Post V1 rejected take off...yeah or neah?

[johns7022]

Your just past V1, a fuel truck zips by, clips your right side somewhere, you hear a bang...plane is still going straight down the runway....do you pull the aircraft off, or try to stop it...

Serious replies and reasons please.

[TheChitterneFlyer]

I'd like to think that we might have seen the offending fuel truck prior to reaching V1. After all, he's probably not doing more than 30 mph and we're doing something like 100 kts... you'd have a few distinct clues that you were heading for a collision; prior to V1.

You want a serious reply? It's a bit of a nonesense hypothetical situation! If, as you say, that you're past V1; you're going to take the fuel truck with you beyond the end of the runway/stopway. :ugh:

[Pugilistic Animus]

early pull-up is probably safer,...just hope you reach Vmu before you impact..:suspect:

[mutt]

SSG AGAIN:ugh::ugh::ugh::ugh:

Didn't we play this game last year?

Mutt

[FE Hoppy]

It's déjà vu all over again!:{

[Dengue_Dude]

Well Hoppy, as you well know, if everyone has done their jobs properly AND you are at performance limiting weights (masses), then it's really and truly dicing with death NOT to get airborne. There are so many variables - stopway etc etc

However, (there's always one isn't there) if you're light, V1/VR is unity you get there quickly (like ferry flights on a wet runway where you're committed to a full power take off perhaps), you've probably got enough runway to stop anyway. The key phrase in all this is:

"Performance Limiting"

Emerald Airways 748 (I think) is a famous example of what not to do and get away with it - you'll always hear of some exceptions.

[Right Way Up]

Mutt, FE Hoppy & SSG,

Its hard to not get sentimental!! Where did that year go?;);)

[Chesty Morgan]

It's déjà vu all over again!

I knew you were going to say that!

[Ashling]

The truck is probably being driven by SSG to test out his theory

[potkettleblack]

Is the truck on a conveyor belt?

[johns7022]

FO: Captain! A fuel truck just took of the right wing!

Capt: That's ok, you see we are past V1, a magical thing happens now...planes always fly...it doesn't matter if a bomb took the tail off, the wing fell off, we have 4 flat tires, or the control wheel came off in my hands...planes always fly after V1...when you have been flying as long as I have you will come to understand this....see it's written right here in the SOPs manual....

[tttoon]

SSG, all the answers towards the feasability of a post-V1 reject can be found here:

http://www.mobilit.fgov.be/data/aero/accidents/AA-8-5.pdf

[SR71]

Which V1?

:E

[Tee Emm]

A more serious discussion can be had about the 80 knot airspeed call during the take off roll. Let me tell you what happens in the simulator. Assume captain PF. Passing 80 knots IAS, the PNF says nothing because he either was distracted looking at something or he simply was dreaming. By the time the PF realises there was no call the airspeed is now 100 knots so the PF calls "100 knots my side". F/O comes to life and says "Sorry 80 knots" Immediate confusion. The captain rejects the take off nearing V1. Was the reject necessary? Not really because if he had checked the ground speed at the same time the IAS passed 80 knots the captain would have known his airspeed indicator was operating normally.

The 80 knot call has become so routine that complacency sets in. And the one time there is a serious discrepancy you can be assured of instant confusion. By the time both pilots discover there is a problem the aircraft is rapidly accelerating to V1. Remember the Boeing advice re rejected take off and that is above 80 knots only reject in case of fire or fire warning, engine failure, predictive windshear and if the aircraft is unsafe or unable to fly.

Checking the expected ground speed reading at the 80 knot call is an excellent safety measure. Easier than checking the standby ASI reading in fact. When in doubt with perceived airspeed differences during the take off run call above 80 knots, a check of the expected ground speed can resolve the differences and if necessary because things happen so quickly, consider falling back on the ground speed reading to plan the rotation. Might be a lot safer than a high speed abort and the ground speed indicator doesn't care if the runway is wet or dry.

A Boeing recommendation is the PNF (or should I say PM!) makes call-outs based upon instrument indications etc The PF should verify and acknowledge. If the PM does not make the required callout, the PF should make it. An incident to an A330 illustrates the point. Unknown to the captain as PM the captain's ASI under-read significantly because of an insect blocking the tube. The F/O was PF. During the take off roll the F/O noticed the captain had not made the 100 knot call. Assuming the captain had forgotten the PF continued the take off and was near VR when the captain called "100 knots". Sensing an airspeed problem the captain took control and rejected the take off at high speed. Hot brakes and tyre deflation due heat then occurred.

If when the PF was passing 100 knots and no call from the PM, the PF had called "110 knots my side" (allowing for acceleration), the ASI discrepancy would have been discovered much earlier. Better still, had the captain noticed his airspeed reading and ground speed reading in the early part of the take off roll were significantly different, the outcome may have been different.

[Pugilistic Animus]

...just to add RTO after V1 is for catastrophic failure when the ship is unflyable...so yes if you lose a wing or hit a fuel truck and burst into flames then I suppose you have no choice...either way it looks pretty bad:rolleyes:

what if a meteorite hits you after V1 or the sky falls after V1...:zzz:

[Mach E Avelli]

Reject past V1? Sure, I would rather go off the end at 50 knots than face the alternative of a loss of control in the air. Leaving half a wing in the side of another aircraft, flight control jam in a type that has no control split system, full reverser deploy? Who knows what the effect could be until it actually happens?
As most good ops manuals state, it is impossible to write a procedure for every eventuality. In such a situation the PIC is authorized to do whatever it takes. Some enlightened regulations say that, too.

[gearpins]

Its difficult to come up with a generic answer. its not a situation of one size fits all.the variables are: (and the list is not exhaustive)
1.type of A/c
2.TOW on the given day
3.Are you using V1 min?
4.RWY length/stop margin available
5.local knowledge of what lays beyond the RWY-may be a snow bank or a sheer drop
can Somebody add to the list.......?

[johns7022]

So now that we have concurred that flying an un-flyable aircraft doesn't make sense....then it follows that a post V1 RTO, would be easier accomplished with the maximum available amount of runway in front of us.....

Ergo.. max power take offs, would burn up less runway to V1, meaning more runway for a post V1 RTO......vs... a reduced thrust take off....

So it would follow that the prudent pilot, trying to mitigate all risk from the flight, would embark to get to V1 as quickly as possible, using the minimum amount of runway, that in the event of a post V1 catastrophe, he has more runway to stop...

I would also suspect that if I hypothetically traveled up and down the runway at high speed....that I have a statistically higher chance of FOD, errant fuel trucks, aircraft taxing through intersections, other aircraft landing on me...it seems the least amount of time on the runway..reduces the risk of all these factors.....

So from a safety standpoint...wouldn't the safest option to be a max thrust take off vs reduced thrust take off?

[Pugilistic Animus]

Ergo.. max power take offs, would burn up less runway to V1, meaning more runway for a post V1 RTO......vs... a reduced thrust take off....

but continuous use of full thrust will add to the likelyhood of an RTO; it really all depends on what is limiting but usually the plane but the kinetic energy build up with acceleration on a jet is rapid and is not linear but would be proportional to the square of the velocity...

and even if the rwy length were not limiting it may become limiting or excessive and dangerous, just a few knots from V1 and at a limiting V1...your stopping technique [ especially if there's no RTO autobrake/auto spoiler selection] must be test pilot perfect AT V1...and honestly whatever side you are on it takes lots of faith in the performance analysis...and from reading here the FAA leaves a lot to be desired in terms of both ASDA, TODA and flight path protection...It would be nice if everyone were as cautious as the performance experts who frequent this forum :)

RTOs after V1 should never become a 'routine' in lieu and such decisions are best reserved for dire catastrophe as described by others, there have been precedents of course were such a decision did save lives but it resulted from pilot error and it there was no choice it was luck and everyone knows that Hawkers a built very very tough


it seems you have improved your approach to us here...I hope

[LongTimeInCX]

So from a safety standpoint...wouldn't the safest option to be a max thrust take off vs reduced thrust take off?
errmm no!

The safest option would be to not commit the sin of aviation to start with.

Sure it's a pureist answer, but we all know aviation has many risks.
To eliminate all risk is clearly impossible, as much as to ignore all risk is a folly.
Therefore, one takes a suitable compromise between cost and risk.

Reduced thrust take-offs are one such area of compromise that has generally been found to pass the test of prudence by most pilots, although academics may question the logic.

[jimmygill]

Does a clipped right side make the aircraft un-airworthy?

Whats the consequence of rejecting a takeoff at V1+5 knots?

[LongTimeInCX]

Does a clipped right side make the aircraft un-airworthy?
How long is a piece of string?

Whats the consequence of rejecting a takeoff at V1+5 knots? Depends, field limited or space shuttle type runway. So, probably minimal, but possibly fatal.
As previous posters allude, an awful lot of variables, which is why you would make a quick snap decision of fly/nofly and then live(or not:confused:) with that decision.

[johns7022]

Pug - why do you think 'a continuous use of full thrust will add to the likelihood of an RTO' ?

In corporate operations, the use of max thrust for every take off is normal...but of course we overhaul our engines at specified TBOs... in the interest of fairness, would it be prudent to use max take off power on a 25000 hr engine vs a 3500 hr one...no...but then again...if the goal here is to stretch engine overhauls out as far as possible...reduced thrust makes sense....if saving money is the chief consideration...

[Denti]

First of all: Don't feed the troll. Johns7022 is the same user as ssg (www.pprune.org/members/80134-ssg) and a ton of other banned nicks. The same stuff was posted last year in this thread (http://www.pprune.org/tech-log/327267-would-you-abort-after-v1-2.html), read up there and you will see that replying to that guy will achieve nothing.

[lomapaseo]

First of all: Don't feed the troll. Johns7022 is the same user as ssg (http://www.pprune.org/members/80134-ssg) and a ton of other banned nicks. The same stuff was posted last year in this thread (http://www.pprune.org/tech-log/327267-would-you-abort-after-v1-2.html), read up there and you will see that replying to that guy will achieve nothing.

Yes, but's it's fun to get into these mind games if we keep it civil and have fun :E

Your car is in a skid ........

do you aim for a petrol station or a school yard?

no time for thought, just do it

[john_tullamarine]

My views align with lomapaseo's ..

(a) whether johns7022 is/is not the same person as any other username, largely, is irrelevant. Provided he/she observes the reasonable niceties, he/she is welcome to play in the sandpit

(b) if anyone finds offense in the presence of a given participant, then one is not obligated to participate ...

(c) johns7022 proposes an extreme view which is permitted within the normal regulatory and operational processes.

(d) whether his/her proposals are good, bad, or indifferent is not the important point. Rather, the extreme views are useful to force other participants to consider their own positions critically and offer either supporting or contrary views.

.. and, of course, it is good fun.

[rudderrudderrat]

would it be prudent to use max take off power on a 25000 hr engine vs a 3500 hr one....no...but then again...

TOGA power on a 25000 hour engine (which has had it's life extended by using Flex) is perfectly acceptable.

@ Johns7022/SSG - I don't think you understand "creep" of hot turbine blades.
Have you ever been curious why Full Take Off power is limited to 5 mins (or 10 mins with Engine Failure) but climb / cruise power can be set with no time restriction?

[capt. solipsist]

Depends on the model of the truck and the brand of its tires. :ugh:

[muduckace]

do you aim for a petrol station or a school yard?

School yard of course, survival of the fittest, natural instinct.

[Pugilistic Animus]

Jet engine failures in either case are rare, so the specific operational limitation seem to work out...in part 135/121 maintenance is progressive...91 subpart K it is based on a more absolute approach...and they seem to both work

turbine creep is proportional to centrifugal forces and operating temps...and I believe that that factor is the biggest pain regarding turbines

perhaps and A&P or AMT could add based on personal direct observation...of engine conditions

[Pugilistic Animus]

I think these guys have the timing to do it right

YouTube - Big Sid Catlett & Gene Krupa in "Boy, What a Girl" (http://www.youtube.com/watch?v=c8tk6P3HPr0)

sorry I love'em:}

[Pugilistic Animus]

honestly though would you really want to have to stop this?

Aviation Video: Boeing 767-400 - Delta Air Lines (http://www.flightlevel350.com/Aircraft_Boeing_767-400-Airline_Delta_Air_Lines_Aviation_Video-1911.html)

[sunset_contrails_10]

Well I say that if you lost part of your wing than you would be significantly lighter and be able to stop the aircraft in time. However, who needs a wing to fly..continue on to your destination.


F-15 flying with one wing by an Israeli Pilot - YouTube - Truveo Video Search (http://www.truveo.com/F15-flying-with-one-wing-by-an-Israeli-Pilot/id/1362490168)

[johns7022]

Pug - Yeah, it make sense that max takeoff is the norm, regardless of engine hours...if you need it, you need it..and no one is going to tell you that the engine will fall apart if you need max power....the engine is either airworthy or not......and that reduced thrust departures are nice to use, given the conditions, runway, that allow lower fan/turbine speeds, temps to reduce engine wear...curious though that people do reduced thrust departures, then run max cruise power settings all day long...you would think to be consistent with reduced power departures, reduced cruise settings would be pushed as well....hard to believe all the engine wear is in 2 minutes of take off power vs 10 hours of flying basically fire walled at cruise...

But...I am just throwing out there...that by reducing take off thrust...putting your self farther down the runway on purpose...limits runway available to stop....pre or post v1...

So why not just give yourself more options...more runway is nice...if you have the choice, why not take the option that gives you the best chance of a successfull RTO vs feeling pushed to just fly it off, and hope for the best?

Personally I don't see a problem with an RTO..if we can land a plane at 120 kts, we can surely stop one already on the ground doing 110kts...the only question is available runway....

[galaxy flyer]

hen run max cruise power settings all day long...you would think to be consistent with reduced power departures, reduced cruise settings would be pushed as well....hard to believe all the engine wear is in 2 minutes of take off power vs 10 hours of flying basically fire walled at cruise...

Just a curious question, when is the engine putting out more thrust--on take-off or "firewalled at cruise"? Hint--air density. And, what CI does your airline operate at that "firewalled" is cruise power?

Another question, do you land the plane on the last 2,000 or 3,000 feet of runway? And what is the comparative gross weights on take-off versus landing? Hint--Newton's laws apply and cannot be overruled.

Yes, in an extraordinary case not contemplated during certification or training, stopping past V1 may be sensible and a reasonable risk, but that is not how it done in 99.9% of the cases. In the 0.9%, make that 0.09%, cases doing as we train and brief is a far better answer.

This thread, in various forms, has gone on ad nauseum, but Johns I suggest you do several dozen max gross weight take-offs at full power watching the lights at the far end rapidly closing in before baiting an argument on RTO policies. Dust off the overrun a few times.

GF

------------------------Edit------------------------------------

Now, I have re-read page one, I am left wondering John's hatred of reduced power take-offs. What about derates, John? My GLEX has a flex power option in the FMS, so it is not just an airline thing. If you are aware of performance, you know that reduced power may result in somewhat improved controllability near Vmcg (J_T, Mutt, I promise not to mention that V speed again), derates can actually improve runway performance at light gross weights, so there are as many pluses to reduced power as your perceived minuses. Already mentioned, is greatly reduced wear and tear.

[crj705]

If you hit a fuel truck on the runway after V1, will an extra 1000 or 2000 feet really matter??

[Loose rivets]

what if a meteorite hits you after V1 or the sky falls after V1...

Probably not going to be a meteorite, unless it's flicked up off the ground. :}

Ped mode: OFF


Then there was my Naples incident. So, not always true Mr Flyer.

I'd like to think that we might have seen the offending fuel truck prior to reaching V1. After all, he's probably not doing more than 30 mph and we're doing something like 100 kts... you'd have a few distinct clues that you were heading for a collision; prior to V1.

Naples. BAC 1-11. Hot day. Heat haze...how deep? 2' ? Maybe. That was my guess. At just about V1 - a tad, a bowser became visible out of the top of the haze. We'll get round the back of it!!! Says I. Good plan . . . until we see the :mad: great trailer it was pulling.

I went for the next notch of flaps and pulled. Landed again, tidied up the flaps and continued the take off. We never even mentioned it back home. No point, on the list of silly things happening in those days no one would have bothered to read it.

One training skipper, flying with a new captain at Palma, pulled back at what he thought was Vr, and nothing happened. Story goes that they looked at each other, carried on another 10 - 20 kts, and then took off. The training captain went on to a long career in the Ministry of Planes.

[galaxy flyer]

Mr Rivets

I salute you and your laundress!! i suspect a fairly short field length to pull that off.

GF

[Pugilistic Animus]

well one thing, with the crappy payload/range, especially with the STC'd belted potty seat of most smaller corporate equipment you have to use full power; limiting TO's are more common, if you want to carry any substantial fuel of payload :}

love the ads for them carries 8 pax 500mn has a range of 1200NM with four occupants
the whole thing deals with cost/benefits and risk/benefits the safety criteria performance criteria, still have to be met...but on the whole how many engine failures are there a critical moments? the Thomson incident made famous by youtube shows that the criteria work..also thrust generally does not just cut out, engines will produces something until they are shut down at the appropriate height. they just produces too much power to use it all all of the time, and it's a real benefit for 'on-condition' engine appliances..but you don't have to use it as there seems to be no such pressure in your operation

also, MCT ,is rarely used in the airlines these days fuel saving depending on the CI analysis, as GF mentioned

LR meteor :ouch: :p

oh I forgot:eek::D

[proxus]

Quote "Checking the expected ground speed reading at the 80 knot call is an excellent safety measure. "

Well the problem is that if you got all your static ports blocked then you still would have problems because the ASI shows accurate speed up until you're airborne and start to accent to less pressure.