Incidend during take off in Doha [Archive]

Mr Good Cat

9th Oct 2011, 13:15

they have had engine fail before V1 and despite of that they took off??

Well they possibly made a very good decision then.

V1 is the speed at which the first stopping action must be taken in an RTO... (it most certainly is NOT a decision speed)...

...so, if the failure occurred at 1-2 knots prior to V1 (depending on what certification standards you're dealing with) and there was not enough time to assess the damage then the correct decision was made. No?

Of course none of us know exactly what the circumstances are, so unless we're big-league quarterbacks with monday-morning ball practice let's just refrain from Kangaroo-courting our colleagues and show some respect?:=

MGC

itsbrokenagain

9th Oct 2011, 16:50

Mr Cat, are you sure about that ?

"V1 is the speed at which the first stopping action must be taken in an RTO... (it most certainly is NOT a decision speed)..."

You missed a very key word there is your paraphrase " MAXIMUM ". If you put this word in there correctly you certainly have a decision to make at this point dont you ?

let me take the EASA definition as we are taking bus here, which is pretty much the same as the FAA anyways...

‘V1’ means the maximum speed in the take-off at which the pilot must take the first action (e.g. apply brakes, reduce thrust, deploy speed brakes) to stop the aeroplane within the accelerate-stop distance. V1 also means the minimum speed in the take-off, following a failure of the critical engine at VEF, at which the pilot can continue the take-off and achieve the required height above the take-off surface within the take-off distance.

145qrh

9th Oct 2011, 17:49

Almost correct with V1 speed.

JAR certification gives a 2 second buffer or thinking time in which to start the process of stopping ie brakes/rev etc

FAA if I recall only allows 1 second, although that may have changed.

So if fire bell goes at exactly V1 the perf figures allow for 2 seconds in which to make your decision and start stopping :) , so you will go above V1 and the figures have an allowance built in for this. Not much thinking time I'll grant you but it's there.

It also explains why types certified under grandfather rights have "better" figures than new types.eg 737 has 1 sec , 320 or newer types have 2sec so worse performance on paper but in reality a fraction safer.

Wizofoz

9th Oct 2011, 18:01

145,

Yes, the calculations of V1 include this buffer, but that does not mean it should be used. We always have buffers built into the performance figures, but we then try and not eat into them.

You do not have one or two seconds after V1 to initiate an RTO. If it has not been initiated by V1, the takeoff should be continued unless the aircraft is unflyable.

MGC is correct in saying that a failure close to V1, with insufficient time to react and initiate an RTO before V1, should be taken into the air.

jeff748

9th Oct 2011, 20:57

What about the incident?

GoAround_Flaps20

10th Oct 2011, 03:12

That's the reason why many operators all over the world are using the "V1" callout 5 kts before the calculated V1.

Nice & safe flights!

fatbus

10th Oct 2011, 04:35

What operators around the world are calling V1 early as SOP, I,m sure their regulators would like to know or other Regulators would as well. V1 is V1

FrankR

10th Oct 2011, 06:00

Just curious, but what did the captain brief prior to takeoff regarding engine failure...

Non Zero

10th Oct 2011, 09:00

The FAA is changing the definition of V1 Decision Speed into V1 Action Speed ... if you didn't start any actions (reject take-off maneuver) before V1, it is safer to threat whatever you have as an in-flight emergency!

devilavocado

10th Oct 2011, 09:20

I believe this is the old case which has happened one or two months ago.It was not typical engine failure, it was power lost at 80-90 kts.
Most probably we will learn about that situation in next flight safety bulletin.

bettigio

10th Oct 2011, 15:39

Any failure before V1 is a STOP or GO.
If they decided to continue take off still is a good and safe choice.

Landflap

10th Oct 2011, 18:34

Good grief ! What are they teaching you kids today. My present company SOP briefing could not be clearer. " Up to 80 kts I will CONSIDER stopping for anything. Between 80 & V1, I WILL stop ONLY for an Engine FIRE, FAILURE , Thrust reverser deploy or ANY other failure which affects the flying quality of the aircraft. Oh & yeah, nearly all of us are calling V1 at V1-5..............pretty bog standard throughout the industry. Question bubbles at or slightly before V1 really worries me.

blusky75

10th Oct 2011, 23:26

BETTIGIO...are u serious? ANY failure before V1 stop or go???

I think that "before V1 for eng fire, eng failure, or aircraft unable to fly the Aircraft must be STOPPED"....if other master caution it is for sure safer to continue..."

if they had an ENG FAILURE Before V1...even if there is not much time to UNDERSTAND WHAT KIND OF FAILURE u can understand that 1 eng has gone ..so ABORT t.off....

anyway as someone said who knows what conditions they ahd that they...:ok:

Landflap

11th Oct 2011, 08:40

Blusky 75, well said. One of the few on this thread who seems to know what he is talking about. 'Sittingidly' adopts his familiar attack frame of mind which worries me even more than the other contributers. "credibility" ? Good grief man. I wonder who are the Trolls and who are the Professionals and who are the Ameteurs. Be reminded, lots of people who are not pilots read these forums. I can see them reaching for the ticket cancellation option when reading some of this nonsense. For the real professional pilots out there, no need for reminding you what to do before V1 and what to do after V1. 'Sittingidly' , over to you for your customary English Language lessons, spell checks, off thread persuasion etc etc; Yawn Yawn !

Farrell

12th Oct 2011, 05:34

...we are actually duped into the mindset of criticizing our fellow pilots before we even know the facts? Management really has won the battle, much to the detriment of flight safety.

Should be written in stone above the crew-room door.

bettigio

12th Oct 2011, 06:18

Blusky 75: Yes I'm serious: "Any failure before V1 is a STOP or GO decision.
Now off course depending on the failure and the speed which may occur I will decide what to do.
I will reject for anything below 100 kts for sure, no doubt.
I will reject above 100 kts and before V1 only for severe malfunctions such as engine fire, engine failure, loss of control or anything I decide it's better to stay on ground.
Exactly at the V1 I will continue for sure, no matter what.
"An engine on fire still is an engine giving thrust" :ok:
Happy flights.

B737NG

12th Oct 2011, 07:48

Did they return ? after dumping fuel ? What was the title of this thread again ?

I love KIS, Keep It Simple, for the Bobby Drivers and as described lovely from a Colleague of mine who got accused to be a POW Veteran: Before 80 kts, between 80 kts and V1, before or at V1, the Criterias are outlined and cristal clear, after V1. The Bus Drivers hear 100 kts and next call is V1.... clear shot as well.

There is no time / space for personal preference as V1 -5 or other hobbies when it comes to the distance / speed / time critical subject.

In real life when the day comes why you are paid for and you stop on the paved surface after the bell rings, (better to hear after listening to the CVR), determination and conclusion would be: Good Boy / Girl, you end up with the Nose Wheel in the Mud: Bad Boy / Girl.

Never think your Fleet Manager, Chief Pilot or other Desk Fliers will protect you because of skidded over a Banana Leaf or something else, fact is you are in the Spot Light and you create a shadow. You have to face uncomfortable questions and also accusations. Suddenly you are the only one who then realises that you are on your own and defense is not that easy done in such cases. You have had a "split second" to decide, the Desk Flier has hours, even day´s, to read and repeat the action that should have been taken and if it is not the same you have choosen in the split second you have to face the cold wind first.

Remember if, God forbidd, you ever have such an event: Everything you state afterwards can and WILL be used against you, from all involved. The Manufacturer will not take any responsibility if he can avoid that. The Airline will not take the blame either, the Insurance Company is also interested to find if they can send the Bill off to the Airport maybe and finaly the Authority is happy to put the blame on someone else then themselves. So be aware that the "bad card" is handed around and the last in the chain got bitten.

Fly safe and land happy

NG

Landflap

12th Oct 2011, 08:08

B737NG, terrific post. My faith, slowly being restored. And those of us who do not fly "the bus"....geees, what is that (?) the number 31 to Hammersmith ? According to one, we are irrelevent. We do not get that auto call on my Boeing so, I would say, everything helps. V1-5 is a real concentrator for me. "Bettigio", my hero training Captain at Seattle once reminded me that a jet engine is ALWAYS on fire..............c'mon, relaxed me a little. Safe flying chaps.

WELCO

12th Oct 2011, 20:12

I would have been absolutely pleased of this discussion if this thread was based on FACTS from the incident that has happened during that particular day and that particular flight from Doha! But with all my respect to the contributors here, you just don't know what were the events that have led to the crew decision!

I'm sure that many of you here are speaking out based on the superior knowledge and superior skills as superior pilots. But how relevant is that if you cannot construct the factors together and come up with a definite conclusion?

What is shocking though, is to see the great variation in opinions about handling RTO,s and making the Go/No-Go decision!

dimsum88

14th Oct 2011, 16:06

One of the facts: It was engine stall at 90kts.
Something interesting: TM did test flight next day and he had the same problem and he continued T/O for purpose of test. Same again: engine stall,engine over limit etc...
Returned safely to Doha.
( I know it is hardly to believe)!

Swansafa

14th Oct 2011, 17:21

Landflap, calling V1 at minus 5kts??? Why not simply operate the aircraft as it was designed to be operated and as you were trained (supposedly) to operate it?

If you can't operate to the intent of the V1 concept, then you might be better off in a different career.

I hope you're not teaching other pilots to operate like that.

Landflap

15th Oct 2011, 08:46

Mmmmmm, Sittingidly. A right old rant pulling off thread too. Good Troll though. What I will comment on before I hit the ignore button is this; "UK pilots like yourself".."Condescending pricks like itself".presumably, you meant, 'like YOURSELF' ! Geees, glad to be a Uk imperialist . At least we can write correctly. And then you claim membership by referring to "fewllow pilots" ! Doubt you have admission to this very special club when you burst into flames at the slightest cause. Back to thread though, the other guy referring to V1-5 as the "call". We have done that for years, because, dear kids, by the time you say "V1".er, you will be AT V1. Point, obviously escaping you chappies. Now, I am back to being seriously worried about you fellas in the sandpit. ER, V1. Should I stay or should I go?. V1-5, no, minus 10, er no, plus 6, er no v2 minus 8 Aaaaagh. What was that ? Bang, no, thrust reduction, no engine exceeed.whaaaat? Who's in the bath ? No one, .STOP.NO, GO.......... Aaaaaaagh. Lets call it ABANDON again..NO NO NO, STOPANDON........ Good grief. Good luck Ladies, you really are going to need loadsa that stuff. OOOOOps, sorry Pprune English Language Masters; I meant, "loads of "............... ! Blimey , what a daft bunch.

punkalouver

15th Oct 2011, 11:26

Keep in mind that the VMCG was not determined with the big crosswind that you are now experiencing on this particular takeoff. Your real VMCG may be higher or lower depending on the direction of wind combined with the side of the failed engine.

Microburst2002

1st Nov 2011, 17:23

Someone asked, and I want to know, too

What the hell did they brief?

What do they brief every day?

If they brief that engine fail is STOP (before V1) then they should have stopped.

Do as briefed, unless circumstances are special. If circumstances are special, make decision and good luck.

Doha is kind of looong, isn't it?

wadefac

3rd Nov 2011, 00:20

Would be really funny if this incident was just a "rumour" annd never really happened..... :oh:

slowjet

3rd Nov 2011, 09:09

Got Sittingidly well & truly riled though.Customary vitreol from a poor contributor. We too cal "V1" at V1-5. Done that for the last twenty years. No-one "made it up". We call it 'AIRMANSHIP'.

Patty747400

3rd Nov 2011, 11:07

Slowjet

Do you call "minimum" at DH plus 20 feet?

I agree with you that getting closer to V1 I'm more and more in "GO" mode and on a slippery runway I'd probably made a "GO" decision already at V1 -5. Absolutely nothing wrong with that.

However, I still think that V1 should be called at V1. Om my fleet we have some aircraft with automatic V1 call and some without. Would be really pissed off if the FO called V1 early to be followed by another V1 at the actual V1.

But, if everyone in your company do this as a result of your SOP:s then I guess it's just another way of skinning the cat...

Black Pudding

3rd Nov 2011, 19:12

So you think calling V1 -5 and taking a fire into the air is a good idea then. Idiots

V1 is V1

White Knight

3rd Nov 2011, 21:40

LandFlap and WK were probably sitting at the front of the class congratulating the instructors

SI;Does the phrase...

... are c*nt what silly you a ?... ring any bells?????????????????????

gdukkoq

3rd Nov 2011, 22:17

Usually brief, any failure before (70 or 100knts depending on type) abort, between (70 - 100knts) and V1 any red lights abort otherwize GO and after V1 GO.
But then again depending on the situation specific of the day you should brief accordingly.

slowjet

4th Nov 2011, 17:00

Sittingidly, I can see why you call yourself that. Get a life . Well, to your opening statement; did I say that ?? NO. Not only are you unable to understand , or write , or speak English, it will come as no surprise that you have little comprehension of anything significant to these open forums. A call of V1 at the V1-5 IS SOP in my company and HAS been for the last 20 years ! Read it again, sittingidley, stop slurping the fave juice, stop smokin de pot man (that is Caribbean, by the way) and get your PPL notes ready for your next re-try !Stop trolling your way through the professional forums because we see through you. Now look, sitting.....idley....get it ? Most of us have....we have put your toys back in the pram & Mummy says she will give you a cuddle.Bless, it's ok. C'mon. Cuddle Daddy. You can do it. Pull the stick back, the houses get smaller.....push the stick forward...c'mon .Sittingidley.what will happen ?? Nah, no hope. A wanabee................there is a forum for you. A wanabee English Gent...............NAH (that means NO, by the way), back to Oz or SA or Zim...or.....could it even be de jungle (that means, THE jungle)..oh, why do I bother ? I have faith. Sittingidley might, one day, get his PPL.......NAH (that means NO) !.....Excellent troll though.....I will give you that. For the real pro's (can we hear from some ?) Up to V1.STOP. After V1.GO...............Gawd (Sittingidley, that means.GOD ). Damn. I am enjoying this, Much to Sittingidley's hate.yes, buddy (that means, DUDE,or PALL, or whatever) I was PRESIDENT of my debating society when at Oxford. Oooooooh, eat your heart out (that is a university in the English Kingdom).......c'mon clown, opposite rudder..............Ok. I give up ! "God save the Queen".well, where you come from, that probably means, ..."God save the Sky Chef"..ooooooh, B...h !

newday

5th Nov 2011, 05:58

Slow, do not sabotage this post any more,please. And by the way, you should check your mental health, for sure!

slowjet

5th Nov 2011, 10:08

I think SI did that with his pure vitreol & vicious swipes at many posters. I did fall for his troll & congratulated him for that. Quite sportingly, I feel. The original Poster asked for details of the incident. Are we any closer ?

Black Pudding

6th Nov 2011, 11:26

So clowns, you would be happy to call V1 5 kts early and take a fire into the air. How bad is that ?

gdukkoq

6th Nov 2011, 12:42

:D :D :D :D

slowjet

6th Nov 2011, 13:55

Sittingidley, nice courteous post, so, I will respond. As a Line pilot, I always respected SOP however daft I might have thought some things were. For example, I flew 757 with one operator and the final flap call after take-off on cleaning up was "Flaps up".With a new Operator, same aircraft, the call was "Flaps IN". As new joiners, we were told that this came from the DFO himself & he took it all, dearly to heart. Call "Flaps UP" and one could expect a roasting. I thought it was all a bit silly but adopted to my new employers SOP. My early years on slow accelerating aircraft meant that conversion to high speed, heavy jets where things started to change rapidly, caused heavy reliance on my piers who, simply, knew better. A call of "V1" at V1-5 kts was something I, too, quieried but was quickly advised that by the time you say "V1", you will be there. Please, let us not, now, descend into huge debate about how it might depend on accents, quickness of speech etc . It just made good sense & I did it, because it was SOP & as a Trainer,now, I continue to teach it, not only because not only does it still make sense but it is still SOP in my company. Notice, SI, note how a follow on poster refers to us as "Clowns"....back off & have a go at him now please. Thanks a lot.

White Knight

7th Nov 2011, 18:16

So clowns, you wuld be happy to call V1 5 kts early and take a fire into the air. How bad is that ?

It's pretty bad... And could be very ugly too:hmm::hmm::hmm:

Better listen to SI though... He's good! Very very good....

....at talking BS:\:):D

Landflap

8th Nov 2011, 08:14

WK, agreed. Very much on your team here & I think Slowjet will sign up too. Some are simply not for learning, or like Maggie Thatcher, for turning ! Bailing out of this one but before I go, consider this one Sittingidley; Highly esteemed mate of mine, just retired, commented that soon after qualifying on the trident, an incident in Bilbao caused much head scratching. Aircraft entered a very long puddle of water prior to V1 and stopped accelerating. It showed no signs of decelerating but ASI's just, sat there. While heads were scratched and think bubbles emerged, lots of runway was being eaten up ! "Should I stay or should I go" springs to mind again. Theoretically, there was now insufficient runway to stop & insufficient to accelerate to VR & continue with all the V2, climb protection theory either ! Big grey area now hovering round that magical V1 stuff, don't you think SI ? Finally, before I grab the eject handle on this one,BACK TO THE THREAD PLEASE !! Does anyone know what happened at Doha (the start of the thread) ??

WELCO

8th Nov 2011, 10:18

Does anyone know what happened at Doha (the start of the thread) ??

1 million dollar question?!:suspect:

gdukkoq

8th Nov 2011, 16:56

There goes you just said it yourself and it is not most it is all manufacturers and almost all SOP.
By the way what happen about this incident :E any lead people ? Someone must know something! :{

Flyer1015

9th Nov 2011, 01:37

The problem with calling V1 at V1 is that if a moment before V1 there IS an issue, by the time your brain processes the information and action taken by reducing the throttles to idle, you will be in a situation that you are above V1 by the time the abort is initiated. Now all the data goes out the window and you can bet the final report will state that pilot aborted above V1.

That's why MANY carriers throughout the world have a practice of calling V1 at V1-5 kts. By doing this, you are reducing that window of decision making at highspeed to be in your favor. If in those 5 knots something DOES happen, by the time you process it and decide, you will be above V1.

There have been far too many accidents with high speed aborts, and the majority of times, taking off and coming back around would have resulted in a better result.

So clowns, you would be happy to call V1 5 kts early and take a fire into the air. How bad is that ?
By the time your aural nerve processes the master warning, your eyes send the signal to your brain for an engine fire, your brain processes the signal to the hand to pull the throttles back to abort, you will be above V1. Take your life experiences in flying for what you will, but if I have a single engine fire at V1 - 5kts, we're taking off.

Flyer1015

9th Nov 2011, 01:40

And for those interested in high speed aborts near V1, look up the Columbia SC Learjet accident in 2008. Near V1 some of the main tires blew out. The FO, much more experienced than the CA in this case, instintively called out "Go, Go GO!" and the CA, much younger and lower time in experience, said "what have we got?" "uh, go?" "no" By the time the abort was initiated, they were FAR above V1. Of course, didn't help the thrust reverser squat switch was taken out by the tire rubber shrapnel, and pulling the TRs out actually resulted in forward thrust, killing all but two onboard.

Wizofoz

9th Nov 2011, 03:19

The problem with calling V1 at V1 is that if a moment before V1 there IS an issue, by the time your brain processes the information and action taken by reducing the throttles to idle, you will be in a situation that you are above V1 by the time the abort is initiated. Now all the data goes out the window and you can bet the final report will state that pilot aborted above V1.

V1 calculations take this into consideration.

There is sufficient time to recognize and take the first action of an RTO built into V1, such that you may in fact slightly exceed it during the actions, but still have sufficient runway to stop.

Similarly you may have a failure BEFORE V1, but with insufficient time to start the RTO, and still have enough runway to accelerate to Vr and achieve 35ft over the far threshold.

Being able to react within those time buffers is a skill required to pass your type rating.

Put it this way- if you are going to call V1 5 knots early, why not BUG a speed 5 knots slower and call THAT V1?

Well, the speed we calculate as V1 effectively does just this. Even on what we calculate as a perfectly balanced field, there is "Fat" on either side of V1 for a late RTO decision, or an early lack of detection and "Go" decision.

Adding fat to the fat doesn't make a lot of sense, as you are now in no-mans land. Do you KNOW you can make Vr before the end of the runway if you make an early "Go" decision?

Your Learjet example was an example of not achieving a timely or correct decision- firstly because "Go" is the recommended decision if you lose tires (as you also lose braking ability) and "What have we got" is not an appropriate question at any time during a takeoff roll!!

Where they between V1-5 and V1 when the tires blew?

gdukkoq

9th Nov 2011, 03:20

That is why you only abort for a few major failure at high speed, indeed you brief it if it's above 70knts or 100knts. We brief any red lights and lost of directional control. Otherwize GO!

mutt

9th Nov 2011, 08:58

Sittingidly, where are you getting 5 Seconds from?

If you call V1 early and something nasty happens in those 5 seconds, and you continue the takeoff

At that stage in a takeoff you are accelerating at approx 7kts per second, so the concept is that as you finish saying V1, you will have reached that speed. During training in Seattle, Boeing told us that Lufthansa had introduced this procedure.

Mutt

Wizofoz

9th Nov 2011, 14:13

7kts/s = 3.6m/2^2 = a little over 1/3g, so no, nothing neck-snapping.

gdukkoq

9th Nov 2011, 15:04

7knts/sec :confused: so 420knts/min... :cool: anyway this threat has turn to a real smart ass conversation. :D

Wizofoz

9th Nov 2011, 17:49

At that stage in a takeoff you are accelerating at approx 7kts per second per second, so the concept is that as you finish saying V1, you will have reached that speed. During training in Seattle, Boeing told us that Lufthansa had introduced this procedure.

That's reasonable enough but, tell me, when is the Auto Call Out the Boeing installs triggered?

Surely if the manufacturer wanted the V1 call to start prior to the speed, it would have installed a device that did just that?

Fact is, I doubt the second or so difference 5 knots is going to make would ever be the difference between success or failure.

THR CLB OP CLB

10th Nov 2011, 10:04

Fack5:

You are correct in pointing out that 7kts/s/s represent

an increase in the rate of acceleration

However, I would presume the second '/s' was simply a typo.

You'll notice Wizofoz made the same assumption and correctly converted a 7kts/s (ie nautical mile/second/second) acceleration into a meter/second/second acceleration. Comparing this to 9.8 m/s^2, the acceleration due to earths gravity (ie 1g), I tend to agree with the statement that

a little over 1/3g, so no, nothing neck-snapping.

mutt

10th Nov 2011, 11:07

Mea Culpa.....:\:\:\:\ Iphone finger trouble...

Wizofoz & THR CLB OP CLB, thank you for the translation. :ok:

Mutt

Kernow 101

10th Nov 2011, 12:01

WOW, 65 posts and only 2 relate to the actual incident!! got to be a new record!! Mods are doing a great job :D:D:D:D:D:D:D:D:D
Why has this not been moved to 'tech log':uhoh::confused::uhoh:

Wizofoz

10th Nov 2011, 21:33

Fact,

I see where you're coming from, yes I assumed (and did my figures) based on Knots/sec (thanks TCOC, It would be NM/hr/s in fact!!)

Yes, DELTA acceleration of 7kts/s/s would be pretty spectacular, and achievable only by the after burning vesion of the GE-90!!!!

Still, as all I did was turn the figures into what the poster originally meant, do you really think the derogatory comment was necessary?

Mutt,

No probs!

THR CLB OP CLB

11th Nov 2011, 15:59

It would be NM/hr/s in fact!!

Oops! :rolleyes: You're right.

As for the alleged incident: The lack of posts providing insight and details to the even suggests perhaps this was a rumour, and nothing but.

Flyer1015

11th Nov 2011, 23:50

V1 calculations take this into consideration.

There is sufficient time to recognize and take the first action of an RTO built into V1, such that you may in fact slightly exceed it during the actions, but still have sufficient runway to stop.

Similarly you may have a failure BEFORE V1, but with insufficient time to start the RTO, and still have enough runway to accelerate to Vr and achieve 35ft over the far threshold.

Being able to react within those time buffers is a skill required to pass your type rating.

Put it this way- if you are going to call V1 5 knots early, why not BUG a speed 5 knots slower and call THAT V1?

Well, the speed we calculate as V1 effectively does just this. Even on what we calculate as a perfectly balanced field, there is "Fat" on either side of V1 for a late RTO decision, or an early lack of detection and "Go" decision.

Adding fat to the fat doesn't make a lot of sense, as you are now in no-mans land. Do you KNOW you can make Vr before the end of the runway if you make an early "Go" decision?

Your Learjet example was an example of not achieving a timely or correct decision- firstly because "Go" is the recommended decision if you lose tires (as you also lose braking ability) and "What have we got" is not an appropriate question at any time during a takeoff roll!!

Where they between V1-5 and V1 when the tires blew?

:=

"Built in" , but no specific numbers and guidance on exactly how much it's built in. Our book specifically states that by latest at V1, you have to take the first action (throttles to idle) and brake. Anything other than that, the NTSB will make note, and the media will drag you, your name, and your family, to hell.

It's amazing how many are contemplating a high speed abort and justifying it that it is okay and stoppable as long as I pull the power back a hair after V1. Not sure what your book states, but ours has constantly changed when they learned that pilots will abort for stupid reasons. They even took out "master warning" as a reason for abort. Now the only criteria is "the preception that the aircraft is UNABLE or UNSAFE to fly." Some people really need to think deep and hard about that. In my particular airplane, there isn't a single master caution I'd abort for in the highspeed regime. As for Master warnings, I wouldn't abort for one in the V1-5knot regime. As for your suggestion of bugging V1 to V1-5, I would say leave V1 as V1. Problem is when you bug a speed, people take that speed as the new measure and act accordingly for callouts. For example, for landing, we used to bug Vref "+ factor" during gusty winds, factor would be +5 knots. If landing speed was Vref 140, then 145 would be bugged with the factor. But what FOQA found for the most part, people would always stay a little above the speed bug during gusty winds. One runway overrun incident later, the procedure was changed to just "bug Vref" and fly up to 5 kts faster if necessary but cross over runway at vref.

Wizofoz

12th Nov 2011, 05:50

"Built in" , but no specific numbers and guidance on exactly how much it's built in. Our book specifically states that by latest at V1, you have to take the first action (throttles to idle) and brake. Anything other than that, the NTSB will make note, and the media will drag you, your name, and your family, to hell.

There are in fact very specific numbers buit in,and the guidance is exactley as you state-you must be able to perform the first action of the RTO by V1 or continue. I don't think anyone is suggesting otherwise.

But, similarly, if you take an Engine Failure into the air, having detected the failure sufficiently early to initiate by V1, you are now eating into the safety factors in THAT side of your performance.

Out of interest, how often do you have a performance limited Take-off in your operation? If you are well below performance limited RTOW, you may well be confident you can achieve the necessary performance. When field length limited, remember it's only 35ft over the end of the clear way, and 15 when it's wet!

Flyer1015

13th Nov 2011, 04:43

Sitting ildly,

"It is a critical call. "

And you are right. It is! But imagine this scenario. Your V1 is 140. At 138 knots, you have a master warning for an engine fire. Both you and the FO will undoubtly take at least a quick peak at the screen to see the failure. By that time, you will be already above V1. Your initial action of pulling the throttles back will come 'late' as defined by NOT having them pulled by 140 knots (V1) in your case.

The closer you get to the V1 value itself, the less time you have to decide and initiate the abort. That is again why many carriers have you call out V1 at V1 - 5kts. That is a good value in which if you catch your engine fire at 134 knots, there's a good chance you can have the throttles to idle by 140 knots (V1) and now be "legal" (at least on paper) to stop.

Anyone entertaining a stop at V1 needs to keep in mind the law of kinetic energy. It is equal to mass times velocity squared. Your energy increases at the square value of your speed. That graph shoots off the charts at high speed values. You better have pulled the throttles back at V1 and not a knot late. There is what's written on paper, and then there's real world as you watch the runway go right by you as you attempt to stop. A RJ crew tried a high speed abort on a 6,300 ft runway. EMAS saved them. Otherwise, had that not been there, they would have been a smoking hole at the bottom of a cliff.

Sciolistes

13th Nov 2011, 08:51

When a pilot adds his personal preference of making the call 5kts early, then either he has decided to use that number as a standard, regardless of acceleration rates, or he is hopefully following company SOP's. If not, then he is performing an action which is critical, in the wrong manner.
I have never come across any document that says we should call V1 early or even anything that says it is allowable.
Absolutely! Vef is assumed to be 2 secs before V1. Calling V1 too early means committing to continue with an event after that and may invalidate your OEI performance and subsequently risk your obstacle clearance too - strictly speaking we only have 35' to play with!