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In this famous video with not to good quality now

I don't believe this IL76 was able to takeoof if the engine failed. Are the rules ignored? Or it's possible to get permit takeoff without V1 and any consideration for engine failure on multi engine airliner?

Update:Ok V1 maybe is not a rule. It's a number that you get after application of certain rules. But MEP aircraft doesn't have V1 and single engine aircraft as well. They all operate and even can carry people. Maybe it's possible get an exception to operate ME turbine aircraft without consideration of an engine failure? For example runway is very short or you are heavily leaded and aircraft will not climb at all with -1 engine.

I was not asking about the V1.

Maybe there is an airport somewhere very high with 40 degrees outside, short runway and down slope. Guys have IL76 fully loaded. They see that there is no way they can takeoff applying standard safety rules. But they run calculation and they see that if they use 100% of runway for take off run they will get 1% climb gradient with all engines on full power. If you want to depart very much maybe it's possible to go to aviation authority and ask for a special permit?

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    $\begingroup$ What evidence is there that V1 was ignored? 4 engine aircraft have very different takeoff profiles compared to 2 engine aircraft. Heavily loaded 4 engine aircraft routinely use more runway than 2 engine aircraft. V1 is just a speed where you can decide to stop on the remaining runway. Vr is when you rotate and has nothing to do with the amount of runway remaining. $\endgroup$ – Mike Sowsun Sep 26 '16 at 13:09
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    $\begingroup$ V1 is simply the point at which you are committed to taking off, regardless of engine failure. Because of the long take-off run and possibly short runway, they may have hit V1 very early on and elected to continue. The video you show is Australian, but I don't know of any "permit" process for take-offs. The worst these guys may have done was violate the Ops Spec manual from the operator. At least in the U.S., you are allowed to use as much available runway as you want. $\endgroup$ – Ron Beyer Sep 26 '16 at 13:39
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    $\begingroup$ V1 is not a safety rule, and as such there is no such thing as getting an exemption from V1. Just like the stall speed is not a safety rule, and you can't get an exemption from stalling... $\endgroup$ – J. Hougaard Sep 26 '16 at 14:21
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    $\begingroup$ "I'm running out of film. I don't know if I'll have enough to film the crash." That is a great line! $\endgroup$ – FreeMan Sep 26 '16 at 20:04
  • $\begingroup$ I wonder if this was a reduced thrust (flex temp) takeoff? That'd explain eating the entire runway, as your all-engine accelerate-go becomes the limiting factor here -- if you lose an engine above V1, you simply put TOGA power on the rest, leading to an engine-out accelerate-go that's shorter than the all-engines case. $\endgroup$ – UnrecognizedFallingObject Sep 27 '16 at 22:21
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To answer the question as asked, no I've never heard of an airline "ignoring" V1.

To address the implicit question, I have no idea what the story is behind that IL-76 operation shown in the video, but I could creatively come up with all sorts of possible explanations for the takeoff roll that essentially matched the available runway: power not set correctly, takeoff data computed incorrectly, poor pilot technique, unexpected tailwind, aircraft loaded heavier than expected, or maybe that crew DID decide that it was so important to get home that they were willing to accept an absurd risk. But I wouldn't take ONE video without explanation of "what really happened there" as any indication of what airlines in general will do.

At its most basic, V1 is simply the point at which you transition from a "stop" mentality to a "go" mentality: if something goes wrong PRIOR to V1, we'll stop; if something goes wrong AFTER V1, then we'll go. Now, there are LOTS of things that complicate that discussion... not everything that can "go wrong" is the same: at 80 knots, getting an "anti-skid fail" light is probably not worth aborting for; at 80 knots, getting a loss of all generators probably IS worth aborting for (assuming that V1 is well above 80 knots). Just below V1, losing an engine IS something you'll stop for; losing one generator or one hydraulic system might not be. And this is all dependent on the aircraft... in the C-130, we were pretty stop-oriented, and we'd stop for all sorts of things immediately prior to V1 that in the 737 -- a much more go-oriented aircraft -- we'd take airborne. The difference being, you can stop the Herk pretty quickly & with a comparatively low risk of problems; a high-speed abort in the 737 (as in many jet aircraft) is much more of a big deal.

All that said, though, there is always a speed below which you'll stop, and above which you'll go. If an engine flames out at 20 knots, you'll stop in nearly any scenario I can think of (that doesn't involve bad guys storming the airport). In the Herk, it was common that your accelerate-stop speed was above your rotation speed, so V1 was essentially at rotation. But there was always some speed where your default choice between stop/go changed over.

You might "ignore V1" by simply saying that once takeoff power is set, we're going to continue regardless, but that's just bad decisionmaking by the crew, and not the sort of policy that I could envision ANY airline ever making. (Again, the case of mortar shells falling closer & closer to the aircraft & bad guys overrunning the airport might be an exception to this... take our chances with the ground rather than with the bayonets. But the outlandish nature of this exception illustrates how rare it would be to "ignore V1" in any considered scenario.)

Airlines tend to accept far fewer risks than other forms of aviation. The mission of an airline is to make money, and nothing interferes with that mission like the bad publicity & loss of assets (and potentially, certification) that comes from a crash. In the military, there can be a mindset of accepting lots of risks because troops are counting on us completing this mission. In general aviation, there tend to be individual decisionmakers, with little institutional guidance & corporate wisdom to back them up. But the airlines tend to be entirely willing to postpone a flight if it can't be performed safely, so for "airlines" to ignore V1 or other safety rules seems highly unlikely. (Which isn't to say that an individual crew might not do so, although at least at US carriers, they aren't likely to continue to be employed if they're found out.)


--- EDIT, added in response to updates/edits in the original question:

What you're asking is, in essence, can "they" get permission to take off knowing that takeoff roll = available runway, and if anything goes wrong after the point at which stopping takes all of the remaining runway, then they're dead. If takeoff roll = available runway, using all engines, after you've reached the speed at which you can no longer abort the takeoff within the remaining runway, and then you lose a motor, you now

  • Don't have enough runway left to stop, but also
  • You don't have enough runway left to accelerate to takeoff speed with the remaining thrust (less than the original case)

That's more or less the "bad guys storming the airfield" scenario, where you know that you're dead if you stay, so it makes sense to take off & hope that the motors keep running through the takeoff roll. Given that the risk of staying is so high, the risk of losing an engine during those seconds of the takeoff roll is the lesser of the two evils. And yes, in Viet Nam there certainly were times when C-130's would accept those sorts of risks to get the badly wounded out of dirt strips in combat.

Now, is that a reasonable thing to do in peacetime? Not in my simple mind. If we are assuming that the IL-76 crew did their performance computations correctly & their long roll was a known & accepted risk, then maybe they reached the opposite conclusion. It's not something that I'd expect an airline to ever approve with passengers on board, and we'd have to get creative to find a scenario where they'd approve it for a ferry.

Can a crew make that sort of choice on their own? Well, yeah, at least once. Would an airline approve that option? Hard to imagine.

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    $\begingroup$ +1 for bad guys storming the airport. I imagine a pilot slamming the throttles to max while bad guys carrying AK47s are running across the field. $\endgroup$ – kevin Sep 26 '16 at 16:02
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    $\begingroup$ As long as we are making up possible reasons, a couple that follow the rules but still end up there would be an actual engine failure (at V1 on a field limited takeoff) or windshear on takeoff which extended the takeoff roll. $\endgroup$ – Lnafziger Sep 26 '16 at 18:32
  • $\begingroup$ @kevin On the other hand, it just might not be the best idea either if the bad guys carry man-portable SAM weapons. Even a short range SAM could make for a bad day. Then again in such a situation it might be worth it just taking your chances... $\endgroup$ – a CVn Sep 26 '16 at 19:35
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    $\begingroup$ Just to add to the running commentary, it's also possible that the aircraft was incorrectly loaded (more weight than the pilots knew about), or even that they just never bothered to calculate their performance and assumed that it was "good enough". That's the problem with this question, we really have no way of knowing. (That being said, if I remember right, the story goes that the tower was recording the takeoff because this particular flight/operator was known for doing really stupid things so it may be more of a pattern....) $\endgroup$ – Lnafziger Sep 27 '16 at 16:16
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V1 is not a rule, it's a fact. You cannot ignore and you cannot get an exemption for it. V1 is the speed at which the remaining runway is too short for stopping the aircraft.

In other words: no matter what happens to your plane after V1, you have to take off. If a fire breaks out, an engine falls off, the windshield shatters, your flight computer dies, it doesn't matter. There simply is not enough runway left to brake, you must take off, climb out, and then you can figure out how to land again.

"Ignoring" V1, i.e. trying to abort a take-off after V1 simply means that you try to stop the aircraft, but will fail, so the aircraft runs off the end of the runway and bad stuff happens. The idea of "getting an exemption" from V1 doesn't make sense: basically, that means that all of a sudden out of thin air another couple hundred feet of additional runway magically appear. Which won't happen.

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    $\begingroup$ Not necessarily -- if you're accelerate-go limited on T/O performance (vs. accelerate-stop), you may have runway available in case of an abort after V1. In fact, there are cases where you must abort after V1, for obvious reasons (like your elevators coming undone when you go to rotate). $\endgroup$ – UnrecognizedFallingObject Sep 27 '16 at 1:39
  • $\begingroup$ V1 is a rule. If engine failure is not considered during takeoff V1 is not necessary. $\endgroup$ – Andrius Sep 27 '16 at 6:20
  • $\begingroup$ @Andrius V1 is not a rule, in any sense of the definition. V1 also does not relate only to engine failures, V1 is the speed at which any reason that would cause you to abort a take-off, that the take-off can still be safely aborted on the remaining runway. For example blowing a tire, smoke in the cabin, etc. are all failures at which you can abort prior to V1 but not after. $\endgroup$ – Ron Beyer Sep 27 '16 at 13:30
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    $\begingroup$ @Andrius V1 is a rule of physics. After a given aircraft, with its current load and runway, at the current temperature and altitude reaches a speed that has been pre-calculated (for this set of conditions) and called V1, that aircraft in, those conditions will run out of runway (paved or otherwise), if the pilots attempt to abort the takeoff. Pilots are free to choose to abort the TO after V1, but it will, most likely, have disastrous results. $\endgroup$ – FreeMan Sep 27 '16 at 14:50

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