Fatal takeoff accidents

[DavidHoul52]

October's AAIB report makes sad reading. Two fatal accidents and both on takeoff. Another common theme is that both based decisions on incorrect information (in one case wrong airfield information, in the other a sudden change of wind direction). Both were experienced pilots.

For me it brings home the need to take extra care to double check everything when flying near to limits.

[SNS3Guppy]

Double check everything, whether you're flying near the limits, or not.

Remember, you don't go to the limits, they come to you. Keep distance, for safety.

Measure twice, cut once.

[Lookforshooter]

Why don't you tell him how it's done in the airlines...how SAFE things really are?

[Final 3 Greens]

David

From someone with a little more experience than you, but less than others here.

You can always stop before you take off (I'm speaking for practical purposes in SEP.)

If I doesn't quite feel right, reject and then analyse what happened safely on mother earth.

Happy landings.

[BRL]

Why don't you tell him how it's done in the airlines...how SAFE things really are?

Can we just try and keep this to Private Flying and keep your politics from the airlines out of it......

Go start a thread elswhere if you want to harp on about how safe they are, please dont start anything here.

Email me rather than post back here if you want to discus this further please.

[AMEandPPL]

October's AAIB report

also contains a very brief report, recording very minor damage to a Cirrus SR22, and no injuries whatever (page 24, reg N434A).

Refers throughout just to "the pilot", and does not mention that this is actually the star of TV's "The Apprentice" whose catch-phrase is "you're fired".

[Jumbo Driver]

You can always stop before you take off (I'm speaking for practical purposes in SEP.)

This is not really true - now is it ... ? There are cases where the book says you can go but are you really saying that, at rotate, you could ALWAYS stop in the runway remaining? I don't think that light aircraft POHs (or even Performance Manuals) offer sufficient performance information to show this one way or another. However, if you were to say "in many cases", then I believe your assertion would be correct.


If I doesn't quite feel right, reject and then analyse what happened safely on mother earth.

I certainly would agree with this principle - it must be preferable to abort with a single engine if you have any doubts about the performance capability - if you can in the space remaining, that is ...


JD
:)

[wobble2plank]

I thought all fatal accidents began with a take-off or attempted take-off! :E

Sorry ;)

I'll get me coat!

(And before I get harangued yes I have lost some close friends in accidents but they had the same warped sense of humor/destiny.)

[Fright Level]

The CAA actually produce a very interesting document on this topic (Safety Sense Leaflet 07: Aeroplane Performance (http://www.caa.co.uk/application.aspx?catid=33&pagetype=65&appid=11&mode=detail&id=1913)).

It's daft to try to relate single engine/unclassified aircraft performance to commercial operations. In the public transport multi-engine world, there is always a stop/continue decision to be made (and most company's have SOP's dictating when a stop is always required). In the SE GA world, it's more grey but with a single engine, much of the choice is taken away from you. I know I'd prefer to slide through a hedge at the end of the runway in deceleration than decide that I must continue with some kind of problem with the airworthiness of the plane and run the risk of a later accident from height, at greater speed or under high power settings as I tried to get airborne.

[AMEandPPL]

I thought all fatal accidents began with a take-off or attempted take-off!

Not quite true - CHIRP mentions possible fatalities here

http://www.chirp.co.uk/downloads/GAFB/GAFB33.pdf

in relation to "prop-swinging". Collisions and subsequent fires have also occurred during taxiing.

So serious or fatal accidents can occur before any attempt at all to take off !

[wobble2plank]

True, but at some point after the incident they were to attempt a take off! :E

Semantics.

[stillin1]

BRL

Very well put. Exactly the thoughts I had as I read down the post, but with a lot less blasphemy!:ugh:

[Final 3 Greens]

Jumbo Driver

This is not really true - now is it ... ? There are cases where the book says you can go but are you really saying that, at rotate, you could ALWAYS stop in the runway remaining?

Have you ever seen an accelerate-stop distance in a single POH?

Me neither, which is why I used the caveat "for practical purposes."

I'd rather hit the fence at 15mph, than stall in from 50 feet, so I go aliong with Fright Level's view.

[Fright Level]

I go aliong with Fright Level's view

Not many people usually do!

Have you ever seen an accelerate-stop distance in a single POH?

I guess you could always add the ground distance for take off and the ground distance for landing. Work it out for a 5kt tailwind at MTOW on a wet runway and you'll have a worst case figure to bear in mind when you operate from shorter strips.

Practise a couple of RTO's but wait until you need new tyres as under max braking you'll need to be using cadence braking to avoid locking up the wheels :)

[Zorst]

you'll need to be using cadence braking to avoid locking up the wheels
Wrong.

In cadence braking the wheels are locked in each cycle.

It's one of those things that lots of people talk about, very few understand, and a tiny minority can do.

[SNS3Guppy]

I'm not sure what's being implied by "cadence braking," though it sounds a lot like one is pumping the brakes. If this is the case, it's poor technique. Nothing is gained and stopping distance is increased. Steady continuous pressure shy of skidding a tire will provide maximum braking. If at any time a brake is locked up or a tire skidded, braking and stopping effectiveness is reduced.

Many of the aircraft flight manuals for light piston powered airplanes don't include detailed information on getting the airplane stopped with an engine failure, but then many of them don't take excessive amounts of runway to get off the ground or get stopped...and in a single engine airplane following an engine failure, you're definitely returning to earth. The entire planet becomes your stopway, because every engine failure will become the same; you're coming back down. With this in mind, one should plan a takeoff in a single engine airplane not just for the purposes of getting stopped on the runway, but getting stopped after the runway, too. Plan your takeoff accordingly.

[Jumbo Driver]

Have you ever seen an accelerate-stop distance in a single POH?

F3G, that's rather the point I was trying to make, because I don't think your assertion that

You can always stop before you take off (I'm speaking for practical purposes in SEP.)

is correct.


JD
:)

[Final 3 Greens]

JD

Don't wish to labour the point, but unless it is a very short field, you are likely to be able to stop - I got to 55 knots and stopped easily in a PA28 on a 700m grass strip when I saw wisps of smoke coming from behind the panel and smelled burning.

If it is too short to stop, you have a difficult decision to make - hit the fence with speed decreasing (not nice), or take the problem into the air - if it will go there (maybe not nice at all.)

As SNS3Guppy says, better not to put yourself in that position to start with.

Safe flying ;)

[Jumbo Driver]

Sorry, F3G, then we shall have to differ on this one.

If you were flying a taildragger out of a grass strip - much shorter than your luxurious 700m strip - I can assure you that you would not be so confident of being able to accelerate-stop. Also, if the PA28 you mention was a PA28-140 and you were three-up on a warm day, that might be another case in point for you to consider. In my experience, a rejected take-off at close to lift-off speed in a light aeroplane off a typical grass strip will not always provide the relaxed picture you present in your original response.

Your answer seemed to be addressed to all light aircraft fliers. In that context, I still think it is misleading and incorrect. Substitute "in many cases" for "always" or specify that you are talking about a nice long tarmac runway and I will go along with what you say.

You fly safe, too ;)


JD
:)

[Pilot DAR]

Yes, I held my words, and then BRL supported what I was thinking.

That said, trying to overlay the concept of accellerate stop distance onto a single engine light aircraft is rather pointless. Among the several reasons, is that there is a disclipline during the takeoff of such advanced aircraft, of adhering to certain speeds, at certain elements of the takeoff, and I just don't see light aircraft flown that way. If the proper discliplines used for takeoff in an aircraft for which these advanced techinques were the norm, were used in general aviation, I'd say we'd see an improvement in takeoff safety even before things started going wrong during takeoff. People would just be more aware of what they were doing during takeoff. If the aircraft manufacturers did publish such data, would pilots refer to it anyway? Worse, every operation of an aircraft out of a runway shorter than that published value, would have the insurance company declaring that the published performance data for the aircraft had not been followed, and thus insurance was not valid. If you were to see such data for heavier singles like a Cessna 206/210, or Piper Lance, a lot of commonly used runways would suddenly be off limits. Cessna 210 and 310 have quite similar speeds, and the balanced field length for the 310 I used to fly exceed 5000 feet in some conditions. Would 210 pilots want to be restricted to runways longer than 5000 feet? there'd be an outcry!

I am certainly guilty of flying a scary circuit in a defective aircraft (both single and multi), where aborting the takeoff would have been the much more prudent thing to do. My failing is that my head just was not where it should have been. As long as I was able to climb away, that's what I did. Not always the best idea. Being very scared is a good tool to assure that such circumstances will be given more consideration next time!

The accellerate stop distance (balanced field length value) is predicated on the rather dramatic failure indication (on a left and right multi engined aircraft) provided by a failed engine. It is not there for other failures, which might be much more challenging to recognize, and act upon correctly in the very brief period of time allowed to make the required decision, and take the correct action. Consider the numerous accidents in Cessna 336 and 337 aircraft where the pilot did not recognize the failure of the rear engine during takeoff, and attemped to continue the takeoff. Once you reach Vr or V1 as appropriate, the time required to recognize, decide and act upon an unusual event is very short, and gets much more critical as the takeoff is allowed to continue, with delayed action. In single engined aircraft. engine failure at Vr is an obvious reason to abort (like you had a choice!). What other failures are proposed for the single engine pilot to recongize and act upon at that critical phase of flight? If these skills were on the private pilot skills test, there would be many fewer passes!

The original post's wording could be interpreted to suggest that the pilot in each case did not necessarily operate close to aircraft limits, but perhaps just exceeded his own limits. (though I am not at all familiar with the details of either accident). "Experience" is a relative term, and it does not automatically convey to me the the pilot with the "experience" necessarily has personal skill limits approaching those of the aircraft he is flying. So tell him the balanced field length for every aircraft, will he use the information correctly anyway?

"Good judgement comes from experience, experience comes from poor judgement".

Yes, Measure twice, cut once = Think it through twice, fly it once...

Pilot DAR

[Final 3 Greens]

If you were flying a taildragger out of a grass strip - much shorter than your luxurious 700m strip - I can assure you that you would not be so confident of being able to accelerate-stop. Also, if the PA28 you mention was a PA28-140 and you were three-up on a warm day, that might be another case in point for you to consider. In my experience, a rejected take-off at close to lift-off speed in a light aeroplane off a typical grass strip will not always provide the relaxed picture you present in your original response.

You can always stop, as SNS3Guppy said the whole world is your stopway :}

We are in danger of drifting off thread into the world of personal risk judgement and management, so let's agree to differ :ok:

[DavidHoul52]

The original post's wording could be interpreted to suggest that the pilot in each case did not necessarily operate close to aircraft limits, but perhaps just exceeded his own limits.

In the one accident the pilot had incorrect information about the length of the strip, but even this was less than that set down by the CAA. Very strange circumstances - the pilot had returned from a trip to France (did he file a flight plan?) and chose to land in the UK in a small unlicensed strip.

The other was at Sandown on the Isle of Wight. Here is a summary of the AAIB report:

The aircraft departed from Runway 23, with four people on board, on a flight to Pontivy, France. Its takeoff ground roll was noticeably long and, having lifted off, G-AVRP climbed to about 50 ft agl and maintained that height as it flew over rising ground beyond the end of the runway. As it approached trees at the top of the rising ground, the aircraft was seen to pitch up and clear the trees before its nose dropped and it descended out of sight. The aircraft struck another line of trees and crashed into a field. The aircraft rapidly caught fire. The fire was extinguished by the Airport Fire-fighting and Rescue Service (FFRS). All the occupants of the aircraft died in the accident and the aircraft was destroyed. It was established that the aircraft’s predicted performance, at its estimated takeoff weight and in the prevailing conditions, should have enabled a successful departure. Its failure to do so may have been the result of reduced engine power, a tailwind component, a greater takeoff weight than estimated, an incorrect piloting technique during takeoff or a combination of some or all of these factors.

[SNS3Guppy]

David,

At the outset of this thread, you attributed the second mishap, quoted above, to a tailwind...the quote you provided does not say this.

[Rod1]

In the “real world” it appears to me that things are very different to the numbers set out by the CAA. We have licensed airfields with runways a little over 300m of often wet grass doing training in tired 152’s. We have aircraft with no or almost no POH, and we have lots of unlicensed strips. If the CAA safety factors were rigidly applied there would be a reduction in accidents because there would be a huge decrease in flying!

Rod1

[DavidHoul52]

At the outset of this thread, you attributed the second mishap, quoted above, to a tailwind...the quote you provided does not say this.

It does mention "tailwind component". In the report itself it goes on to say


Photographs of smoke rising from the crashed aircraft, taken three minutes after the accident had occurred, and another 12 minutes later, appeared to show that the surface wind at the accident site varied during that time between a south-easterly and north-easterly direction.

The impression was of a light wind. The pilot of another Piper PA- 28-140, which took off from Runway 23 at 1030 hrs, reported that the indications from the wind sleeve on the airfield, at that time, were of a surface wind from between 110° and 120° ie a tailwind


I was perhaps not quite correct to say that this accident was due to limits as


It was established that the aircraft’s predicted performance, at its estimated takeoff weight and in the prevailing conditions, should have enabled a successful departure.

[DavidHoul52]

We have licensed airfields with runways a little over 300m of often wet grass doing training in tired 152’s.

This was a PA-32, an uphill slope and no flaps were used.

[SNS3Guppy]

It does mention "tailwind component". In the report itself it goes on to say


The report "mentions." It does not provide a cause. It also mentions other "possible" contributing factors, but does not give useful information with respect to what actually occured. It is best not to speculate, nor to cite the case as one in which a poor decision to takeoff with tailwind was the cause...because there is nothing to suggest such a thing. It's best to stick to the facts.

We have licensed airfields with runways a little over 300m of often wet grass doing training in tired 152’s. We have aircraft with no or almost no POH, and we have lots of unlicensed strips.


An instructor who fails to ensure his students calculate performance data has failed the student, and a student who is not made to calculate performance data has not received proper instruction.

One has no business flying any given type of airplane unless one owns the appropriate flight manuals. It should be one of the first books one buys when one undertakes flight training, and it should be an immediate investment each time one undertakes to fly a new airplane.

I don't know what the requirements in the UK are, but in the US if the airplane doesn't have the aircraft flight manual on board, it's not airworthy, and therefore not legal to fly.

With respect to an airfield of unknown length, one should take the time to walk the field before use and determine it's length, obstacles, and surface condition. There are unusual conditions when this isn't possible, such as flight to a remote location where no visit beforehand is possible...but for those doing flight training, there's no excuse. The instructor should have a sure knowledge of the field, and should demonstrate to his student how to obtain that knowledge.

A good practice, especially at an unknown field having a grass or dirt runway and an undefined length, is to pace it off, check it's condition, and make a determination based on objects near the runway as to when the airplane will be airborne...as well as where to go during an engine failure. This is basic airmanship.

[Final 3 Greens]

One does wonder about the thought process behind taking off in a PA32, uphill on a sharp initial upslope, with about 300m and trees at the far end, bearing in mind the pilot had little time on type.

When I converted to PA32s from PA28s, I found Dick Collins 3,000 guideline for this aircraft to be helfpul.

Essentialy that said if you have more than 3,000 feet of runway (about 900m), the weight is less than 3,000 lbs and the density altitude less than 3,000m she is a pussycat. Variance from 3,000 in a limiting way requires some consideration.

I know that I wouldn't try to take a PA32 out of 300m, even solo and at light weight - there may be people who can but they have better skills than me.

RIP.

[Rod1]

“One has no business flying any given type of airplane unless one owns the appropriate flight manuals.”

This is tosh. There are 1000’s of vintage aircraft which are flying with a POH of 2 or three pages, or nothing at all. There are 1000’s of home built aircraft which have a set of plans and a few lines of “handling notes”. I built and fly a modern home built, which has a generic POH, but it does not cover my airframe, engine, prop combination and my performance is significantly different. As I said, the real world is a very different place…

Rod1

[SNS3Guppy]

This is tosh. There are 1000’s of vintage aircraft which are flying with a POH of 2 or three pages, or nothing at all. There are 1000’s of home built aircraft which have a set of plans and a few lines of “handling notes”. I built and fly a modern home built, which has a generic POH, but it does not cover my airframe, engine, prop combination and my performance is significantly different. As I said, the real world is a very different place…


Rod, believe it or not, I fly in the real world, and have been doing so for many years. Obviously one cannot buy a manual that does not exist...that much doesn't even bear repeating. That said, most student training doesn't take place in obscure vintage airplanes. Even in the absence of a flight manual, there is never an excuse for failure to become intimately familiar with one's airplane, including the performance thereof. One should NEVER guess as to what the airplane may or may not do, or may or may not be capable of doing.

[JOE-FBS]

I've only got 43 hours and no licence yet so perhaps the old and / or bold posters on this thread could comment on this thought please. I will discuss it with my instructor as well! It has always been in my mind that if my take-off run scan (max rev's achieved, good oil P & T, air speed increasing, adequate air speed, rotate) reveals a problem or if I hear or see anything untoward (bangs, flames, smoke, etc.) then by far the safest thing to do is shut the throttle, brake hard and if necessary ground loop the aeroplane in order to keep the problem on the ground. I do have the fortune to learn from a field with either a 1200m or an 800m well kept grass runway so maybe I'm spoilt.

Thanks

[gasax]

I'll accept the never guessing about the performance. The trick is of course to find out about it in a much safer environment before trying it in an environment where performance really matters.

My last two aircraft do not have POHs (well the present one has a generic one but it reads more like a sales brochure). The one before that had a fully CAA approved one - without take off distances or fuel consumption.....

But to some extent this is a side issue. If you 'know' the aircraft you will very quickly work out what distance it needs, try a few different surfaces, loadings and conditions and it is pretty straight forward.

But these accidents would probably happen even if there were 'proper' POH numbers - would these people use them? 4 up in a 150hp Cherokee on a very (by UK standards) hot day. Large aircraft (by single standards) on a pretty short strip. The tiniest amount of imagination would tell you what is likely to happen unless you get everything right.

Finally I hesitate to take issue with Guppy but I for one do cadecence brake - usually I cannot tell when a wheel has locked up. On tarmac my present aircraft cannot lock a wheel so leaning hard on them is OK and the best I can do - on grass it is all too easy to lock up and hence the need to 'pump'

[david viewing]

I'm surprised that there's no mention of takeoff flap on this thread so far and little discussion of it in the AIB report. In my reasonable experience of the PA-28-161 on grass, takeoff flap is a very desirable feature, primarily to reduce rolling resistance. In the case of high weight, grass, limited length, hot temps and so on I'd regard flap as crucial to success and indeed survival.

The AAIB limit themselves to saying that there are no performance figures for flapped takeoff in the POH (or is AFM?) and that the flap lever was retracted when found. There is a reference to 'some flap being selected' but it's not clear if this refers to this accident or a previous episode since it is described in the 'Other accidents' section.

In my experience of deliberately trying flapless takeoffs on adequate grass (not very often!) I'd say takeoff is leisurely and that the last 10kts to flying speed take much longer to come than usual. With flaps selected (I always use 20deg) the aircraft bounds into the air and needs to be held level to gain climb speed. It's my direct experience that it will happily go out of fields with flaps that would be frightening without them.

I wonder why the AAIB didn't go into this and question why flapped takeoff on grass is not recommended in the POH?

[Lurking123]

I share Gasax's simplistic view.

a. A PA28-140 with 4POB and some fuel is always going to be interesting.
b. A PA32 on 350m of uphill grass is lunacy/madness/ignorance.

[scooter boy]

You have to know the performance capability in the ambient conditions to make a safe judgement about whether it is safe to go or not.

I am lucky being the sole pilot of both the aircraft I fly, so I can preplan fuel loads knowing the weight that I have to lift for the next few sectors.

e:g I was in Jersey last Weds solo in my ovation. I would have loved nothing more than to fill my tanks to the brim with cheap avgas. Knowing that I had 2 friends to collect and fly back from Guernsey to Plymouth on Sunday I kept the load safe by a good margin and only half-fuelled on Wednesday.

When we made the transit by R44 from Plymouth airport to a friend's rather enclosed paddock with a full helicopter I only had half tanks - we had loads of power in hand in the event of needing to make a go-around.

and wasn't the weather in the South just wonderful this weekend!

PPPPPP (perfect planning prevents piss poor performance)

SB

[DavidHoul52]

It is best not to speculate, nor to cite the case as one in which a poor decision to takeoff with tailwind was the cause...because there is nothing to suggest such a thing. It's best to stick to the facts.

I didn't say that the decision to takeoff with tailwind was the cause. I said that there seemed to be a decision based on incorrect information. If you read the report you will find that the pilot would not have known the wind had changed as he did not have a clear view of the wind sleeve and the AAIB recommended that one be placed at that end of the runway. This has now been done - according to the report.

The change in wind direction might have been a factor according to the report. I myself doubt (not claiming to be any kind of expert on the performance of PA-28s!) whether it would have been the only factor as the winds were light and this is what the reports seems to suggest. But would the pilot have decided to go ahead with the take off if he knew the winds were changed, knowing that he had a heavy load?

Speculation I know but I read the reports with a view to learning from them to become a safer pilot.

[gasax]

To answer you David I think he would have gone ahead with the take off.

Through ignorance or arrogance he would have tried it.

Sit back and imagine your life (well certainly your happiness) depends upon a couple of knots of wind, add in somehwat unfamilar circumstances and you have no margins left. If the machine and you work correctly you succeed if either one fails bad things follow....

I, like the vast majoirty of pilots actually like to have a big fat margin. That drives a lot of our behaviours. A lot of this thread is about takeoffs having less margin than most other aspects of flight and that is certainly true.

The AAIB report discussed aircraft performance testing in the Sandown incident - I think it missed the point. If you are not getting the right static rpm as you open the throttle - that is your first opportunity to avoid an accident - and yet it was not mentioned. You can discuss rejected takeoffs and where you decide to try and (how to) brake to a halt but if the engine does not generate the right rpm - that is the time to stop. If the acceleration is slow then you have another opportunity and the end of the strip is looming then it is much more fraught - but still 'doable'.

Neither of these accidents seems to have had much thinking going on, its that lack of thought that caused them.

[DavidHoul52]

If the acceleration is slow then you have another opportunity and the end of the strip is looming

Presumably that would be obvious long before reaching two-thirds down a 884 metre runway?

[Final 3 Greens]

Presumably that would be obvious long before reaching two-thirds down a 884 metre runway?

I can't comment on this particular case, but I once got nearly half way down a longer runway in a PA28-140 before the penny dropped that rejecting was a good option.

To be fair, I was low houred, but the scary thing was that when I taxied back to the clubhouse and went through the loading with the CFI, the ship was 50lbs under gross.

It was evening, not hot, so what does this tell you? (BTW old airframe, engine about halfway to TBO.)

[bookworm]

b. A PA32 on 350m of uphill grass is lunacy/madness/ignorance.

I've seen a lot of remarks like this. The AAIB report quotes the following gross distances at the weight with a 13 kt headwind component, provide 25 degrees of flap is used:

237 m ground roll
268 m to 20 ft (height of the hedge)
316 m to 50 ft

The headwind is merely an estimate based on the aftercast. The pilot apparently struggled with the crosswind on the way in, and may have thought that the headwind component was greater. The aircraft was found with the flap lever in the retracted position, though it's not known for sure what the position of the flaps was.

Such a take-off is not my idea of a fun afternoon's flying, but I don't think it's helpful to dismiss it as "lunacy". A combination of inaccurate information on the strip length and the possible failure to configure the aircraft correctly turned "too tight for comfort" into an accident.

[Final 3 Greens]

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.

[DavidHoul52]

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!"

[Final 3 Greens]

David

A wise decision.

When you have more experience on type you may or may not decide to take the same decision, but good for you for resisting peer pressure and making your own mind up.

[Lurking123]

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?

[gasax]

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.

[bookworm]

Would you have had a go in exactly the same circumstances?

It's difficult to imagine "exactly the same circumstances". I don't fly the Saratoga, I don't fly off grass, and I have rather more hours on type.

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.

[bjornhall]

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.

On the other hand, if we write off lunatic decisions as lunacy*, we emphasize that we would never do something like that. When faced with decisions to operate outside limitations set forth in regulations, POH or one's personal minima (established from the comfort of one's arm chair, not defined in the cockpit in the heat of the moment), we should say that we would never make such decisions.

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.

[SNS3Guppy]

We are, after all, not lunatics.


Quite correct, and chances are that those involved weren't either. We must always remember that every mishap involves a chain of events, any one of which could be broken to interrupt and prevent the mishap from occuring. A series of things went wrong, and most of them in any given case are fairly innocuous by themselves. Easy to miss. Seemingly normal.

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.

[Flying Farmer]

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?

[bjornhall]

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.

That is always reoccuring in this thread and others, as if it was either news or some trivia worthy of no more than the occasional reminder. 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?

You all do use the CAA recommended factors?

I do, except they don't have CAA on them and they are mandatory rather than recommended. I do that because my decision making skills are not better than anyone else's; therefore, I only rely on those skills when there are no simple rules to follow.

[Flying Farmer]

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!

[gasax]

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.

[sycamore]

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.

[Jumbo Driver]

A useful reference, sycamore ... :ok:

For those interested, the GASCo Performance Calculator can be found here (http://www.gasco.org.uk/upload/docs/2005_1_Flight%20Safety16-18.pdf), within a Flight Safety article entitled "Avoiding the Far Hedge".


JD
:)

[bookworm]

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?

52 The commander of an aircraft shall take all reasonable steps to satisfy himself before
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.

[Rod1]

“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

[Lister Noble]

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

[IO540]

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.

[bjornhall]

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?! :confused: "

I don't think the safety factors are unfeasible. I think flying from insufficient airstrips is unfeasible. JMHO.

[Final 3 Greens]

Bookworm raises an interesting point

The pilot apparently struggled with the crosswind on the way in, and may have thought that the headwind component was greater.

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?

[Flying Farmer]

bjornhall I'm glad to see that a few of us here take a realistic view on perf calculations.

My approach to flying from an 800 Mt grass strip was the same approach I now take flying public transport ops. If the figures didn't add up I wouldn't fly, it's so simple really.

[gasax]

I think bjornhall is missing the point or perhaps perverting it. If you do not have practical experience of your aircraft under a specific set of circumstances then the margins begin to disappear. Now you need the books.

Why you would want to add 'non-conservative' factors completely escapes me and in no way represents the GASCO/CAA numbers or any other that I have seen. So smokescreen or misdirection.

Certainly add a factor of safety of the nut behind the wheel onto these factors - your own experience should determine what that is. But these accidents happened because none of this happened, the pilots did not calculate performance - they did not even appear to think about it - these people just decided to go for it. And both of these accidents happened under conditions which theoretically should have been good enough (just) for successful takeoffs.

The pilots' performance did not match the test pilots - well there is a surprise. Had they real experience of the aircraft performance they probably would n't have tried it. If they had calculated it they probably would n't have tried it. But they appear to have had neither of these things going for them.

[Gertrude the Wombat]

I don't think the safety factors are unfeasible. I think flying from insufficient airstrips is unfeasible. JMHO.
I do the fully factored sums.

I don't fly anywhere with a runway that's too short according to those sums.

OK, so there are some places I choose not to go that the aircraft might well be physically capable of ...

... but I'm still alive.

[bjornhall]

Why you would want to add 'non-conservative' factors completely escapes me and in no way represents the GASCO/CAA numbers or any other that I have seen.

Just to take an example, adding 15% of the ground roll distance for takeoff from a dry grass runway is not conservative. I am thinking of POH figures, not the CAA safety sense leaflet figures or some such. What you want to do, IMO, is to take non-factored, non-conservative performance figures from the POH, and then add the appropriate safety factors (CAA, or whatever jurisdiction you're flying under) to come up with a conservative figure suitable for actual use.

And both of these accidents happened under conditions which theoretically should have been good enough (just) for successful takeoffs.

Exactly, which underscores the point I was making.

The pilots' performance did not match the test pilots - well there is a surprise. Had they real experience of the aircraft performance they probably would n't have tried it. If they had calculated it they probably would n't have tried it. But they appear to have had neither of these things going for them.

Sure agree there too. And that contrasts wildly with the view that "the recommended safety factors would make much flying unfeasible, therefore we won't use such safety factors".

[DavidHoul52]

But these accidents happened because none of this happened, the pilots did not calculate performance - they did not even appear to think about it - these people just decided to go for it.


in a nutshell!

[jxk]

Should there be a factor for the 'age' of the engine? There is probably a peak time for performance when the engine is 'broken' in and after that there is a slow degradation. On our usual 4/6 cylinder Lycomings & Continentals the usual engine performance test is done by using a differential compression check. This check does not take into account cam-shaft wear etc.. The AAIB report about the sad incident of the PA28-140 on the IOW eludes to this problem. It seems to me that any aircraft that is not 'new' will never make manufacturer's book figures. The CAA used to conduct air tests to rate climb performance against the POH but as far as I'm aware never indicated the affect this would have on T/O distances.

[gasax]

The problem is not that complicated. The AAIB report recommended going back to performance tests - but that is a one off, every three years - and so will not detect camshaft wear, which even they admit generally preceeds faster than that. So the report did not impress me much in that respect.

How about static rpm checking? Every time you open the throttle you have an immediate indication of whether the engine is producing its rated power. Simply checking you are getting the expected static rpm will tell you the engine is OK - or not.

It is one of the things I always check, once the wheels start turning has the engine made its static rpm? Because this is the perfect moment to close the throttle and wonder why not if it hasn't.

Why this did not come out of the report baffles me.

[NigelOnDraft]

It is one of the things I always check, once the wheels start turning has the engine made its static rpm? Because this is the perfect moment to close the throttle and wonder why not if it hasn't. What exact Static RPM are you looking for? And how do you adjust it for Headwind / tailwind / groundspeed?

A check is a good idea in broad terms, but defining hard limits v go/no-go decisions :confused:

NoD

[Jumbo Driver]

What exact Static RPM are you looking for? And how do you adjust it for Headwind / tailwind / groundspeed?

By knowledge of the aircraft - or from the POH/Handling Notes or AFM I would have thought ...

To give you an example, a Continental C-90, fitted with a 71x52 propeller will deliver around 2100 rpm at start of take-off. Only a very small increase in the rpm will occur as a result of headwind; groundspeed is not relevant as the check is made as you initially open the throttle - and tailwind won't apply on a limiting take-off, surely?

I think gasax makes a very valid point.

JD
:)

[jxk]

OK - so your engine doesn't make the static RPM what do you do? Spend £10,000 getting it replaced!

[Jumbo Driver]

OK - so your engine doesn't make the static RPM what do you do? Spend £10,000 getting it replaced!

Long term, you may well need to - but short term, don't continue the take-off on a limiting runway!


JD
:)

[mm_flynn]

Certainly spend some money with an engineer. An engine should be able to make very close to full rated power for its TBO. If there is any significant degradation something is actually on its way to failing! Engines are very simple things and lack of power is going to be due to a blockage in airflow (i.e. valves not fully opening), lack of compression (valves not closing or significant ring/cylinder issues), lack of fuel flow, or lack/low/wrong time spark - all of these are due to mechanical problems that are probably going to get worse reasonably quickly.

[Rod1]

Max RPM is one of my first checks when I open the throttle. It does not vary by more than 50rpm from the 5400 I set when I built the aircraft. If it did, I would abort immediately and investigate.

Just to be clear, it is the CAA safety factors which are regularly ignored and which would impact a lot of the short runway flying that goes on. The system gasax explains is how most people do it. Interestingly, it is generally not the based aircraft which hit the hedge, but the visitors.

Rod1

[Say again s l o w l y]

OK - so your engine doesn't make the static RPM what do you do? Spend £10,000 getting it replaced!

What do you do?

Are you insane? Do you have a deathwish? If not then anyone with more than 2 braincells to rub together will go "Hmm something not right here, lets stop."

All takeoffs should be assumed as to be rejected until proven otherwise.

You stop and get the people in oily overalls to have a look. What you don't do is continue the takeoff!

I use a basic rule of if I haven't reached 70% of flying speed by 50% of runway available, then I stop.

Taildraggers are a bit different as you can't just stamp on the brakes. Well you can and you will stop quickly, but you might have a bit of a problem with using the aircraft again.

[AMEandPPL]

Interestingly, it is generally not the based aircraft which hit the hedge, but the visitors

Very true, as we see quite regularly at EGCB with visitors who are more used to two miles of tarmac ! A prominent recent one was Sir Alan Sugar - - though, of course, that was a landing mishap, not a take-off one.

[possel]

As regards the accident at Shotteswell, how many of the people posting have flown in there? I did once, and I looked at the short runway and thought "downhill only, on a good day", and that was with 200 hours experience in the aircraft operating off a 600 yard strip.

I'm afraid that I agree with the comment about "lunatic". He took off uphill in an aircraft type he hardy knew, with a huge hedge at the far end (which he had taxied past but could not see at the start of his take-off). The other matters of airmanship which the AAIB mentioned as fact without comment make you wonder if you would have rented your own aircraft to him!