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galaxy flyer:
Yes, V “go” must take Vmcg[1] into account. On 4-engine airplanes configured like the B707, that’s quite limiting to the range of V1s when you are light. But on those (rare) beasts like the VC10, Comet/Nimrod (and maybe Concorde/B1), with less asymmetry, Vmcg can be quite low. Must admit I’d forgotten the difficulty of obtaining a range of V1s with present-day instant tables or computer programmes. Good idea of yours to use the RTOW case to find the top figure, but wouldn’t know how to find the bottom one. On the VC10, we used to do it all from basic principles, taking about 10 minutes (including a Flex calculation). Surprised to hear of 50% braking in some single-failure circumstances on your present type. Pace and Diesel8: Yes, a double engine failure before VR sounds unlikely on a 3 or 4-eng aeroplane, so why did we consider it unofficially on the VC10? Because the engines are behind the landing gear and mounted in pairs, like the Comet/Nimrod, Jetstar and Concorde (not to mention the B1 and B52). As far as conventional aeroplanes are concerned, there was the El Al B747F that was unlucky enough to throw a blade from one engine into the other over Amsterdam. By the way, the VC10 can get airborne on 2 quite nicely even at medium-to-high weights, particularly at sea-level. [After all, it’s only like a twin losing one, although the performance regs don’t have to cater for it.] Not so the under-powered Seven-oh. And I seem to remember the 707-320 with JT3D-3Bs had a Vmca[2] of 147kts, so it could not manage it even at low weights, if the failures were on the same side. ssg: I know that you are, to some extent, playing Devil’s advocate. But in relation to Flex, don’t forget that TOGA is still available as a bonus (though not assumed in the calculation). De-Rate, of course, is another matter. Having “taken the shilling”, I advocate sticking to SOPs to the letter; but not all scenarios can have an SOP. The trick that we all hope we will never have to perform is that of recognising that there is no applicable SOP, no time for “DODAR”, and still making a good decision. |
So Chris, in the VC10, if you are at VR and both donkeys on one side decides it is time to eat hay, are you stopping?
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Chris Scott has written:
Having “taken the shilling”, I advocate sticking to SOPs to the letter; but not all scenarios can have an SOP. The trick that we all hope we will never have to perform is that of recognising that there is no applicable SOP, no time for “DODAR”, and still making a good decision. Ssg you should heed his words brother:ok: |
Chris
What I said was that if the engine failure were accompanied by loss of fluid in one of the two systems that power the brakes, I would have 50% of brakes. The brakes on Challenger/Global are divided inboard and outboard powered by system 3 and 2, respectively. Yes, it is a compounding emergency, but loss of fluid quantity could be caused by uncontained hot bits from an engine disintegration. The brakes normally have two pumps powering them-AC and Engine-driven, so it is a remote possibility. Once the fluid is gone, no power for those systems. The C-5 was similar where loss of system fluid required switching to alternate brakes-just a switch actuation by the Co-pilot, but easily missed in the heat of a overspeed abort. But you did then have all the brakes. My point was it is better to address these issues airborne. I presently have plenty of brakes for stopping with a 50% loss, if it is planned for. BTW, the C-5 has a low Vmcg of around 80 knots, dry, no crosswind. We computed corrections for both runway condition and crosswind. I'd like to think the low Vmcg was due to having four very powerful APUs as engines. |
"Now that is a true/ well conceived / learned and balanced statement--"
Agree indeed! |
Having “taken the shilling”,
Loud and clear...families to feed and all that...a faustian choice....who knows one of these days I might be up there planning my egress into the stop way...rolling down the runway, less power then available, yanking it up at VR, over the fence...rolling left because of the tanker I just clipped...before I go in...I joke to the FO....'well atleast were getting paid' It's no different then corporate...to be honest...the owners would have me working main st for $5 a pop if they could get away with it...hang on to your unions boys.... P. Animas...don't worry I'm a whore just like everyone else but I have limits... |
SSG that's the spirit of the business:D You've been Schooled!!:}
I'm gonna take my meds now:) CAVU! |
Airlines.....
A jetliner was forced to pull out of a landing at Sao Paulo's Congonhas airport yesterday as new footage emerged of the Airbus 320 that crashed earlier in the week, showing the aircraft travelling along the runway at more than three times the usual landing speed.
Security video footage appeared to show the aircraft hurtling down the runway in just three seconds. Video footage of a similar aircraft landing just minutes beforehand showed the plane taking more than 10 seconds to complete the length of the 1,900m runaway. More than 180 people were killed when the flight careered off the runway and burst into flames after hitting buildings at the northern end of the airport. |
BTW, the C-5 has a low Vmcg of around 80 knots, dry, no crosswind. We computed corrections for both runway condition and crosswind. I'd like to think the low Vmcg was due to having four very powerful APUs as engines. and a VMCG of 80 KIAS--or is it KEAS for you?---would never have guessed! |
Mulitple entries in the AF 4098 Take-off worksheet-about 50, I'd guess. A good engineer could do one in 20 minutes, if there wasn't a difficult climb gradient problem. We always had Vmca2, refusal speed on the pilot's card. Normally, refusal and rotate were computed and then compared to Vmbe and Vcefs (critical engine failure) and the limiting one became Vgo (V1). On take-off the PM just called "GO" signally stopping was no longer an option. Did a near GO stop at Sigonella once, just made it. Then "rotate", of course. Gust increment was added to Rotate and V2. It was a very marginally powered aircraft, or too heavy, if you prefer. Above 712,000, its originally gross weight, additions were notable in performance. OEI climb gradient could be as low as 2.3% with no obstacles. Surprising amount of this stuff stuck, but I instructed to pilots. Who were not impressed!
KIAS, not EAS, but Old Smokey smiles at you mentioning it. :D |
KIAS, not EAS, |
Diesel8,
I wasn't using those examples as strictly relevant to the case initially proposed in the thread, but rather to demonstrate how what one might consider nigh on impossible, has probably already happened to someone somewhere.... Who would have thought a 777 could have a "double engine failure" on short finals over London until a few months ago (not strictly true, but to all intents and purposes, that is what happened)? I have to say that everyday I get airborne I'm cognizant of the fact that my flight director scheduling, should I have an engine failure, is designed with AA191's experience in mind. Its a sobering thought. We all know what the statistics say (although I have to say they won't be much comfort to me when the proverbial hits the fan), we've all read The Pilot Guide to Takeoff Safety... I'll bow out with a quote from that document: There is more to the Go/No-Go decision than "Stop prior to V1" and "Go after V1". :) |
No one said anything about v2 or single engine...Citation Vs, Ultras and Encores can do 4000 ft/m...for while So now that you are back peddling, please answer the question, how do you ensure your obstacle clearance following an engine failure? Mutt |
So now that you are back peddling, please answer the question, how do you ensure your obstacle clearance following an engine failure?
Mutt A few years ago I was involved with a forum for Microsoft Flight Simulator. I did some development work with addon companies, wrote reviews and was fairly active in their forums. The problem with all these forums is that they are open to a lot of people who hide behind a cloak and claim to be something they are not. There was one guy in particular who challenged the real world pilots on those forums and fair enough some of the stuff he came up with was quite convincing. But in other ways his approach was very purile and he made major blunders. We discovered that this experienced so called pilot was infact a 12 year old kid who was merrily googling his answers on the internet and somehow getting a kick by playing out his act. He fooled a lot of airline and corporate pilots for some time. Pace |
A jetliner was forced to pull out of a landing at Sao Paulo's Congonhas airport yesterday as new footage emerged of the Airbus 320 that crashed earlier in the week, showing the aircraft travelling along the runway at more than three times the usual landing speed... This accident was caused by not putting both thrust levers to idle then only reversing the idled engine thus resulting in 1 engine giving positive thrust, the other in reverse, and no spoilers deployed. It's got nothing to do with aborting past V1... off topic! What are you trying to pull here? *our legs?* :E |
and I am still waiting for those engine overhaul numbers and cost And I dont believe that you did answer the question about obstacles... humor me... quote me the page from the FMS guide where it says that the takeoff path can be calculated with an engine out, and also tell me who is your obstacle data provider...... Mutt |
Since SSG is so desperate for the numbers, I'll give him one a from a now defunct operator... got it from the guy who had worked there... accuracy not guaranteed. I can't give the exact numbers for obvious reasons.
Numbers for the 733/4/5, average hour to cycle ratio 1h10m, 10 cycles a day average. Destinations are all <2500m runway (mostly <100ft elev, ISA+15C) except for 5 airports with 3000m - 3600m runways. Derate take off & derate climb policy = about 50USD per cycle. at 10 cycles a day, equivalent to 100k - 150k USD per year. Derate take off only would save about 30USD per cycle (less fuel and engine wear, whereas the derated climb expends just a little bit more fuel, but significantly reduces engine wear). |
Curious...what is the cost of the engine they were using and the total cycles allowed...engine cost divided by cycles = cost per cycle.
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Armchair Decisions
Quote from Diesel 8:
So Chris, in the VC10, if you are at VR and both donkeys on one side decides it is time to eat hay, are you stopping? [Unquote] The short (and honest) answer is that I don’t know. The slippery one is that you haven’t supplied me with enough data! [You should ask one of the RAF guys; I’m over 30 years out of date.] Think I should admit first that anything offered here is, by definition, merely an armchair decision... Let’s assume that ssg’s 5000ft-excess of Balanced Field is leaving us with about 5500ft of runway remaining at Vr. At sea-level, if not already rotated, I think I’d go, as she should fly okay − even at MTOW. But with that amount of pavement remaining, she should also be able to stop. If rotated significantly, I’d go. At Nairobi (5327ft amsl, if memory serves), both options are less attractive. TAS/GS would be higher; thrust lower. We’ve already used 8000ft of the 13500ft runway, so we are pretty heavy. Initial climb would be marginal. The gear will have to stay down initially, because of the extra drag of opening the gear doors. Think I’d stop, and almost certainly overrun the runway. If already rotated, I’d have to go, and fuel dumping would start asap. On the B707-320 with 2 out on the same side, the decision is simple: stop in all cases; because of lack of thrust when heavy, and the high Vmca[2] when light. Cannot comment on the various types of DC-8s, B747s and A340s; never flew them. |
Sounds like one of those..
.'you have to be there..see what the planes actualy doing...make a decision' |
This has been a spirited thread.
Procedural points to keep in mind .. (a) several folk have complained about some of ssg's posts. Be aware that I am following along behind and I alter/delete posts which I think are a bit out of line .. not just ssg's .. any ... (b) so long as the posts are not too far out of order and the subject remains reasonably on flying matters the thread can remain here to stir up objective passions (c) if individuals get to the stage where they feel that the thread is going in circles or whatever, there always remains the option to ignore it .. when enough lose interest it will, like near all threads ... sink into the abyss. As a moderator, it is not my personal task to be the arbiter of what content should or should not be in threads .. only that they reasonably follow PPRuNe requirements. The only "rule" we have here is that outright rudeness etc., will be modified or deleted as we consider appropriate |
Post V1
Just a few thoughts:
1. I worked on a 767 which RTOed after no engine failure but failed to get airborne after Vr and sitting on the tail skid. Good thing they went for the RTO option as the airline calculated the various V speeds and put the wrong mass in for the take-off. (I seem to remember it was ZFW they put in when it was going off on a 10 hour jaunt but the pilots did fly short sectors at low masses in it too). 2. A 747 where the incorrect flex power was set and failed to get airborne 3. Please remember that more airports have full length 300 metre runway end safety areas than used to and some have delethalised (eugh!) the run off areas (size dependent on runway length) 4. The DC-10 multiple tyre failure scenario was made much worse by the (then) tyre design standard (or should it have been tire?) which only required the other tyres to carry 1.5 times the rated load. With the DC10 beam deflections, the opposite corner used to carry 1.97 x load which then blew it. Then you were in deep trouble, made worse by the wheel rims fracturing and shattering with subsequent spreading of the bits around at high speed (to cut hydraulic lines and penetrate fuel tanks). Then you have nothing for the brakes to bite into as there were no tyres left. Also the DC10 would not reach Vr when this happened so you were in trouble. Oh, and the brake pack wear could be minimum on all wheels so that you did not have enough energy absorbtion available to stop in time. A change in tyre load standards, wheel rim design standards, brake pack wear requirements and trying to get the V1 as close to Vr as possible helped stop the DC10s from falling off the end of the runways as often as they used to. 5. Not sure if the locked wheel non-rotation when taking off on an icy runway scenario still exists that did for the odd DC8 on departure. The wheels slid without rotating and the subsequent extra drag stopped the aircraft from reaching Vr. I seem to remember it was Anchorage, it was full of US Marines or similar so the evacuation was relatively successful based on fit males all willing to listen to commands etc. 6. If you have to stop, think about flaps which are generating lift and consider (coffee break only time, not when it is happening) raising them. The spoilers should kill the lift but I am working on one with no spoiler deployment. You probably don't have time to even think about the action when doing it for real, but it is worth talking through! 7. Remember to press the brake pedals as if you life depends on it. It does. Many pilots used not to press them hard enough. NASA simulator studies (ok, old data here) showed lots of pilots at the 70% pressure level. I hope that this has been trained out in many cases now. 8. If you RTO off the end and the nosegear collapses, many big jets will lose the PA from the cockpit. Makes the evacuate call a bit difficult to hear. I hope that you never have cause to find any of this falling into "useful practical advice" classifications in your worlds. Unfortunately, I do in mine on a daily basis. |
Doesnt JAR OPS assume engine failure at Vef, followed by a 2 second acceleration past V1 prior to executing and RTO, as part of accreditation?
Personally think that this is one of those areas where you on the day have to make the call, only however if you understand if its the wrong call and you have gone against SOP, you are going to get crucified. |
Remember that of the 97 overrun accidents recorded, 55% could have safely got airborne!
Saving about 200 lives!! |
There will always be an accidents where someone who should have flown, rejected, and there will always be accidents where people who should have rejected, flown.
I just wonder, if more people died trying to fly a bad aircraft then reject into the grass at the end. The accident statistics tend to say 'go' given all the bad reject accidents, but if someone tallied up the deaths from either way, I suspect the deaths from skidding off the end, are much less then flying to the scene of the accident. |
Angels 60, whereas you're the same poster who was recently banned as ssg and Trickle 451, now back under a different name, where are you headed with this?
When one continues the takeoff after V1, one doesn't fly to the scene of the accident, one flies to safety; that's the point of continuing after V1. Same agenda for you, or do you intend to keep backpeddaling? |
As I recall in the early 70's there was a Northeast Trident 1E that abandoned after V1 on RWY 28 in Bilbao. There was a large hill at the end of the RWY and in the Captains opinion the a/c had stopped accelerating (big split between V1 and Vr). The result was an excursion off the side of the RWY, one main gear collapsed and no-one hurt.
Initially the captain was held at fault until investigation complete when he was completely exonerated as it was found that deep puddles on the RWY which were not notified to the crew made it a contaminated RWY and the a/c was unlikely to have ever reached Vr. With speed trend arrows that we now have I have on occasion seen the acceleration cease momentarily during a T/O and if this was substantially below V1 at Max Wt it would certainly make me think (usually more thrust is available).:ok: |
Look at the facts, read the statistics and then make your own mind up!
The aviation authorities all agree, the manufacturers all agree. see what the FAA think |
BusyB...Probably took a stong will to go against his company SOPs, social pressure, and the chance to get called on the carpet. Sounds like common horse sense and good situational awareness won out that day.
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Fanatic-someone who won't change their mind and won't change the subject!
Chris: The VC-10 was one truly powered airplane if it could rotate and fly at SL with 2 out on a side. Vmca2 on the C-5 was fairly low, like the Vmcg, but flying off with 2 out would be hard to fathom except at very low weights, about 525,000 or less and favorable conditions. At that weight, Vmca2 would be close to V2. |
Look at the facts, read the statistics and then make your own mind up! Those that want to argue their points will always selectively select any facts that support it without regard to historical statistics. The belief being that if you accept their arguments that it will change the future statistics. |
Pilots who think Discount ....+1 Today 11:55 It sounds like he was detailing improper handling of RTO's and ---you can throw the best SOPs at any one but---if you can't correctly compute performance---then how that the fault of anyone---yes, you can force yourself to RTO after V1---but that's mostly pilot error--forgetting gust locks improper use of performance chart an improper configuration with the warning out---no one ever said there's Never a reason to RTO --and certain freak events [the DC-10 has had it's bad days:(]---but it will most likely be YOUR fault---but what if there's a 200' drop at the DER? or a gas station a group of row houses?---excepting freak events you --GO!!! period----it would take some resolve to take that shaking aircraft into the air---that's why you need heart!! split second decision have saved lives--such as when a United 767????---held off on rotation because of an incursion----or when the pilot forgot the gust lock on a Challenger 600??? and aborted at past Vr and flew into a building and they all lived---and sometimes Fate is a Hunter!!!! for the most part in 99.99% of cases you GO!---the other .001 cases perhaps could have been avoided and a few:( that's life---- that's flying---live with it--- die with it or get out!!! nuff said PA and no I'm not back pedaling I've said basically the same thing earlier |
With all due Respect
The wording of the question invites misunderstanding. Would you abort? Well, Yes, for obvious reasons, discussed here. The question implies discretion on the part of the Pilot. V1 means go, (Fly). It is a pre-decided V speed, and by definition, Removes (most) Pilot Discretion. Some Pilots, for reasons of inexperience or lack of understanding of English, will argue that V1 doesn't do what an experienced Pilot knows that it Does. If you like, whisper to yourself at Vef "Mother May I ?", then Launch, immature Ego intact.
Airfoil V1, that speed at which I will continue the Takeoff Roll in every instance except those in which I cannot Fly, in which case I won't. "I cannot Fly" : that condition in which, in my belief, the A/C will not Fly (God I better be right), or, the A/C refuses to Fly, (much better). |
Pardon my Trollfeeding lads, but someone's gotta do it! :E
There will always be an accidents where someone who should have flown, rejected, and there will always be accidents where people who should have rejected, flown. Interesting that Ssg would only use the accidents where continuing the flight leads to an accident and where aborting would lead to a successful outcome. Nice that the FAA has said that in cases where one elects GO, an overwhelming majority of cases leads to a successful result, and does not get reported... so the reasoning that SSg use is... moot to say the least. PK-KAR |
V1 is V1 end of story
V1 Is V1, if you cannot follow the rules dont play the game. You have to work in realtime not hindsight.:mad::ugh:
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Nightmare!!
SSG you would be the worst nightmare on the flightdeck in an emergency.
Move over fast fingers freddie, we now have Second Guessing Git or put simply the SSG factor. The time to start being dynamic and using lateral thinking and problem solving is not at V1. := |
Yes I would...if the plane didn't accelerate to VR, massive control failure..missle hit the wing...anything that I knew would keep the plane from flying up in the air, I would take my chances in the overun.
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Considering there is no useful information available at this time, and most parties involved in the upcoming investigation aren't even on scene yet, speculation is unprofessional, and inappropriate. One may rest assured that all the details will come out in good time.
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ssg at the controls?
Maybe ssg was flying the B747 and attempted to abort after V1. Very sorry, could not resist.
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