Fatal takeoff accidents
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Bookworm
I didn't describe the decision as lunacy, but given the pilots experience on type, could we agree that it was an unwise one?
You need to nail everything to get out safely - as I said in my earlier post, I accept that some people could do this, but I am not one of them nor would many people be with a few hours on type.
I didn't describe the decision as lunacy, but given the pilots experience on type, could we agree that it was an unwise one?
You need to nail everything to get out safely - as I said in my earlier post, I accept that some people could do this, but I am not one of them nor would many people be with a few hours on type.
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Some weeks ago I phoned Bembridge with a view to a visit. They said runway 23 was in use. This is 380m unlicensed. I said that I was flying in in a Cessna 152 and they were most encouraging "we often have Cessna 152s on that runway".
Being a low hours PPL I said "Thanks, but I think I'll give it a miss!"
Being a low hours PPL I said "Thanks, but I think I'll give it a miss!"
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Bookworm, I still think it is lunacy, especially for a 4hrs on type pilot. Doing the math(s), he had 3:07 flight time in the PA32 for the Wellsbourne-Dieppe-Shotteswell round trip. So, two successful landings, two successful take-offs and whatever he got in his previous hour long checkride.
Would you have had a go in exactly the same circumstances?
Would you have had a go in exactly the same circumstances?
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If you are halfway along the runway and the aircraft is not starting to get 'light' and look like flying then this is the last moment you have to stop before things get exciting.
I've flown aircraft / strip combinations where there is not a lot of margin but if the aircraft does not feel like it is about to fly - then it probably will not. I've given up a few times, usually waiting for either much cooler conditions or a decent amount of wind (or turfing out a fair bit of weight!). Either option will work.
My present aircraft will fly away at 45kts, the last 10kts takes a surprising amount of distance - or seems to when the strip is short! But I can use 250m without much thought. Flying heavier low powered aircraft is very much more challenging and it was while I had one of those that the balancing act of weight / length / density altitude was necessary. But if you have not got the experience of what looks right and works then you become a test pilot. If you do not think clearly about what might happen then it probably will.
I've flown aircraft / strip combinations where there is not a lot of margin but if the aircraft does not feel like it is about to fly - then it probably will not. I've given up a few times, usually waiting for either much cooler conditions or a decent amount of wind (or turfing out a fair bit of weight!). Either option will work.
My present aircraft will fly away at 45kts, the last 10kts takes a surprising amount of distance - or seems to when the strip is short! But I can use 250m without much thought. Flying heavier low powered aircraft is very much more challenging and it was while I had one of those that the balancing act of weight / length / density altitude was necessary. But if you have not got the experience of what looks right and works then you become a test pilot. If you do not think clearly about what might happen then it probably will.
Would you have had a go in exactly the same circumstances?
If the question is, would I take-off in my aircraft from a runway where the calculated take-off distance to 50 feet was 10% less than the strip length available, and the calculated take-off distance to clear a known obstacle at the end was 76% of the distance to that obstacle, then I'd think very hard about it. If I did, I'd like to think that I'd remember the flaps. But I'm spoiled by operating from oversized tarmac most of the time. Are you really saying that anyone operating with those margins is a lunatic? I meet a fair few lunatics then...
My concern is that if we write accident pilots off as lunatics, we say to ourselves that we would never contemplate doing something similar, and thus don't learn from the (flawed) decision-making process. We are, after all, not lunatics.
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My concern is that if we write accident pilots off as lunatics, we say to ourselves that we would never contemplate doing something similar, and thus don't learn from the (flawed) decision-making process. We are, after all, not lunatics.
If we start thinking we might bend the rules, then we are more than half way towards actually bending them. On the other hand, if we feel operating outside of normal standards is unthinkable, then we already have a high barrier against operating in such a manner. The decision makes itself; outside limits = no.
I think there is much more to learn from success than from failure.
*) Not implying any specific decisions discussed in this thread represent lunacy.
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We are, after all, not lunatics.
By human nature, it's too easy to let little things slide, but little things become big things, and at some point big things become bigger than us, and then it may well be too late.
A few degrees warmer than normal. Not a big deal. After all, haven't we taken this airplane off before, somewhere, when the perspiration was running down our forehead and into our eyes? This can't be a problem.
Different airfield today? Not a big deal. After all, we fly to all sorts of airfields, and it's never been a problem before.
Obstacles at the end of the field? Not a big deal. We'll certainly fly over them, and failing that, around them. We always have before.
The lineman overfilled us by a few more gallons or liters than we'd requested. However, it's a big, thick wing, and we can handle a few extra pounds. After all, none of us are spring chickens and lightweights either, and the airplane carries us just fine, too. Not a big deal.
A very slight tailwind, but it's nearly calm. The runway is slightly uphill, too. And it's grass, but it's probably firm under the grass, and it doesn't look very wet. Not a big deal. We've seen worse.
It was a long night last night. Glad when this divorce is over, finally. Not a big deal today, though, because we have this flight to take our mind off our troubles, and with a shot of coffee and a doughnut, we're right as rain.
Slight head cold, but that shot of nose spray and a couple of tablet seems to have made it go away. Not a big deal. Besides, we won't be climbing very high.
Yada, yada, yada...
It's well said that justification is the narcotic of the soul. The world is filled with not a few addicts. Think about it.
Anytime we find ourself justifying what we're doing, we're screwing up.
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Lots of talk about POH perf figures in this thread. Its worth remembering that the POH figures for take off roll required and take off distance required (to 50 ft) may be unfactored.
Once you start adding in factors for density altitude, up or down hill slopes, grass(wet, dry or long) and an overall safety margin some of these shorter strips in anything piper or cessna are not doable with full pax loads and fuel. With a zero flap setting a departure from a short grass strip in a PA28-161, let alone a 140 is utter madness!
You all do use the CAA recommended factors?
Once you start adding in factors for density altitude, up or down hill slopes, grass(wet, dry or long) and an overall safety margin some of these shorter strips in anything piper or cessna are not doable with full pax loads and fuel. With a zero flap setting a departure from a short grass strip in a PA28-161, let alone a 140 is utter madness!
You all do use the CAA recommended factors?
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Once you start adding in factors for density altitude, up or down hill slopes, grass(wet, dry or long) and an overall safety margin some of these shorter strips in anything piper or cessna are not doable with full pax loads and fuel.
You all do use the CAA recommended factors?
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Its not trivia and does need occasional reminders. Performance planning is not covered in enough depth or detail in my opinion.
The CAA factors do not need to be applied for a private flight but in my opinion should be, just as they would be for any public transport flight, unless you are alone of course then go kill yourself if you like!
The CAA factors do not need to be applied for a private flight but in my opinion should be, just as they would be for any public transport flight, unless you are alone of course then go kill yourself if you like!
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There is a bit of a difficulty with the CAA performance figures.
One they are advisory - and for good reason they are very conservative. Unfortunately they are in many cases so conservative that they are nearly unworkable.
So great advice but advice which experience quickly tells you is overly conservative. This is a flaw with much of the CAa output - if 'your' evidence is that the advice is 'for babies' then it is ignored.
The underlying 'lesson' if there really is one is that all aircraft have runway lengths which should not be messed with. The particular challenge is that light singles have performance which is radically altered by their loads.
My LSA type design carries 40% of its mauw as disposable load, but its performance at mauw is still effectively stol.
a cherokee or cessna with 150hp is a different beast. Light quite pleasant, almost stol, heavy they almost rely on the curvature of the earth. So radically different performance from the same aircraft.
Saratoga - I've not flown one but a locaql para dropping outfit had one which operated from 510m of concrete so probably the gradient 'did for it'.
But how many ppls have any real experience with gradients? We have a local strip where taxiing up it requires over 2000rpm. Impossible to takeoff uphill, radically easy down. My learning from using this strip is if I have to force land it will be uphill if there is nothing long enough and flat enough.
But that is the key to this hobby (apologies to those real professionals!). It is terrific fun but can be very unforgiving if you get it wrong.
One they are advisory - and for good reason they are very conservative. Unfortunately they are in many cases so conservative that they are nearly unworkable.
So great advice but advice which experience quickly tells you is overly conservative. This is a flaw with much of the CAa output - if 'your' evidence is that the advice is 'for babies' then it is ignored.
The underlying 'lesson' if there really is one is that all aircraft have runway lengths which should not be messed with. The particular challenge is that light singles have performance which is radically altered by their loads.
My LSA type design carries 40% of its mauw as disposable load, but its performance at mauw is still effectively stol.
a cherokee or cessna with 150hp is a different beast. Light quite pleasant, almost stol, heavy they almost rely on the curvature of the earth. So radically different performance from the same aircraft.
Saratoga - I've not flown one but a locaql para dropping outfit had one which operated from 510m of concrete so probably the gradient 'did for it'.
But how many ppls have any real experience with gradients? We have a local strip where taxiing up it requires over 2000rpm. Impossible to takeoff uphill, radically easy down. My learning from using this strip is if I have to force land it will be uphill if there is nothing long enough and flat enough.
But that is the key to this hobby (apologies to those real professionals!). It is terrific fun but can be very unforgiving if you get it wrong.
You can use the GASCo planner to assist in working out your T/O and Landing perf;`GASCo- Flight safety-Avoiding the hedge `,and download it as a handy reference,if you can`t remember the fiddle factors.
Another way that you can check the a/c perf,even if you have/have not got any suitable perf charts,is to consider this; have a marker/something to indicate the runway midpoint,then, if you haven`t reached 71% of your speed to rotate ,by that point-STOP;;It is based upon those boring acceleration/decel. `equations of motion`,and if you have the graphs you can work it out mathematically;I do it as a check of time vs.speed vs. distance when I do airtests.
Another way that you can check the a/c perf,even if you have/have not got any suitable perf charts,is to consider this; have a marker/something to indicate the runway midpoint,then, if you haven`t reached 71% of your speed to rotate ,by that point-STOP;;It is based upon those boring acceleration/decel. `equations of motion`,and if you have the graphs you can work it out mathematically;I do it as a check of time vs.speed vs. distance when I do airtests.
I'm not too familiar with UK regulations; is it actually optional to make performance calculations using all relevant performance factors, such as the ones you mention, before flight?
the aircraft takes off:
...
(g) in the case of a flying machine, that having regard to the performance of the
flying machine in the conditions to be expected on the intended flight, and to any
obstructions at the places of departure and intended destination and on the
intended route, it is capable of safely taking off, reaching and maintaining a safe
height thereafter and making a safe landing at the place of intended destination;
If the law instead required the application of public transport safety factors (1.33/1.43) against published TODAs, I think a great deal of currently feasible flying would have to stop, and many smaller airfields would close.
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“If the law instead required the application of public transport safety factors (1.33/1.43) against published TODAs, I think a great deal of currently feasible flying would have to stop, and many smaller airfields would close.”
Absolutely, this is why in the real world they are not used very much.
Rod1
Absolutely, this is why in the real world they are not used very much.
Rod1
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On our 600 metre grass field if you add all the safety factors for take off,abort at last second before take off,then apply all factors to stop it brings one very close to the end of the runway with some aircraft.
At the end of runway 19 there are hangars, a house and hedge,so many choose to take off on 01 where there are open fields at the end, even with a slight tailwind.
Lister
At the end of runway 19 there are hangars, a house and hedge,so many choose to take off on 01 where there are open fields at the end, even with a slight tailwind.
Lister
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I wouldn't use the word "lunacy" but I wonder where the AAIB got those super precise figures from ("268 m").
It reminds me of reading some newspaper article about how good forensic science is; there was some road accident where they determined from how far the victim was flung that the driver was doing 49.75mph, and he got prosecuted for it. Yeah, right, pull the other one..... getting one significant digit out of that "data" would be good going, but not four.
I tend to avoid grass basically because the plane ends up covered in muck and (if the grass is tall, say 7"+) the prop acts as a lawn mower and the whole plane gets covered in very hard to shift green stuff, and also many are poorly maintained so there are potholes etc.
But I've been to a fair few grass runways and the one thing I notice is how variable the takeoff distance is, with surface and grass condition, wetness, grass length, etc. This kind of stuff is almost impossible to predict and one needs to apply hefty margins. The POH data, which is usually just for hard runways, is not useful for grass distance estimating and one needs to add anything from 20% (for a perfect surface, the likes of which are few and far between) to 100% (for 8" wet grass). And then some for any upslope - around 10% extra for every 1% of upslope.
One can use soft field takeoff techniques but they require good currency on type (because you yank the plane off the runway way before it is at flying speed, Vr) and are dodgy in crosswinds. Also, while the acceleration once airborne in ground effect is impressive, one ends up with tons of elevator drag up to the point where one gets into GE, and the tradeoff between the two is questionable.
It reminds me of reading some newspaper article about how good forensic science is; there was some road accident where they determined from how far the victim was flung that the driver was doing 49.75mph, and he got prosecuted for it. Yeah, right, pull the other one..... getting one significant digit out of that "data" would be good going, but not four.
I tend to avoid grass basically because the plane ends up covered in muck and (if the grass is tall, say 7"+) the prop acts as a lawn mower and the whole plane gets covered in very hard to shift green stuff, and also many are poorly maintained so there are potholes etc.
But I've been to a fair few grass runways and the one thing I notice is how variable the takeoff distance is, with surface and grass condition, wetness, grass length, etc. This kind of stuff is almost impossible to predict and one needs to apply hefty margins. The POH data, which is usually just for hard runways, is not useful for grass distance estimating and one needs to add anything from 20% (for a perfect surface, the likes of which are few and far between) to 100% (for 8" wet grass). And then some for any upslope - around 10% extra for every 1% of upslope.
One can use soft field takeoff techniques but they require good currency on type (because you yank the plane off the runway way before it is at flying speed, Vr) and are dodgy in crosswinds. Also, while the acceleration once airborne in ground effect is impressive, one ends up with tons of elevator drag up to the point where one gets into GE, and the tradeoff between the two is questionable.
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So you take performance figures from the POH, unfactored, representing what a test pilot could achieve while expertly following best-practice procedures in a mint condition aircraft. You add non-conservative corrections for the most easily estimated adverese conditions, such as a smooth, dry, short grass surface, temperature, and some head or tail wind. Now you have your best-possible, optimum takeoff or landing distance.
On top of that, you have the condition of the aircraft, pilot technique, pilot skill in accomplishing the chosen technique, grass that is a little longer and more wet, a strip that is not so smooth, slope that may be varying, possibly some gusts from the wrong direction, and so on and so forth... But do you add a safety margin for all this?
No! Because that would mean your flight couldn't take place, and such rules are "for babies" anyway. Let's just go fly.
"Gee, you know what? I see in the latest AAIB bulletins that there are an awful lot of fatal takeoff and landing accidents taking place... Why do you reckon that is?!
"
I don't think the safety factors are unfeasible. I think flying from insufficient airstrips is unfeasible. JMHO.
On top of that, you have the condition of the aircraft, pilot technique, pilot skill in accomplishing the chosen technique, grass that is a little longer and more wet, a strip that is not so smooth, slope that may be varying, possibly some gusts from the wrong direction, and so on and so forth... But do you add a safety margin for all this?
No! Because that would mean your flight couldn't take place, and such rules are "for babies" anyway. Let's just go fly.
"Gee, you know what? I see in the latest AAIB bulletins that there are an awful lot of fatal takeoff and landing accidents taking place... Why do you reckon that is?!
" I don't think the safety factors are unfeasible. I think flying from insufficient airstrips is unfeasible. JMHO.
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Bookworm raises an interesting point
Remembering when I converted to the PA32 with prior PA28 experience, the longer fuselage did make the larger aircraft weathercock more and this felt worse than it really was during the approach to land.
Maybe the pilot misread this as a stronger wind?
Given the choice of a very short and a longish runway, if the cross component was 17 knots or less, I'd take the longer distance, probably add 5 knots to Vr if the wind was gusting and then bring her off very cleanly. Once off the ground, the weathercocking will cease to be a problem.
Any other thoughts?
The pilot apparently struggled with the crosswind on the way in, and may have thought that the headwind component was greater.
Maybe the pilot misread this as a stronger wind?
Given the choice of a very short and a longish runway, if the cross component was 17 knots or less, I'd take the longer distance, probably add 5 knots to Vr if the wind was gusting and then bring her off very cleanly. Once off the ground, the weathercocking will cease to be a problem.
Any other thoughts?