why not stabalise engines with brakes on?
Guest
Posts: n/a
It has taken me about 3 days to pluck up the nerve to enter this high powered debate with some obviously very knowleadgeable individuals. I fly very light metal by comparison (to anything 
), so please bear with me.
How do these manufacturers' performance figures translate into 'real life' when used by a pilot of average ability in a machine of some age, maintained to some 'average' standard? I realise that these data can be considered as Factored Performance Data, but how realistic are they? What margins (if any) do you add?
....Puts on flame proof undies and steps back....
------------------
-.-- --.- -..-
[email protected]
), so please bear with me. How do these manufacturers' performance figures translate into 'real life' when used by a pilot of average ability in a machine of some age, maintained to some 'average' standard? I realise that these data can be considered as Factored Performance Data, but how realistic are they? What margins (if any) do you add?
....Puts on flame proof undies and steps back....
------------------
-.-- --.- -..-
[email protected]
Guest
Posts: n/a
CB
This is the problem of concern - in regard to accel stop, there is essentially no useful safety margin for a critical refusal.
In general the certification data is quite reasonable and, if you can replicate the circumstances and conditions, such data will stand you in good stead.
However, for an old bird in not too brilliant a condition, and especially with unpleasant ambient and runway surface conditions, this throws a heavy, greasy spanner into the works.
An operator's factors ? ... therein is the 64 dollar question. The simple matter is one of just how measurable and repeatable are the real world conditions. Hence my suggestion that the operator has to establish his own comfort position, somewhere on the conservative side of the minimum standards. Not an easy ask in a competitive world - but try a nasty court case after the event to put it all into perspective ...
[This message has been edited by john_tullamarine (edited 03 June 2001).]
This is the problem of concern - in regard to accel stop, there is essentially no useful safety margin for a critical refusal.
In general the certification data is quite reasonable and, if you can replicate the circumstances and conditions, such data will stand you in good stead.
However, for an old bird in not too brilliant a condition, and especially with unpleasant ambient and runway surface conditions, this throws a heavy, greasy spanner into the works.
An operator's factors ? ... therein is the 64 dollar question. The simple matter is one of just how measurable and repeatable are the real world conditions. Hence my suggestion that the operator has to establish his own comfort position, somewhere on the conservative side of the minimum standards. Not an easy ask in a competitive world - but try a nasty court case after the event to put it all into perspective ...
[This message has been edited by john_tullamarine (edited 03 June 2001).]
Nobody has yet mentioned the inherant fudge factor supplied by the statistical improbability of a failure at or about V1.
When you are talking in the sub 1000 foot range for added "safety factors" to allow for a V1 abort you are talking probabilities in the multi millions-to-one!
Probably due to the influence of simulator training I have never experienced a full engine failure (a few partials) - yet in the Sim 99% of failures occur around or at V1. This skews pilot's perceptions of the probability of this event actually occurring.
When you are talking in the sub 1000 foot range for added "safety factors" to allow for a V1 abort you are talking probabilities in the multi millions-to-one!
Probably due to the influence of simulator training
I have never experienced a full engine failure (a few partials) - yet in the Sim 99% of failures occur around or at V1. This skews pilot's perceptions of the probability of this event actually occurring.
Guest
Posts: n/a
CB,
The probability of any of these nasty certification things happening is comfortably low - agreed.
For instance, not many wings fall off these days ... but, then again, we don't routinely operate at Vd. Vno offers a moderate margin. Similarly we don't routinely operate at limit load factor.
In the situation where all the little yellow performance ducks are lined up in a nice neat row, I am not too terribly concerned - on paper.
The important thing, I suggest, is that pilots (especially the younger people - having been brought up with an inherent regard for, and belief in, the wonders of technology) have some consideration for the differences between the rather idealised certification situation and the real world. The two are, in some respects, worlds apart.
Quite clearly, we are not too concerned about the situation where a runway is significantly non-limiting. All of these discussions revolve around the real world limiting case and, I suggest, the (two) areas of concern are limiting accel stop (and, to a lesser extent, a limiting landing case).
The historicals remain, quite firmly, that -
(a) the majority of refusals occur for reasons other than the certification fuel cut engine failure at (or shortly before - depending on which edition of the rulebook applies - and the latter applies predominantly these days) V1. Data readily available suggests that around 75 percent of incident RTOs are due to reasons other than a simple failure. This tends to compromise some of the assumptions on which the AFM data is based.
Those which occur significantly below V1 are of little concern.
Those that occur in the vicinity of V1 are most definitely of concern in the limiting runway case. The non-certification reasons for refusal create a problem in the uncritical application of the normal rote-learned refusal responses. The simple fact is that there is a high likelihood of an overrun in the event of a high speed refusal on a real world limiting runway, like it or not.
Those which occur after V1 have a generically predictable outcome.
(b) the real runway world is beset by touchdown zone contamination right in the area where maximum braking coefficients are needed. The dynamics of the beast involve a comparatively high deceleration gradient with the implication that any degradation in the capability of the aircraft to effect the planned deceleration will significantly add to the potential speed at which the runway departure occurs.
(c) except in realworld situations where the acceleration assumptions are reasonably valid, the use of a speed to determine the case, instead of distance, is a potential problem. With this is allied those minor variations which are approximated in the usual calculations - such as slope profiles.
(d) lineup allowances are not applied generally.
Now I confess that my experience is far less than that of many others. However, in around 1000 hours of (predominantly) simulator endorsement training time, my observations of students is that this concern is one which ought not to be dismissed flippantly, nor swept under the carpet.
It is not a case of making the performance numbers invariably more conservative - that would be to go down the path of suggesting that all aircraft ought to be left locked up in the hangar. Both are equally silly positions to adopt.
Rather, I suggest, there is a safety benefit to be had if the pilot is more aware that the numbers which come out of the AFM are very good as reference data under nominated conditions but may have some significant shortcomings in some real world circumstances. Armed with this sort of understanding, and with appropriate data, he/she is better placed to make sensible operational decisions from time to time.
If these arguments are sound then it follows that, just maybe, routinely exposing the realworld takeoff to the limiting accel stop case might not be the best risk solution in the operator's corporate strategies - level playing field profit motive notwithstanding. We all accept that, when it is necessary, then we accept something in the nature of an increased risk.
I agree wholeheartedly with your inference that simulator training may, itself, cause some of the problem in that the pilot so trained comes to hold a set of expectations which may, on occasion, prove to be seriously flawed.
As to 99 percent of training failures being imposed at or near V1 - that
(a) presents altogether a different line of training philosophy argument, and, I suspect
(b) is very unfortunately the case.
Amazing the number of pilots who are quite competent in handling the V1 case but suffer a very great surprise if the failure is imposed shortly after liftoff. I suspect that many have never seen that case. Conversely, those who are trained for the latter and can well manage the hands and feet problems in that very dynamic circumstance of a failure during the rotation flare ... have no difficulty with a garden variety V1 cut.
The probability of any of these nasty certification things happening is comfortably low - agreed.
For instance, not many wings fall off these days ... but, then again, we don't routinely operate at Vd. Vno offers a moderate margin. Similarly we don't routinely operate at limit load factor.
In the situation where all the little yellow performance ducks are lined up in a nice neat row, I am not too terribly concerned - on paper.
The important thing, I suggest, is that pilots (especially the younger people - having been brought up with an inherent regard for, and belief in, the wonders of technology) have some consideration for the differences between the rather idealised certification situation and the real world. The two are, in some respects, worlds apart.
Quite clearly, we are not too concerned about the situation where a runway is significantly non-limiting. All of these discussions revolve around the real world limiting case and, I suggest, the (two) areas of concern are limiting accel stop (and, to a lesser extent, a limiting landing case).
The historicals remain, quite firmly, that -
(a) the majority of refusals occur for reasons other than the certification fuel cut engine failure at (or shortly before - depending on which edition of the rulebook applies - and the latter applies predominantly these days) V1. Data readily available suggests that around 75 percent of incident RTOs are due to reasons other than a simple failure. This tends to compromise some of the assumptions on which the AFM data is based.
Those which occur significantly below V1 are of little concern.
Those that occur in the vicinity of V1 are most definitely of concern in the limiting runway case. The non-certification reasons for refusal create a problem in the uncritical application of the normal rote-learned refusal responses. The simple fact is that there is a high likelihood of an overrun in the event of a high speed refusal on a real world limiting runway, like it or not.
Those which occur after V1 have a generically predictable outcome.
(b) the real runway world is beset by touchdown zone contamination right in the area where maximum braking coefficients are needed. The dynamics of the beast involve a comparatively high deceleration gradient with the implication that any degradation in the capability of the aircraft to effect the planned deceleration will significantly add to the potential speed at which the runway departure occurs.
(c) except in realworld situations where the acceleration assumptions are reasonably valid, the use of a speed to determine the case, instead of distance, is a potential problem. With this is allied those minor variations which are approximated in the usual calculations - such as slope profiles.
(d) lineup allowances are not applied generally.
Now I confess that my experience is far less than that of many others. However, in around 1000 hours of (predominantly) simulator endorsement training time, my observations of students is that this concern is one which ought not to be dismissed flippantly, nor swept under the carpet.
It is not a case of making the performance numbers invariably more conservative - that would be to go down the path of suggesting that all aircraft ought to be left locked up in the hangar. Both are equally silly positions to adopt.
Rather, I suggest, there is a safety benefit to be had if the pilot is more aware that the numbers which come out of the AFM are very good as reference data under nominated conditions but may have some significant shortcomings in some real world circumstances. Armed with this sort of understanding, and with appropriate data, he/she is better placed to make sensible operational decisions from time to time.
If these arguments are sound then it follows that, just maybe, routinely exposing the realworld takeoff to the limiting accel stop case might not be the best risk solution in the operator's corporate strategies - level playing field profit motive notwithstanding. We all accept that, when it is necessary, then we accept something in the nature of an increased risk.
I agree wholeheartedly with your inference that simulator training may, itself, cause some of the problem in that the pilot so trained comes to hold a set of expectations which may, on occasion, prove to be seriously flawed.
As to 99 percent of training failures being imposed at or near V1 - that
(a) presents altogether a different line of training philosophy argument, and, I suspect
(b) is very unfortunately the case.
Amazing the number of pilots who are quite competent in handling the V1 case but suffer a very great surprise if the failure is imposed shortly after liftoff. I suspect that many have never seen that case. Conversely, those who are trained for the latter and can well manage the hands and feet problems in that very dynamic circumstance of a failure during the rotation flare ... have no difficulty with a garden variety V1 cut.
Guest
Posts: n/a
Hi ZS-BOK! I don't know if u are still following the thread which has become slightly technical, nevertheless here my small grain of salt:
On a powerful and lite aircraft (e.g. A300-600 or A310 or similar), the brakes will hold the aircraft standing still, but not the tires !!! The power is such that the whole bird will start with a hopping motion that becomes stronger and stronger until it starts moving forward, rubbing the smoky tires on the ground
Hardly good for the tires, the landing gear, the structure or comfort
On a less powerful aircraft (such as the ARJ I'm presently on ) you will apply and wait for a max stabilized power at very short places like LCY, LUG and such.
Cheers!
------------------
... cut my wings and I'll die ...
On a powerful and lite aircraft (e.g. A300-600 or A310 or similar), the brakes will hold the aircraft standing still, but not the tires !!! The power is such that the whole bird will start with a hopping motion that becomes stronger and stronger until it starts moving forward, rubbing the smoky tires on the ground
Hardly good for the tires, the landing gear, the structure or comfort On a less powerful aircraft (such as the ARJ I'm presently on
) you will apply and wait for a max stabilized power at very short places like LCY, LUG and such.Cheers!
------------------
... cut my wings and I'll die ...
Join Date: Jan 1997
Location: UK
Posts: 7,737
Likes: 0
Received 0 Likes
on
0 Posts
Excellent point Checkboard,
Our training, just as much as the takeoff calculations revolve around the V1 cut. I won't belabour the points John T has made in reply to you - I'm in broad agreement and support all his points and conclusions.
Whether with our sim training or performance calculations we're trapped in the world as the regulators see it. This isn't borne out by the facts. Initial research by the insurance companies or allied groups such as Airclaims on hull damage and writeoffs was followed with investigation by Boeing.
The work by Boeing makes it pretty clear to the average reader through its analysis of hull losses and advocation of 'Go mindedness' that the V1 cut has nothing to do with the vast majority of real world accidents and incidents. Further, they make it obvious that the calculations we work to do not serve us at all well in the real life world we operate in.
The regulators framework we work to in the sim combined to the time restraints place on all trainers, no matter how wise, thoughtful or knowledgable, mean the boxes with failures above and below V1 have to be ticked. This is despite the full and detailed records available of the many real triggers to accidents while still on the runway.
The real G readings of available decelleration are not programmed into our sims despite the state of slick, coated runways worldwide. That one item would do more to get senior pilots and trainers banging on the desks of the regulators. In turn the regulators own test/check pilots would be exposed every working day to sailing off the end and into the bundu.
Call me a hopeless optimist if you like but I reckon they'd eventually work out that there's something wrong........
------------------
Regards from the Towers
[email protected]
Our training, just as much as the takeoff calculations revolve around the V1 cut. I won't belabour the points John T has made in reply to you - I'm in broad agreement and support all his points and conclusions.
Whether with our sim training or performance calculations we're trapped in the world as the regulators see it. This isn't borne out by the facts. Initial research by the insurance companies or allied groups such as Airclaims on hull damage and writeoffs was followed with investigation by Boeing.
The work by Boeing makes it pretty clear to the average reader through its analysis of hull losses and advocation of 'Go mindedness' that the V1 cut has nothing to do with the vast majority of real world accidents and incidents. Further, they make it obvious that the calculations we work to do not serve us at all well in the real life world we operate in.
The regulators framework we work to in the sim combined to the time restraints place on all trainers, no matter how wise, thoughtful or knowledgable, mean the boxes with failures above and below V1 have to be ticked. This is despite the full and detailed records available of the many real triggers to accidents while still on the runway.
The real G readings of available decelleration are not programmed into our sims despite the state of slick, coated runways worldwide. That one item would do more to get senior pilots and trainers banging on the desks of the regulators. In turn the regulators own test/check pilots would be exposed every working day to sailing off the end and into the bundu.
Call me a hopeless optimist if you like but I reckon they'd eventually work out that there's something wrong........
------------------
Regards from the Towers
[email protected]
Guest
Posts: n/a
.. I guess what we are driving at ... is that the rote training and such, allied with an uncritical thinking which is seen in many quarters ... provides not as useful or effective an outcome ......as such training allied with sound and relevant knowledge .. and that basic captaincy skillset value .... to be able to put the foot down .. and occasionally draw a line in the sand .....
The sim is a great tool in which to develop hand eye co-ordination skills and to see things which would be far too dangerous on the real aircraft.
The risk lies in believing too much of it ....
The sim is a great tool in which to develop hand eye co-ordination skills and to see things which would be far too dangerous on the real aircraft.
The risk lies in believing too much of it ....
Guest
Posts: n/a
I've certainly learned a lot from this thread in spite of significant lacking in the technical department. However I would say as a pax that has experienced a couple of max. energy departures in a 757 on a hot day from SNA that I am certainly a confirmed member of the rolling take-off club!
Guest
Posts: n/a
John Tullamarine is away for a while, so I’m going to answer the easy questions first.
Code_Blue,
The manufacturers data is usually broken down into discrete segments, these are engine failure recognition / brake application / thrust levers to idle position / speed brake actuation. A 2 sec delay is added to account for differences in pilot reaction.
On older aircraft such as the 707/737-100/200 V1 is the engine failure and recognition speed.
On newer aircraft (733/744/757/767) certification is based on the engine failing 1 second prior to V1 (VEF), The brake application is conducted at the same time as the engine failure recognition (V1). Throttle chop and brake application follow. All of this is derived from demonstrated flight testing. The rules then require a 2 second arbitrary time delay to be used to calculate the distance based on full braking with no deceleration credit. Thrust reversers are not used in these calculations.
Mutt.
[This message has been edited by mutt (edited 15 June 2001).]
Code_Blue,
The manufacturers data is usually broken down into discrete segments, these are engine failure recognition / brake application / thrust levers to idle position / speed brake actuation. A 2 sec delay is added to account for differences in pilot reaction.
On older aircraft such as the 707/737-100/200 V1 is the engine failure and recognition speed.
On newer aircraft (733/744/757/767) certification is based on the engine failing 1 second prior to V1 (VEF), The brake application is conducted at the same time as the engine failure recognition (V1). Throttle chop and brake application follow. All of this is derived from demonstrated flight testing. The rules then require a 2 second arbitrary time delay to be used to calculate the distance based on full braking with no deceleration credit. Thrust reversers are not used in these calculations.
Mutt.
[This message has been edited by mutt (edited 15 June 2001).]
Guest
Posts: n/a
One of the good things about this hiatus is that I was able to solicit email comments from others, this is one of the responses.
The impact on temperature on true air speed Derate/Assumed temp field length limit is same as max thrust safety limit but diff between assumed and actual build in safety factor.
These other guys should think themselves lucky they don't do too many max
thrust field length limited takeoffs.
Once you bring approved data into question you may as well pack your bags
and go home. Be aware of the limitations though.
Mutt.
The impact on temperature on true air speed Derate/Assumed temp field length limit is same as max thrust safety limit but diff between assumed and actual build in safety factor.
These other guys should think themselves lucky they don't do too many max
thrust field length limited takeoffs.
Once you bring approved data into question you may as well pack your bags
and go home. Be aware of the limitations though.
Mutt.
Guest
Posts: n/a
Towers, your assumed temperature limit (48C) is driven by the length of a fax page, are you still going to use this limit if you start using a cockpit laptop?
Mutt
(PS, I’m not trying to increase my posting count, I’m just breaking up my messages for clarity.)
Mutt
(PS, I’m not trying to increase my posting count, I’m just breaking up my messages for clarity.)
Guest
Posts: n/a
The Vicar asked about the difference between taking off at an ACTUAL TEMPERATURE versus ASSUMING that temperature. For those of you that haven’t seen this before, I hope that this example taken from the Boeing Takeoff Safety Guide explains whats going on.
Conditions
Typical 4 engine airliner.
Sea Level. OAT 16C
10,100 feet runway.
Runway limit weight = 762,200 lbs
Actual weight = 717,500 lbs, this allows an assumed temperature of 40C.
Parameter………Actual 16C ………. Actual 40C…….Margin
…………………Assumed 40C
EPR………………1.376…………..…1.376…………..0
V1 (KIAS/TAS)…..146/146…………146/152……….-6 ktas
VR (KIAS/TAS)….156/156………….156/163……….-7 ktas
V2 (KIAS/TAS)…..164/164…………164/171……….-7 ktas
Thrust @ V1 lb/eng..31,210……….....30,960………....250 lbs
FAR Field Length….9,310 ft…………10,100 ft………790 ft
Acc/stop Eng Out… 9,050 ft………… 9,800 ft… …..750 ft
Acc/Go Eng Out…...9,050 ft………….. 9,800 ft……....750 ft
Acc/Go All Eng……8,100 ft…………...8,800 ft…..…..700 ft
2nd Segment……….3.54%……………..3.42%………...+0.12%
2nd Segment Climb….582 fpm………….586 fpm………-4 fpm
Make sense???
Mutt.
Conditions
Typical 4 engine airliner.
Sea Level. OAT 16C
10,100 feet runway.
Runway limit weight = 762,200 lbs
Actual weight = 717,500 lbs, this allows an assumed temperature of 40C.
Parameter………Actual 16C ………. Actual 40C…….Margin
…………………Assumed 40C
EPR………………1.376…………..…1.376…………..0
V1 (KIAS/TAS)…..146/146…………146/152……….-6 ktas
VR (KIAS/TAS)….156/156………….156/163……….-7 ktas
V2 (KIAS/TAS)…..164/164…………164/171……….-7 ktas
Thrust @ V1 lb/eng..31,210……….....30,960………....250 lbs
FAR Field Length….9,310 ft…………10,100 ft………790 ft
Acc/stop Eng Out… 9,050 ft………… 9,800 ft… …..750 ft
Acc/Go Eng Out…...9,050 ft………….. 9,800 ft……....750 ft
Acc/Go All Eng……8,100 ft…………...8,800 ft…..…..700 ft
2nd Segment……….3.54%……………..3.42%………...+0.12%
2nd Segment Climb….582 fpm………….586 fpm………-4 fpm
Make sense???
Mutt.
Guest
Posts: n/a
mutt:
Thanks for the replies.
I suppose I was asking the unanswerable about the relevance of these data sheets to aging machines.
Out of interest, do you know of any manufacturer/agency that has rerun these tests on older machines for a comparison with the fresh-off-the-line ones?
regards
CB
Thanks for the replies.
<font face="Verdana, Arial, Helvetica" size="2">Once you bring approved data into question you may as well pack your bags
and go home. Be aware of the limitations though</font>
and go home. Be aware of the limitations though</font>
Out of interest, do you know of any manufacturer/agency that has rerun these tests on older machines for a comparison with the fresh-off-the-line ones?
regards
CB
Guest
Posts: n/a
Code Blue,
The difference between the theoretical regulations and real life are known. There is an FAA manual called the Takeoff Safety Guide which discusses more of them in detail.
It is interesting to note that although this document is 10 years old, they havent seen fit to change the regulations!
Mutt
[This message has been edited by mutt (edited 17 June 2001).]
The difference between the theoretical regulations and real life are known. There is an FAA manual called the Takeoff Safety Guide which discusses more of them in detail.
It is interesting to note that although this document is 10 years old, they havent seen fit to change the regulations!
Mutt
[This message has been edited by mutt (edited 17 June 2001).]
Guest
Posts: n/a
If I might be permitted to add some comments -
(a) for those of us who are still only allowed to play with dinosaurs (damn), the V1 2 second fudge pad doesn't apply - so accel stop is VERY serious in limiting conditions.
(b) keep in mind that approved data are based on specific presumed conditions which may, or may not, bear very much resemblance to the conditions of the day. Because of this consideration, I prefer to view AFM data as reference data - to be used with a modicum of commonsense.
(c) so far as the performance of ancient mariners is concerned, most countries don't require a periodic demonstration of an individual aircraft's ability to match the original performance capabilities. As a first approximation, if the the climb and cruise figures are still somewhere near book, then I would probably be reasonably comforted. This presumes that the operator is keeping up with the normal maintenance activities so that brakes etc are in reasonable condition.
[This message has been edited by john_tullamarine (edited 20 June 2001).]
(a) for those of us who are still only allowed to play with dinosaurs (damn), the V1 2 second fudge pad doesn't apply - so accel stop is VERY serious in limiting conditions.
(b) keep in mind that approved data are based on specific presumed conditions which may, or may not, bear very much resemblance to the conditions of the day. Because of this consideration, I prefer to view AFM data as reference data - to be used with a modicum of commonsense.
(c) so far as the performance of ancient mariners is concerned, most countries don't require a periodic demonstration of an individual aircraft's ability to match the original performance capabilities. As a first approximation, if the the climb and cruise figures are still somewhere near book, then I would probably be reasonably comforted. This presumes that the operator is keeping up with the normal maintenance activities so that brakes etc are in reasonable condition.
[This message has been edited by john_tullamarine (edited 20 June 2001).]
Guest
Posts: n/a
Hello all,
Thank you for a fascinating thread. It is great to see how others think and learn from it. What did we do before the internet??
cpdude,
You stated that "some take offs are Vmcg limited".
I looked up my 767-300 performance manual and it stated "V1 must never be less than the minimum V1 for control on the ground...". In this case min V1 is 109 knots. I checked the Vmcg and it is always less than 109 knots inside our environmental limits. For us, this means the take off is never Vmcg limited.
Given this is for a B767 I would thought the same philosophy would be used on most if not all airliners.
Does your or any one elses airline operation allow Vmcg limited take offs???
Do the various regulations allow this?
I would have thought not but this thread has taught me to be a little sceptical of certification data and regulation.
Thank you for a fascinating thread. It is great to see how others think and learn from it. What did we do before the internet??
cpdude,
You stated that "some take offs are Vmcg limited".
I looked up my 767-300 performance manual and it stated "V1 must never be less than the minimum V1 for control on the ground...". In this case min V1 is 109 knots. I checked the Vmcg and it is always less than 109 knots inside our environmental limits. For us, this means the take off is never Vmcg limited.
Given this is for a B767 I would thought the same philosophy would be used on most if not all airliners.
Does your or any one elses airline operation allow Vmcg limited take offs???
Do the various regulations allow this?
I would have thought not but this thread has taught me to be a little sceptical of certification data and regulation.
Guest
Posts: n/a
GaryGnu,
Your normal V1 wont be VMCG limited, but what happens when you make MEL or contaminated runway corrections to it?
TCAS Climb,
You have confused me, surely there is a difference in weight between the two runways? Why would you expect to have a V1 decrement on the shorter runway?
John, welcome back.
I guess that you are talking about the 727? I dont know about OZ certification rules, but my Boeing book states that under the FAA the 2 second rule did apply. A 1 sec time delay was added to (a) Brake application to thrust reduction on remaining engines (b) Thrust reduction on the remaining engines to speed brake action. A 3 sec time delay was used on B727-100 aircraft without and engine failure warning system.
Mutt.
Your normal V1 wont be VMCG limited, but what happens when you make MEL or contaminated runway corrections to it?
TCAS Climb,
You have confused me, surely there is a difference in weight between the two runways? Why would you expect to have a V1 decrement on the shorter runway?
John, welcome back.
I guess that you are talking about the 727? I dont know about OZ certification rules, but my Boeing book states that under the FAA the 2 second rule did apply. A 1 sec time delay was added to (a) Brake application to thrust reduction on remaining engines (b) Thrust reduction on the remaining engines to speed brake action. A 3 sec time delay was used on B727-100 aircraft without and engine failure warning system.
Mutt.