V1 question

['round midnight]

Ppruners with a penchant for performance related questions, this is one is for you...

This hypothetical V1 question is being asked by a reputable company to prospective candidates, and I am interested in knowing what you think -(I appreciate that the company in question is more likely to be interested in the factors and issues raised by the question than a definitive answer):

(Credit goes to to Ppruner 'flyingmogul' for raising it first)

'Which is better: failure 10 kts before V1 and continue T.O or failure 10 kts after V1 and abort T.O?'

No assumptions are made or given, so please feel free to elaborate on your answers and vary the variables either way (e.g wet runway, dry runway , high Vmcg, balanced field, 2/3/4 eng. aircraft etc...)

Answers on a postcard...

'round midnight.

[santiago15]

'Which is better: failure 10 kts before V1 and continue T.O or failure 10 kts after V1 and abort T.O?'

Good one. It would as you say, depend on a number of variables; are you obstacle limited brings to mind. However, given that lots of companies reduce V1 by 10 kts if the runway is wet, surely from a dry runway V1-10kts would get you airborne - assuming a failure at V1 - albeit reducing the screen height to 15'?

S15

[hetfield]

Which failure?

[Dan Winterland]

Depends. In simple terms you need to know what Vgo and Vstop are to make a decision. If say for example you are at MRTOW on a balanced field, then Vstop will equal Vgo and you will have a smjall margin in which to make your decision and neither will be correct. If taking off at a lower weight then these speeds will change - but by how much? And remember that V1 should not be below Vmcg.

[Centaurus]

It is a general and vague question so the general and vague answer is keep going if 10 knots below V1.

[OverRun]

Some of the answers for the V1-10 case are in the threads:
http://www.pprune.org/forums/showthread.php?p=2470374
and
http://www.pprune.org/forums/showthread.php?t=148251

[Old Smokey]

Question - "'Which is better: failure 10 kts before V1 and continue T.O or failure 10 kts after V1 and abort T.O?"

Answer - NEITHER

Assuming that you were in a Balanced Field situation where Accelerate-Stop and Obstacle limits are equal, reject from V1+10 would inevitabely result in an overrun. For a dry field you will have the small bonus of reverse thrust being available, but this would probably be insufficient to dissipate the additional 10 knots of kinetic energy.

For the continued Takeoff from engine failure at V2-10 you MIGHT get away with it, as the margins for the continued takeoff are somewhat better, BUT, what if the original V1 was Vmcg limited and you're now attempting a continued takeoff with inadequate directional control? - You crash. And again, even if not Vmcg limited but field length limited, do you have the performance available to accelerate an extra 10 knots with an engine inoperative from Vef to V2, I doubt it - You crash.

And what of the comment somewhere here that we regularly reduce V1 for Wet runways? True, we do, and apply a usually hefty weight limit to go with it, but, on a dry runway your limiting weights were calculated for the higher V1 - You crash.

And what of the enquiry afterwards (assuming that you survive)? - You crash.

The numbers work, they're well proven, use them properly, know the means by which your aircraft was certified, and don't fiddle with them.

Regards,

Old Smokey

[rhovsquared]

Old smokey: Did you mean V1-10 and not V1+10 knots for a RTO SPD? a little typo I guess.

BTW looking for myself at TODR vs WAT and OEI-Climb gradients vs WAT-assumed from the screen as well as scheduled V1's for particular limiting conditions (first actions initiated BY V1(TL's closed, spoilers up, I assume) and the continued climb one you definitely make it on either side. So checkout various combo's on the WAT curves for yourself they all schedule safe margins.
56% of overruns occur after V1; others times there have been W@Bal errors contributing, and at other times improper handling of aborts. It may be of little help because of the real life startle factor, but all you airlines guy's if you can i would ask if (if extra time remains on the sim) for a V1 cut after EFATO very soon before V1 under WAT limiting conditions; and a WAT limited OEI climb at V2 with EFATO occuring just before V1 so that you will have proven to yourself that the schedules work on either side.When flying small multi's ( about 40 hrs). I have to rely entirely on the performance data and many times one contends with a lot of "grey area" combinations where you can't STOP and can't GO and have to wait until it cools a bit outside:uhoh: Feel grateful for a jet's performance IMHO V1 and V2 sound very comforting.

Oh... I've read Old Smokey's response more carefully, it's just seeing V1+10 cause an involuntary motor-eye reflex.

[oldebloke]

Assuming the limiting runway scenario,at V1+10 YOU crash in an overrun..(if as smokey says the dry brake and reverse thrust don't save you.)
V1-10 one doesn't meet the the 35'screen,but who cares ,
one doesn't meet it anyway on Wet ops(15').
GO man GO....:ok:

[rhovsquared]

to quote one of my prior post

"normally V1 should not be tampered with unless the AFM allows a V1 range either V1 min. For field length limitations (such as when a clearway exist that can be overflown within the TODA and the aircraft meets appropriate screen heights for rwy conditions -ASDA v. ASDR- and obstacle clearance on the first and second segments of the net flight path. and everything is scheduled in the perf. tables or afm or the perf pages of the afm or the FMC. and nothing is overtly limiting ). or pick a V1 max for wat limited or obstacle limited departures where you want to stop as late as possible where field length is obviously not limiting and AOTA)) and as y'all said V1 can never be less than Vmcg cuz you'd drift of the side at high power".

with a small digression added :8

[rhovsquared]

play with this http://www.caa.co.uk/docs/64/DAP_ACD_TYPEA_EGHH.pdf and
thishttp://www.boeing.com/commercial/airports/acaps/767sec3.pdf and
your V1's and oei climb charts and really convince yourself:} 767 choosen randomly to exclude a bias

[Old Smokey]

oldebloke,

Yup, up to a point I agree with you, you might possibly get away with a continued OEI Takeoff from V1-10 and tolerating a much reduced screen height, but what concerns me is that the screen jeight might be zero, that is, you haven't yet become airborne at all. The acceleration from Vef to Vr and V2 is a massive performance demand for any aircraft, particularly the 2 engined aircraft. Nevertheless, the GO decision in these 'odd-ball' circumstances is probably the lesser of 2 evils.

All of these discussions, of course, relate to engine failure, other events such as tyre/tire failure are clear cut GO cases.

If I can harp on about the lower V1's that we accept with a lower screen height for Wet runway cases, it must be remembered that this performance is based upon a lower Takeoff Weight limit, and to apply Wet runway data and procedures to a Takeoff at the higher weights permissible for a Dry runway is very risky business.

rhovsquared,

You make good points, but in FAR25 (and it's equivalents) aircraft rarely operate to the WAT limit, takeoff is usually limited by Accelerate-Stop and/or Obstacle clearance. Certainly, for an aircraft such as the B737 operating from excessively long (say, 3,000M/10,000 ft plus) runways, WAT will probably be the limiting factor, and 'messing with the speeds a bit' probably wouldn't do any harm, no guarantees. Similarly, if the aircraft is meeting the minimum OEI 2nd segment gradients, but no obstacles exist (e.g. over water), then again, you'll probably get away with it, again, no guarantees.

A historian once said that given the choice of living your life with Adolf Hitler or Josef Stalin, you would be living in great danger in either case, but more likely to survive your time with Adolf Hitler. I think that Herr Hitler would favour the GO case from V1-10, and that's about the only time that I'd agree with him.

Regards,

Old Smokey

[oldebloke]

Smokey,remember Boeings reference to this in 84 AIRLINER figure 4 shows the schematic of 'variable decision speeds on the takeoff performance'
to quote the article"It can be seen that a takeoff continuation with an engine failure recognition speed 5 knots below V1 would place a 2 engine at 18' instead of 35' required by regulations.However,an abort decision 5kts above the scheduled V1 would cause the airplane to continue over the end of the runway at a speed between 50 and 72 knots depending on weight..
Boeing go/no go...
At the risk of being cheeky I note your out of Singapore,ergo wouldn't you have the WET info in your AFM...You don't sound convinced of the wet data's 15 screen??
regards:ok:

[Flight Safety]

'Which is better: failure 10 kts before V1 and continue T.O or failure 10 kts after V1 and abort T.O?'

I think this is a weed-out question. If you're silly enough to debate the merits of one over the other, to the point that you start thinking about one of these as a possiblity, they move on to the next candidate.

[Hedncld]

It isn't all that silly. The long and short of it is it's better to continue v1-10 than v1+10 and abort. Because to continue means a screen height of 15 feet or so on the MD-80 (no different then adjusting v1 for contamination) however aborting at v1+10 means going off the end of the runway at 80knts.
At American Airlines they make a big deal of this b/c of the number of high speed aborts. We even have charts to figure the effects of different abort or continue speeds and its effect on the crossing height over the end of the runway.
Just my 2 cents

[Hedncld]

It isn't all that silly. The long and short of it is it's better to continue v1-10 than v1+10 and abort. Because to continue means a screen height of 15 feet or so on the MD-80 (no different then adjusting v1 for contamination) however aborting at v1+10 means going off the end of the runway at 80knts.
At American Airlines they make a big deal of this b/c of the number of high speed aborts. We even have charts to figure the effects of different abort or continue speeds and its effect on the crossing height over the end of the runway.
Just my 2 cents

['round midnight]

Thanks to all for your contributions.

Flightsafety, you make a very valid point and I'm sure we'd all preface our answer by saying that the qustion should be re-phrased 'which is the least reckless course of action, continue V1-10 etc...' then by showing that you undestand the issues raised you can demonstrate some good understanding of Performance A.

[FE Hoppy]

I would counter with the question; what is the limiting factor in the take-off calc? If it was runway or brake limited then of the two bad options go is better. If it was any climb or obst limit then maybe stop. if it was structural then who knows? next question?

[Flight Safety]

Round midnight. I agree.

However consider why anyone would continue with a failure at V1-10? The only way to know if this has a good probability of success with the right conditions, is to plan it ahead of time, but who does this? Without a plan for continuing at V1-10, you can't work all the factors in the few seconds between V1-10 to V1, so there's no way to guarantee a good decision. Nobody is trained to make this particular decision, so if a failure happens at V1-10, there's no training to fall back on except to abort, which is the correct high probability of success decision.

[BGQ]

Going back to the original question, not enough information is provided.

To get the best answer one would need to know whether the takeoff is Accelerate/Stop limited, runway limited or obstacle limited.

Having said that, most airlines are using balanced field performance data and maximum available reduced thrust.

If you were in a 737 on a 12000ft runway with no obstacles if the takeoff path either decision would be okay as you would have enough runway to accelerate to Vr and go or alternatively stop well before the end without seriously hot brakes.

If the same aircraft (on a shorter runway) was using balanced field performance and was accelerate /stop limited it would definitely go off the end in the abort at V1+10. You might reduce the amount of damage if reduce thrust is available as it is not taken into account in stopping performance calculations and would be a bonus.

In the go case your screen height will be reduced from 35ft to 15ft but the aircraft will perform and outclimb any obstacles in the takeoff path. If you were using reduced thrust you have the potential to achieve even greater obstacle clearance by restoring TO/GA thrust.

The better decision in most cases is the go one and that's what your recruiter probably wants to here.


Because a lot of guys ask this question about continuing at speeds significantly below V1 I have run many of these scenarios in the simulator over the years and never seen a failed takeoff attempt from V1 -10. I have seen plenty of overruns from aborts above V1.

I'm also sure that plenty of people have tried single engine takeoffs in the sim for fun.

If it was me being asked the question I would have asked for more info but I am well past the stage of interviewing for new jobs....... I hope. :eek:

[BGQ]

With respect FlightSafety, the question didn't allow the abort at V1-10. The poor candidate gets to answer on the basis of two not so great options.... continuing at V1-10 or stopping at V1+10.

Normal training would have us do the opposite. I suspect the interviewer was trying to see how well the candidate understood the implications of both.

He could have added further complication by suggesting the takeoff was a reduced thrust takeoff on a wet runway where V1 is already reduced by 10kts... so you would be going at V1-20 or stopping on a wet runway at V1+10.

Bet nobody wants me interviewing them for their next job now ! :{

[Old Smokey]

I think that Flight Safety got it right, it's a weed-out question at interview. I was curious why Mutt and John_Tullamarine didn't take a bight at this one, they typically would, but methinks that they saw what Flight Safety saw. Of course, Mr. Gullible (ME) was "In like Flynn". I should have stuck to my original post in this thread (#7) where I said that neither option was acceptable. Such is life.

oldebloke, from one oldie to another, I don't have an aversion to Wet runway data at all, in fact it's essential. What does concern me significantly is the criteria used in determining the data. I've done a lot of flight testing, including RTOs at limiting conditions, and to put it lightly, they're a close run thing. Statictically the RTO produces a far greater number of accidents and serious incidents than does the continued Takeoff case. It's not just a statistical thing, there are very generous performance margins provided for the continued Takeoff case, but precious little for the RTO, and therein lies the root cause of the statistics. The only bonus is that, for dry runways, we have no accounting for reverse thrust. Many pilots place great stock in this, all the roaring and snorting of full reverse seems impressive, but in terms of Accelerate-Stop distance reduction, the bonus is very small, but nevertheless a bonus. The certification for the wet runway consumes in it's entirety the only bonus that we ordinarily have (reverse thrust), leaving us NOTHING. As for the 15 ft screen height, NO, I don't think that it is nearly enough. I know that the 35 ft screen height is simply an arbitrary 'line in the sand' (as John_Tullamarine would put it), but not too bad a 'line in the sand' at that. One regulatory authority to which I prepared and submitted performance data point blank refused to accept the 15 ft data (although legal) insisting upon 35 ft on all occasions. It was the happiest refusal of my career, I relished the additional work to re-do the performance data for 35 ft, with the Regulatory Authority to hold up to the company as the 'bad guys', not me.:E

What really bugs me is when the F/O pulls out the wet runway data for a runway that could only be described as a bit damp. Good manners prevail, but I'm sorely tempted to say "What? You want to take away the only margin that I have?"

Just my thoughts, and as for the Singapore wet runway situation, I would say that we have less wet runway "time' here than elsewhere. It comes down in buckets, makes our runways very wet for an hour or so, and goes away. In some places it just rains aaaallll day:(

Rant over,

Regards,

Old Smokey

[fireflybob]

Would not another factor be the topography of where you are?

I would not want to go off the end at, say, Madeira or Luton (RW 26), where there are "vertical drops" down to the beach or Vauxhalls factory (if it's still there!) but a few feet low at the screen height would not worry me quite to much!

Alternatively some runways have stacks of "emergency distance" beyond the end of the "official" ASDA.

[Jonty]

This developed some discussion on a recent trip to Dalaman.
We decided that the question was nuts as either course of action will result in disaster.
But having said that we reckon that its better to stop at V1+10kts than go at V1-10kts. The reason being that in either case your going off the end of the runway, but if your stopping at V1+10 then at least your slowing down. If your going at V1-10 then your going off the end of the runway with full power and no breaking effect.

[Obscurum per obscurius]

Chaps, RTFQ. The question says FAILURE at V1 +/- 10kts, not action. Since the mid 90s V1 has been redefined, it is no longer a failure speed or a decision speed it is an action speed. Simple!
"The maximum speed in the takeoff at which the pilot must TAKE THE FIRST ACTION to stop the airplane within the accelerate/stop distance.”
Thus any failure must occur some time before V1 for you to safely decide and then take action prior to or at V1.
Of interest the B777 'ENG FAIL' alert on the PFD is inhibited 6 knots before V1, I think those clever chaps at Boeing are trying to tell us something!

[Jonty]

Since the mid 90s V1 has been redefined, it is no longer a failure speed or a decision speed it is an action speed. Simple!
"The maximum speed in the takeoff at which the pilot must TAKE THE FIRST ACTION to stop the airplane within the accelerate/stop distance.”


It also states: "V1 also means the minimum speed in the takeoff, following the failure of an engine at which point the pilot can continue the takeoff and achieve the required hight above the takeoff surface within the takeoff distance"

Also when the AFM is produced all the figures are predicated on a failure 1 second before V1

So to answer the question you need to know the acceleration rate of the aircraft. Which is why its a naff question!

[Obscurum per obscurius]

If the AFM calculations are "predicated on a failure 1 second before V1", then surely that equates to roughly 5-10kts.

I know I wouldn't be able to make the decision AND first action within 10 kts of a rapidly approaching V1.

So the safest option has to be to continue if you have a failure just below V1.

[AirRabbit]

I would very much appreciate it, if any forum member could provide some inputs to the following question:
What would be more dangerous? Engine failure at V1-10 knots and continue or engine failure at V1+10 knots and abort.
Thank you in advance.
This is sorta like the question "What do you do before you land?" Well, there isn't just one answer, and it greatly depends on what assumptions you make as you decide what answer to give.
When I was doing some interesting work with a -10 series DC-9 about a hundred years ago, we made several takeoffs "on one engine." It takes a good deal of nosewheel steering input along with judicial application of the single engine's thrust until the rudder gets aerodynamically effective, but the takeoffs were no problem. Of course we were at the old Clinton-Sherman Air Force Base in Oklahoma, with almost 13,000 feet of concrete and the airplane was at relatively light weight. So, under those circumstances, experiencing an engine failure at V1-10 knots and continuing the takeoff would be no sweat. And, I would suspect that an abort at V1+10 knots wouldn't have been a real sweat either. Now start taking large chunks of runway away from you, jack up the gross weight, and the sweat begins to become more prevalent - all the way down to a balanced field for the conditions. In that scenerio (i.e., balanced field) I'd go with the old addage that its better to stop when you can't stop than to go when you can't go. Of course, I'm sure you could come up with conditions that would turn that upside down as well!
Sorry, I know that doesn't answer your question very well, but that's the nature of such questions. Oh, and by the way, the answer to "What do you do before you land?" -- The answer I gave was "takeoff."

[DOVES]

Thank you AirRabbit!
Now I know! Now I've seen the the light!
Why should I study (after 40 years, 20.000 flying hrs, 4 carriers, 12 type ratings etc.) those silly things (almost a 7000 questions test: I'm becoming a VFR I.P. to honorably and altruistically complete my career) like VMCG, VMCA, Second segment, obstacle limit, Low energy and High energy rejected Take off, and the reasons why we perform them, etc.; when/if YOU tell us that it's possible to take off with a single engine on a twin! (Do you remember a brand new B-747/400 trying to take off from Hong Kong on three, and miserably ending in the lagoon?)
Please Fly Safe
DOVES

[A330AV8R]

Did you say 10 kts after V1 and ABORT T/O ????

:ooh: :confused:

[DOVES]

And now my opinion:
It's better to continue T.O. with a failure 10 kts before V1; with some 'distinguo' in case the failure is an engine one: What's our weight today? is our a balanced T.O.? which the meteo condintions and the rwy contamination? Is the field elevation high? Are there obstacle in the T.O. path?.
Never abort T.O. (10) any single kt(s) after V1 for any reason! (Except of course in case of a locked elevator)
Fly SAFE
DOVE

[AirRabbit]

Thank you AirRabbit!
Now I know! Now I've seen the the light! Why should I study (after 40 years, 20.000 flying hrs, 4 carriers, 12 type ratings etc.) those silly things (almost a 7000 questions test: I'm becoming a VFR I.P. to honorably and altruistically complete my career) like VMCG, VMCA, Second segment, obstacle limit, Low energy and High energy rejected Take off, and the reasons why we perform them, etc.; when/if YOU tell us that it's possible to take off with a single engine on a twin! (Do you remember a brand new B-747/400 trying to take off from Hong Kong on three, and miserably ending in the lagoon?) Please Fly Safe DOVES
:yuk: Excuse me? Well, Doves, when (or if) you get your blood pressure back down below the price of gold (for just a moment) and dial down the sarcasm (just a bit), I'd like to suggest that you go back and re-read what I posted. After doing so, you'll likely see that I was NOT advocating anything close to disregarding aircraft performance. As someone with your experience should know, IF you have enough runway in front of you (as I obviously did in the example I provided) the question asked (should you or can you stop 10 knots past V1 speed; or should you or can you continue if you lose an engine at V1 speed -10 knots) is almost IRRELEVANT! THAT, my very experienced (40 years, 20.000 flying hrs, 4 carriers, 12 type ratings etc.) friend, is what I was pointing out. I sincerely hope that you aren't spring-loaded to such a sarcastic self-serving monologue EVERY time you quickly read something and reach an erroneous conclusion. Remember, sometimes it is wiser to keep one's mouth closed and risk looking like a fool, rather than opening it for confirmation.
:mad:

[SAM 2M]

See AIC 141/1998 Pink

Rejected Take Off - UK Registered Aircraft

[DOVES]

Dear AirRabbit
Perhaps I didn't understand exactly what YOU meant. YOU will pardon me my less than perfect mastery of your language; and that's one of the reasons why I won't sink in a sterile bickering in answering (without opening the mouth) your last aphorism.
YOU wrote:
..."When I was doing some interesting work with a -10 series DC-9 about a hundred years ago, we made several takeoffs "on one engine." It takes a good deal of nosewheel steering input along with judicial application of the single engine's thrust until the rudder gets aerodynamically effective, but the takeoffs were no problem. Of course we were at the old Clinton-Sherman Air Force Base in Oklahoma, with almost 13,000 feet of concrete and the airplane was at relatively light weight. So, under those circumstances, experiencing an engine failure at V1-10 knots and continuing the takeoff would be no sweat. And, I would suspect that an abort at V1+10 knots wouldn't have been a real sweat either."...
Am I right?
1) I would only have justified YOU if YOU were in a simulator. I confess that I was taught the same manoevre in the sim. during my last type rating in the 737-300, almost 4 years ago; the Instructor told us: "Who knows? Some day you could face an emergency situation in which this could be the only escape route". I would even have admired YOU if YOU were doing some test flight, alone on board.
2) ..."So, under those circumstances, experiencing an engine failure at V1-10 knots and continuing the takeoff would be no sweat."...
But YOU forgot to mention which engine failure: the one kept idle 'cause I'm sure YOU would never had taken off with one engine shut down on a twin'; or the other at full thrust; in which case continuing the takeoff to the rotation would have been very very very difficult.
I've always thought that the art of flying is very far from the circus. Fly the numbers, as OLD SMOKEY writes often, and I add: Fly the books.
Perhaps that's the reason why I'm still flying airplanes and not a 6-Drawer Oak Desk.
Fly Safe
DOVE

[earnest]

Can I recommend everyone follows SAM 2M’s lead and reads the relevant AIC. The AIC Sam quotes has recently been superseded by AIC 24/2006, by the way. This document finally lays it all out in, I think, simple and unambiguous terms, and hopefully will lay these arguments to rest, at least in the UK.

http://www.ais.org.uk/aes/pubs/aip/pdf/aic/4P094.PDF (You need to register but it’s free).

A few quotes from the AIC:

2.1 The decision speed (V1) is the highest speed by which the pilot should have made the mental decision to reject the take-off in the event of a relevant failure. Safety margins, in the form of delay times or extra distance on either side of V1, are built into the accelerated-stop distances published in performance data issued in compliance with JAR-OPS 1 and the Air Navigation (General) Regulations.

2.1.1 Thus, considerations of pilot recognition of a failure and reaction in response to that recognition are allowed for.However, V1must be respected as the latest speed by which a decision to stop must have been taken to assure a stopping capability within the distance available on a limiting runway.

2.2 The published accelerated-stop distance makes no allowance for a decision to stop from beyond V1. It follows, therefore, that such a late decision presumes a judgement that a failure, or combination of failures, has occurred such that getting airborne would pose a greater risk than overrunning the end of the runway. On anything close to a limiting runway, the overrun is liable to occur with the aeroplane still travelling at significant speed and to impose a significant risk to the aeroplane and its occupants.

2.3 Some margins are provided in the continued take-off performance in the event of a decision to continue the take-off with an engine failure below V1 but these could be eroded to such an extent that the aeroplane may not be able to lift off by the end of the runway and/or to clear obstacles once airborne. This is particularly so when using a 'wet' V1.

[airamerica]

''Which is better: failure 10 kts before V1 and continue T.O or failure 10 kts after V1 and abort T.O?'’

Simple isn’t it or am I missing something??????

If a reputable company asks this type of question, well ask your self the question why are you being asked this question?

‘’This hypothetical V1 question is being asked by a reputable company to prospective candidates’’.

Two key words to be considered here.

‘’Reputable’’ –how was that status achieved? And the second word-‘’prospective’’- obviously not by hiring ‘’prospective’’ pilots who tend to question the sciences associated behind the rules, especially by pilot extraordinaire’s that perhaps know something that years of testing yielded unfounded results.

Answers are all about justification for following laid down prescribed rules, procedures and regulations, and from a ‘’prospective’’ point of view- hence you are tested on your decision making skills with an own explanation as to why you would choose either.

What a pointless debate.

Oh and safe flying.

[AirRabbit]

Dear AirRabbit
Perhaps I didn't understand exactly what YOU meant. YOU will pardon me my less than perfect mastery of your language; and that's one of the reasons why I won't sink in a sterile bickering in answering (without opening the mouth) your last aphorism.
YOU wrote:
..."When I was doing some interesting work with a -10 series DC-9 about a hundred years ago, we made several takeoffs "on one engine." It takes a good deal of nosewheel steering input along with judicial application of the single engine's thrust until the rudder gets aerodynamically effective, but the takeoffs were no problem. Of course we were at the old Clinton-Sherman Air Force Base in Oklahoma, with almost 13,000 feet of concrete and the airplane was at relatively light weight. So, under those circumstances, experiencing an engine failure at V1-10 knots and continuing the takeoff would be no sweat. And, I would suspect that an abort at V1+10 knots wouldn't have been a real sweat either."...
Am I right?
It appears that the “quote” function works correctly, if that is what you are asking.
1) I would only have justified YOU if YOU were in a simulator. I confess that I was taught the same manoevre in the sim. during my last type rating in the 737-300, almost 4 years ago; the Instructor told us: "Who knows? Some day you could face an emergency situation in which this could be the only escape route". I would even have admired YOU if YOU were doing some test flight, alone on board.
Perhaps its because English is not your native language, but I’m not sure what you mean about you “justifying ME if I were in a simulator.” Let me be clear. I was in an airplane, not a simulator. In fact, I WAS doing a flight test. As you probably would recognize, it would be foolish and irresponsible (not to mention illegal) to operate a DC-9 alone. Therefore, we had several folks on board – as you might understand, you typically have a couple of other folks along when doing flight tests.
2) ..."So, under those circumstances, experiencing an engine failure at V1-10 knots and continuing the takeoff would be no sweat."...
But YOU forgot to mention which engine failure: the one kept idle 'cause I'm sure YOU would never had taken off with one engine shut down on a twin'; or the other at full thrust; in which case continuing the takeoff to the rotation would have been very very very difficult.
Well, let me correct my oversight … no, we did not make the takeoffs with one engine shut down. The takeoff tests were done from as close to the approach end of the runway as we could maneuver the airplane, and with brake release, slowly added thrust on one engine until we reached the computed maximum takeoff thrust for that engine. And, yes, it was somewhat difficult. As I mentioned, it took considerable amount of nose wheel steering and forward control column pressure to maintain adequate directional control until the rudder became effective. And full thrust on the one engine was not possible until adequate airflow over the rudder allowed it. But once that occurred, full thrust on the one engine wasn’t much of a problem; and yes, we did continue the takeoff roll through the rotation, and getting airborne. And, each pilot on board did it several times, alternating the engine used, ultimately achieving full thrust on one engine for each takeoff. In each case the other engine was running at forward idle thrust. Pilots made takeoffs from both the right and left seat.
The reason for my example and the point I was making – but apparently not sufficiently well for your understanding – was that if a pilot were to experience an engine failure at V1 –10 knots and have a substantial amount of runway still in front of the airplane, OR to accelerate to a point of V1 +10 knots and experience a serious problem at that point with the same substantial amount of runway still in front of the airplane, the question of whether the takeoff should be continued or the takeoff should be rejected is almost irrelevant. The irrelevancy coming from the fact that there would still be enough runway in front of the airplane to support a continued takeoff or a rejected takeoff decision.
I've always thought that the art of flying is very far from the circus. Fly the numbers, as OLD SMOKEY writes often, and I add: Fly the books.
Perhaps that's the reason why I'm still flying airplanes and not a 6-Drawer Oak Desk. Fly Safe DOVE
Well, there we agree – flying is no circus – and I happen to agree with OLD SMOKEY about flying the numbers. Personally, however, I prefer to fly the airplane not the book. I don’t know very many “books” that have made a good decision or landed any airplane. And, with all due respect sir, if you manage to continue to fly safely for a long enough period, maybe your company will promote you too, and let you do your flight briefings and debriefings at a similar 6-Drawer Oak Desk. They kinda “grow” on you.