B737NG engine fire just below V1
 

Engine fire just below V1, is it always correct to reject take off?

No.
If the engine is producing thrust as normal and all other indications are normal, I would continue, shut the engine down at 500' and return to land on the full length of the runway.

I had thought that the fire bell was inhibited with sufficient margin to allow for either a statistcally safe abort or a statistically safe continuation, without the additional burdens in complicated "what-if" decisions by the crew.

The fire bell is never inhibited automatically on any aircraft that I know of. It can be inhibited by the crew, but other visual warnings remain.

Engine fire warning right up to V1 is a class A1 reason to reject the takeoff. If you have an uncontrolled fire on the aircraft (and every fire has the potential to be uncontrolled), you have about 3 to 4 minutes to destruction.

Reject! (But not at or above V1)!

Regards,

Old Smokey

Strictly speaking you must have initiated a takeoff rejection by V1. But now, if you have an engine fire just below V1 and you abort or reject, you´re doing exactly what you´re supposed to do, exactly what they teach us in the sim, and exactly what the judge will determine as legal.
All takeoffs are "go minded" which means one tends to let the airplane do what the airplane knows best.....fly ! but there are a whole bunch of possible scenarios where one can´t speculate with "oh well I am a few knots below V1, no matter what happens I´ll keep going" because that speed is based on the aircraft´s capability to stop against its capability to be controlled and to accelerate safely for flight. What if you´re taking off on a contaminated runway and V1 is really low, and of course the fire is a REAL fire, and the engine also quits...not the simulator fires, where you only get the bell but the engine performs perfectly... What if you´re departing with anti skid inop...and your V1 is even lower...you decide to continue a takeoff with very low speed, low weight, you might have controllability problems...and may not accelerate, could tail strike and lose control.
All I am trying to say is that you can´t deal in absolutes here. High speed failiures are the probably the most critical scenarios and you can´t just say "I will never reject a takeoff maneuver this many knots below V1 or beyond certain point at the rwy or whatever. Someone came up with a V speed called V1 and your course of action must keep in mind this value.
Regards,
SW.
PS: and yes, old smokey ´s very correct..if its a fire...and you don´t abort, you could have 3 o 4 minutes to destruction, if it was IMC and you had to fly an instrument approach eww..nasty..hope those freon bottles help...

Hey this is my post #100 !!!!!

How do you know if a warning fire at -10Kts V1 is a real fire?

Better to fight the fire at 500 ft or at the end of the Rwy?


Cheers

Even if you had a shock-horror moment on hearing the bell (as most of us would) and actually reached V1 before rejecting, in my opinion that would be the safer option because as old Smokey says, in the air a fire could destroy the vitals in 3 or 4 minutes. Better to go off the end at 20 knots, grind to a halt, get the pax out with a few broken limbs than to be faced with a Concorde-type situation in the air. And really, how often are you really, really stopping distance limited in a B737 from V1? On 25% of all take-offs? Depends on where you operate I suppose. So then we get into the actual odds of running off the end if the reject is actually commenced bang on V1.
At V1 minus 5 or even 10 knots you do not have the luxury of assessing how serious the fire is. You have to assume the worst and do what most briefings state in one form or another - reject for any situation which could make the airplane unsafe in the air. Argue the legalities of what constitutes V1 from the safety of the courtroom, not from the grave.

So where are you going to stop second guessing the aircraft systems?
As old Smokey posted, if you get a fire warning prior to V1 ...Stop. That is what V1 is for! (+ all your perf. calcs.)
If, (the one in a million) it is false, then you are on the ground no harm done, rather than, "oh it may be false" & the wing falls off three mins after take off!
Or, what would you have done in the unfortunate Concorde accident?
ATC calls "Fire" crew initially had no warning & continue. Had they rejected the take off perhaps some/all would have survived?(remember they had second(s) to assimilate that call before VR ,& they were already past V1)
Where do you start becoming a medium & stop being a pilot?
Hindsight is a wonderful thing after all..........
EDIT..(Gas-chamber & self must have been drinking the same mind altering brew!)

Regarding the Concorde:
The warning from ATC came 10 secs after V1.

The Concorde accident had different causes, but your last posts are really interesting.

Why Rubik101 and many others believe is better to go? Do you want add something else?

Guest27

Caveat .. didn't fly the NG only the Classic so my comments have to be generic ..

This is one of those conundrums where you might very well be "damned if you do and damned if you don't" . The correct answer is determined retrospectively by the outcome on the day .... and the Judge at the Enquiry ... if the outcome was less than fortunate on the day ..

As with so many things we discuss in this sandpit ... it all depends.... Certification tends toward the black and white (as it must do ... to be achieveable and repeatable) while the real world is a murky mixture of all shade of greys ..

Things which concern me include ..

(a) the chart accel stop data is based on a fuel cut at Vef .. ie one winding down rapidly and the resulting speed overshoot being contingent upon that very significant thrust reduction

(b) fire warning leaves you with two engines and a significantly higher acceleration (and speed over run .. 5-15kt might be a reasonable ball park figure) while you are going through the reconfiguration from go to stop mode ... ie if the takeoff is seriously accel stop limiting you are absolutely guaranteeing an over run if you stop ...

(c) how far below V1 is "just below V1" when the event manifests itself ? .. considering the particular Certification Basis for the aircraft ...

(d) how long is it since the far end has been cleaned of rubber deposits ? what is the over run like ? what is the crosswind ?

(e) if the runway is not accel stop limiting and has a comfortable margin (bit rubbery until the margin is large) .. then stop

(f) if the runway is accel stop limiting and the over run is nasty .. I'd keep going on the basis that the historicals favour that option on a risk management basis

(g) let's not argue about reverse thrust .. in a real serious situation the maximum effort deceleration is sufficiently high (those who have felt the effect of nosewheel brakes on the 727 will understand what I mean) that the practical effect of reverse is comparatively small in the overall scheme of things.

Of course, we could come up with a few more considerations with a modicum of thought .. but, whichever way you look at it ... it's not a nice place to be.

you have about 3 to 4 minutes to destruction .. which is why some of us push students on endorsements with a contrived minimum time circuit exercise .. engine or cabin fire .. same sort of scenario and concerns ..

.. some days one really should have stayed in bed .. for instance I have a friend who has driven a wheelchair for many years ... having stood in for another colleague on a particular test flight ... same sort of consideration at play .. all one can reasonably do is operate conservatively .. load the dice reasonably to your benefit ... and hope that Lady Luck, on those occasions that she is irritated, visits other people instead of oneself ...

Well I know where I would prefer to fight a fire especially with the help of the airport fire crew and that is not at 500 feet!

"Before 80 kts we abort for any malfunction,
after 80 kts cancel master caution.
Between 80 kts and V1 we abort for severe malfunction, fire, failure or incapacitation."

That would be a part of my emergency briefing.
So basically,
Before V1 = stop
At or after V1 = go
V1 is also normally reffered to as take-off decision speed.

My understanding is, start stopping at V1 and you go through the fence. (You need to have started stopping by V1). Continue the Take-Off at V1 - 10kts and you cross the fence by 20 feet. Not much, but you cross it. And that assumes total failure of the powerplant.

Of course, runway length is a factor. If you are Vr limited, stop. If you are otherwise limited with a V split, god speed. (Or not speed)

I (on a short runway) agree with coming around for a whole runway, fire brigade in force, low speed landing.

Plus, you have the whole circuit to plan your legal defense.

you´re not going off the fence if you initiate actions right at V1. An enormous set of unfortunate things should take place for that to happen.
1) improperly executed maneuvers
2) figures not correct (last minute wt adjustments or excess baggage not declared)
3) unconsidered wind changes
4) a performance deterioration factor not kept in mind
5) excessively worn out brakes
etc.......

Besides keep in mind that for a certain weight, flap, temperature, and wind, V1 is the same in a 6000 ft rwy as in a 12000 ft rwy (except improved climb) so you´re in one scenario you´re not going to go off the fence, no matter what..and the other one you might if things (or you) don´t perform as expected. V1 is generally unrelated to rwy length.....generally.

1: The majority of overruns happen with two engines producing thrust.

2: Boeing (NG) recommends to abort for fire warnings prior to V1.

In general I would abort.

If runway limited, particular if on a contaminated runway, I would not. Yes, I know all calculations say I'm OK to stop at V1 anyway, but real world is real world, and theory is theory.

Boeing want you have taken the 1st action to stop no later than V1

With a fire before V1 I will stop. Having lost a friend to an airborne fire I have no desire to take an unecessary risk. Structural failure may occur as early as 4-5 minutes if the fire is uncontained and spreads. I do not practise turnbacks (onto reciperical) mvrs in the sim but I do practise stopping from V1 or below. The sim conditions you to fly a pattern back to land you may not have the luxury of that time as has been tragicaly proven several times.

It seems that most of you prefer to split between theory or sim (RTO below V1) and real scenario (keep going below V1 if blah, blah, blah).

Personally I agree with John when says "This is one of those conundrums where you might very well be damned if you do and damned if you don't".

Do you think Boeing should spend some more words about that or the right choice is just related to the pilot's wisdom.

I would definitely be stopping.....but...

Can anyone recall an engine fire in a pod mounted engine which resulted in structural failure when airborne in recent years? Granted a fuselage fire is something else.

And I'd like to discount the 737-200 and that's a specific installation.

Sudden Winds,

...makes a good point for me.

On most runways of significant length you can do an improved climb T/O.

The V1 spread may be anything up to 30kts.

On these runways you can reject long past a normal speeds V1 and be assured of a theoretical stop on the runway.

Playing with fire?

I endorse what John Tullamarine says though...the call on the day is going to depend on a number of issues and it may prove to be a day on which you wished you'd never got out of bed.

:\

Please tell me which airlines those of you who won't abort for an engine fire warning at V1 fly for?

So that I can avoid them!

Beagle, you won't be able to fly again then. All airlines follow the procedure that if the engine fire/failure occurs at V1 then the take-off will be continued. Find me an airline that doesn't teach that and I won't fly with them!

All right then, before the V1 call.

It should always be possible to reject a take-off before V1 - that's what it means.

But it requires prompt performance from a practised crew; and the closer you get to V1, the more important this becomes.

But rarely is V1 so limiting that an abort precisely at V1 will not allow the aeroplane to be brought to a halt on the RW/stopway remaining.

I must have initiated hundreds of fires/failures at V1 over the years (in the simulator, I hasten to add). Rarely did anyone screw up an abort disastrously - but they did have the luxury of at least 9 x 3 hour simulator sessions per year. Something which I doubt airline beancounters would ever allow these days.

Putting the desirability of procedural standardisation to one side .. one of PPRuNe's values lies in providing a forum for discussion ... it still depends on the circumstances.

It should always be possible to reject a take-off before V1 - that's what it means.

Depends on the certification basis for the Type/Model .. in particular, two engines operating vice one.

Depends on the environmental circumstances .. runway surface contamination, over run environment, and how limiting is the accel stop case (the 2 second pad may not apply for many of our older aircraft)

The correct answer is that as long as you can take the first action to abandon the take-off by V1

No decision to consider here .. in a limiting case, once you have initiated the stop, particularly when the brakes come into play, there is no changing your mind ...

Overall, we go with standardisation for all the usual reasons .. but it is appropriate that we are aware that there are sets of antipathetic circumstances which are going to bring us unstuck if we follow the "standard" gameplan.

A well considered, thought provoking, reply, JT. Nicely put.
Interesting statements noted that structural failure due fire damage could occur with 3-4 minutes. Maybe so, although others may have contrary opinions on the safe time left.
Yet, in the many Pprune posts on engine fires (theory of) observed over several years, the majority of correspondents felt there was no great hurry to close down the engine and firing the bottles. These opinions appear to be based on the theory that the engine will probably fall off the wing before causing fatal structural damage. Again all theory and precious few facts.
In the simulator we see time and again, pilots who delay actioning the fire bottles until at least a minute - and worst case two minutes, after the initial fire warning. "There is no urgency" is their mantra - the excuse being the aircraft must be got under control before the crew look around the cockpit to see what the red lights are all about.
If an engine has failed after V1, (whether simultaneously with a fire warning or not) I would have thought the pilot would have not only immediately had the aircraft under control but the crew would have taken action to shut down the engine and fire a bottle if appropriate. This is notwithstanding the oft mentioned minimum height of 400 ft being attained before the first action is started.
Complacency in handling an engine fire can be potentially dangerous. There is no authorative guide that explains how much time is available before structural failure occurs following an un-actioned engine fire.
That being the case, a crew cannot afford to take the risk that all will be well and the bottles can be actioned at pilots leisure. The 3-4 minutes of safe flight available mentioned in these posts, suggests that others think along similar lines?

In my previous life we relied heavily on rear crew to tell us what was going on. In two cases the info they gave enabled the flight deck to make the decisions required to save all their lives. Nimrod with bomb bay fire at St Mawgan when they turned back to land on reciprical and Nimrod ditching in the Moray Firth after an uncontained fire started by an errant air valve/starter motor. In both cases it was later assessed that the aircraft had been very close to structural failure within minutes. Tragicaly in Afganistan the crew were unable to get on the ground before that structural failure occurred.

I accept that pod mounted engines are different as they should fall off but it does illustrate how deadly an uncontained airborne fire can be and how little time may be available to you. For all you know the fire may be due a fuel leak ala Concorde which will rapidly spread so best to stop in my view. Would I stop at V1/rotate on a long non FLL runway with 7000' left ?, in the sim no, in the aircraft with a fire warning then yes I would and take my bollocking.

As an aside I always make a point in the sim of getting the senior cabin crew to do a visual on any engine that indicates the fire has been extinguished as fire wires have been known to burn through and thus indicate all is well (ish) and previous indicates that info from the rear may well be crucial.

The data is clear that far more accidents have occurred for aborting takeoffs between 100 kts and rotation then for continuing a takeoff after a fire warning. In tne analysis of engine fires (the cause of the firebell) there is little data that shows that the fire will progress beyond the engine pod itself for several minutes while airborne.

The greatest majority of serious engine fires which have disabled the aircraft, have been associated with ruptured fuel tanks and ground pool fires after the aircraft has been brought to a stop. So yes my arguments are based on statistics and not one-offs like a Concorde

In the case of the high workload decision making in a takeoff environment, the addition of a firebell ringing at the point where intent of go-no-go and rudder control are paramont is an additional pucker factor that may impact on the more paramont decsisions of the bolded above. Hence, I believe that some aircraft automatically inhibit the firebell in this time frame. (perhaps a check with your aircraft manual might confirm this).

A fascinating discussion with some interesting views for and against. As stated before my money is on stopping but I still want data!

As a friend of mine often says "without data you've only got opinions".

I have looked and searched many places but there is no hard data that I can find of engine fires in podded engines causing quick structural failure. Similarly how many engines go 'bang' at V1 (or close to it)?

That said you'd look pretty stupid carrying an engine fire into the air when using a take-off alternate. Imagine flying for an hour with an uncontrollable fire....doesn't bear thinking about.

Which why I will still reject the TO when the fire bell rings. Trying to weigh up the alternatives near to V1 is not part of a sensible gameplan to my way of thinking.

July 2004, a 757 bound to La Havana, is at take off.
9 Knts before V1, engine fire n. 2 goes alarm

Commander, decides to continue. Both fire bottles are discharged, however the fire alarm stays on (later they will lean that the extinguishers managed to put off the fire, but the alarm remained because damage to sensors wires).

Commander decides not to discharge fuel and land immediately.
Passengers are evacuated, the investigation will find that a ruptured fuel hose caused the fire.

Report just published, in Italian with many portions are in English and clear photos.
http://www.ansv.it/cgi-bin/ita/EI-CXO%20ansv.pdf

The pilot was commended and nobody questioned that he exercised his command authority is a sensible manner during all phases of the emergency.

once saw a channel express F27 which had an engine fire just after take off, after take of, the fire was so severe they did a procedure turn to land on the opposite direction rwy, having seen the damage caused by a few minutes in the air, if they flew a full circuit to land on the correct rwy, I doubt the the crew would be flying today, the damage to the engine wing was pretty horrific.

At the risk of being controversial, it is important to note that the Industry's operations are based on risk assessment and risk management.

For the very great proportion of occasions and events within that set, the "standard" approach will work pretty well and is commended. We note that the standard procedure is not necessarily the best but is structured to provide a high probability of a successful outcome.

However, we must accept that, infrequently, circumstances are such that the usual procedure may be quite inappropriate .. should we vary our actions to suit ? do we have the capability even to detect the subtle differences from the norm ?.. is there even a sensible answer ?

Industry history has numerous examples of good outcomes and bad following out of left field unusual situations ... I suggest that it comes down to a mix of knowledge, skill ... and a very large helping of good or back luck .... which determines the ultimate outcome.

I think back to just two tragic cases where the crew apparently did all the "right" things ... but died with their passengers ... [Concorde at CDG and the DC10 at O'Hare]. Would the outcomes have been better had the Concorde been dumped unceremoniously back on the ground ? ... had the DC10 maintained the initial higher airspeed rather than pitch up to achieve V2 ? ... hard to say with any certainty at all.

United 232 .. I suspect Al Haynes et al would concede that Lady Luck played a part in keeping the toll as low as it was ....

While we push standardisation for a bunch of very good reasons, flying generally is not about guaranteed, black and white outcomes ... it is about risk and probabilities ... about loading the dice towards the desired, favourable outcome .... about constraining and controlling ill-disciplined operational behaviours ... etc ... etc....

Yes, but if you are below V1 and the fire bell goes, you're quite simply a dork if you take it airborne. No ifs, buts, whatever. To consciously take a potential fire airborne when you are already on the ground and freely able to stop, even on a limiting contaminated runway, show peculiar judgement. One needs to go into a darkened room and re-examine one's decision making processes. Period. There is no exception.

Next question please!

El thanks for the link...interesting reading (well looking at photos cos my Italian is not good! :)) and Rainboe, yes I'm still in your court with the stop call. JT as ever good comments. Pilot, yes the F27 engine installation puts that a/c at much more risk of severe structural damage from an engine fire, but in podded installations is the question here.

I suppose what I'm really asking is are we still examining the correct basic failure with the traditional V1 cut and engine fire? Whilst I agree it's possibly the most serious incident we could face from a handling sense, the industry data tends to point to more human factors issues as being where we need to concentrate our focus to bring down the accident rate.
Oh yes...and having reasonable Smoke procedures that are simple and workable......don't get me on that one as it's my favourite hobby horse and I would be accused of thread creep again!

There is no time to assimilate information whist on the takeoff roll so they make the decision rule-based.Its cut and dry.Below V1 you reject,at or above,you go.Its one of the few scenarios in aviation that is like this.Why do you think that poor Concorde pilot took his crippled aircraft to the skies?
As for ever taking a fire into the air below V1,well if you realized at high speed that the perf calculations were for another runway then you might push the thrust levers forward and elect to go at V1-10.The old eyeball method will tell you what is best.

Actually Old Smokey not quite true.

B757 Operations Manual:

'Warning Inhibits

The Master WARNING lights and fire bell are inhibited for fire during part of the
takeoff. The inhibit begins at rotation and continues until the first to occur:

• 400 feet AGL, or
• 20 seconds elapsed time

If a fire occurs during the inhibit, an EICAS warning message appears, but the fire bell and Master WARNING lights do not activate. If the warning condition still exists when the inhibit is removed, the fire bell and Master WARNING lights activate immediately.'

What interests me, apart from this thread of whether to sto with a fire before V1, is what to do after V1 with a fire. Classic training is to handle the emergency, climb, clean up, Mayday, S/E procedures, circuit and emergency land. A good 10 minutes minimum with possibly an uncontrollable one burning. Thinking of BOAC 707 1967 LHR doing that and burning out, and Airtours MAN 737 about '88 that could have ended up airborne with a 6 inch column of fuel on fire pouring out of the wing, and many other incidents where fires don't give you that time. So, you have an engine fire, do you do the classic, or do you leave flap alone, 80 degree course reversal, and land reciprocal as soon as poss? We are all coming round to the thought now that with a fire, every minute you save could save you.

(Please! ONLY experienced large jet jockeys PURRLEASE! Or clearly state you are not if you have to interject).

In case of ongoing fire in VMC stop climb in Acc Alt and depending on the airport layout make visual on fastest available rwy

IMC = radar vectors for fastest available ils again depending on airport layout e.g. crossing rwy

Everything prepared in fmc and setup wise and briefed in t/o emergency briefing

Hi,

Boeing asks you to be so kind to stop takeoff below V1 for an engine fire. Is it a real fire ? You will discover it later on. If you stop take off above V1 then this is not correct. But you already know that a few knots before V1 you will probably end up by rejecting above that speed, especially if it is the fourth leg of the day by night. Next time you go in the sim try to reject within 5 - 6 knots from V1. Do it 10 times and try to get some statistics from that.:ok:

Bye.

Rainboe - If I got a fire on the -400 after V1 I'd pull the gear up, leave the flaps where they are and thus keep the speed down for a tight circuit or course reversal, depending on airport. Minimum time in the air being the aim.

All sim training focuses on doing it properly, and in good time: climb straight ahead, handle the immediate emergency, continue, retract flaps no turning, then think about returning on one, with a very long downwind leg to fly. I agree an early return is needed, but I'm not sure you have that long. Maybe an 80 degree low altitude course reversal/land back on reciprocal, on one engine might be pushing one's luck a bit, but I think there is a case for training: 'get this sucker back on the ground as soon as possible- no! That's too long!'. In other words, a very rapid, immediate low level emergency circuit. Perhaps even briefing before take-off whether another cross runway is even quicker. But we are not trained to even think like that, and do it in the sim and you will be hammered. But I would far rather get back on terra-firma and hand it to beefy firemen than try and heroically deal with it in the air, then land.