one question about the 737 aborted take off

[citizensun]

hi all, could anyone tell me that during take off, the speed is between 80kts and V1, a engine overheat light and master caution light illuminates, what will u do, abort or continue the taking off?
thanks a lots~
:D:D:D

[punk666]

QRH says abort the take off if any of the following conditions occur after 80kts prior to V1.

1. Engine failure
2. Engine fire
3. predictive windshear
4. The aircraft is unsafe to fly.

[capt. solipsist]

let's put that into certain scenarios:

warning at 100kts, you reject.

very long runway, you reject.

around 10kts to V1, runway not as long, you can continue, sort out the thing at 400ft (mostly retard T/L) and return to land w the whole length of the runway avbl to you.

you can add more scenarios to that.

lesson is, safer to continue the takeoff and come back for a landing rather than betting on being able to stop w/in the ASDA w high energy and w/o any other incident (ex: blown tires)

[Eff Oh]

Continue. After 80kts and prior to V1, the Boeing QRH states that you should reject the takeoff for the reasons stated by Punk666 above. Except it states "fire or fire warning" that statement is not engine specific. In other words it could be an APU, cargo or other fire warning. As an engine overheat does not fall within any of these categories, then you continue.

[citizensun]

thank you punk666~
here then comes my cofusion, is a engine overheat is a kind of unsafe situation for the flight?
according to the QRH refers to the engine overheat , it`s a memorized checklist: disengage the A/T ,reduce the throttle, if the overheat light does not extinguish, then perform the engine fire severe damage or seperated checklist. so I am thinking if you don`t retard the throttle back during take off ,is there any protential for a engine fire or something（that is a NO GO situation)?
then what is the correct decision for this situation?

[citizensun]

thanks capt. solipsist, your idea is quite inspring~
thank you all~~:D:D:D

[Checkboard]

The idea is that the risk of the overheat developing into a fire - and that fire giving you any real problem (ie loss of thrust) is less than the risk of skidding off the end of the runway in a high speed abort.

With modern, pod-mounted engines, an engine fire without a catastrophic failure (which you would abort for) isn't a great risk.

Besides - keep going and you make the local news! :ok:

[Denti]

It could develop into an engine fire, however it is not a reason for an aborted take off and no action to be done below 400ft.

Aborting a take off because something could happen is a recipe for disaster, we only abort a take off because something did happen (one of the 4 cases posted above).

[citizensun]

hoho~~
thanks checkboard,
i dont want to show up on the newspaper~~
here comes my another question during take off for you guys: between 80kts and V1, one of the cabin door open light illuminates and definately the master light will turned on, are you going to continue or abort?

[Checkboard]

It's pretty unlikely, but continue - definitely. An open door doesn't make the aircraft un-flyable.

[citizensun]

well , if one of the door is opened, and you continued, a pax was suck out of the cabin in the air and :\. after this happened, someone will ask you why didn`t you abort. i know the door open light most of the time is a faulse alert, but what if it`s really opened, do you think it`s a great risk?

[N1 Limit]

Part of the take-off briefing says:
We'll abort for any Master caution below 80 knots,after 80 knots we'll abort only for engine fire,failure or loss of directional control.

[lomapaseo]

well , if one of the door is opened, and you continued, a pax was suck out of the cabin in the air and http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/wibble.gif. after this happened, someone will ask you why didn`t you abort. i know the door open light most of the time is a faulse alert, but what if it`s really opened, do you think it`s a great risk?



Somebody will always ask afterwards, "what if"

You can't go wrong if you protect the aircraft first. It's sure to save more lives that way.

[AirRabbit]

well , if one of the door is opened, and you continued, a pax was suck out of the cabin in the air and . after this happened, someone will ask you why didn`t you abort. i know the door open light most of the time is a faulse alert, but what if it`s really opened, do you think it`s a great risk?
The only way anyone or anything would be "sucked" out of the cabin would be if the differential pressure were great enough to do that. The cabin pressure and the outside pressure during takeoff are almost identical. In fact, it is rumored that airplane training flights were sometimes flown with the windows open in the cockpit, some of the time in the summer. Of course, I couldn't verify that as being true, but there ARE those rumors.

[citizensun]

thank you all for your helps!
and i have one more question:)(endless qyestions)
recently,our company had two rejected take-offs,the cause was take off configuration warning at speed of 75kts and 90kts, they all rejected.
what`s your opinions then~~
thanks ~~

[ImbracableCrunk]

How did they get to 90knts and then get a config warning? Trimming during the roll?

[citizensun]

yeah,i also doubt about that, the takeoff configuration warning should sound when the TLA is more than 52° and some configurations incorrect,
but it really happened, after the rejected takeoff, they found that all the configuration needed were correct, it`s only a false alarm.
the key question is, are you guys will continue the takeoff or abort when you are not sure the warning is true or not ,even the speed is between 80kts to V1?
i want to know your ideas, very appreciated~~

[RMC]

CS - Nothing wrong with "asking endless questions".
What we are talking about here is point (4) on the Punk666 list "A/c unsafe to fly". Manufacturers put this in to cover product liability claims...it enables them to look at an incorrect RTO decision after the event and blame the pilot.
To be fair it is not realistic for Boeing or anyone else to provide an exhaustive list because the crux of the matter (as Capt Solipist pointed out) is that it is situational.
Yes there are a lot of clear rights and wrongs....obvious gos or no gos...but there is also a lot of grey in the "unsafe to fly" catch all.
One key element (and there are many) is runway length...if you are taking off from a 3000 metre runway you will typically reach 80 knots in the first 10% -the rate of acceleration slows rapidly as you approach 100 knots.
My view on the scenarios you mention...
(i) Engine overheat - There are people who show relatively little concern for this warning. Bad move - the core section overheat warning triggers at 343 degrees ....this is serious heat (core fire warning is not much higher at 454).
I had to abandoned a take off at Belfast Aldergrove due to an overheat warning...the rate of increase of turbine temp was also seen to be accelerating rapidly (another variable...single or multiple indications). Cause failure of a pipe weld and mass ejection of core air into the nacelle. Even though the thrust levers were retarded immediately the engine temeprature continued to rise during the deceleration and it cooked itself. Senior engineers subsequently advised that if take off thrust had been maintained then in less than a minute the engine would have failed catastrophically.
(ii) Take off config. As has already been said this warning should have gone off as soon as the thrust levers were advanced. If vibration has just taken the the trim slightly out of the take off range no big deal. If the flaps have retracted from 5 to zero and you rotate at flap 5 speeds the aircraft will stall as soon as it leaves ground effect.
(iii) Door open...again it has been said this is not an unsafe to fly condition which would cause a high energy reject on a runway limited take off. If on 3000m strip with 15 knot headwind a door fully opens at 90 knots airspeed....you will feel it on your ears and there will be a yaw. Although in a court of law you may successfully defend continuing the take off (re. point 4) this would be a poor decision....not least because the groundspeed (which is the important number) was only 75 knots.

[citizensun]

RMC,thank you~
i agree with your "Yes there are a lot of clear rights and wrongs....obvious gos or no gos...but there is also a lot of grey in the "unsafe to fly" catch all."
this phrase "unsafe to fly" is quite"grey"
it`s situational~

a proper rejected take off decision is quite difficult, because it`s unexpected, sometime complicated and the time for you to think is really tight!

i think we`d better check the QRH for the max speed for aborted take off with the brake energe acceptable before every flight. to difine another speed sector for the GO and NO GO~

[B777Heavy]

well , if one of the door is opened, and you continued, a pax was suck out of the cabin in the air and . after this happened, someone will ask you why didn`t you abort. i know the door open light most of the time is a faulse alert, but what if it`s really opened, do you think it`s a great risk?

A. What was this hypothetical passenger doing near the door? :}
B. Plug type doors, kinda stay closed even if not "latched", I doubt they will fully open. :ok:

[bArt2]

2. Engine fire


Are you shure that it does not say "ANY FIRE"

To put it in another way, would you continue take-off with a cargo or other fire.

Bart

[bArt2]

well , if one of the door is opened, and you continued, a pax was suck out of the cabin in the air and http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/wibble.gif. after this happened, someone will ask you why didn`t you abort. i know the door open light most of the time is a faulse alert, but what if it`s really opened, do you think it`s a great risk

What if it was just a faulty microswitch that you aborted for, went off the runway for and the aircraft broke appart catching fire and killing 50 people.

Last time I checked the door opened toward the front of the aircraft. I'm pretty shure the 80+ knots of wind will keep it from opening enough for a passenger that is strapped to it's seat to fall out of.

[BOAC]

How did they get to 90knts and then get a config warning? Trimming during the roll? - well, we had 737-200's at LGW in BA that would reliably give you a config warning just before V1/R - faulty reed switches.

Now, what did we brief we would stop for......................................?

[ImbracableCrunk]

A reed switch? Is that what the Queen's English calls a microswitch? :ok:

My QRH says if you hear that intermittent tone, you assure appropriate takeoff configuration. I've always assumed that you'd do that on the roll if you were over 80 knots. If you needed to go from F0 to F25, you might be in a tight spot.

[Oakape]

You would most likely be unable to open the door during the take-off roll. It is a plug type door, which means it has to move in before it can move out. The aircraft is slightly pressurised during the take-off roll, so the chances someone could get it to move in against the pressurisation is slim, if not impossible.

In my experience, a warning light after pressurisation usually means that the handle has moved slightly up - either by vibration or someone playing with it.

[BOAC]

A reed switch? Is that what the Queen's English calls a microswitch? - no. Try Google?My QRH says if you hear that intermittent tone, you assure appropriate takeoff configuration. - if you refer to the 737 I suggest you need to read the whole of the descriptive - and tell us what it says about the warning at 120kts?

[ImbracableCrunk]

If the intermittent warning horn sounds or a
TAKEOFF CONFIG light (if installed and operative)
illuminates on the ground:
Assure correct airplane takeoff configuration.
■ ■ COMPLETE ■ ■

No guidance here in the QRH. I don't have may FCTM here, maybe there's something there.

[VH-ABC]

I am struggling also BOAC, 120kts warning??

[BOAC]

Obviously a 'different' 737 QRH
The intermittent cabin altitude/configuration warning
horn sounds and the TAKEOFF CONFIG lights (if
installed and operative) illuminate on the ground
when advancing the thrust levers to takeoff thrust.VH - it is simple actually - old and dodgy reed switches on the LEDs. Air loads and vibration give 'unlocked' = Config warning @120kts. Had it several times.

[ImbracableCrunk]

So at about 120kts on the roll, the LEDs get pushed into a position where the reed switches sense movement or incorrect config. Interesting. Thanks for the reed switch pointer, too.

Is this a model-specific issue?

[BOAC]

Yes - 'was' - "well, we had 737-200's at LGW"

[ImbracableCrunk]

It'd be nice to have a detailed list of the causes of 737 RTOs. I'm sure there's a list somewhere.

Anyone know if there's one available to us lowly pilots?

[captjns]

Engine overheat??? producing thrust??? no fire indication??? keep going sort it out in the while away from the ground.

[A37575]

Here is one. Not me though. B737-200. While taxiing for departure crew see intermittent flashing of wing body overheat light on one side. It goes out after a while. Capt lines up and briefs F/O if the WBO light comes on before 80 knots he will stop the aircraft. Runway length very limited with no over-run area - just a cliff into the sea.

Aircraft scarps down the runway and 10 knots below V1 master caution and wing body overheat occurs. Captain aborts but forgets speed brake for a few seconds and aircraft stops literally 10 metres from edge of cliff.

After taxi back and shut down, startled F/O (total 500 hours on his log book) asks captain why he aborted when he had briefed he would keep going if problem after 80 knots.

Captain was perfectly truthful and said it was an instant reaction when the Master caution light came on and he could not explain why he made the decision to stop.

It was an interesting and thought provoking statement. The shock of seeing a master caution light coming on at high speed has caused many pilots to abort the take off run when there was no need to. A lightning fast reaction may seem all very professional but could also lead to more problems than it solves. That is why there is wisdom in the manufacturer's recommended standard procedures which are often based on world wide experience gleaned from accidents.

[eez]

regarding the go no go decion during t/o we have a "guideline", but in my opinion there are many factors to be considered (even if rwy tables guarantee...):
-speed
-aircraft weight
-rwy length and conditions
-wind
-crew operational fatigue(time reaction)
-etc.

anyway statistics indicates that after an rto, an overrun may occurs