Citation Incident at Leeds

[Daifly]

Anyone know any more?

BBC News - Two rescued as aircraft overshoots Leeds airport runway (http://news.bbc.co.uk/1/hi/england/leeds/10260026.stm)

[doublesix]

CLDVRVR AND REDSNAIL

I can't see the relevance of your sarcastic comments. Please explain?

[Chinchilla.612]

I used to fly that aeroplane, and know the owner........afraid I don't see the same funny side you guys seem to about this :=

[baron_rouge]

I witnessed the incident from the Multiflight side of the airfield and it was definitely no laughing matter. The Citation was just airborne when the decision was made to abort so was travelling at around Vr and the pilot immediately put down on the runway (14). I'm not going to speculate on why he aborted rather than go around as only the pilot knows the full circumstances and it's a matter for the AAIB. We all know that a good landing is one you can walk away from so the good news is that nobody was injured.

[DX Wombat]

Engine fire - one person I spoke to said flames were clearly visible coming from the aircraft and no, I didn't put the idea into his head, he volunteered the information as he had seen it happen.* Lots of bits of debris all over the 34 threshold. Aircraft now roosting in a tree in the 32 undershoot. I'm really pleased the two on board got out safely.
* Baron-rouge - he probably had a better view than you did as he was parked on the elevated section of old road next to the cemetery at the end of 32.

[fastjet45]

"I witnessed the incident from the Multiflight side of the airfield and it was definitely no laughing matter. The Citation was just airborne when the decision was made to abort so was travelling at around Vr and the pilot immediately put down on the runway (14)."


Hate to say it; but if he was airborne and therefore past V1 why on earth did he consider landing again, wonder what was briefed prior to departure? were was he trained to land back on the runway after V1? :eek:

[BigNumber]

I don't think it our place to assess or make a 'morning coffee' analysis of the situation the crew faced.

Only the crew can possibly know the situation that they faced. I'm sure they will let the relevant authority know in time.

I am certain that there will be a compelling reason that they followed their course of action. Frankly none of us know anything at all other than a 'hear say' interpretation of what might have been half seen perhaps.

[Neon Circuits]

#2 and #3, use of so called 'comedy' is not appropriate, funny or welcome.

Reject after V1/VR? They were probably using the same value for both, perhaps they considered that they were light, on fire, plenty of runway? Depends if they rotated, all speculation please wait for AAIB.

[Uncle Wiggily]

got to be a consideration if light, on fire, plenty of runway

Maybe I'm not reading your post correctly, but after V1 is reached there is no decision to be made because you are getting airborne regardless. Prior to V1 you can abort and safely bring the aircraft to a stop, but to say to yourself after V1, "gee it still looks like we have more than enough runway, lets disregard that V1 call and keep the jet on the runway" defeats the whole purpose of assigning a V1 speed to your takeoff/data calculations. I can't imagine something written like that in this comapny's SOP's, lol.

Anyhow, I'm sure I misread your post.

[bingofuel]

There was an incident many years ago when an HS748 disgorged the right hand turbine blades through the wing just after take off, resulting in an uncontrolled fire on the wing.

The Capt put it down on the remaining runway in front of him.

If I recall correctly, the investigation concluded that had he tried to fly a circuit to land the wing would have burned through and detached. It was concluded his actions saved lives.

There is always an exception to the rule.

Lets stop the speculation and wait for some FACTS.

[Trim Stab]

Maybe I'm not reading your post correctly, but after V1 is reached there is no decision to be made because you are getting airborne regardless. Prior to V1 you can abort and safely bring the aircraft to a stop, but to say to yourself after V1, "gee it still looks like we have more than enough runway, lets disregard that V1 call and keep the jet on the runway" defeats the whole purpose of assigning a V1 speed to your takeoff/data calculations.


The FMS's that I have used on Citations (Collins 3000 and UNS-1) both calculate V1 and Vr by working out what values give a balanced take off for the aircraft weight, temps and pressures. The TODA is not a parameter that is used in the calculation. If departing from a very long runway, it is thus technically possible to abort after V1 and land back on the runway.

[Uncle Wiggily]

TrimStab:

Interesting. So, what was your procedure/decision once V1 was announced?

Thanks

[fastjet45]

The FMS's that I have used on Citations (Collins 3000 and UNS-1) both calculate V1 and Vr by working out what values give a balanced take off for the aircraft weight, temps and pressures. The TODA is not a parameter that is used in the calculation. If departing from a very long runway, it is thus technically possible to abort after V1 and land back on the runway.


:eek: So after V1 then VR how much runway have you used whilst airborne? how much runway is left? how much runway do you need to land and stop depending on how fast you are now going? I think you need to study performance again! of course TODA is a parameter V1 on a performance A aircraft is there for a reason; accelerate to and stop in the remaining distance or exceed V1 and continue to get airborne safely in the remaining distance to 35ft.

[CL300]

To best of my knowledge and information given by training providers and manufactures there has never been an instance were it was necessary to make such a decision due to an engine fire on a multi engined civil jet aircraft, they are designed to fly after such a failure.

Falcon 20 in LBG, Concorde at CDG, the only 2 that spring to my mind...
It is generally safer to take the problem in the air... uncontained fire/engine failure is not anywhere in certification...This is one of the reason , there is still pilots in flightdeck..

[hawker750]

It is very clear that nobody on this thread knows much about what V1 is. V1 can be a range of speeds depending on what you want it to tell you. Most small jets use V1=VR because it is convenient. All this tells you is that at V1 you can stop or go safely. Most small jets will use the same speeds (V1/VR) regardless of whether they are taking off from a 6000 ft runway or a 16000 ft runway, so in a sense TODA does not come into the equation. It only comes in if the runway length is limiting and the MTOW has to be regulated.
As to whether it is safe to land back after VR or abhorts after V1, the V1 speed will not tell you this information, only that the plane will safely continue. Great research has gone into this subject and concluded in no uncertain fashion that stopping close to V1 is not an advisable course of action. Why people continue to do so is a mystery, in light jets probably a throw back to light piston engine flying when flying on one (or nil) engines was not a very heatlthy thing to do close to the ground.
May I suggest similar to the citation ex Biggin where proper procedures and SOP's were not in place or followed?

[Chinchilla.612]

Fastjet45,
I think what Trim Stab was getting at was that the V speeds calculated from the FMS on that aircraft type do not account for runway length (except in so much as highlighting if the TODR is greater than the TODA). If you have a particularly long runway, you could in theory still have room to land ahead......but personally I would not be keen to do so. I do not get the impression Trim Stab was suggesting he would abort after V1, just that at the right airport it could be possible.

To answer your other points at Vr they should have used somewhere around 3000' of runway (rough figure). Once airborne the remaining runway is decreasing at a little over 200fps. If fully configured for landing (which they wouldn't be) it should be possible to stop in around 3000-3500' of runway. If I remember rightly, Leeds is a little over 7000' in length? So there could be something like 2 or 3 seconds while airborne to reconfigure if you wanted to land ahead successfully at Leeds in that aircraft?
Only approximate figures and depends how high they went before trying to land again, so please don't get too fixated on them.
Chinchilla.

[Trim Stab]

http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/eek.gif So after V1 then VR how much runway have you used whilst airborne? how much runway is left? how much runway do you need to land and stop depending on how fast you are now going? I think you need to study performance again! of course TODA is a parameter V1 on a performance A aircraft is there for a reason; accelerate to and stop in the remaining distance or exceed V1 and continue to get airborne safely in the remaining distance to 35ft


You should read my post again - I said "technically" it is possible if the runway is long enough. I did not say that it was an advisable procedure. Neither did I claim that TODA is not part of a performance calculation - I merely pointed out that Citation FMS's that I have used do not use it in their calculations.

On a VLJ not many runways are limiting and there are plenty of runways where you could actually get airborne, and still safely land back on the runway. At somewhere like Ramonskoye (18000ft runway) you could probably do it three times in a light CJ3.

[fastjet45]

On a VLJ not many runways are limiting and there are plenty of runways where you could actually get airborne, and still safely land back on the runway. At somewhere like Ramonskoye (18000ft runway) you could probably do it three times in a light CJ3.

Trim Stab

The whole point of my previous arguments: "probably do it three times"

V1 is a calculated figure, along with all the other performance criteria required before departure so that in the event of such a situation the crew have the best chance possible of executing the correct procedure instead of guessing. SOP's :ugh:

[Trim Stab]

Really? So if you took off at Ramskoye in a CJ3, and had an engine fire just after V1, you would continue, and try to climb and do a circuit to return to the threshold, even though you had some 17000ft of runway directly in front of you?

As I said, the FMS's on the CJ do not take into account the TODA, and there are occasions where, with a bit of experience, you can take V1=Vr.

[fastjet45]

Trim Stab


Really? So if you took off at Ramskoye in a CJ3, and had an engine fire just after V1, you would continue, and try to climb and do a circuit to return to the threshold, even though you had some 17000ft of runway directly in front of you?


Yes I would;
Because at that moment in time I and my crew would be in a position that we have been trained for, we would be following the manufactures SOP, we would have ensured that all the performance parameters had been met to operate safely from V1 to a landing, we would be in a position to deal safely with the emergency and inform ATC in a timely manor to ensure emergency services were at the correct point to meet us, we would have had time to brief the passengers accordingly, shall I go on?


As I said, the FMS's on the CJ do not take into account the TODA, and there are occasions where, with a bit of experience, you can take V1=Vr.


As I said before; how do you know if there is enough runway left, it depends how high you where, how fast you were going, what configuation you were in, do you brief such an event to your crew?
Were does a bit of experience start? and when do you become experienced enough to start guessing?

[Trim Stab]

depends how high you where


I said after V1, not after Vr.

So if you are still on the ground, and you have a major failure, you would continue the take-off, even with 17000ft of runway in front of you, just because a computer had incorrectly calculated V1?

[Uncle Wiggily]

TrimStab: If you were on a Type Rating sim check and you rejected after V1 and argue that you did the correct thing because you have ample amount of runway still ahead of you, that the examiner would still have to fail you.

[BizJetJock]

In the Piper Alpha oil rig disaster in the late 80's, all the people who followed the emergency procedures died. The survivors were all people who chose to actually assess the situation in light of the circumstances and followed a course that was expressly advised against.
Never is a very strong word.

[Trim Stab]

TrimStab: If you were on a Type Rating sim check and you rejected after V1 and argue that you did the correct thing because you have ample amount of runway still ahead of you, that the examiner would still have to fail you.


Absolutely - if I had used the FMS to (incorrectly) calculate V1, and had set that incorrect speed on the bug. I don't think many examiners would fail me though if I calculated the true V1, taking into account the TODA, and set that on the bug, and explained why I was doing that before the departure. I might try that next time!


Read your own statement!!!!!!!


I have done - I said after V1, not after Vr. But I see that you are being pedantic.

[Trim Stab]

In the Piper Alpha oil rig disaster in the late 80's, all the people who followed the emergency procedures died. The survivors were all people who chose to actually assess the situation in light of the circumstances and followed a course that was expressly advised against.
Never is a very strong word.


Plenty of examples in aviation too - SR-111 springs to mind.

[fastjet45]

I have done - I said after V1, not after Vr. But I see that you are being pedantic.


Trim Stab

What more can I say to clarify it for you, greater than V1 then GO thats the SOP :ugh: why then change your mind to try and consider stopping after V1

[Miles Magister]

Hawker 750, thank you for a very sensible post.

CL300, I believe that one of the certification standards of Part 25 is that an uncontained engine fire will not couse the loss of other flight critical items for a period of 5 mins. However I do not currently have access to the books and am not sure which model of citation it was, so whether it was a Part 25 or Part 23 certified type.

It is quite possible to land back on after V1 if the parameters are correct. However please remember that it is important to have done the calculations before the event and to operate as you train. If you do not practice the manouvre then do not try and fly it. Stick to what you trained for. Attempting a manouvre you have never seen before when there are many other variables you have never experienced before is normally one of the elements of the chain of disaster.

However the captain's decision is final and it is nice to be able to argue about it afterwards. I once landed well overweight with a cabin fire which could not be extinguished and received much criticism at the time even though we did practice it in the simulator, however when time proved that it was the best decision only one old pilot came back to say well done. You must make your decision, stick to it and fly it accurately.

MM

[7AC]

I suspect the younger pilots are the ones who will say keep flying and follow procedures and it is the older ones who say keep it on the ground. This was a small aeroplane and perhaps taking the fire into the air just might not be the best.
Time will tell.

[EESDL]

........or perhaps AAIB findings of Biggin incident on another Cessna confused their decision-making process?

Only speculating, like the rest of you as staff at FBO certain that aircraft was not airborne as 'eyewitness' on here has said.

Hindsight is wonderful - and I doubt we'll hear from pilot as A.C.E. will be in full flow.

Great to hear all ok.
I'm sure AAIB will reveal all - with or without a CVR.

N-reg, was it maintained/based at LBA?

[bingofuel]

This thread seems to have evolved into the 'we must always do it a certain way' and the 'sometimes we throw away the rule book' camps

At the risk of being accused of thread drift can I put forward a scenario.

Medium size jet, IMC, uncontained engine fire, duct overheat/rear bay overheat (possible APU fire), electrical problems, passenger with suspected heart attack.

You descend to your minimums of 200ft on the ILS at a major airport who was reporting overcast at 250ft ,with all the emergency equipment.

Nothing seen.

Do you, commence a go around and divert or do you continue below 200ft?

I had this scenario in a simulator, what would you have done.

[Sweet Potatos]

I'm with Bingofuel here, the same pilot with the same problem may do it differently on different days depending on he - and the problem - feels.

Speculation is ridiculous, we should wait for the facts.

Here is what I know, as someone who saw it from a vantage point shall we say. The pilot called "aborting" some way down the runway, the tower controller saw flames from his undercarriage - as did I - on the starboard side. Brake parts were found all along the runway. The pilot said something didn't "feel right" - now at which point that was, V1/VR and distance from runway end etc. is debatable and only the pilot knows that.

The question is, which came first, the undercarriage fire and then the abort or was it the braking after the abort which caused the fire?

Anyway, It happened, he managed to steer away from the localiser array and they both walked away and were evacuated when the AFS arrived.

Thank god they are ok. If there are any lessons to be learnt, we will learn them when the report with all the facts is issued.

[OutsideCAS]

.....okay....admitting i'm a little confused as sweet potatos' post seems to suggest a brake fire ?? or was it initially a rejection (T/O) due to an engine fire Master Warning etc. and then subsequent brake o'heat and fire ??

the only reason i ask is as there is a quote saying the pilot said "it didn't feel right" or words to that effect, am wondering if maybe there was a problem with the brakes rather than the engine ?? was there genuinely an engine fire or is the press report incorrect ??

:)

[Daifly]

Thanks for the helpful and unhelpful replies.

I just rather wondered who it was rather than whether it was careering towards a school, at closing time, while a bus of nuns were sitting whilst waiting to tend to the homeless.

[x933]

while a bus of nuns

Never been to the Leeds Bradford area, have you? :E

I was most dissapointed not to see a cross section of the replies in any of the national rags this morning...

[QWERTY9]

Which citation and type was it ?

[Pace]

Medium size jet, IMC, uncontained engine fire,

BingoJet

I had the sim guy give me 100 ibs of fuel a side an engine failure and 100 ft overcast and an RVR below minima :ugh:

What did I do? sod the cloudbase LAND.

Different horses for different courses!!! remember the Boston Airline crash where the Captain wanted to dump fuel and the co wanted to land?

Remember the football team (uncontained fire) the Captain landed from 200 feet up in the climb thank god he did.
What was that saying? rules are for wise men to question and fools to follow?

Pace

[bingofuel]

Did we have the same sim instructor? Yes I remember the football team in the 748, I mentioned it earlier.
I did much the same as you in my sim scenario, continued and landed.
Was I right or wrong?, were you right or wrong?
I believe I was correct, as did my co. and the instructor.
I made a judgement call based on my training, knowledge of the aircraft, the situation, facts available and experience. Is that not what a command decision is?

[Newforest2]

Type and reg.:)

ASN Aircraft accident 07-JUN-2010 Cessna 525 CitationJet CJ1+ N646VP (http://aviation-safety.net/wikibase/wiki.php?id=74703)

[hedgehopper]

http://www.pprune.org/biz-jets-ag-flying-ga-etc/343437-incident-jersey.html

HH

[G-SPOTs Lost]

Some replies on here are classic, so some of us would forego the 17,000 feet of runway ahead and go flying, the Leeds chaps deserve our full and frank praise as they both got out uninjured and even managed to evacuate prior to the AFS arrival.

Watch it burn as you look over your shoulder as you walk away

Full marks chaps.

I had the pylon fire/OEI/sick pax & wx below minima situation demonstrated to me me by a TRE in the sim, the procedure in the C550B was 71% N1 S/E and let the AP fly you into the ground if necessary - worked very well and always managed to get a reference.

It was derived from the "Full Flap when landing assured" perennial arguement

[Trim Stab]

I think that the more pertinent lesson here is that perhaps Cessna should certify an FMS that calculates V1 taking into account TODA/ASDA so that even an inexperienced crew can take advantage of a non-limitative runway.

Landing straight ahead after Vr on an 18000ft runway will have to remain the prerogative of the experience of the Captain...

[Mad (Flt) Scientist]

I think that the more pertinent lesson here is that perhaps Cessna should certify an FMS that calculates V1 taking into account TODA/ASDA so that even an inexperienced crew can take advantage of a non-limitative runway.

Landing straight ahead after Vr on an 18000ft runway will have to remain the prerogative of the experience of the Captain...

Agree 100% with the latter.

Disagree somewhat with the former. Almost by definition, the circumstances under which it is an appropriate decision to abort after V1, or after Vr even, are exceptional. Therefore, it is impossible to predict what the ACTUAL aircraft performance will be. So any calculation would be dubious. Ultimately, this is a question of airmanship.

For example, suppose you have a dragging brake, or a pair thereof. Only once they heat enough to generate smoke and flames is there any hint of problems, other than the accel (which is usually unmonitored, at least against a defined go/no-go, a topic for another thread I think).

By the time you get to the calculated V1 with dragging brakes your performance calcs are already shot to hell. Go? Nogo? Damned if I know. Certainly no chance of a default FMS calc telling you anything useful. You may already be too far down the runway to stop. You may already be too far down the runway to go successfully (never mind carrying a couple of brake fires into the air). You may, in fact, already be facing a choice between two very bad options, neither of which is in any way covered by type certification.

[Pace]

MAD

But in that scenario your V1 distance calculations would be meaningless too!
a dragging brake or problematic engine would extend the time and distance to achieve V1.

Maybe better to know your runway length and visually pick a spot which would give you a stopping distance and use that as your reference as whether to try and stop or not.

Pace

[CL300]

We are all trained to the certification line, V1, stop or V1, go is a day to day operation but every take off is different.
As said above, they made it out, fine, not even a hull loss, no real issue then.
Anyway, we do react to the training, and i hope that this captain will have the support from its hierarchy for not having followed the approved check list ( or memory item or whatever ).
As certification is concern, fire should not spread to vital components, but as numerous examples taught us, fire is nothing you can control, you barely deal with it. We can discuss the what-ifs for years, but they save their lifes , and this is really the main point.

[RAPA Pilot]

So if the Captain didn't follow the company SOP's or the manufactures recommendations is the aircraft still insured?

[Miles Magister]

RAPA,

My experience managing insurance claims is that insurance will not normally be invalidated by decisions on how to handle an emergency. They will only normally dispute the claim if the aircraft was deliberately operated outside of the policy terms which will normally include the legal requirements.

As I have mentioned here before, I used to use Hayward Aviation as the insurerers for aircraft I managed, partly because the policies I took out included liability protection for the pilots. This is something we should all ask our employers for as part of our contracts. I am not linked to Hayward, just found that they seem to understand business jet operations when I used them.

MM

[RAPA Pilot]

Thanks Miles, thats reassuring. I will ask mine for the policy details, I'm sure it would make interesting reading down route sometime.

[Pace]

partly because the policies I took out included liability protection for the pilots. This is something we should all ask our employers for as part of our contracts.

Miles

That is a very valid point we probably all need to check as it is always a worry flying multi million $ hardware that any of us could at sometime miss something which invalidates the insurance and leaves us liable.
I for one am going to check with the brokers.

If its not there do you know if adding liability protection is an expensive addon?

do you also know whether operating free lance through your own limited company adds any protection in itself? I have had mixed opinions on this.

Pace

[African Drunk]

The V1 speed was put in due to the Munich crash to stop overun's. I can agree that if you have 18,000 feet ahead then land back. However in Leeds and many other uk airfields that is not available. These a/c are certified to continue post V1 with a fire.

Many pilots have never had an genuine "may-day" emergency. The chx lists, SOP's and manufactures recommendations are based on learning from previous incidents. Where is the knowledge and experience coming from that says I will undertake a different course of action.

[Miles Magister]

Pace,

I can only offer my opinion and please be aware that it is opinion, although I believe it to be based on my personal experiences.

Your liabilities when operating as a freelance will depend entirely on the signed agreement with the client. I do not fly much these days but would always state my repsponsibilities and liabilities and exclusions in my assignment agreement. If you are operating as a company then it would be wise have at least 3rd party liability insurance yourself.

The insurance policies I took out included the liability option for whoever was flying the aircraft, not for named pilots and the total price was competative. I also made sure they included airside car insurance for any vehicle visiting that particular aircraft, something that is not normally covered.

I can always let you know my contacts by PM but do not wish to be accused of advertising here, especially as I have no contact with the insurers comission!

MM

[NuName]

This is not intended as a comment on any accident, but, "pilot error" has never invalidated an insurance claim, after all, that is a large part of what you are insuring youself for in the first place.

[Martin Barnes]

I had an engine out on a CJ a few weeks back at v1/vr so I took it into the air.

the bad engine was a cessna loaner which had a vibration problem which caused a weld on the main fuel feed pipe to the FCU to fracture leading to zero fuel flow and a massive spray of fuel into the engine compartment.

I rather be airbourne with a 160kt airflow blowing the fuel out the back and creating plenty of time to evaluate the situation, shut it down and return which is what happened.

be aware there may be a few more of these faulty fuel feed pipes out there, the tell tale signs include a small fuel leak from the check pipe under the engine cowl and a slight hesitation on the N1 when applying take off thrust.

the MOR we filed should lead to further investigation. There is an old AD citing the fault part numbers .

I firmly believe its better to take the problem into the air rather than risking
an overun, blown tyres and the possibility of a bad fire due to the lack of a strong airflow to blow it out and besides you will be working on controlling the aircraft rather than firing the bottles.

discuss !!!

[Fokkerwokker]

Martin

I concur

[NuName]

If I had a fire on or about ROTATION, if I had 2,3 or 4 times runway legnth left for a SAFE touchdown, IF I had all this knowledge at that milisecond, I would not get airborne. I once had an "incident" on rotation, not fire related, I cut the throttles, landed and ended up in the grass, best decision I ever made. I do not condone anything that is not a part of a good solid training environment, but, it has to be remembered, almost all safety training is a generalisation, blind adherence may not always save you. Swissair airborne fire springs to mind. Getting airborne takes away quite a few alternative options, one important thing is, you can't run away. The whole idea of getting airborne and dealing with it as an airborne emergency is only to facilitate a safe landing, if the bit between departure and arrival can be dispensed with, SAFELY, why not. I wait patiently for the abuse :rolleyes:

[NuName]

BA 777, Heathrow?????????

[10DowningSt]

Just a little question, please, in an interesting thread which caught my eye......where in the world (apart from the one cited earlier and perhaps a salt lake or two in the USA) are these 17-18,000 ft runways? Are they relevant to the discussion?

I have been long involved in the same argument as applied to single-engined aircraft and using the full runway so that there's a fighting chance of landing straight ahead when it all goes quiet at 300ft. My heart sinks when I see a student being told to use an intersection by ATC or - worse - an instructor.

[Chinchilla.612]

10DowningSt,
Whilst not quite as long as that, we are not far off it here in Doha (OTBD) with 15,000' of runway.
We still plan on post V1 being a go speed though...........

[10DowningSt]

Thanks Chinchilla, I had forgotten Doha; oddly since I was at the meeting where the Ruler decreed that it was to be the longest in the world. He understood perfectly well that this was not technically needed!

There are a zillion good reasons why keeping flying post V1 is the better option in almost every circumstance. But there is always the unpredictable and unpredicted case which might change things if one of the decision factors is the possibility of landing ahead and stopping in or before the RESA.

[JEM60]

Used to p..s off the controllers at Luton years ago when flying a 172, and they asked me if I wanted the extension. I always took it. The runway ahead always looked a better bet than the Vauxhall factory car park if it suddenly went quiet!!! Few things more useless than runway behind you.

[Pace]

There are a zillion good reasons why keeping flying post V1 is the better option in almost every circumstance.

I would agree with the above statement for 9 out of 10 situations but then It is also important to think out of the box.
On very long runways i will know what STD my aircraft needs (stopping distance :) look at the runway chart and pick a feature along that runway which will give me a decent STD :) and use that visual point as a go no go.
It is pretty stupid on a runway which could have a Citation Take off 3 times to get airbourne with the normal V1 rules in the first 1/3 of the runway.
But that is only on long runways.

Pace

[Chinchilla.612]

Pace,
Fair point, but also bear in mind that the stopping distance required may also vary depending on the nature of the problem.
I know of one CJ that took roughly 10,000' to stop after blowing a tyre (before V1), so to be fair even go/no go won't work every time at every airport.....V1 is a good safety speed for "most" situations though and that is the point of it.
Also, for the point of where this discussion started lets not forget that Leeds does not have a runway long enough for a Citation to take off and land once (safely), never mind 3 times eh.
Chinchilla.

[deefer dog]

On very long runways i will know what STD my aircraft needs (stopping distance http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/smile.gif look at the runway chart and pick a feature along that runway which will give me a decent STD http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/smile.gif and use that visual point as a go no go.Sorry Pace but I don't think it is possible to "know" this stopping distance when considering weight, altitude, temperature as well as brake energy.

In respect only of Vbe (brake energy), E =1/2MV2 tells us that a stop commenced at only 20 kts more than a 100 kt V1, (typical of Citation I would guess) will actually require 44% more brake energy to bring you to a halt. At 30 kts past V1, the required brake energy will be nearly 70% more!

It's pretty had to stop an aircraft when there is no energy left in the brakes, or with blown tire fuses.

[Pace]

Deefer

The problem with that is that you are talking about ANY above VREF landing.
naturally if you are off the ground at say 50 feet and put it back down at VREF+20 your stopping distances will increase dramatically but so would the case be if you land at VREF+20 on a normal approach and landing.

That would also change in both situations if you were on a soaking wet runway or a dry one etc.

I am not advocating chucking away the V1 rules but suggesting that in certain rare occasions it may be better to think out of the box on the RIGHT runway and come back to a stop!

If that means taking out a hedge at 20 kts then what is better THAT or diving into the ground at 200kts plus only the end result will tell you!

Pace

[deefer dog]

Pace,

I'm not inclined to argue with you but now you seem to be talking about landing distances, and not rejected stop distances. In response to my post above you state:

The problem with that is that you are talking about ANY above VREF landing.No I was not talking about Landing REF speeds. In my post I was referring to the rejected take off - that is what the thread is about. You tell us that you can judge with your aiming point method how much runway is required for a rejected take off above V1, and I simply pointed out that there are a lot of factors - not least of which is brake energy. Unless you have a great deal of experience of high speed rejects I would think it unlikely that you could possibly "know" how much distance your aircraft could stop in if rejecting above V1. The manufacturers don't publish such data.

if you are off the ground at say 50 feet and put it back down at VREF+20 your stopping distances will increase dramatically but so would the case be if you land at VREF+20 on a normal approach and landingYou now seem to be changing the concept from the rejected scenario to that of landing distances at speeds in excess of Vref. This is a completely different subject, due to the fact that LANDING distances, by their very nature, start from the beginning of the runway, not half way down it!! In the Citation (which we are talking about here) there is no possible event that should cause you to be touching down at speeds in excess of V1 half way down the runway, even flapless at max gross wieght!!!

If you are inclined to argue the point, please let us know how you calculate your "known" stopping distances when deciding to reject AFTER V1. Please quote an example using a standard day, sea level, zero wind in your Citation at gross weight, with a reject at 5kts above V1 and tell me how much distance it will add to the published Balanced Field Length...and how you calculate it?

[Pace]

Deefer Dog

due to the fact that LANDING distances, by their very nature, start from the beginning of the runway, not half way down it!!

I know a few pilots who half way down it aint far off :E

I just had a quick look in a 500 manual which is the baby of the 500 series.

Sea level, standard at grosse is just over 2300 feet landing distance so use that as your ref point. On a 10000 foot runway that gives you a new landing point at 7700 feet down the runway or make it 7500 feet if a good visual marker is at that point and you want a bit more.
As you will use 3000 feet to get to V1 that leaves you with 4500 feet of free runway to play with before you need to land or whatever from V1.

You will be quids in on a V1 stop so a good safety margin.
Take a 10000-12000 foot runway and you will have used around half the runway to get to takeoff speed and stop leaving you enough to do it all again so in a severe engine fire why go?

Like with the 748 Stanstead Leeds fire where the aircraft was seriously on fire and the pilot actually landed back you have to beg the question even if you take out a hedge is that better than diving in from altitude?

http://www.aaib.gov.uk/cms_resources.cfm?file=/3-2001%20G-OJEM.pdf

Read section 2.1.2 which deals with post V1 Stopping and the CAA comments that had the aircraft continued the takeoff to a circuit and landing that it was very unlikely that it would have made it back. The aircraft was between 200 and 600 feet up when they decided to land on the remaining runway.

I am NOT suggesting braking the V1 rules for takeoff as a norm far from it! but saying that in certain rare situations thinking out of the box may just save you.

And at Heathrow who needs brakes??? ;)

09L/27R 3,901 12,799 Grooved Asphalt
09R/27L 3,660 12,008 Grooved Asphalt


Pace

[orion1210]

From what I gather, both engines were servicable at the time of leaving the runway.

[DX Wombat]

From what I gather, both engines were servicable at the time of leaving the runwayJust interested, if what you say is correct then where did all the debris come from which was scattered all over the 32 threshold? It was all being catalogued and photographed so presumably came from the aircraft engine as the aircraft didn't disintegrate.

[orion1210]

Brake unit(s), wait for the AAIB report. I didn't want to see this thread continue in the wrong direction!!

[Pace]

Hi Viz

Just imagine you were having this discussion with the pilots of the 748 incident (link above) They were actually commended by the CAA for thinking out of the box, ignoring standard prcedures and landing back.

It was also accepted by the CAA that had they attempted a circuit back to a new approach and landing that the aircraft would not have made it.

Yes you are correct as V1 and VR are very close in the Citation we are in reality talking about landing back which would mean re configuring the aircraft to full flap and the correct VREF.

No its not something I have practiced hence the discussion here but it is something that runs through my mind when I am lined up on a 10-12000 foot runway knowing that 1/3 down that runway I will be airbourne with if you like a new runway and touchdown point in front of me.

We are getting lost with the whole V1 arguement because in reality we are talking about being airbourne.
We are not talking of an aircraft with a large speed spread between V1 and VR meaning a descision to brake and abort post V1 but before VR!

Maybe the arguement should be whether you fly a complete circuit to place yourself back at the start of a 10-12000 foot runway or use a 5000 foot new runway in front of you?

With the Citation at a small airport 5000 feet maybe all you have anyway ;) so why fly off when you are already on very short finals for a 4 to 5000 foot runway ahead?

Finally we are talking about some awful situation which may make you consider " do i put this baby back down on terra firma or fly it maybe another 12 nm to get a chance of putting it back down again".

It could be even a worse scenario with an overcast ceiling at 400 feet and an RVR of 800 metres meaning not a visual circuit back to landing but a much longer procedure while handling a major failure in IMC icing surrounded by high ground etc.

It may never have crossed your mind but it has mine and I hope the what if never occurs but landing ahead is an option? whether it is the correct option is the big question.

Pace

[Opsbeatch]

What's the old saying?

'It's better to be on the ground wishing you were up in the air than up in the air wishing you were on the ground...'

Boys done well, glider pilot myself, any bit of ground will do!!!

OB:ok:

[deefer dog]

Ok, it's clear now...

"blah blah blah....after 80 we will only stop for loss of thrust, engine fire, loss of directional control or runway incursion. Got that? Good. Right, now can you see those two hedgehogs down there? No not those two there you retard, those two on the right side! Yes, them. Now today, we will use those as our emergency V1 - err, lets call it V1E just so there's no confusion, cos we don't want any of that do we? Good. Now, assuming that they don't move, and if something really abnormal happens, like....well I don't know, but err let's say a big engine fire, not just a normal one, and say for example it coincides with err, let's say the bosses wife notices the fire, or starts moaning about the cabin temp or something like that, well then we will use V1E - that's the hedgehogs. Get my drift? Is that all clear? Right okay, it's you leg today, so I'll set the thrust for you and I'll keep an eye on the hedgehogs...just in case. Any questions?

What? Are you taking this piss? Be serious! If the hedghogs move onto the runway we'll already be flying you idiot, so what's the problem, we just contine over them! Oh **** it, I can see this is too complicated for you - I'll fly this leg - don't touch anything - just look at the hedgehogs!

[Pace]

Deefer

I do not know a scenario where you may need to land back but they had one in the 748.

Flight before Christmas Co forgets to close door, door insecure light fails, door comes open, Large Christmas Turkey goes out of door through engine showering stuffing all over the place worse than Ash.

Owner drops Brandy bottle folowed by fat cigar interior on fire, both Captain and co about to pass out due to inhalation of owners wifes latest perfume, The RVR drops to below minima on touchdown end of runway while cavok on the rest. Pilot remembers he has forgotten to fuel aircraft and blames co. Co is bursting and relieves himself shorting out all the latest displays so blank screens ..............

I thought hedgehogs were protected creatures and either had an underpass below the runway or mini traffic lights to let them cross?
If they are on the runway you will just have to take them out even if it means punctured tyres

Deefer enjoyed reading your post :D funny

But I will add I dont discount anything in aviation and that includes 7000 feet of runway ahead of me when the wheels leave the ground. I dont care how many hedgehogs are on it!!!

Pace

[Miles Magister]

Many years ago when we did every t/o calculation by use of a graph, quite often by D&X, we had a low V1 and a high V1. The low V1 being where we could still get airborne following the failure of a critical power unit and the high V1 being when we could just stop on the runway available. On a long runway there could be a significant range between them. This does not seem to be considered in modern business jets.

The captain would nominate which V1 we were using in his takeoff brief.

[DX Wombat]

Thank you Orion. :ok:

[Mad (Flt) Scientist]

Ah, but fastjet, are you sure you understand the limitations of that V1 calculation?

v1 is intended to cover the range of LIKELY failure conditions, and as such, the normal procedures associated with its use can be followed in the large majority of the events you may encounter.

But a speed above v1 does not guarantee successful flight - it doesn't even, in fact, guarantee flight at all. Nor, for that matter, does a speed below v1 guarantee a successful stop. When that lightning bolt strikes from a clear sky, the assumptions behind the V1 calculation are out of the window. At that point all that is available is airmanship, and the best course of action may be that which goes against the normal procedures, because the scenario itself is so unusual.

[CL300]

Well actually, it covers ONLY the loss of thrust at VEF; anything else is just a plane....V1 is just a point on the runway where the decision "taken" at VEF is applied ( stop or go); past or before VEF, test pilot territory.
One will always find an occasion where stoppping pass V1 was a sensible action; however generally speaking it is safer in the air, all things behing considered.

All this leads to the fact that we do not have Automatic take offs; needs some fuzzy logic to a decision; need better sensors, and "political" decisions...

Fly safe past VR...

[Pace]

I witnessed the incident from the Multiflight side of the airfield and it was definitely no laughing matter. The Citation was just airborne when the decision was made to abort so was travelling at around Vr and the pilot immediately put down on the runway (14). I'm not going to speculate on why he aborted rather than go around as only the pilot knows the full circumstances and it's a matter for the AAIB. We all know that a good landing is one you can walk away from so the good news is that nobody was injured.

FastJet

Firstly this is a forum for discussion where we can in safety challenge and discuss and take apart established principles before coming to personal conclusions.

No body but a fool would ignore V1 and I have not seen a post where that is indicated.

This was about a Citation which had a serious fire and where the pilot decided to put down as the witness statement above indicated.

As it happens with the CITATION V1 and VR are so close as to almost be one so we are not discussing a V1 matter but simply are there any situations where you are better putting the aircraft back down rather than flying another 12 NM to Land.

The Stanstead Leeds 748 crash was one example where the pilots were commended by the CAA for ignoring procedures I suppose you would put them in your little black book as pilots you would not employ? Personally I would employ Pilots!

So I say again on a long runway ie 10000 to 12000 feet (Leeds is relatively short) with a serious fire internal or external do you IGNORE 7000 feet of perfectly good runway remaining in front of you and take to flying a circuit or even worsen the problem by putting you in IMC or do you do what these guys did?

On a 10000 to 12000 foot runway in a CITATION not a 747 I am not sure!!! The circumstances would probably dictate ??? i hope none of us are faced with that decision with a major fire on board.

We all are trained to operate to procedures and do so. Occasionally an incident occurs which is unusual call it "out of the box" where following procedures MAY not be the best decision.
Because we discuss it doesnt mean we flout procedures far from it. I hope it shows we are thinking and questioning pilots no more no less.

These pilots may have continued the takeoff dealt with the problem in the air flown round on one engine and landed with no damage to the rest of the aircraft there again they may have also crashed we will never know.

Thankfully they were not injured running off the end of the runway but at Heathrow they would not have run off the end of the runway and that is the question in my mind.

Pace

[eckhard]

Previously posted on another thread, but felt that it might be relevant here as well:

A few years ago I had a main-gear tyre that disintegrated shortly before V1 in a CJ1.

All my training told me to continue the take-off.

If I rejected at this speed, we would only have a fraction of the full length of the runway in which to stop and the braking effort would be reduced due to the damaged tyre.

If we continued and got airborne, we could leave the gear down, complete any required checklists, reduce our landing weight to a minimum and then land on the full length with the fire crews in attendance.

All these thoughts went through my mind in a short time-frame.

While I was pondering this ‘received wisdom’, the aircraft was shaking and vibrating so much that the instruments were unreadable.

We were drifting to the right of the runway, towards scrub and rough ground.

There was still quite a lot of runway remaining ahead.

What did I do?

Did I make the right decision?

What did I learn?

I stopped.

Why?

Because I was scared that we were going off the side of the runway at high speed and I figured that if that happened, I would rather be slowing down already instead of blasting along at full power.

I wasn’t sure that we could get airborne before we left the paved surface, partly because the ASI was unreadable with all the vibration. Also, although I felt that the swing and vibration was caused by a tyre problem, I was not certain that some other damage to the flight controls, engines or structure had occurred.

The 'bottom line' was that the aircraft was in effect 'out of control' and I wanted to get it back under control. The simplest way seemed to be to close the thrust levers and hit the brakes. The decision was influenced by the fact that my last memory of the ASI was that it was below V1 and that there seemed to be quite a lot of runway remaining.

We closed the thrust levers, applied brakes (deployed the speedbrakes as well) and were worried to find that the RH brake pedal was 'floppy' and had no effect. The LH pedal seemed to be working but that gave us a yaw, which, although in a beneficial sense to start with, was going to give us problems eventually......so we took our feet off the brakes and used the manual emergency brake handle.

As this was happening, the vibration stopped and the aircraft adopted a right-wing-low attitude. The rudder was effective in helping us regain and maintain the centreline until the speed reduced.

We slid to a stop on the centreline with about 2,000ft of runway remaining. Everything from that point on (shutdown, ATC comms, Fire Services, etc) was as ‘routine’ as you would expect.

On inspecting the damage, the RH tyre had completely disappeared, the RH wheel rim was worn into a ‘D’ shape, the RH flap, gear door, lower wing and tailplane had impact damage from the rubber fragments and the RH brakes were leaking fluid.

There was a bright metal skid mark leading back from the RH wheel down the runway, which then changed into a black rubber skid mark.

The ‘balanced field length’ for this take-off was about 4,000ft. We had a 10,000ft runway and we elected to use the full length. OAT was about 32C and the elevation was about 1,000ft.

We used 8,000ft of runway, about double the ‘book figure’ for the conditions. I think this is explained by the following factors:

* We were very close to V1 when the problem occurred;
* We took a few seconds to recognise, control, analyse, and decide; and
* The braking effort was not 100%.

Did I make the right decision?

Based on the successful outcome and the actual damage inflicted on the aircraft (over $100,000 repair bill) I think on balance it probably was the right decision. Had I managed to get the thing airborne, I think in retrospect it would have been flyable. I would have kept the gear down and eventually would have landed back on the full length of the 10,000ft runway. Against that, the extensive damage that I saw after the event helped to convince me that keeping it on the ground was the right thing to do. I did have some doubts during the initial few minutes after we stopped: ‘Were we above V1?’ ‘In the simulator, we were trained to continue the take-off.’ ‘Could I have got airborne before going off the side?’ etc, etc.

On the other hand, if we had got airborne, we could have had jammed elevators, jammed flaps, fuel leaks, etc. The damage was serious enough that all of these ‘nasties’ were a real possibility.

To be perfectly honest, I just had a ‘bad feeling’ as we were sliding towards the side of the runway, and ‘self-preservation’ over-ruled the theoretical training which was going round my head at the time. It was almost instinctive to close the thrust levers.

What did I learn?

1. Self-preservation is a very powerful impulse; it can be difficult to resist even if your training tells you that another course of action may be appropriate.
2. Balanced field lengths assume timely and correct action in the event of an RTO. They also assume that the brakes will be working correctly.
3. The old adage, ‘one of the most useless things is runway behind you’ is true! Intersection take-offs are of course fine, but the full length is better!
4. Burst tyres can cause loss of control, severe difficulty in reading the instruments and lots of structural damage.
5. A real ‘event’ is probably going to be quite different to what you have seen in the simulator.

Who knows what the guys at Leeds were experiencing when they made their decision? OK, they appear to have aborted above V1, but if they genuinely felt that the aircraft was not safe to fly, and given that they walked away from it, why are some of us so quick to criticise them? Had they continued the take-off and then subsequently suffered a loss of control or structural failure, would they be heroes for following SOPs, or idiots for not following their 'gut instinct'?

I have flown with the captain involved more than once and would rate him as being at the 'high end' of ability and airmanship.

Eck

[Paradise Lost]

Excellent post by Eck....in particular his: What did I learn?1. Self-preservation is a very powerful impulse; it can be difficult to resist even if your training tells you that another course of action may be appropriate.2. Balanced field lengths assume timely and correct action in the event of an RTO. They also assume that the brakes will be working correctly.3. The old adage, ‘one of the most useless things is runway behind you’ is true! Intersection take-offs are of course fine, but the full length is better!4. Burst tyres can cause loss of control, severe difficulty in reading the instruments and lots of structural damage.5. A real ‘event’ is probably going to be quite different to what you have seen in the simulator.I totally agree with each of his 5 points, and specially No.5 because most times the aircraft does not behave as expected from simulator training.In this whole lively (and surprisingly tolerant) discussion, many have expressed their opinions as to what decisions they would make depending upon TODA/circumstances etc. Personally I fall in the camp of post-V1, get airborne. The few examples of pilots aborting post V1 and getting away with it are far outnumbered by those who "went" and managed the emergency in the air, as per their training, and recovered safely. Somewhat like the discussions about wearing safety belts in cars....everyone knows someone who survived because they were thrown out of the vehicle because they weren't wearing their seatbelt, but there are no stats for the vast majority who survived because they WERE wearing their belts.For my controversial input, rather than the Go/No Go at V1 topic, I'd like to suggest that the Take-Off brief be amended from the "Before 80 kts stop for anything etc." to take into account the prevailing conditions of TORA, weather, A/C weight, etc. In most of the corporate jets today, the "decision time" between 80 kts and V1 is so short that for the PF to transition from take-off to abort, from the PNFs Stop/Stop call, the a/c will almost certainly due to accelerative inertia, have reached V1 anyway. So in order to prevent the tediously repetitive recital of the Take-off poem, why not, when runway permits make the "Stop" decision for ALL discrepancies at V1, thus obviating the need to work out whether it's a pre-80 kt or post-80 knot problem. I shall await incoming flak!

[OutsideCAS]

With all the aforementioned in mind with regard to this incident, i will admit to being a little curious as to whether most C525 guys do their renewals in a simulator or if it's done in the aircraft ?? the only reason i ask as if as i suspect, it's mainly in the a/c, then perhaps a lack of exposure to all the "whistles and bells" including the relevant flashing lights when simulating engine failures etc., may make it a startling event (even though trained for) when it actually occurs and therefore can lead into a temptation to reject a T/O after V1 ?? - please note, i'm not suggesting this is the case in this instance, or any other for that matter, just throwing the idea "out there" for discussion.

[eckhard]

Paradise Lost I agree wholeheartedly with your general policy that 'post-V1, I'm getting airborne'.

I think one of the interesting points during my event was that I wasn't convinced that we could get airborne before running off the side of the runway. Although I was sure that the failure itself occurred prior to V1, with the delay in recognition, etc, it's quite possible that the abort was initiated beyond V1 but I can't be sure as the instruments were unreadable due to the vibration.

I also agree that having an extra criterion at 80kts in a light jet can be unnecessarily complicated, especially on a long runway. On a 'short' runway however, it may help to focus the mind on the 'go case' if one restricts the reasons for a 'STOP' call above a nominated speed (typically 70 or 80kts) to a short list (red lights, etc). I suppose it all comes down to how confident you are of the success of a Rejected Take-Off at a speed close to V1 under the prevailing conditions. On a long runway (as in my case), you have the comfort factor of knowing that you could stop for 'anything' up to V1 and stop relatively easily. On a short runway, you would be more likely to be 'go minded' for a minor failure, as you would be aware that the margin for error in accomplishing the RTO manoeuvre was much smaller. That's when a distinction between major and minor failures might be appropriate.

Bral I didn't know it was a tyre failure until I got out and had a look at the damage.

I suppose I could have started my post by saying, 'A few years ago I had sudden severe vibration, steering difficulties and unreadable instruments shortly before V1 in a CJ1, all of which led me to believe that I had some sort of tyre failure.' I was just trying to convey the essence of what happened in an economical way.

The shaking was so severe that I was actually concerned about structural damage. That, combined with the steering problem convinced me to reject. I didn't immediately try to decide whether it was a tyre deflation or failure; there were no 'lightning fast reflexes and abilities' (but thanks for the compliment anyway). I was simply trying to stay alive by avoiding going off the runway into the bundu at 100kts +.

On a Perf A aircraft V1 is V1; unless the aircraft won't fly, you get airborne. I suspect there a few who are incapable on taking that onboard or think it better to ignore their training and justify their decisions with too much bullsh!talk after the event.

I'm not sure that your statement is relevant to my post; Firstly, the symptoms appeared before V1; secondly, I wasn't sure that the aircraft would fly (subsequent viewing showed that the damage to the flaps, wing and tailplane was quite severe and there was a possibility of elevator jamming due to rubber fragments); and thirdly, I don't think that my actions would indicate that I ignored my training, nor that I am incapable of taking the concept of V1 onboard. I could have described another incident in a 737-400 when we got a momentary stick-shaker just as we got airborne. We continued and sorted it out before landing uneventfully.

I'm sorry if you feel that I'm trying to justify my decision with bullsh!t talk after the event. I welcome any constructive criticism and if anybody can explain to me that what I did was wrong, please go ahead. I'd be the first to admit that I've made some bum decisions during my career. I felt it would add to the debate to describe my experience and some of the thought processes. If you believe I made a mistake, I'll take it on the chin and try and learn from your opinions.

I do ask that you re-read my post first and you may see that we agree on the fundamentals!

Thanks for the input anyway!

Outside CAS I think you've hit the nail on the head. I've conducted (and been subject to) many recurrent checks in the aircraft and the sim, and it's true that for 'procedural checklist' training, the sim wins hands down. For stalls, steep turns, etc, the aircraft is better. I'm sure there is a difference in crew reactions if they have never seen the 'bells and lights' until they get an actual problem in the aircraft.

Eck

[bingofuel]

Outside CAS, I think you have raised a very valid point. If you have not experienced emergencies in the sim with all the bells and whistles, then the first time something such as a fire warning sounds for real you are having a new experience, and as such cannot have practiced for it. Having an examiner close a throttle is virtually an expected event, as you can see him move. The sim is much more realistic and a far better training aid.

Recurrent training at FSI or similar is a lot more expensive than an hour in an aircraft. Unfortunately some owners or operators put cost before competance or at least effective training.

I am not making any comment as to the crew involved as I do not know where or how they trained, just making a comment for discussion.

[His dudeness]

Eckhard, I liked your first post. One could just learn from it.


I also agree that having an extra criterion at 80kts in a light jet can be unnecessarily complicated, especially on a long runway. On a 'short' runway however, it may help to focus the mind on the 'go case' if one restricts the reasons for a 'STOP' call above a nominated speed (typically 70 or 80kts) to a short list (red lights, etc).

One classical case especially for the small citations is the Power Brake Low Pressure light below 80kts. Some guys I do checkrides with brief that they will stop for any light below 80kts and only for a red one bewteen 81 and V1.
Rejecting for the power brake low pressure light at, say, 79kts can lead to a problem, on a short runway....

[His dudeness]

Spot on, I like many others did all my initial training in the aircraft, and didnt see a sim for years. When I did it was a real eye opener!

+1. I flew the first CJ2 in Europe and did the rating on the airplane since no slots were available at the time. Went to the sim 6 months later and I´m really thankful that Clive Cessnas products are usually reliable.

I´ve said it before and say it again, instead of the most things JAR and EASA have introduced to increase safety they should have put the requirement for sim training into their regs and that would have a way higher impact on safety.
I`d gladly turn in my CRI licence...

[DFC]

I think that everyone has been talking about two separate issues.

1. The go/stop decision.

With a very very long runway, it may be possible to accelerate to cruise speed and still stop.

However, the V1 speed has to respect the maximum tyre speed so that reduces the maximum speed since it is no good trying to accelerate past a speed where the tyres start to fail.

This speed may also be too high for the brakes (Vmbe) which depends on brake applications during taxi, turn round time etc etc etc. So this may further reduce the V1 speed since it is a bit silly to slam on the brakes at a higher speed than they can stop you from.

Finally, it has been found that it is more efficient to fly the aircraft than to drive it so the manufacturer will have a rotation speed that is set a safe margin above stall and Vmc where it is a good idea to start flying.

Now here is the important bit - one you rotate and start flying you can not abort because it is too late - you are flying - no matter what you do next you have taken to the air and it is too late to change your mind.

Therefore V1 can not ever be more than Vr - ever.

Please read that last statement several times before reading the next.

2. Dealing with an emergency in the ai (even if it is at 10ft and the airborne time is only 1 second).

When airborne and faced with an emergency, the PIC is quite entitled to land the aircraft on that open space in front of them - be that a straight piece of tarmac (that just happens to be the same runway they departed from), a highway or farmer brown's field, it makes no difference. The PIC uses the information available, time available and their knowledge / skill to do the best they can.

So for all those that think landing back on the runway is aborting the take-off, please think again. Once you have left the ground the ability to make a choice of not leaving the ground has passed.

[His dudeness]

However, the V1 speed has to respect the maximum tyre speed so that reduces the maximum speed since it is no good trying to accelerate past a speed where the tyres start to fail.

This speed may also be too high for the brakes (Vmbe) which depends on brake applications during taxi, turn round time etc etc etc. So this may further reduce the V1 speed since it is a bit silly to slam on the brakes at a higher speed than they can stop you from.

DFC, has anyone suggested taking the aeroplane past max tyre?

Lets use the numbers for a CJ...
Highest V1=109 KIAS.
Highest VR=109 KIAS

Highest Vref=113 KIAS (for MLM)
Highest Vref for flaps inop in icing= 138 KIAS
Max Tyre 165 KIAS

I guess taking the airplane 56 knots over V1 was not intended by anyone. Even - if we talk brake energy - going 29 KIAS faster was not what we discussed here I think. BTW, it would require really hard work to keep the airplane on the ground at these speeds.

Brake energy tables in smaller Citations are really simple...meaning: you can stop the airplane from 138 KIAS within ALDR x 1,45 (IIRC) [or higher], to lazy to crawl through th manual, but I think they nowhere mention speed in these tables.
Cessnas are made for simple minds such as me.

[DFC]

I think you have missed the point I was making.

Everyone was getting confused with applying V1 and the balanced runway concept on very long runways. Therefore I was pointing out that on a long runway that while in theory a stop could be made from a very high V1, there are other issues preventing V1 from being very high.

As for tyres - don't forget that it is groundspeed that will really be the tyre limit because that is what causes the stress on the tyre. So if you have 225mph tyres then you can not travel down the runway at 225mph and a 10 Kt tailwind and be within limits.

Therefore in a situation where the TAS is a lot higher than the IAS and there is a tailwind, you might not have as much a margin as you think - unless the limit speed has been set a long way beyond the maxc you will ever use.