Would you abort after V1?

[ssg]

Thanks Mutt...I had a feeling this would come up..

I wonder how many guys in here reduce power to extend balanced field numbers to fit long runways, then come in here and try to say that every take off is a nail biter 'because that's how it's done in the airlines"

Well yeah...I could take off with 50% power too, burn up 12000 feet of runway, rotate a thousand feet off the end and say...'I had the numbers", then wipe my brow...look back at the passenger, 'whew...just made it by the skin of our teeth'...

In corporate if you crash the plane at the end of the runway..then tell the boss you were trying to save engine overhaul costs, ... won't quite do it.

The engine saving argument is a tough sell. Having put a few engines through hot sections and overhauls, personaly going through the bid process, inspections ect, test cells....having run them easy, then harder, then right to the edge,...I didn't see a cost diff.

Here's what I want to know...does a 737 at Sea level, max weight, burn up 7000 feet of runway using max power?

[Old Fella]

V1

Is ssg for real? V1 means V1. Why bother determining a V1 figure if there is any doubt about your actions in the event of it being a consideration.

You can safely abort, all other things being equal, before V1. Above V1 you must GO. Many more people have died as a result of attempts to abort above V1 than have than when the aircraft is flown off and the emergency is handled airborne.

[ssg]

That's not true

Take a look at the guys that tried to go around vs the guys that ran off the end of the runway......now see who walked away..

Usualy when a plane skids off the end of a rejected take off roll (probably too heavy), they just slide into the grass..might make a mess of the landing gear but people walk away...

But when those guys try to fly a defective aircraft up into the wild blue...well, just google ' airplane crashes on take off' and see all the nice pics...

[john_tullamarine]

Guess that there exists a variety of considerations here ..

(a) the basic requirement is that the takeoff meets the Type Certification and, by inference, the relevant Design Standard

(b) rated thrust is fine, and available for those who want to use it

(c) derate/flex is fine, and available for those who want to use it when it is available from a certification (AFM) point of view

(d) no matter how anyone might want to skew the story, jets don't like the high end of the temperature range .. a few degrees cooler reduces maintenance/operating costs. I am sure that Mutt can comment on this ad infinitum

(e) use of derate/flex is only available when rated takeoff is not limiting ... otherwise rated is mandatory

(f) use of derate/flex doesn't have to be taken to the point of making a non-limiting takeoff limiting (which appears to be what is upsetting some of the posters). Although I don't know what they do now, in the early days of flexing, Qantas imposed an arbitrary 1000 ft pad to the figures to keep the crews happy (at least that was Wal Stack's story at the time ..) Similarly, any operator can impose whatever fat it may choose corporately. I did the sums for one operator for many years and the Chief Pilot and I, in co-operation, applied a variety of considered pads to various runways with corporate blessing .. the corporate side was quite comfortable with the idea of balancing the mighty dollar against maintaining a good argument for any legal conflict.

(g) equally, an operator may run the derate/flex to the nth degree to squeeze the last bit of advantage out of it .. so long as the TC/design requirements and any operational restrictions are met. Many of the posters whom we read in PPRuNe work for operators who do just this.

(h) would I have a problem paxing on an operator which scheduled limiting derate/flex ? .. Certainly not just for that reason .. provided the overall operational risk philosophy was reasonable ...

(i) certification doesn't address a bunch of multiple failures .. in the event of such a circumstance, the crew is called upon to exercise its great knowledge, experience and skill at a moment's notice (not too sure where this leaves a minimally experienced crew .. but that is the way it's going these days) .. and then the Captain has to try and justify these decisions at the eventual enquiry in painfully slow and intricate detail ... For those who have had no experience of such inquisitions, the recent Australian military BoI into the Nias mishap makes good bedtime reading. Another which comes to mind was the KingAir 200 (?) crash at Sydney years ago ... an Ansett captain operating into Sydney at the time (and patently unrelated to the crash) sustained a very lengthy cross examination at the enquiry. I am sure that most of us can cite numerous such cases.


I suspect that ssg may not have had any/much experience with derate/flex takeoffs.

For those who have, and seek to champion its benefits .. please keep in mind that folk like ssg's operator are perfectly OK to operate at rated thrust if they wish. Many years ago I worked for a government operation which, amongst other Types, operated a Dart powered bird .. which they operated wet takeoff routinely .. often running up to takeoff power on the brakes .. even when empty from long runways. Didn't do the maintenance/operating costs much good but that was their choice .. our taxes at work. Centaurus could add much comment to this as he was a Captain for that operator at the time and did his best to inject a bit of commercial commonsense into the operational philosophy .. with not a great deal of success.

[ssg]

John...

Thanks for the primer on flex power...

Just because I am not one of those operators that uses flex power to 'fly it to the fence' every time, doesn't mean I don't understand how unsafe it is.

Flex power is always a choice...a choice to put 200 people as far down the runway as possible, accellerating the slowest, v speeds as close to the fence, the obsticles as near as possible, and giving the crew the least time to stop, or go, or make a decision. Flex power is a intentional way to decrease all safety margins to nil on take off to save for the intangible and hardly quantifiable benefit of saving on engine overhaul cost through operator imput.

It's no wonder that all these airline guys have a 'go' mentality...they are so close to edge, that should they lose and engine they can go, but also add 10-50% more power on thier last good engine...

[Denti]

Why can't you take off max thrust vs reduced...which seems less safe...

Simple, because it costs too much. We try to keep our engines on the wing for over 40.000 hours on the shorthaul fleet and we have succeeded a couple times allready. That alone saves several hundred million dollars over the lifetime of an airplane in maintenance costs. Besides, we are told (as a pilot i cannot prove or disprove that) that reduced power take offs save quite a lot of fuel, which becomes more important with higher fuel prices.

We are free however to give us safety margins if we deem it necesarry, for example we often calculate the performance figures for an intersection take off instead of full length simply because it gives us more flexibility in take off points to choose from. Or we can deselect certain things in the performance tool, some captains dont like to use improved climb so we dont use that in those cases. I can understand that, running into the red red lights before you rotate at 175kts is not really fun (boeing classic/NG).

However i would still be interested in real comparable figures about take off accidents between GA and airline business per 100.000 sectors and operating hours. Single cases as the ones you mentioned don't prove or disprove anything if you cannot set them in a statistical significant perspective of overall operating hours and sectors flown.

[mini-jumbo]

But when those guys try to fly a defective aircraft up into the wild blue...well, just google ' airplane crashes on take off' and see all the nice pics...

SSG,

Please tell me you're not basing your arguments on google images.

Anyone remember the Thomson Fly birdstrike at MAN. They continued, flew a perfect vectored circuit to land single engine, vacated the runway and after an inspection by fire crews, taxied to stand. No drama, no heroics, just did what they were trained to do, and what they briefed to do. Had they rejected, I suspect many injuries, if not fatalities. Then, factor into the equation the ensuing evacuation, thus causing more injuries.

There's a great video on you tube and other sites of the whole event.

[Old Fella]

Add 10-50% more power on their last good engine

Having read ssg's posts it seems he is unaware that there are aircraft out there with more than two engines. Regardless, it seems he/she is unwilling to accept that you must Go if above V1, that derated/flex thrust take-offs are safe and that they add to engine life. There again, I suppose that the wealth of information available is somehow unable to penetrate every cranium out there.

[A37575]

but my own experience has been that once the fire is detected, sit on your hands and count to ten, then address the problem with a workable cadence and some measured patience.

The 10 seconds that you sit on your hands could cost you your life. You have no idea of the severity of the fire - it could even be a false fire warning. But you simply do not know. The advice in the Boeing 737 FCTM is all you can go by and that says:
"Indications of an engine fire, impending break-up or approaching engine limits, should be dealt with as soon as possible."

Don't purposely build in breathing space just because you fear you may stuff things up. There is no shortage of advice from well meaning simulator instructors or other pilots when it comes to defining engine fire action drills.

[Pace]

Old Fella

Every situation is different and every aircraft is different. 999 times out of a 1000 by the book is the best way but very occasionally by the book will kill you.

I used the example of a few years ago where an aircraft aborted after rotation at Leeds because of a massive fire from the engine which was burning through the wing.

Had the Pilot continued all would have perished. The Pilot and that is what we are sussed up the situation quickly and made the right decision.

The beauty of human beings is that we can think unlike computers or set procedures. With that ability to think also is the ability to make the wrong decision hence why most accidents are pilot error. To reduce that we are trained to react in a set manner which most of the time works.

In unusual circumstances you have to throw away the books and get back to being a quick thinking Pilot surely? otherwise we are no more than trained zombies or programmed computers ourselves.

Pace

[clevlandHD]

SSG, the accident you refer to in Goma was actualy an above V1 reject. They got airborne and decided it was safer to "return" from a few feet off the ground.

Your operator might not try to squeeze every cent he can to turn a profit at the end of the year but most do. If they don't save there, they will cheap somewhere else...

Using TOGA every TO will reduce engine reliability thus componding your odds of having and engine failure at TO.

If would push the landing instead of going around, my operator would take care of finishing me off (if,as you believe, I would walk away). Could you tell me of a well executed GA that ended with a prang?

I am happy to flex when I can and I would continue the TO above V1 unless I know for sure the aircraft won't fly! I wish you (and your estate)luck if you ever fly your airplne outside the manufaturer's parameter. The lawyers would have it easy!

[Old Fella]

Throw away the book

999 times out of 1000 doing things by the book is the best way, but very occasionally going by the book will kill you, says Pace. The rejection at Leeds you cite Pace poses another question for me. You state that the aircraft suffered a massive fire which was burning through the wing. Do you honestly believe that the pilot knew the magnitude of the problem at the instant he decided to put the aircraft back on the ground? I seriously doubt that he did. Your statement that 999 times out of 1000 going by the book is the best way says it all for me. Of course we are all capable of making decisions which are not covered by the book however, smarter people than me, and I suspect you too, have determined that if the aircraft has reached the predetermined V1, and you suffer an emergency, your best chance of survival is to take it into the air and deal with it. The decision to abort, even just a Knot or two below V1, can be more likely to end in grief than to keep going. It would seem to me that the Leeds incident outcome was more "good luck" than the result of good judgement based on knowledge of the magnitude of the problem. I have no idea what you fly. I do know that in close to fifty years in the flying game I am still on the side of the "GO" brigade.

[Pace]

I am with a V1 brigade too with a caveat. I do not fly heavies but corporate Citations as a captain.

I had an engine failure in a twin Seneca a few years ago at grosse weight and 200 feet in the climb. Had I followed laid down procedures I know that I would not be here to write this.

Pace

[Black Knat]

I think the Leeds incident refered to may in fact be the 748 out of STN, en route to Leeds. The Dart engine shed part of its 'internals' (at or around V1) which ended up with an uncontained engine fire/failure. Channex had a similar thing on one of its F27's only in that incident it was at 400'.
Believe the 748 ended up off the end of the runway.

[G-ALAN]

I was going to bring up the incident at Manchester but mini jumbo beat me to it. Anyway here's the link to the video.

http://www.youtube.com/watch?v=9KhZwsYtNDE

[Denti]

Pace, remember a Seneca is not a transport category certified aircraft and therefore has different performance specs. I certainly hope that Citations are certified according to FAR/JAR 25, but as i dont fly them i don't know if that is the case.

We used that thing (seneca V) during training but shortly after i was done my flight school got rid of it due to very poor dispatch reliability and safety concerns (around 40% dispatch reliability). We flew it to full airline procedures, however we knew that there is a certain range during take off where an engine failure is not really survivable if you use balanced field length.

[powerstall]

in regards to the training in the sim (type rating), didn't the TRI taught us .. AT or Above V1 we continue take off?....

in case an accident does occur, doesn't the investigating body check your last recurrent or your training?

what does the "book" say?

[GlueBall]

ssg . . . if ever you transition from the Citation to the B74, your perception of aborting after V1 will quickly evaporate; even when departing at JKF's longest pavement, 13R [4442m/14572'] If you recall when many moons ago a TWA TriStar crew had aborted on 13R after V1 with disasterous consequences.

[criss]

ssg, news for you - history actually knows fatal "airplane crashes on take off" caused by runway excursion due to ill-decided rejection.

"Flex power is a intentional way to decrease all safety margins to nil on take off to save for the intangible and hardly quantifiable benefit of saving on engine overhaul cost through operator imput." - sure, taking off with max power all the time does not decrease safety thru more strain on the engine.

PS. One has to admire how tolerant ppl can be in this thread.

[SNS3Guppy]

Since when does anybody use flex or reduced thrust to "extend balanced field length?"

From my perspective as a pilot, we've used reduced thrust where able in most types of aircraft I've flown, certainly most all turbine equipment, including agricultural, corporate/charter airplanes, and airline equipment. It's been a practice in most types of operations I've flown, from firefighting to ambulance to crop dusting/ag, to cargo, charter, corporate, government, and yes, airline. Where it's safe to do, allows ample takeoff and stopping margin, allows adequate obstacle clearance etc, it's perfectly acceptable.

A reduced thrust takeoff means that one always has the option of pushing up the power as required, though all the performance calculations take into account climb gradients, going, stopping, and obstacle clearance without having to do so. This includes an engine failure; when we calculate reduced thrust takeoff performance, the performance data assumes losing an engine and continuing the takeoff...still at reduced power, still able to make the required gradients. Stopping is a no-brainer; the power will be retarded, ground spoilers deployed, and the aircraft stopped on RTO brakes where installed, or manual braking. Not rocket science, and it's all factored in...without reverse I might add. Reverse only shortens that distance.

Our operations manual spells out exactly when a reduced thrust takeoff can be used, and when it can't. Every reduced thrust takeoff is planned with the specific runway and runway conditions in mind, including any appliable NOTAMS such as temporary obstacles or reductions in length. Every takeoff is planned with an engine failure in mind, as is the departure path after takeoff. Nothing is left to chance.

We utilize reduced thrust takeoffs, and reduced power climbs as part of the nearly universal standard noise abatement departure procedures. We also have reduced climb thrust above 10,000'.

From a mechanic's perspective, reduced engine temperatures make for substantial increases in engine and component life. I've been an aircraft mechanic and inspector as long as I've been a pilot, going back to my early teenage years. I've been working on large radial engines, small pistons, turboprops, turbojets and turbofans for several decades now. I've had these engines apart, boroscoped them, handled every internal part as a regular function of inspection and repair. The differences in operating techniques or procedures show up in burned blades, cracked cans, metal creep, etc. A ten percent reduction in power equates roughly to a ten percent increase in engine life. If this can be done safely, all the more power to the operator...increased engine life also equates to improved engine safety, longevity of components, increased mean time between failures for stressed and hard use items such as turbine wheels and blades, etc.

A common method of operating reduced thrust is to use an assumed temperature. This isn't a wild idea made up by flight crews, but comes directly from the engine and airframe manufacturers after ample testing and design. One assumes a takeoff at a much higher density altitude based on a plethora of criteria and data, and determines if the aircraft could be safely flown off the current runway under those conditions. If it could still do so, still meeting all go and stop criteria applicable to each segment of the takeoff, then it can also be taken off at a reduced power which replicates a takeoff at the higher assumed temperature. The performance data is recalculated using the reduced power to ensure it matches, and when all data adds up, the reduced power is established for the takeoff. Nothing precludes pushing up the power at any point in the takeoff where required, nor performing a full power takeoff if required. However, it isn't required, and where a reduced power takeoff is performed based on an assumed temperature calculation, an engine may be lost and the takeoff continued at that reduced power, and still meet all the takeoff criteria.