SSG

If you'd left it at the title then you would have got a different set of answers but you quite clearly gave us a scenario and asked for a response to it. You did not elaborate beyond that scenario and then instantly berated all of us who said continue for being robots.

We all answered your question correctly and you got all upset instead of accepting the answer and moving the discussion forward positively.

BOAC

When I first got involved in this discussion SSG brought up a serious point one that had crossed my mind a few times on takeoff in a Citation approaching V1. That was "what sort of failure would make me as a Captain decide to ignore V1 and take my chances on the ground. Or even having rotated as with the 748 fire, put the aircraft back down again. Rememeber I was talking about a citation not a 747 and a citation on a runway where it could take off or land twice.

SSG i really feel that having started a valid discussion you are now coming over as being on some sort of Ego trip, I am cleverer than you sort of thing and you cannot let go.

The problem with forums are that they are faceless text. Text can be misread, misunderstood so my apologies if any of my text has come over wrong. My thanks to all the very experienced and clever people who have contibuted to making the subject clearer and so interesting.

On that I am bowing out of this thread as it has dried up for me and thanks to everyone

Pace

The pilot got lucky. Doesn't mean he was right.

No SSG,
You set the tone by asking a question then preaching/insulting experienced pilots giving you an answer. I'm not tapping out of this thread as I'm interested to see where you go from here. Having alienated your only ally in Pace in such an insulting way I look forward to your next move. :rolleyes:

so let me get this straight;
if you got a flap asymmetry warning, an un-commanded slat retraction, a trim runaway, an obvious control jam or hard-over, a double engine flame out, (if you only had two for the less astute among you) after V1 you would not even consider aborting the take off because you had said so???:ugh:

I have no issue with SOP's but if you cannot think outside the box you should not be in it. I am with SSG here.

My next move....hmmm
 

Well I was sitting here, pretty much ignoring most of what you said...then my cat hopped up onto the keyboard...I got to thinking...

If all there is to a take off judgement is to pull the levers before V1, push them forward after V1,...can a cat be taught that?

I mean cat's have terrific reflexes, are very fast...and if all they have to do is watch the airspeed indicator for V1...maybe we could put a little mouse on the levers to keep her interested...corporate will love the low costs, they never get sick and they work for kibble.

:)

Pilotbear,
I don't believe anyone has said that they would would always continue after V1. They have answered the original question with reference to engine fire and because it does not fit the "SSG model" they have been flamed for it.

BTW that post was aimed at SSG because of the uncalled rudeness to Pace, who left the arena in a composed way.

There is no doubt that there are situations that we think outside the box and use our best judgement at the time. That is why if their is sim time left at the end of a check we always try to throw something unusual at the crew.

I cant see what the problem is aborting at v2. I fly out of stn. A little rudder straight onto the M11. Loads of room!!!!! No problem.:ok:

http://www.smartcockpit.com/pdf/flig...erodynamics/28

In principle, I agree with one V1 per T/O.

But in extremis (which is the point of the discussion isn't it?), with a V1 split of ~30kts....

Reminds me of that Eddie Izard sketch, "Cake or Death"...

http://www.youtube.com/watch?v=BNjcuZ-LiSY

Of course, what complicates things is Vr...

:ok:

SR71
 

Great link to the Boeing sit on min and max V1...I learned something!!!

Question.....if balanced field for the day is 5000ft on a ten thousand ft runway...could you calculate max V1 to just make the stopway on a rejected take off on that runway?

SSG, on my aircraft you can select whichever V1 suits you. Our performance gives mean V1 for starters but we can also check (& use if need be) the min & max V1 to suit the situation.

The answer is a very definite MAYBE :)

Some aircraft its easy, others not so easy... all depends on the year of manufacture and the available software.

Mutt

Ssg--V1 is advisory-if the aircraft is uncontrollable then we'd all abort and take the 50/50 chance of dying common sense but in 99.999% of cases no--simple--that's why you have to love this game you alway have a chance to die!!!oh well better than dying on the ground-I guess:\

Well
 

I have to admit that going to the Boeing link opened up my eyes..see my post on Flex ops.. Infact I invented a new V speed...I'm not kidding....:)

I don't think a post V1 abort wouldn't be so iffy with 7000 ft of runway left, a 1000 ft stopway, and miles of Iowa cornfield beyond...

Stealing my post a few pages back on refusal speed. If you don't recognize the term, I refer you to ground school. I will agree with the idea of stopping in the instance when V1 and Vr are "split" IF you know you can stop in the TODA and have the brake energy available. However, few civil planes have refusal speed charts or, for that matter, any relevant performance charts. In my old C-5 engineers computed about 50 entries in the take-off data sheet, including Vmca, Vmcg, take-off ground run (all 4 running) gradients, refusal speed, brake energy, climb capability on 4, 3, and 2 engines. A bit anal,but if you knew performance, good stuff. You cannot eyeball, in high performance airplanes, the take-off. The Force is with Luke, not you.

Would I abort after V1, yes, if the plane was uncontrollable (flight control problem) or suffered an extreme failure, say an engine explosion. If an engine fire lite came on as I went thru V1 and accelerating-NO. We're not trained that way, it is not briefed that way and the briefing is where critical decisions are made, not thundering down the runway making it up as one goes along.

For example, an old friend had a severe tire failure taking out most a bogey on a 707, after V1 and airplane stopped accelerating, stuck short of Vr. All went for brief swim in SFO bay. Two different friends have taken different C-5s airborne after bird strikes during rotation, one with 200,000 pounds of Class A explosives on-board). Both came around and landed under control with no damage. Aborts would have certainly overrun the available runway, the take-offs were that close and they lost one engine and significant thrust on the one other. A CO DC-10 did something similar in EWR and landed.

If you want a better idea, consider this: review the data available, using a runway analysis, determine the heaviest weight acceptable for the runway, IF the V1 for that weight equals or exceeds Vr for the planned take-off weight; set V1 equal to Vr. Yes, you have "unbalanced" the field length, not operating IAW with the training and FAA certification, and the insurers might disown you, but I'm guessing it will at least provide a logical justification for your operation. A few giggles, too.

At an airline I worked for, SSG, your mode of work was called, "in business for yourself".

PS: if you dare bring up the recent C-5 accident, the response is: THEY OPERATED LIKE YOU WANT TO--Unbriefed, uncoordinated, and poor technique under stress. The plane was perfectly flyable, IF they flew as trained by the book.

Mutt: I agree-few civil planes have the charts available for what is needed.

Quote of ssg’s original scenario:
Assume you have 5000 ft extra runway past your balanced field length, your light, cool weather, everything is in your favor...you accelerate past V1 twards V2, and you get an engine fire...
Would you fly it off the ground or try to stop it?
[Unquote]

Not sure if you’re a pilot, ssg, but you certainly made us all examine our principles and understanding of take-off performance. No bad thing. But there are at least two factors in your scenario that you seem to have overlooked.
1) Once VR has been called and rotation initiated, there is a major handling issue, as others have commented. [Granted V1 can be 30kts below VR.]
2) Bringing the aircraft safely to a halt on the runway with an engine fire is not necessarily non-fatal. If an engine fire occurs before V1, we must also assume thrust failure; so performance theory suggests continuing is not normally an option (unless someone wants to propose that on another thread). In that case we must settle for extinguishing the fire at a standstill − backed up by the fire service. Think of the B737 at Manchester, when a light crosswind blew the flames into the fuselage. After V1, even assuming the crew has a choice, taking the fire into the air may be the safer way of handling the fire. Trouble is, there are engine fires and engine fires. Perhaps other Posters will comment?

The scenario you have chosen is predictable at the planning stage. So the decision can be made then, by choosing V1 = VR (but NOT V2). When there is so much surplus runway, a big range of possible V1s is available (between BOAC’s Vgo and Vstop); provided your company’s performance manual or computer is up to the job… Having said that, you may decide to choose a low V1 if departing an airfield with no engineering support, for example, in a 4-engine aeroplane.

Once a V1 has been briefed, there has to be a very extreme failure to justify flouting it. The above performance calculation is always based on the failure of ONE engine, as in your scenario. A more difficult case would be the failure of more than one (before VR). Amending your scenario to the recognised fire and/or failure of 2 engines on a light DC10 before VR, I think most of us would hope to make the decision to close the throttles. In a 4-engine jet, it's not so clear-cut (we used to practise it in the VC10 simulator, but the second one didn’t quit until we had rotated).

Chris: Hope "low" V1 is referenced to Vmcg.

One thought not brought to light. I am taking off between V1 and Vr, experience an engine failure/fire-unknown immediately is the loss of Sys 2 hydraulic power due to damage. Now, in my current steed, I'm down to 50% brakes-big loss of stopping power. If it were Sys 3, I'd have 50% brakes and no steering (yes, differential brakes, but further degrades stopping). Heavy transports frequently have lots of other system problems that would best be defined, handled and planned for airborne. Once airborne, the emergency landing will be accompanied by CFR, flight attendants will be ready for an evacuation, all aircraft problems will have been addressed. The approach can be planned so the crew/ATC is ready. I just believe the airplane is safer airborne unless it cannot get there. SSG-as opposed to the Citation (I have about 2800 hours in them) most transports, even large corporate jets, just do not always operate with oodles of extra runway. I have done plenty of take-offs in the GLEX at heavier weights where we didn't 3000 feet extra. And we use APG perf calculations on every take-off. Hell, on the Kennedy Skid Strip or Edwards AFB, I'd do lots of things with an engine failure. EDW is 13,000 long by 300 wide and goes into Muroc Lake Bed.

Good Posts..
 

I think we can all agree that taking off from a 5000 ft field in a 737, balanced field is 5000 ft...20000 hour trend monitored engines, burning lake of lava at the end.... Is a little different then a Citation on a 12000 ft field, balanced field is 3000 ft, Iowa cornfields for miles., and new engines with 100 hours on them....

The later shows that the pilot has more discretion because he has more time, more options...To purposely take away those options by choosing a shorter runway, using Flex, adding weight...adds risk...I didn't say dangerous, I said risk...

I beleive that 'Pilot Discretion' is a problem for many in here...they want the pilot to have the numbers, the facts...not just look at the airspeed and runway remaining and make a call..the more they keep him from making a decision and just going to the checklist, they feel the flight will be less prone to a screwup.....I can understand that...

But stories abound of pilots that made quick descisions that saved lives that weren't on the checklist or calculated ahead of time, and we have seen the opposite as well...if anyone in here can brief for all possible scenarios, my hat's off to you...

History judges hard the ignorant...and luck favors the prepared...

Seems we are always finding a way to crash a plane who's problem wasn't on the checklist or the checklist was wrong when you encountered it...but we move forward by the ensuing discussion and learn from our mistakes...

Personaly discussing these scenarios and hashing them out ahead of time, looking at all the angles is better then waiting for another accident then trying to figure out what went wrong and adding another line on the checklist.

I have commented sadly to students, that someone had to die for every line on a checklist...and the checklists keep getting longer.....

They get longer because many times we encounter some form of ignorance, something that everyone overlooked, or outmoded concepts and training that needed to change... but again, a plane had to crash to uncover that hidden truth.

I feel these forums are a better way to uncover that truth....

rubbish!

having witnessed at close quarters the development and certification of a QRH for a new type before it's entry into service I can categorically state that no one died during the whole process. Nor have they died in the revisions of said QRH.

God help your students!

Ssg, could you comment as Mutt has brought up on the 15' wet screen height as well the four[I think] different possible certification scenarios and how they would work against your pax too----? compare and contrast :}

Also explain to me what are the basics of the segmented takeoff profile?-because a 4000'/min segmented climb oei at V2 wow:hmm:


although you've got us going man---:ooh:

PA

PA,

Some light jets can still climb like a ruptured duck on one during second segment on up, or a single engine missed approach.

I still remember my right seat checkride in the Sabreliner 60, coming from older radial four engine equipment. I was very impressed with the performance. When I was given a missed approach off an ILS on one engine, I began pulling the power back on the good engine. The examiner had a fit and asked why. I had too much performance and only had three thousand feet to climb to the missed approach hold. It's a matter of perspective somewhat, there. He thought we had hardly any performance left, I thought we had too much.

A 20 series Learjet will hold 6,000 fpm in the climb easily enough, and the initial climb can exceed 12,000 fpm when light. It can hold several thousand fpm up through about FL290 or so. The cost, of course, is that you can actually see the fuel gauge move...:E

---(that's on two engines, not one)

SNS3Guppy

I think that the LEAR 20 series are not turbojets they're space rockets---or wannabe F4's:}---although I can tell you [as you know] they have taught some of the bigger jets how to really get upset though...I'll forever miss that baby though:(

Did anyone say you can't? As long as the V1 is below Vmbe and V1stop and Vr.
But then if you want to abort after Vr... that's a different story... I'd do it if I can't even reach V2 and decelerating if I still got the fence in front of me. If the fence is behind... well, pray...

Multiple engine failure etc? Well, if you are sure you cannot attain safe flight (for a safe return), just stop and pray you won't hit the petrol station on the other side of the fence (even if there is an extra 5000ft clearway after the 5000ft runway remaining).

Flex is dangerous? *bangs head on table*
Let's put it this way, estimated value of risk from FLX / estimated value of savings from FLX. As long as your take off performance is legal, and your climb numbers are OK, if that equation yields an answer of <1, then FLEX is the way. If >1, well, the insurers will surely have a word with management.

It won't add another line the checklist...

PK-KAR

I understand the argument.. I hear 'legal' numbers and 'ok' climb...so Fly it to the fence to save some money on overhauls, even if you have to push balanced field into the overrun?

The Lear 24 is the only aircraft I flew in which I declared minimum fuel while taxiing :p.

Stuck in the lineup at Phoenix on a very hot summer day, 45 minutes into the wait, the reserve was gone and the air conditioning was non-existant. I asked the controller how long, he gave a mystical response about time and space and birthdays to come, and we declared minimum fuel. He asked if we were kidding, and we told him, no, we needed to taxi clear and go back to the FBO for fuel.

One of my reserve fuel tanks today holds nearly as much as the whole airplane did then...but it still kills us to hold short today for very long when we only allot 3,000 gallons for the taxi...some things never change.

I think that translates somewhat to this thread; it's different scales for different sizes of airplane, but the principles remain true...including those for V1.

Several posters here have thrown out some outlandish concepts regarding locked flight controls and so forth, and then asked the utterly ridiculous question as to whether one will continue the flight or not. Clearly when flight is not at all possible one will not...that shouldn't even need to be dignified by discussion...but where the airplane will fly and is able, there's just no good reasont to stay on the ground. Even in a Lear. With a drogue chute...

Of course, in a citation, where the biggest threat is experiencing bird strikes from behind...

>Also explain to me what are the basics of the segmented takeoff profile?-because a 4000'/min segmented climb oei at V2 wow<

As this thread has taken on a new lease of life and everyone appears to be changing sides I would like to know which Citation will climb at 4000 feet per minute at V2 unless it has literally no fuel and no pax ?

Pace

"if you got a flap asymmetry warning, an un-commanded slat retraction, a trim runaway, an obvious control jam or hard-over, a double engine flame out, (if you only had two for the less astute among you) after V1 you would not even consider aborting the take off because you had said so???"

If the space shuttle, operating on UHF Freq, lands 2000 feet in fron of you, but you have an engine over temp at Vr, are you still going to attempt to stop? What if it is a UFO?

Isn't this getting a bit esoteric? If you have a loss of both engine, it will be a very short flight, whether one rotates or not. All the rest of your examples are just about the same, the a/c isn't going to fly, well again, at least not very far. However, I am at loss to any of your examples ever having happened, doesn't mean they can't, but it is highly unlikely, bordering on impossible. I mean really, dual engine flameout on the runway???

No one said anything about v2 or single engine...Citation Vs, Ultras and Encores can do 4000 ft/m...for while

Dieasel 8

Probably the most sensible thing said. Dual flameout forget V1 VR and the rest because you are not going anywhere fast.

Control failure the same. Massive engine fire or airframe fire and I am taking my chances earthwise, If need be at the end of the runway I will do a formula 1 turn up a taxiway :-) to extend my ground run.

The rest sort it out in the air.

Pace

Isn't it an oversized fighter with fighter wings and a plush cabin instead of a bomb bay? :E

if the company wants to go to the overrun as part of the stop, so be it, I'd probably just move companies. Flex it as far as the stop goes to just short of the overrun and the climb numbers are OK is fine by me. If the company wants to loose the tyres being sunk in a soft overrun, it's their choice. The insurers will have a nice chat with the management.

But when that's the V1 chosen, definitely no abort past V1 unless the conditions dictate it's better to stop and pray I make it before the petrol station on the other side of the fence.

Basically aborting past V1 as per the majority of your posts and flex is the same in that you're making the decision with less stopping distance available.

If you've been preaching you'd stop past V1, I don't see why you'd look down at flex t/o... unless, you want to abort past V1 so much that you'd never flex t/o because you know U'd be in deep doo-doo whenever you make a stop or go decision past V1high... :=

Have a read at that link again, with V1low, feel free to be stop minded, with V1high, be go minded. Your choice, your life... we won't laugh. If your stop minded with V1high (which I'm sure U're not), then we won't laugh, we'd just shake our heads. http://www.indoflyer.net/forum/upfiles/smiley/joget.gif

If you're nitpicking as to which is safer, and your workplace has a V1 policy you're not comfortable with, just move somewhere else that can give you the comfort (dunno and dun really care which companies go for V1bal, V1low or V1high, take yer pick), and accept the fact that some others have a different V1 policy to what you want that's still legal (and safe ..

With great respect to the crew of AA191, I bet they were pretty unimpressed with the outlandish event which led to them losing No 1...after all, initially, the indications probably just looked like any other engine failure...

Diesel8,

Un-commanded slat retraction - 1979, AA191

Obvious control jam, hard-over - 2001, LH A320 Cross-wired Sidestick

Double engine failure - 2001, S360 departure from EDI

Say again, what you think is impossible?

The point is, that there may come a time, when near, at, or above V1 you might be called upon to make a decision about whether or not your aircraft is able to fly...

I figure the fact I don't have feathers is a pretty good reason...

The problem is, that regardless of what decision you make at that point, if the outcome is successful its self-justifying...but whether or not there was a better outcome, will always be debatable. Plus, you'd be a brave pilot to admit as much, esepcially if there were fatalaties...

When operating at the edge of the envelope, I prefer not to extrapolate based on the norm...that is bad practise in any mathematician's book...

Hoping it never happens to me....

:ok:

SR71
 

+1....well said / There are alot of pilots in here living a world where things don't go wrong, just pull the levers before V1, push them up after. I take solace in the fact that maybe these posters are retired, don't fly, unemployed, or at the least FOs where they are not allowed to make a decision...

Of course you and most others here have a damn good idea of how to make rational decisions of whether to go or not.

The problem is the time base that you are constrained to rationlize such a decision and so little training or experience in creating rational thoughts outside the box in this time period.

So I'll rather trust my life with pilots that think inside the box (of their training), for that has been proven statistically safe.

Your absolutely right..we can monday morning quarterback for hours all these scenarios when in real life the decisions have to be made quck..

But I will throw this at you...if they can't make the right decision in front of thier computer, how will they do it at 120kts having just clipped a fuel truck post v1?

Er?!
 

With a thread this long I looked at the first page and the last.

There really is no point in debating this apart from certain acedemic aspects to the process which can be interesting since it throws up a couple of curved balls.

There is no data in the FM for braking distances beyond V1. And for good reason. If you decided to flip that particular coin then you become your own test pilot and I'm not too sure the rest of the crew will thank you for it. Even if the decision to remain on terra firma after V1 is taken and gotten away with due to extreme circumstances the post flight euphoria will diminish when the investigation reveals that you were happy to keep the problem earth bound. No protection in a court of law for that. Then you are on your own; a lonely place to be.


:=

I was wondering when this would come up..
 

Gee Whiz can't anyone in here look at some pavement and get a decent idea if they have enough to stop? We do it every day in cars...what's the diff?

"Un-commanded slat retraction - 1979, AA191

Obvious control jam, hard-over - 2001, LH A320 Cross-wired Sidestick

Double engine failure - 2001, S360 departure from EDI"

And in which ones of those were the a/c still on the ground past V1 with the ability to safely stop?

Cannot speculate on 191, although the uncommanded slat retraction was a we all know, due to the fact that the engine seperated from the a/c. Had it just been an engine failure, little doubt they would have survived. Had they stopped, for a "mere" engine failure past V1, it is not known, that the a/c would have stopped on the remaining rwy, it may well have plowed into houses, broken up and burst into flames. The report would have certainly faulted the crew for that, afte all, that would not be SOP nor the manufacturers recommendation.

In this article, you will notice, that the engine loss/slat retraction was deemed surviveable, after having re run the scenario in the sim, however, certainly we cannot blame the pilots on AA191, rest their souls, for the outcome. http://en.wikipedia.org/wiki/America...nes_Flight_191

LH was not a control jam, the controls moved freely, the CA sidestick was miswired, the F/O stick was working properly. They found out when the a/c was airborne, that is when the CA used roll input. He would not have been aware prior to V1, that is unless they had noticed the anomaly during the control check at taxi. Of course, in that case they never would have taken off. Certainly you are not advocating the LH pilots should have tried to land on the same rwy after having been airborne, with a stick malfunction to boot. That surely would have led to an overrun or worse, a crash. Interestingly enough, Airbus FBW do have a procedure for frozen or malfunctioning sidestick and no one was harmed in the incident.

The SD360 was at 1200 feet when they experienced trouble, a couple of minutes removed from V1, is that example even pertinent? Why not mention the SAS MD-80 out of Stockholm, they had dual engine failure a minute or two removed from V1. Maybe they Gimli glider should have aborted at V1 plus 20, then they never would have suffered dual engine failure in cruise.

None of your examples appear to offer much that is relevant, nor anything that supports the argument of stopping past V1. In two of the cases, the a/c was already airborne, with no indications of malfunctions prior to and in the case of AA, the crew had no indications of anything other than an engine failure. The AA crew at the time, made the right choice based upon what hey knew, since they couldn't possible have known the engine was torn off and that the slats would retract.

Statistic show, that the safest course of action, past V1, is to continue the takeoff. It has been proven time and time again. It is the recommendation of all FAR 25 manufacturers, all airlines, all training academies etc, etc.

Is it possible to come up with situations where it would not be the prudent course of action, yes it is. Dual engine failure on the ground, an aircraft that will not rotate, loss of an entire wing, etc. However, do any of those happen on such a recurrent basis, that it should be considered normal, besides, under such scenarios, is there even a choice?

Is there any emergency when taking off that you would consider normal.?

Funny, the latest accidents I see are blown tires, plane doesn't accelerate, someone horses it off the runway then crashes...

gotta go, gotta go....

True Ssg there's been tons of bloodshed in aviation to make it safe--and yet we insist on recreating the original TO and LDG accidents--for historical and educational purposes I suspect :*

"Is there any emergency when taking off that you would consider normal.?"

Nope, but then again, losing an engine, considering the excellent training we get now a days, could probably be considered more of a non routine. A blown tire shouldn't cause much grief in the front office either. Having been through both, cannot say they were much of an event.

Here is a great example of some well executed airmanship:

http://www.youtube.com/watch?v=uYNpB-8_BSo

Should they have tried to stop?

This one was an RTO at supposedly 12kts above V1:

http://aviation-safety.net/database/...?id=20060607-0

http://www.youtube.com/watch?v=wj8UP...eature=related