John you have to go apples to apple....whether you abort at V1 or you abort 5 knots past...all the factors are the same...

If you want to chase down the over run argument again...then it's simple.....when you calculated balanced field and notice that you had 5000 feet left over...that tidbit of info goes into the back of your head...

If you purposefully plan out that extra 5000 feet..then again...your simply giving your self less options ON PURPOSE...which is a variable I am not willing to accept with passengers in back....by myself...sure.....

I plan for the most layers of safety, not purposefully take out all the buffers, back up systems, fudge factor and safety pillows because financial thift and corporate policy direct that I do so.

Johns7022

What if I told you that a derate power take-off actually increases your margins and reduces your V1? How do you feel about 3-engine take-offs and I don't mean on a tri-motor? Again, based on your plans when BFL is less than ASDR, do you calculate an accelerate-stop distance and a refusal speed, that is maximum speed on all-engine acceleration and stop and a maximum brake energy speed? An actual tire limit speed would also be a good idea, if you do these calcs. If not, how do you know your performance limits?


Now that ICAO Annex 6, as amended requiring SMS and an Operations Manual, have done a risk assessment on youre operating rules?
GF

PS: if you read my post, you would have noted it wasn't a Boeing product. But one that turns into a 28-tired, 24-braked art gum eraser when the anti-skid is functioning. Ever see an acre or two of anti-skid marks?

J_T

On the thread Brian referred to, a poster offered a LH "formula" that for every knot over V1 that the reject is initiated, the plane will overrun at 10 knots. That is, a 1 knot exceedence of V1 will result in a 10 knot overrun on a limiting runway. A mad scientist ran the numbers and thought that was correct in the 6-9 knot range, a greater multiple at slower speeds and a lower one at greater speeds. Works for me.

GF

That makes no sense...what's a 10 knot over run? That you over run at a speed of 10kts, when you get to the end of your balanced field?

What if you have 5000 feet of buffer? Which has been my premise........oh that's right you never do...because no matter what the runway length is...your derate it right into the over run.....

So yeah, I guess, if you decide to burn up 12000 feet in your balanced field numbers...passing the 6000 ft taxi way at 32 knots...sure I get it...at the very end...if you abort past V1...you will hit the weeds a little faster..

Sure I buy that...

Evidently, Newtonian mechanics wasn't your forte. 1/2mv squared is a pain, the higher you speed when beginning a stop translates into greater distance to stop or a set speed when going off the end, pretty elemental.

A 10 knot overrun occurs when, after rejecting above V1 by 1 knot, apply all the braking, spoilers deployed what speed you go into the grass on a field limited runway. If you are such an aviator, you should be aware of this si ple physics problem.


The BR700 series doesn't offer derated, but flex power is available on the FMS and used when indicated.

How are those answers coming?

GF

You want to talk physics...ok..and let's use Brian's numbers....

Assuming I am on my 10,000 ft field...balanced field today is 5000 feet...135 standards...not 91...when I RTO 5 knots past V1, just prior to VR.. then passed my original balanced field point of 5000 feet...at 50 knots...I now have 5000 feet to stop my aircraft that is only doing 50 knots...which might be...what? 200 feet? Nah...let's I take it easy...and not even apply brakes and let the plane coast for 5000 feet, on it's own....

I guess I will be sitting there at mid field......looking at the bomb hole in my baggage department that just took out half my controls, and reduced the structural integrity of my empenage by 99%

Oh by I forgot, I am supposed to pull the plane off...sorry...my bad...

The example is not a BFL 5000 feet and an ASDA of 10,000 feet, the example is BFL = ASDR, no overrun or stopway, just a cliff, down into a gorge. FAR 91 or FAR 135. no difference, the physics are the same.

How do you pass the end of BFL at 50 knots, at that point you should either be stopped (ZERO Knots) or at V2 at 35 feet, V2 better exceed 50 knots!

GF

No one disputes that aborting past V1 might result in a stop past your calculated balance field length...although the argument could be made that my using TRs, better braking technique, soaking up manufacturer's fudge factor......vs the 200 hour pay to fly guy you have in your plane might result in my stopping at the end and you going into a lake of lava at the end....

But that said....if my balanced field equals the runway...a very rare condition that only lives in the world people who run derated/assumed thrust or people who routinely fly jets, heavy, in and out of short runways....

I have to tell you..that I would take my chances with a post V1 RTO if prior to rotation, if I saw some Tali-ban with an RPG a few taxi ways back, then heard an explosion in my tail......

Not an unrealistic scenario to consider, if your flying around Iraq and Afghanistan these days.....

No PTF pilots t my operation, it's not an airline, btw. Though I have taught a lot who have been paid to learn. You still have not understood derate power or flex power and their effects. Try this one-- why can you increase your TOGW by derating?

GF

That is, a 1 knot exceedence of V1 will result in a 10 knot overrun on a limiting runway

Hadn't seen that before but it is in the ball park I would expect to see - the concerns come down to the two items

(a) penalty lost distance associated with the overspeed itself

(b) gradient of the stopping part (and this is the reason that one MUST keep the anchors pushed into the floor until the aircraft lurches to a stop in the angry situation .. more than a few folk have perceived that all was well .. eased off the brakes .. and then danced into the weeds).

My view, on an ASD limiting runway is that I'd rather err on the side of continuing a couple of knots low rather than rejecting a few knots high on the historical stats.

Assuming I am on my 10,000 ft field...balanced field today is 5000 feet...

Of course your argument probably will be valid from the physics of the thing .. you have some fat to elect to reduce speed on reverse or distance and then use brakes if you were in a brake energy limit situation.

However, the Citation (as I recall you fly) is a low Vmcg, low V1 aircraft and not typical of the situation which most heavy drivers face. This is especially the case for the larger twin aisle machines. GF is talking C5A and that has the double whammy of being big iron with flea power motors.

The underlying arguments and concerns, however, are those of

(a) risk management/control (trying to stack the numbers in the pilot's favour on the day) in a rational and objective manner

(b) minimising the need for super rapid decision making with only a fraction of the story to hand at the time .. ie adhere to SOP unless the situation is pretty clear cut. Routinely winging these processes at the time has been shown to be a less than optimal approach over the years.

although the argument could be made that my using TRs

.. true but, other than in contaminated conditions, mainly a maker of noise and not much stopping value

better braking technique

.. that's a silly statement to make .. however, we would be interested in knowing what better technique you might propose compared to that used by the TP .. which will be THE best for the aircraft .. that's why the TP is employed for the purpose.

soaking up manufacturer's fudge factor

.. while there are fudge factors built into most performance data, ASD is pretty well hard data. We have, for instance, negotiated time delays (which usually are quite realistic) and the delay factor required by A/L 42 (which is not all that fat).

Just which manufacturer's fudge factors might you have been thinking of ?

RPG fire is not a daily occurrence, get real! Have a realistic scenario, or are there daily RPG attacks at your base? BTW, on Iraq, where there were RPG attacks, the reject criteria didnt change, just the spiral up procedure.

Why do you ignore questions that you should know, if you operate legally? Don't have answers or don't know wht you're doing? Or does baloney just reject the grinder?

GF

As an aside, we need to keep in mind that some of our colleagues enjoy stirring the pot a little - I have no idea whether johns7022 fits that label or not.

However, the technique does engender vigorous discussion at times and has been used to great effect by some of our more interesting members .. 411A and Milt come to mind .. both are very experienced aviators.

In Milt's case that experience incorporates a long time TP background and one wouldn't be surprised to see his participation in this thread in due course. As another aside, I have no doubt that he will be a little teary-eyed at the withdrawal of the F111 from RAAF service this month, having introduced the Type into operation so many years ago.

JT - you are well aware of my standing views on 'discussions' on a thread and the contribution to safety, I'm sure. All challenges to 'tradition' are always welcome as long as they are rational, and have indeed changed 'established' procedures in the past, as with the BA 737 fatal abort at Manchester some years ago.

You will, no doubt, have a shrewd idea of identity. IF we have a 'SSG' re-incarnation we are wasting our time here

May I draw to the attention of all, from another thread:from that I believe there is quite a lot he/she does not comprehend.

But, for better or worse, not shy about expressing opinions on that which he does not comprehend..........

GF

J_T. The "formula" on overrun speed is on about page 12 or 13 of the thread Brian Abraham linked to on the last page, this thread.

Those that are taught to pour the tea, don't always know how to make it.

You will, no doubt, have a shrewd idea of identity.

Actually, no. We can elicit some information from the system but it is rather generic in nature. End result is that I have no idea who johns7022 might be. However, there are some stylistic similarities so he/she may well be someone else from the past ...

IF we have a 'SSG' re-incarnation we are wasting our time here

I'd take a contrary view. It has always been apparent that the best way to test one's own knowledge is to assess one's ability to express that knowledge. Thus, stimulating discussion (whomever might be the driving source) has the useful value of testing the participating readership's knowledge comfort. Folk such as SSG, and others, might be a tad irritating in some respects but that doesn't, of itself, reduce their value to the discussion.

page 12 or 13

Thanks, GF .. I'll have a looksee at the link.

Those that are taught to pour the tea, don't always know how to make it.

Good point. Knowing the makings may not be a necessary prerequisite to doing the pouring entirely satisfactorily. However, there may be some sideline issues for which the former may assist the execution of the latter.

I am reminded of a final year fluid mechanics exam question from many decades ago ... which considered the case of the PNR tea lady .. daily she would ascend the spiral iron staircase in that august building .. the question assigned one's pondering to whether she ought to stir the tea

(a) before she started up the stairs ?

(b) after she arrived at the last landing ?

(c) or, indeed, was it necessary to stir the tea at all ?

.. an interesting chap, that lecturer.

The answer, needless to say, involved a few pages of manuscript containing the usual run of the mill engineering undergraduate mathematical jiggery-pokery ...

J_T

It was on page 13, here's MfS' quote

That was in response to Clandestino in post #251, about half way down the page. Drove me near round the bend finding it!

GF

Does anyone here fly for an operator that includes an RPG Attack checklist in their QRH? I cannot find one in anywhere.

GF

Erm.... 10 kt overrun for each 1 kt above V1 in runway limited cases isn't actually a formula, it's more like rule of thumb. My apologies if I made it look like one. Mad (flt) scientist has pointed out correctly that actual relation is not linear yet the curve is close enough to 10 in 1 line for everyday use.

Johns7022,

I'm curious. Do you bother calling V1 when you trundle off down the runway? If you do, why?

Also, is your view on post V1 rejects the same for contaminated runways?

When it goes bang and you look out of the window do you consider the weight of your aircraft, temperature, wind, distance to go, acceleration and runway slope in the split second before you decide to stop or go?

What was that bang? Do you consider the possibility of a tyre burst and a reduction in breaking efficiency?

What do you do on short strips where you might have a balanced field? Do you now use V1? What's V1, I aint used that for ages?!

I assume that you have flawless stereoscopic, binocular vision. Maybe Joe Bloggs hasn't so he can't rely on just his eyesight to accurately judge how much runway is left. What do you do if you have a bit of eye tension? That affects you depth perception and ability to judge distances.

Can you easily and quickly judge how much is left when you're taking off into sun with a bit of mist or haze? How about low vis, 300 meters or so? How much runway left now?

How about night? Again, depth perception is changed.

Depth or distance perception is based on previous visions of an object or scene. If you have knowledge of the size of an object from previous experience, then your brain can gauge the distance based on the size of the object on the retina. However, if you haven't seen the object previously then it is much harder for you to judge distance to it. The object, for you, would be the end of the runway. Now say the runway is narrower than your usual one, it would then appear longer and unless you'd seen that previously you are very likely to misjudge the distance to go to the end.

Quite agree, rule of thumb! Sorry to 'dress it up'.

GF

Suddenly, we have moved from a discussion on V1 and the certification criteria attached to it, to terrorism as a foreseeable event that is part of take-off planning. Are you scared to fly?

As i pointed out, at Baghdad Int'l and Balad AB, we didn't change the the reject criteria, just the departure routing and procedure. At V1, we briefed continuing--it doesn't hurt at those weights the V1 = Vr, so we were airborne anyway. But the certainty of over-rrunning out-weighed the statistically remote chances of someone shooting a IR missile; let alone the remote chance of an entirely ineffective RPG hit. If you take-off from the fictional NW International Airport, ID and someone jumps out from the pucker bush, stands up and sends you an RPG round into the tailcone of your Citation at Vr, hell, at V2, be my guest, land straight ahead. BUT, don't tell me 160,000 professional pilots with millions of safe flight hours and statistically sound procedures are WRONG for continuing at V1 with a mechanical failure.

I don't know your career background, but it is obvious you have "issues" accepting that the airlines operate without you. Yes, it is true, they do. And the thousands of captains are NOT robots who don't think every time they advance the throttles--they do--EVERYTIME! I know, I've been there. As have most of the posters on this thread and the others where you have spouted off your damaged crockery ideas. All smarter than me or you.

I fly a GLEX and use FLEX power where indicated, I fly in about 30 countries a year; including such wonders as Beirut and Afghan and Iran overflights. I don't brief RPG procedures despite nearly 30 years of military flying, it just ain't a reasonable planning factor.

What's your reject plan when a printer cartridge of C4 goes off at 50 feet AGL? At 500 feet AGL? There's a reason safety investigations END when the police determines that a criminal/terrorist event occurred--it isn't addressable within our community.

GF

I breath a sigh of relief when the EGPWS terrain display is gone and 1013 is set, especially in Lagos. V1 is too soon.

Please review the definition of oxymoron. And your characterization is wrong, PERIOD. And your understanding of terrorism is equally wrongheaded and based on zero experience.

GF

Beirut and Lebanon is whole lot safer and entertaining than anywhere in the NW, BTW. If the IAF doesn't bomb the runways, as happened in '06, but I left the day before. Much nicer last Fall.

Correct - not all runways are such that you are truly operating with ASDR=ASDA. But unless you actually do the calcs - which for a line pilot, or even an airline performance department, involves going OUTSIDE the scope of the approved data - you have no idea what actual margin you have.

Correct, not all runways have a hostile overrun area. But many do, and even a benign overrun area can cause all kinds of damage if entered at speed. Airliner undercarraiges are not designed to be offroad capable.

Correct, not all brakes fail if used from 1kt above V1. But if V1, today, happens to be set by V1mbe, NO-ONE at any OEM will guarantee that the brakes will not fail. Sure, not every chamber in the revolver has a bullet in it. How many chambers make Russian Roulette a "safe and rewarding game"?

If I look at what we do when we actually conduct the max KE brake demonstration, we have "minimum crew" - because we want to limit the number of deaths we risk. We have those crew wear fireproof suits and the like - in the hope that they might have time thereby to escape the aflame vehicle. We have airport CFR actually present, at the predicted stop point of the test, so that if it all goes pear shaped they might get the the aircraft before its engulfed in flames, and thereby rescue the test crew. And we inspect the hell out of the aircraft - especially the wheels and brakes assemblies - so that we understand exactly what kinds of risks we are running.

When you take your aircraft potentially past max KE speed and then decide to brake, you have NONE of these mitigating factors. Sure, there are some conservatisms in the flight test demo - we use worn brakes, for example. But NOT 100% worn - how worn are YOURS? Our tyres are in decent shape - are yours? All it might take is one bad tyre, that lets go early. Suddenly now you have to do the rest of the stop on just three brakes, not four. You're going to be pushing all the remaining energy into those other three brakes - probably inducing more problems. As the brakes heat they are going to fade - not fail, 'just fade'. Which means they are going to stop working as well as you'd like. But of course you can't estimate what that might mean - because the OEM data asumed you'd not be pushing the brakes so hard. Faded brakes are going to take MUCH longer to bring you to a halt - we'll find out how much longer by measuring the distance to the written off airframe, in all likelihood.

I will agree that there are some circumstances, where an aircraft will not fly, where aborting at Vr (if above V1) may be the only option. But you may well be at that point be picking - because you have no choice - a very bad second option only because the first option simply isn't available to you. I don't mind discussing the idea of what would happen for an abort outside the norms. But to pretend there is no significant risk in such an abort - that's just not helpful.

MfS

In my previous plane, not civil, we had charts for, and calculated on each and every take-off, the following:

Critical Field Length, Refusal Speed (accel-stop), Vmcg, corrected for crosswind and runway friction), Vmca (OEI and Two-engine Inop), Vr, Vmbe, AEO ground run, Tire Limit Speed, V2 and Flap Retract Schedule and all the calcs to compute those speeds/distances. V1 was defined as the lower of Vr, Vmbe or Refusal Speed. The handling pilot reviewed the data on a 8x10 sheet of paper and confirmed the data. Very comprehensive.

How is it the civil AFM is so limited in data for pilot use? Is the regulatory bodies afraid of pilots doing the data? This is elemental data.

GF

From Madd = Correct - not all runways are such that you are truly operating with ASDR=ASDA. But unless you actually do the calcs - which for a line pilot, or even an airline performance department, involves going OUTSIDE the scope of the approved data - you have no idea what actual margin you have.


Madd - I think you figured it out.

I have never showed up to the airport and picked up the 'package' of canned flight plans, performance calcs done by dispatch, ect....

Maybe when you run the numbers ten thousand times...you start seeing things other guys don't. Actually this process started a journey of asking deeper questions about flight testing, performance planning......

A boss once said I had too much time by myself up there to 'ponder my predicament'

You know if these conversations ever get to 'go' maybe we can talk about the tough trips that had me scratching my head during planning.

Depends, at least for us, on the type and its intended use. That level of detailed data is often (I hate to say "always") provided where the aircraft is expected to be operated in an airline-like environment. But to some extent that is because we expect it to be used by the airline's perf guys, not actually by the line pilots - often they'll get the analyzed/crunched version specific to their runway today - OS, mutt, to name two, know far more about that end of things than I do.

But where we are intending the aircraft be operated in the biz jet world its common for us to provide a more simplified set of data, since the assumption is that there may not be the planning infrastructure to back up the crews, yet they may be having to deal with a much larger set of potential destinations. We've even been asked to provide that more simplified presentation for aircraft which have changed roles from airline to business operations.

It's not really a regulatory issue - we do provide that data for some cases. It's more a case of tailoring what is provided for the expected needs of each operator.

Now, in the brave new world of computerized flight manual data, one could argue it's easier to provide the more complex data to everyone. But there's still an issue of understanding the limitations in the data - if it's not really hurting your operations, simplified may be good enough.

Discussions of terrorists and so forth are irrelevant to the certification matters.

Let's plan on the basis of nil further such excursions into the fanciful please ?

something new for the discussion on RTOs
 

To add something new to the discussion.... I noticed several comments on Flex/Assumed Temperature Method (ATM) takeoffs in relation to RTO performance. I wonder if crews know what the impact might be on the actual stopping distance during an RTO. Below is the engineering answer to this.

The accelerate-stop distance in FLEX/ATM is based on the true airspeed at the assumed temperature. This assumed distance is the basis for the takeoff performance. As the actual true airspeed (which is based on actual OAT) during takeoff is lower, the actualaccelerate-stop distance would be shorter than the assumed distance. This means, there is always some additional stopping margin when using Flex/ATM.
See: Takeoff Performance Optimization: Balancing Thrust Reduction and Stopping Margin by Dennis Ting, Meghan Nelson, and Greg Haselfeld, The Boeing Company

Likewise with the acceleration. The actual temperature is lower and the thrust level higher which, when added to the better stop distance, results in a degree of conservatism.

I think everybody agrees with that. But for me the choice is about limiting the damage not thinking of avoiding it.

BTW, what makes the Citation a low V1 aircraft? I always surmised that if V1 is less than Vr then it is because the ASDR is greater than the assumed distance remaining at Vr.

My copy of Flight Crew Manual hasn't been updated for a decade, yet I think it still makes some very interesting reading: it states that western built jet transport aeroplanes made about 230 million take-offs in period 1960-1990.

There was about 76 000 RTOs in the same period.

74 of them ended in accident or incident.

2% of RTOs were initiated above 120kt and that's where the large majority of incidents came from.

58% of RTOs that ended in incident were initiated above V1

Only 24% of unsuccessful RTOs were triggered by engine related events.

According to the Airline-that-issued-FCM analysis, 55% of incidents could have been prevented by continuing the take-off, 9% by better preflight planning, 16% by correct stop techniques.

20% were unavoidable.


Well, so much for those John Wayne kind of pilots who can always make a proper and informed split-second decision, whose keen eyesight gives them ability to estimate remaining runway down to a couple of feet precision, who have an absolute pitch and immediately they hear a bang know whether it's a tyre, tires, compressor stall, engine falling off, improvised explosive device in cargo hold 3, Strela-2M taking out the No4 engine or collision with B747 wrecking the most of the aeroplane (I'm only half joking here; the survivors of Tenerife carnage described the sound of two Jumbos colliding as being similar to small bomb going off). 'Tis a pity that such a pilot has never walked the earth or is likely to ever walk it - the safety he would offer his customers would be nearly absolute.

In case you've missed the Big Briefing: the only available safety in flying is the statistical one. Perfect safety is as achievable as the absolute zero. We can only bring chances of having a mishap down to socially, politically and economically acceptable level and that's about it. However, make no mistake: bringing the aviation safety where we have it now was no mean feat, keeping it where it is won't be easy either.

I really don't see the way in which some around this forum pre-meditate the reasons that make post V1 abort justifiable to be beneficial to aviation safety. If aeroplane is unflyable past V1, only thick margins can save the day. If they were not there in the first place, tough. Fate was, is and always will be the hunter. Trick that can extend the operational life is to avoid her favorite hunting grounds and post V1 RTO is the place she certainly frequents.

updated statistics
 

Dear Clandestino,

Please have a look at the start of this tread. That study gives more up to date information than the Boeing study you are referring to.

You guys are sunk now......

- There was about 76 000 RTOs in the same period.-

That's a lot of RTOs...that's a lot of mechanical failures, annunciator lights, problems, issues, ect that are causing the pilots to say...'not taking the plane up'

- 74 of them ended in accident or incident. -

Translated...out of ALL the RTOs... ONLY 1/10th of one percent of resulted in an accident...and that my friends, ends, all your arguments about brake failures, and planes flying off into the end into Lava Pits...done, over, your arguments are toast. One tenth of one percent is so statistically small that I could sit here and blame that on bad tires, idiot pilots, gremlins.. African operators, Pay to Fly.... but for grins let's move forward....

- 2% of RTOs were initiated above 120kt and that's where the large majority of incidents came from. -

2% = 1400 RTOs initiated above 120kts...that's fast...no one died and the plane wasn't structurally damaged.

--58% of RTOs that ended in incident were initiated above V1--

No one died, no planes banged up to un flyable status...

- Only 24% of unsuccessful RTOs were triggered by engine related events. -

You mean to tell me that 76% of the reasons why our pilot's RTOs had NOTHING To with the fire light...shocked, shocked I tell you...you mean things went bump, bang, boom...and they still stopped the plane?

- According to the Airline-that-issued-FCM analysis, 55% of incidents could have been prevented by continuing the take-off, 9% by better preflight planning, 16% by correct stop techniques. -

Sure...so out of 76000 RTOs...only 76 resulted in a plane being banged up, or an injury/death.....they think that these guys should have flown the plane at least half the time.....ok...let's look at that....76000 RTOs...and they think that half the INCIDENTS should have been flown off...ok...700 should have been flown as opposed to an INCIDENT...in other words instead of only an incident they think that 700 crews who slid off the end with no injuries or banging up the plane should have FLOWN the problem up in the air...beyond idiotic.

9% didn't preflight their planes...and 16% don't know how to stop one....not a revelation there...

------------------------

Gentlemen...the argument is done...sticking to a position that brakes fail and post V1 RTOs will kill you is about the same as a Linotype operator railing against copy machines....

So out of all the RTOs....76000, and only 74 resulted in accidents....how many could have been avoided if the crew had more runway in front of them?

Correct - only 0.1% of all RTOs resulted in an accident or incident. Sounds very safe to do an RTO.

But

To count all those low speed RTOs to justify your assertion that post-V1 RTOs are not significantly risky is not valid.

The important point is that 2% of RTOs were above 120kts (incidentally, that includes RTOs where V1 was even higher and so it was a pre-V1 RTO). Its stated that "most incidents" occurred for these cases. let's be generous to your case, and say that half of all accidents or incidents were due to that 2%.

RTO below 120kts : 74500 events, 37 accidents or incidents. Event rate, approx 0.05%

RTO above 120kts : 1500 events, 37 adverse outcomes. Event rate : 2%

You are almost 100 times more likely to end up in an accident or incident if you reject above 120kts than if you reject before 120kts. High speed RTOs are demonstrably more hazardous.

Not sure where you get the idea that none of those >120kts RTOs resulted in death or structural damage - "incident" includes "accident" in most cases.

Nothing is certain - no-one is saying (as far as I can see) "post V1 RTOs will kill you ". It all depoends on circumstances. But what is indisputable from the data is that rejections at higher speeds, and especially rejections above V1, significantly increase the risk, and as a result are only justified in truly exceptional circumstances. The default decision, justified by many years of experience, is to GO after V1. It may not be always the perfect decision - but the odds are definitely on your side taking that choice.

So if an RTO has a 1/10th of one percent of banging up the aircraft... only if I don't preflight the plane, forget how to brake the aircraft, do the RTO at 120 kts or better which by the way, I don't know if I can hold down my plane at 120kts...lol....and statistically only in an airline operation that is probably purposefully using derated thrust departures....


So wouldn't it be logical...that if we were to reduce these types of accidents....we would preflight our planes? Hire or train crews that can pull the levers back and stand on the pedals...and if all else fails we give them as much runway ahead as is possible so they have the most room to stop...???

Does that seem like a stretch????

What percentage of flights that continued with a problem at or after V1 subsequently banged up the aircraft?

Johns7022

Actually, what would be logical is determining why the 55% didn't continue the take-off like SOP and the record of safe flight would have indicated; that would also eliminate those who didn't use the braking procedure effectively or didn't conduct proper preflight planning as rejected takeoffs because they wouldn't have rejected. Leaving the 20% of unavoidables to fix.

Using MfS's numbers, probably half of those 37 "adverse" outcomes wouldn't have happened had the pilot simply took off. "Poor preflight planning" does not indicate they didn't do an aircraft preflight, maybe the failure point could have identified during planning. And I'll bet you won't use the brakes effectively, if under the stress of a field length limited take-off you decide to reject past V1 because you guessed it won't fly. Oh yeah, you don't do the calculations, so you won't know you are past V1. How's that feeble Citation anti-skid work, anyhow? As has been pointed out, using ATM Flex or derate power will, in most cases, increase safety margins, but you don't want to listen to anything that doesn't fit into your visceral hatred of the industry

I think we can agree Johns7022, you can fly your Citation solo in the US Northwest and let the pros fly paying passengers around world, following SOPs developed by other pros who, do performance engineering based on the work of other pros who designed and applied science to the problem of flight. They've alL posted here, with endless patience, and have vast experience in ops and the knowledge of perhaps 300 million flight hours to base their opinions on. You can fly and decide the outcomes using a "seat of the pants" approach that gave aviation it's horrible stats in the early days. The fatal accident rate has come down so dramatically due to advancing beyond your method.

GF

Galaxy - 76000 Crews performed RTOs, with a 99.99% success rate of not hurting the plane or passengers.

Let's not descend into the depths of invective, please.

Back to the thread
 

‘johns’ (#121) is almost back to the original question … how does the industry “reduce the number of unwarranted rejected takeoffs above V1.”
The report (#1) gives several reasons for high speed RTOs, but few solutions amongst the recommendations:-

• Revitalise the ‘Takeoff Safety Training Aid’; a worthy training initiative, but in the current economic climate will the likely meager effort be effective.
  Surely, the critical issues can be covered in less than the current two volume tome.
• Train for events other than engine failure and use realistic scenarios; focus on the limiting cases, we do not have the luxury of ‘infinite’ runways.
  This is another good initiative, but similarly limited by time and resource. It would be foolhardy to expect that every relevant scenario could be covered, let alone remembered for timely recall during a real event, so perhaps we have to identify generic training, i.e. situation awareness, surprise management – issues of human performance – simplifying the decision / action process.
• Understand pilot’s behaviors; yes a good research topic, but the industry has used CRM etc for many years, which in several RTO instances appears not to have helped.
  Perhaps we should take what is currently known about human behaviour and re consider how it is applied.
• Review procedures and guidance; yes these can influence behavior. Provide appropriately phrased SOPs, which together with education can elicit desirable behaviour – preflight ourselves as well as the aircraft. A briefing is the flight-plan for the mind. An RTO requires a new plan, formulated in a moments decision, whereas continuing after V1 is only a revision to the existing plan.
  Standard situations should be reduced to ‘if – then’ decisions, providing of course that the situation is correctly identified.

The confusion surrounding ‘unable or unsafe to fly’ could be reduced by removing - disassociating these aspects from RTO training.
The basis of certification, whilst not perfect, provides sufficient assurance that the aircraft will fly and thus crews should not be overly concerned. The reasons for being unable to fly are in two broad categories.
Those which are self generated, e.g. errors in configuration, wt/cg, and weather assessment; these are generally addressed by procedures and checking (behavioural issues), and warning systems before take off.
Other, rarer events, whilst foreseeable, are so random that perhaps only a human can resolve the situation, e.g. runway incursion, double control jam, multiple engine failure. We could consider the solution of these incidents as mitigating the effects of the hazard or error, and/or reducing the severity of the impending accident. IMHO these activities, and particularly the assessment, decision, and action processes, are sufficiently different from RTOs as to place discussion and training of them elsewhere, and if the pressures of the economic climate minimize the training effort, so be it; better to concentrate on correct recognition and action for the more probable (but still infrequent) RTO / V1 Go scenarios.