10% more runway. I hate to post this but loads of people fly 5% overweight. Your average PA28 making its way across the Channel on a sunny Sunday with 4 people is unlikely to be below that. They get away with it because they operate from long runways. In the UK, most hard runways are about 2x longer than is actually needed by the common spamcans at MTOW.
The front and back of the loading envelope are determined initially by the elevator authority at/near Vs. You can fly a plane loaded slightly in front or behind the envelope if you are flying appropriately faster. That is why, for example, if you have collected a lot of ice on the elevator, you are advised to land at a higher than normal speed, so that pitch control is retained all the way to the runway.
it's often stated insurance would be invalid following pilot error such as this - is that really true and was it in this case?
It is usually said by people close to the business that insurers tend to not pay out if the flight was illegal before it got off the ground e.g. a duff license, duff medical, duff CofA, etc. Overweight should be in the same category but I have never heard of any actual cases on that. It would be interesting to find out. Insurance definitely covers pilot negligence though.
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Insurance have paid and did so within weeks.
Insurance is about agreed hull value. Whilst the forum experts will look for every reason why they think the claim would not be settled on the whole unless the flight was proven to be totally illegal by a court then they will pay up.
On the whole aircraft insurance is actually a pretty fair business. They charge the premiums to make it that way...,
Insurance is about agreed hull value. Whilst the forum experts will look for every reason why they think the claim would not be settled on the whole unless the flight was proven to be totally illegal by a court then they will pay up.
On the whole aircraft insurance is actually a pretty fair business. They charge the premiums to make it that way...,
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I know what "agreed value" insurance is, but that doesn't mean that I can tow my plane out to Beachy Head, push off off the cliff, and collect the agreed value.
Evidently there are unspoken boundaries below which they pay up but beyond which they will haggle. Unfortunately nobody is any wiser about what these are.
Also not everybody has "agreed value" cover.
If this chap got his dosh (a lowish 5 figure sum, I would guess, on a 1978 Lance) that is good, and also interesting. Presumably the insurer would have been unaware of the loading, at the time, but maybe it made no difference given the low insured value.
I had a prop strike in 2002, during differences training with an instructor. The insurer paid the bill very fast indeed, having merely checked the instructor had valid papers. They happily paid 2x more for a new prop with a JAR-1 form, over one with an 8130-3 form
Evidently there are unspoken boundaries below which they pay up but beyond which they will haggle. Unfortunately nobody is any wiser about what these are.
Also not everybody has "agreed value" cover.
If this chap got his dosh (a lowish 5 figure sum, I would guess, on a 1978 Lance) that is good, and also interesting. Presumably the insurer would have been unaware of the loading, at the time, but maybe it made no difference given the low insured value.
I had a prop strike in 2002, during differences training with an instructor. The insurer paid the bill very fast indeed, having merely checked the instructor had valid papers. They happily paid 2x more for a new prop with a JAR-1 form, over one with an 8130-3 form
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Perhaps cost and certainty are the keys?
Checking paperwork to determine the legality of the flight is quick and cheap and gives a simple yes/no answer. An illegal pilot's decision to take off is taken on the ground before the flight, so it must be hard to plead special circumstances.
Anything to do with airmanship, even very, very, basic airmanship, is more arguable and so inevitably slower, more expensive, and harder to establish.
Checking paperwork to determine the legality of the flight is quick and cheap and gives a simple yes/no answer. An illegal pilot's decision to take off is taken on the ground before the flight, so it must be hard to plead special circumstances.
Anything to do with airmanship, even very, very, basic airmanship, is more arguable and so inevitably slower, more expensive, and harder to establish.
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I know what "agreed value" insurance is, but that doesn't mean that I can tow my plane out to Beachy Head, push off off the cliff, and collect the agreed value.
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I presume insurance companies tend to pay out if the flight was intended to be carried out legally. If you jump in the cockpit without a licence and stuff the aeroplane then there is a pretty clear case not to pay out.
The only ones that I know about where the insurance didn't pay out were the ones with either massive paperwork irregularities for the aeroplane or pilot.
The only ones that I know about where the insurance didn't pay out were the ones with either massive paperwork irregularities for the aeroplane or pilot.
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The pilot started to rotate the aircraft at 65 KIAS and, as it became airborne, he realised that it was no longer accelerating or climbing.
Last edited by Duchess_Driver; 14th Mar 2012 at 00:10.
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Having just read the thread for the first time, after reading the AAIB report, I wonder if anyone could comment on the relative performance in marginal takeoff between high wing (Cessna 172, etc) and low wing.
Certainly the Robin tug, being low wing, despite having 180 hp, we think of as a groundhugger, climbs well enough once it gets going. The Piper Cub modified to carry a 180 hp Lycoming will fairly leap off the ground, and being high power to weight ratio, is actually considered by many to be a better tow aircraft.
With either one, taking into consideration length of runway, hot day, tall or wet grass, no headwind, and a heavy glider, we often recommend an alternate method of launch. Of course we have the option of dumping the load if things go pearshaped.....
Certainly the Robin tug, being low wing, despite having 180 hp, we think of as a groundhugger, climbs well enough once it gets going. The Piper Cub modified to carry a 180 hp Lycoming will fairly leap off the ground, and being high power to weight ratio, is actually considered by many to be a better tow aircraft.
With either one, taking into consideration length of runway, hot day, tall or wet grass, no headwind, and a heavy glider, we often recommend an alternate method of launch. Of course we have the option of dumping the load if things go pearshaped.....
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I believe the answer is
A - For a marginally - but successful takeoff - wing position makes no difference as you reasonably quickly climb through the narrow altitude where the ground effect is different (high wing wings being further from the ground at any given wheel altitude than low wing wings).
B - For overloaded, aft CG takeoffs that rotate early and remain behind the drag curve until they crash - the high wing has the benefit of exiting ground effect and sagging back to earth at a slightly lower height above the airfield than the low wing.
I would be a bit surprised if for a given weight, power, drag, airfoil section, wing loading, etc there was a material performance difference based on wing position. On the other hand, I am pretty sure the substantially greater ground clearance on high wings provides more flexibility for big flaps.
A - For a marginally - but successful takeoff - wing position makes no difference as you reasonably quickly climb through the narrow altitude where the ground effect is different (high wing wings being further from the ground at any given wheel altitude than low wing wings).
B - For overloaded, aft CG takeoffs that rotate early and remain behind the drag curve until they crash - the high wing has the benefit of exiting ground effect and sagging back to earth at a slightly lower height above the airfield than the low wing.
I would be a bit surprised if for a given weight, power, drag, airfoil section, wing loading, etc there was a material performance difference based on wing position. On the other hand, I am pretty sure the substantially greater ground clearance on high wings provides more flexibility for big flaps.
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Most planes are designed for some sort of mission profile, and I think that high wing aircraft have tended to be aimed at the short field capability market and thus have a lower wing loading to deliver a lower Vs which then directly translates into a better short field capability.
High wing planes also float less due to the reduced ground effect, which also improves short field landings.
I know Cessna are trying to hit every bit of the GA market but otherwise I think the above is overwhelmingly true in the real marketplace, with maybe the MU-2 being an exception
High wing planes also float less due to the reduced ground effect, which also improves short field landings.
I know Cessna are trying to hit every bit of the GA market but otherwise I think the above is overwhelmingly true in the real marketplace, with maybe the MU-2 being an exception
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I have no particular knowledge of this accident, and I have not flown a Lance. However, I've flown the Cherokee Six, and done many things in Arrows and other PA-28's which have taught me a few things about them. For the puprose of the following, I'm presuming the Lance is similar, but I am subject to being told otherwise. All of the following is relative to the low tail aircraft. T tail aircraft are quite different in this regard.
The high lift Piper wings are great, it's the stabilators which end up causing the challenge, when you drag the plane off the ground too early. Yes, you get get it airborne, and hanging in ground effect at a low speed. However, to escape ground effect, yet more energy will have to be added to climb away. The energy is slowly being added, if you accelerate, as the engine and propeller will become more efficiant.
However, what got you there was a large pitch control input, which equals a large angle of stabilator deflection. Perhaps beyond it's critical Cl max. This was a problem with the earliest Cessna Cardinals, and an AD'd modification to the stabilitor was the result.
In the low tail Cherokee of your choice, with lots of nose up applied, you have lots of drag from the deflected stabilator. A larger deflection angle of the stabilator is necessary than the equivilent stabilizer/elevator arragement elevator deflection, as the stabilator is not changing camber, where the stabilizer/elevator is when deflected. The increased camber of the stabilizer/elevator gives you a better chance of getting the lift, without stalling it, and getting huge drag as the same control input would do with the stabilator.
I have suffered this a few times in Arrows and regular Cherokees. The first time, in the Arrow, I was right seat on a hot day, 1000M runway, just two of us, and very slight crosswind. The pilot owner was inexperienced, and rotated too early. We hung in ground effect, not accelerating or climbing away perceptably. I got more and more nervous. He let it drift left off the runway, and remaining runway was disappearing. As I realized that we were now stuck in ground effect, and could not land back, I retracted the gear, and we slowly accelerated, and climbed away.
I later took a Cherokee out onto the frozen lake, where the runway length was about 25km. Repeatedly, I could rotate too early and too hard, get airborne too early, and stick in ground effect, unable to climb away (and this was with very favourable atmospheric conditions). In that case, landing back was not a problem, though the risk of a tail strike was there.
I don't know if this is well trained to Cherokee pilots, it never was to me. We just jumped in and flew, learning as we went. But this is an aspect of Cherokees which should be highlighted during differences training, if you can figure out how to demonstrate it without falling back to earth. It's just when the pilot least expects this, that it is most likely to happen.
My experience with other stabilator types (Cardinal, for the most part) is the different wing, further out of grond effect, just will not let you get into the air until the plane is going to fly properly anyway.
I have no idea if this could have been a factor int he accident discribed, (and I admit to not haveing read all the posts in this thread) but I think these characterisitcs are relevent in any case
The high lift Piper wings are great, it's the stabilators which end up causing the challenge, when you drag the plane off the ground too early. Yes, you get get it airborne, and hanging in ground effect at a low speed. However, to escape ground effect, yet more energy will have to be added to climb away. The energy is slowly being added, if you accelerate, as the engine and propeller will become more efficiant.
However, what got you there was a large pitch control input, which equals a large angle of stabilator deflection. Perhaps beyond it's critical Cl max. This was a problem with the earliest Cessna Cardinals, and an AD'd modification to the stabilitor was the result.
In the low tail Cherokee of your choice, with lots of nose up applied, you have lots of drag from the deflected stabilator. A larger deflection angle of the stabilator is necessary than the equivilent stabilizer/elevator arragement elevator deflection, as the stabilator is not changing camber, where the stabilizer/elevator is when deflected. The increased camber of the stabilizer/elevator gives you a better chance of getting the lift, without stalling it, and getting huge drag as the same control input would do with the stabilator.
I have suffered this a few times in Arrows and regular Cherokees. The first time, in the Arrow, I was right seat on a hot day, 1000M runway, just two of us, and very slight crosswind. The pilot owner was inexperienced, and rotated too early. We hung in ground effect, not accelerating or climbing away perceptably. I got more and more nervous. He let it drift left off the runway, and remaining runway was disappearing. As I realized that we were now stuck in ground effect, and could not land back, I retracted the gear, and we slowly accelerated, and climbed away.
I later took a Cherokee out onto the frozen lake, where the runway length was about 25km. Repeatedly, I could rotate too early and too hard, get airborne too early, and stick in ground effect, unable to climb away (and this was with very favourable atmospheric conditions). In that case, landing back was not a problem, though the risk of a tail strike was there.
I don't know if this is well trained to Cherokee pilots, it never was to me. We just jumped in and flew, learning as we went. But this is an aspect of Cherokees which should be highlighted during differences training, if you can figure out how to demonstrate it without falling back to earth. It's just when the pilot least expects this, that it is most likely to happen.
My experience with other stabilator types (Cardinal, for the most part) is the different wing, further out of grond effect, just will not let you get into the air until the plane is going to fly properly anyway.
I have no idea if this could have been a factor int he accident discribed, (and I admit to not haveing read all the posts in this thread) but I think these characterisitcs are relevent in any case
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Pilot DAR
For the record, the Lance II involved in this incident was a 'T' configuration.
Let's just say they require careful handling at low airspeeds - others have explained this in detail earlier in the thread.
The original Lance was a low tail config and in my (limited) experience of flying one, a very nice aircraft to handle (then again, I learned on PA28s and had PA32 fixed gear experience.)
It's interesting to read your comments about PA28s, for it seems to me that there are so many different versions with varying power, wing types, gear, tails, that it is difficult to generalise other than to say they are at the docile end of the handling range (but will still bite the unwary and thanks for making a good point about that.)
Your íce runway experience sounds like a -140 to me, can you remember?
For the record, the Lance II involved in this incident was a 'T' configuration.
Let's just say they require careful handling at low airspeeds - others have explained this in detail earlier in the thread.
The original Lance was a low tail config and in my (limited) experience of flying one, a very nice aircraft to handle (then again, I learned on PA28s and had PA32 fixed gear experience.)
It's interesting to read your comments about PA28s, for it seems to me that there are so many different versions with varying power, wing types, gear, tails, that it is difficult to generalise other than to say they are at the docile end of the handling range
(but will still bite the unwary and thanks for making a good point about that.)Your íce runway experience sounds like a -140 to me, can you remember?
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F3G
Yes, I suppose it would have been a PA-28-140. It was decades ago, and I don't remember for sure.
Yes, the T tail Pipers are a whole other type of thing to fly. Good, if you're well trained on them. Not so good for short & soft runways!
Yes, I suppose it would have been a PA-28-140. It was decades ago, and I don't remember for sure.
Yes, the T tail Pipers are a whole other type of thing to fly. Good, if you're well trained on them. Not so good for short & soft runways!
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too heavy to fly?
Immediatly preceeding the AAIB report regarding the Cherokee Lance II at Wycombe, another remarkably similar event is reported on page 28, at Netherthorpe, South Yorkshire. Insufficient runway for the Cherokee PA-28 to take off. It "collided with bushes beyond the end of the runway before crossing a road and coming to rest in a field on the far side." Considerable damage, but right side up, and the occupants only minor injuries.
I do get upset seeing a pilot loading up any airplane which which I am familiar, with large adults and heavy baggage, and have once or twice timidly asked if he has done his weight and balance checks....to be told in no uncertain terms that the calculations have been made and it was none of my business. But if I had said nothing, and the aircraft had come to grief, I would have felt partly responsible. Have others had that experience, I wonder?
On a happier note, I remember watching a friend preflight his 180 Cessna on floats (or was it a 182?). It was kept on a bayou in Louisiana, near Morgan City. My friend had a lot of experience in Alaska, he knew what he was doing, loading up on a hot afternoon, with a crew change for an oil rig in the gulf.
In went sacks and boxes of food and beer, and two very large bearded oilmen. I knew better than to comment, just watched, because like DAR on his frozen lake, he had a runway of infinite length! The Cessna taxied down round the bend, I could hear the engine powering up, and here it came, up the bayou, and round two more bends, still on the water, and eventually, when enough fuel (or beer) had been used, it rose like a goose and headed south.
He took me up one moonlit night, looking down on all that water, infinite choice of places to touch down, or take off. Rivers and bayous, winding through the trees, all lit up with the moon, shining brightly. Who needs runway lights?
I do get upset seeing a pilot loading up any airplane which which I am familiar, with large adults and heavy baggage, and have once or twice timidly asked if he has done his weight and balance checks....to be told in no uncertain terms that the calculations have been made and it was none of my business. But if I had said nothing, and the aircraft had come to grief, I would have felt partly responsible. Have others had that experience, I wonder?
On a happier note, I remember watching a friend preflight his 180 Cessna on floats (or was it a 182?). It was kept on a bayou in Louisiana, near Morgan City. My friend had a lot of experience in Alaska, he knew what he was doing, loading up on a hot afternoon, with a crew change for an oil rig in the gulf.
In went sacks and boxes of food and beer, and two very large bearded oilmen. I knew better than to comment, just watched, because like DAR on his frozen lake, he had a runway of infinite length! The Cessna taxied down round the bend, I could hear the engine powering up, and here it came, up the bayou, and round two more bends, still on the water, and eventually, when enough fuel (or beer) had been used, it rose like a goose and headed south.
He took me up one moonlit night, looking down on all that water, infinite choice of places to touch down, or take off. Rivers and bayous, winding through the trees, all lit up with the moon, shining brightly. Who needs runway lights?
Moderator
I used to fly moose hunters in a 180 floatplane - I had to learn to say "next trip". I used to jumpers in a 185, I had to learn to say "you can't come this time". I used to fly scientists in a 207, I had to learn to say "that can't come". I used to fly the boss's 182 - he used to load the freight I flew.
One day I arrived, the plane was loaded and fuelled. He said: "she's heavy today, take it easy on her". The length of the runway remained unchanged at 1600 feet.
Yup, it was heavy, I took it easy. When I got where I was going, I counted and weighed what came out - 800 pounds over gross!
I find when I test fly, weight and balances are the most screwed up things by far. If people even do them, they seem to very often not really be accurate. I asked for the Caravan to be reweighed, because I didn't believe what I read on the W&B amendment, and I get a new weight 260 pounds lighter... Which one is right? Weigh it again.....
If pilots realized how much the aircraft's handling and ability to be recovered from unusual attitudes, they'd pay a lot more attention to the weight and balance!
One day I arrived, the plane was loaded and fuelled. He said: "she's heavy today, take it easy on her". The length of the runway remained unchanged at 1600 feet.
Yup, it was heavy, I took it easy. When I got where I was going, I counted and weighed what came out - 800 pounds over gross!
I find when I test fly, weight and balances are the most screwed up things by far. If people even do them, they seem to very often not really be accurate. I asked for the Caravan to be reweighed, because I didn't believe what I read on the W&B amendment, and I get a new weight 260 pounds lighter... Which one is right? Weigh it again.....
If pilots realized how much the aircraft's handling and ability to be recovered from unusual attitudes, they'd pay a lot more attention to the weight and balance!