Runway behind you - a way to save time?
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Runway behind you - a way to save time?
I was a bit surprised very recently to find myself in the back of a 738 with 170+ pax taking an unfamiliar and hesitant taxying shortcut to a point 2300 feet down the runway (estimated from Google Earth). The take off roll was approximately 35 seconds and we rotated after about 4000 feet of roll with 1800 feet of runway remaining after the wheels left the ground (some 30 minutes late on final sector of the day I might add).
For what little time and fuel was saved in missing out the usual additional 2300 foot taxy, I personally would have preferred to have left the ground with 4100 feet remaining.
I have always believed that runway behind you is one of the most useless things you can equip yourself with before committing aviation.
Am I being unfairly critical?
For what little time and fuel was saved in missing out the usual additional 2300 foot taxy, I personally would have preferred to have left the ground with 4100 feet remaining.
I have always believed that runway behind you is one of the most useless things you can equip yourself with before committing aviation.
Am I being unfairly critical?
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This should be in tech log I would say.....
And being SLF I should not really comment, however I would say the following....
If your not happy with the taxi instruction you have the right to decline as pilot in command (you are in charge of safety of the plane) and request an alternative - if what is offered does not suit you dont take it.
If you were RHS, and you were uncomfortable with the decision made by the PIC the discussion should not be here but with PIC. It will always be unfamiliar the first time !
In general I would expect your right that the more distance you have for takeoff roll the safer, but economics does not always work like that - it will be a calculated judgement of safety over economy to a reasonable level I would speculate.
Sorry for my 2p worth.
And being SLF I should not really comment, however I would say the following....
If your not happy with the taxi instruction you have the right to decline as pilot in command (you are in charge of safety of the plane) and request an alternative - if what is offered does not suit you dont take it.
If you were RHS, and you were uncomfortable with the decision made by the PIC the discussion should not be here but with PIC. It will always be unfamiliar the first time !
In general I would expect your right that the more distance you have for takeoff roll the safer, but economics does not always work like that - it will be a calculated judgement of safety over economy to a reasonable level I would speculate.
Sorry for my 2p worth.
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Oh not this old chestnut again 
Listen, you got airborne, so there was enough runway in front of you to accelerate and do so. The performance calculations would have been done from the intersection, so if you had needed to stop there would have been enough runway in front of you to decelerate and do so. End of story.
Performance A calcs work, so let's just stop this nonsense about runway behind you, altitude below you, fuel in the tanks etc and move on to something that hasn't been done to death millions of times on this forum.
Listen, you got airborne, so there was enough runway in front of you to accelerate and do so. The performance calculations would have been done from the intersection, so if you had needed to stop there would have been enough runway in front of you to decelerate and do so. End of story.
Performance A calcs work, so let's just stop this nonsense about runway behind you, altitude below you, fuel in the tanks etc and move on to something that hasn't been done to death millions of times on this forum.
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PIC
Slip and turn,
In short, yes, you are being unfairly critical.
You were a passenger and the PIC (well, probably both flight crew) made a decision that adhered to policies and law, therefore I think you are being a tad arrogant to assume that you would have 'made a better decision' by taxying the extra kilometre.
I don't tell everyone how to do their job. Do you?
In a Cessna 172 on a major airfield, do you taxy to the start of a 4km long runway, just in case? That would be ludicrous wouldn't it? Sure, not quite the same, but shows the logical progression of your thoughts. Intersection takeoffs are quite common because the aircraft simply does not need the extra bitumen in order to get airborne. V1/V2 are still within limits, so it's wasted runway...
Just my thoughts, let the professionals make that decision I say.
Matt
In short, yes, you are being unfairly critical.
You were a passenger and the PIC (well, probably both flight crew) made a decision that adhered to policies and law, therefore I think you are being a tad arrogant to assume that you would have 'made a better decision' by taxying the extra kilometre.
I don't tell everyone how to do their job. Do you?
In a Cessna 172 on a major airfield, do you taxy to the start of a 4km long runway, just in case? That would be ludicrous wouldn't it? Sure, not quite the same, but shows the logical progression of your thoughts. Intersection takeoffs are quite common because the aircraft simply does not need the extra bitumen in order to get airborne. V1/V2 are still within limits, so it's wasted runway...
Just my thoughts, let the professionals make that decision I say.
Matt
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A tad arrogant? I can understand why many people could make that the default judgement. I do indeed see that some latenight moderator has made his or her judgement, and fairly stuffed the thread into touch, pronto-like .
I am actually sick of seeing pilots hesitating during taxy at simple airports making up their mind where to go next. I don't mind a performance based decision smartly executed, if that's what it it might have been, but it wasn't.
Personally I think this was another late pilot at another simple airport where the big picture of taxyway layout and intersections between two parallel runways, one used as a taxyway by the jet traffic, just happened to escape him. We dillied and dallied and ultimately did nothing more complicated than leaving the apron on the exact same perpendicular that the aircraft entered on, crossing the parallel inactive directly from the apron, to arrive at the main runway at the exact point the aircraft left the runway when it arrived 30 minutes earlier on the reciprocal. Even when we reached the main runway it seemed someone was in two minds which way we would turn - right for takeoff or left for backtrack and take-off. Maybe it was just me of course having flown from this one too many times
.
None of this is dictated by Smalltown's ATC of course - the airline often expresses its own runway preference 'on the fly' and as there's usually not much else occuring, take-off clearance is also often given early whilst taxying out.
As 2 or 3 or even 5 minutes surely can't be that valuable at the end of the day, I can only assume that perhaps a slot time was about to expire ...
.I am actually sick of seeing pilots hesitating during taxy at simple airports making up their mind where to go next. I don't mind a performance based decision smartly executed, if that's what it it might have been, but it wasn't.
Personally I think this was another late pilot at another simple airport where the big picture of taxyway layout and intersections between two parallel runways, one used as a taxyway by the jet traffic, just happened to escape him. We dillied and dallied and ultimately did nothing more complicated than leaving the apron on the exact same perpendicular that the aircraft entered on, crossing the parallel inactive directly from the apron, to arrive at the main runway at the exact point the aircraft left the runway when it arrived 30 minutes earlier on the reciprocal. Even when we reached the main runway it seemed someone was in two minds which way we would turn - right for takeoff or left for backtrack and take-off. Maybe it was just me of course having flown from this one too many times
.None of this is dictated by Smalltown's ATC of course - the airline often expresses its own runway preference 'on the fly' and as there's usually not much else occuring, take-off clearance is also often given early whilst taxying out.
As 2 or 3 or even 5 minutes surely can't be that valuable at the end of the day, I can only assume that perhaps a slot time was about to expire ...
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Apologies to all the professionals - I missed the key " myself in the back of a 738 "
I will duck out now with head held low - my intentions were good but misplaced.
regards,
Jof
I will duck out now with head held low - my intentions were good but misplaced.
regards,
Jof
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At busy airfields with several intersections ATC will frequently offer an intersection take-off to expedite traffic. Hundreds of flights each day take-off from such intersections without any problems. Keep in mind at that at a large airfield the length of runway remaining from such intersections is probably more than the full length of that at the aircraft's destination..
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I am actually sick of seeing pilots hesitating during taxy at simple airports making up their mind where to go next. I don't mind a performance based decision smartly executed, if that's what it it might have been, but it wasn't.
The reason for hesitation during taxying are many and varied - and if it is a matter of working out where to go next, I'd rather that than the aircraft heading off across a runway or whatever.
As for your concerns about the intersection take-off, I suggest you write to the Ops Director of the airline concerned expressing your views - and your professional competence for doing so - and I am sure that your concerns will receive the consideration they deserve.
PS - I guess it wasn't at LCY this time!
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If your not a pilot then I suggest trawling through the tech log section and reading about balanced field take offs/flex take offs and intersection departures. Other keywords you will find of interest will be accelerate stop distance available or ASDA and TODA. Lots of light reading for the uninitiated that will hopefully enlighten you as to how commercial aircraft can expedite departure from an intersection and safely get airborne.
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It must be a huge inconvenience to see the obvious incompetence displayed while assessing the performance of the flight crew from your seat in 36F!!!
On these occasions where you have experienced such hesitations in taxiing could you provide a little more detail please. Ideally of the airfield layout, the notams of the day regarding taxiway operation whether any additions were mentioned on the latest ATIS and how these related to the ATC taxi instructions provided. It would also help if you could describe the flight crew's familiarity with the airfield. Only so we can sit in the comfort of our own homes and judge the professionals with the same information you must clearly have had.
As for intersection take offs...Perf A calculations and NO airline SOP's countenance using runway ahead after V1 for stopping, so if the calculations show it is within the aircraft performance to use ANY intersection and it will save some time there is no valid reason why it cannot be used. ATC permitting of course (in fact often it is at their request!). Runway behind and fuel in bowsers are all wonderful generalisations of single engine flying. They do not apply in the commercial world where the decisions are much more considered and calculated.
Also as for 2,3,5 minutes not being important...safety is the primary concern following that is commercial expediency. Sometimes by not being able to take the intersection you may need to wait 15 minutes while 4 aircraft arrive and 2 depart from the full length. Did you have the big picture on the occasion or your intersection departure? Was the full length even available on that occasion?
So many questions slip and turn, and so many answers which I'm sure were clear to you from the cabin!
Happy flying.
Jazzy
On these occasions where you have experienced such hesitations in taxiing could you provide a little more detail please. Ideally of the airfield layout, the notams of the day regarding taxiway operation whether any additions were mentioned on the latest ATIS and how these related to the ATC taxi instructions provided. It would also help if you could describe the flight crew's familiarity with the airfield. Only so we can sit in the comfort of our own homes and judge the professionals with the same information you must clearly have had.
As for intersection take offs...Perf A calculations and NO airline SOP's countenance using runway ahead after V1 for stopping, so if the calculations show it is within the aircraft performance to use ANY intersection and it will save some time there is no valid reason why it cannot be used. ATC permitting of course (in fact often it is at their request!). Runway behind and fuel in bowsers are all wonderful generalisations of single engine flying. They do not apply in the commercial world where the decisions are much more considered and calculated.
Also as for 2,3,5 minutes not being important...safety is the primary concern following that is commercial expediency. Sometimes by not being able to take the intersection you may need to wait 15 minutes while 4 aircraft arrive and 2 depart from the full length. Did you have the big picture on the occasion or your intersection departure? Was the full length even available on that occasion?
So many questions slip and turn, and so many answers which I'm sure were clear to you from the cabin!
Happy flying.
Jazzy
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I appreciate that there are a lot of you in aviation and interested in aviation who when down the back are blind, insensitive or just not very interested in where you are headed other than what it says on your ticket. That's just unluck on your part . I obviously think I have abilities that some of you are loathe to credit 
.
Anyway, this was no ATC instruction, and as such it can only have been some time-saving measure, and frankly guys and girls you are welcome to your own views of how it might have been rationalised.
At the end of the day, pilots are tired and want to get home, and I suppose if a slot expiry was imminent then there's the main reason.
It was actually still quite warm, probably 20 degrees, and there was no wind to speak of, but this runway is not elevated.
The runway direction for departure is rarely an issue unless there is a 5+ easterly component. So the airport layout gives the pilot just three potential taxying options:
(a) to the end of the runway via the parallel inactive (main taxiway a la Gatwick)
(b) to the end of the runway via backtrack from the entry point he actually used
(c) what he did.
For those who've added it up, this is indeed an 8000+ feet runway, like Gatwick, but with fewer entry points (just two at each end).
I just don't think that leaving a quarter of the runway behind you when you are not light is good practice. Last time I flew this route I wouldn't have been surprised. There were only about 30 pax, the take of roll lasted only 20 seconds and we launched up to FL400 pretty damn quick. We used the same runway but as we were on time, we went from the end. This time it was 170+ pax.
If a problem had occurred just before V1 then perhaps less than 40% of the runway would have remained available to stop.
Now, I know that even more heavily laden, the same aicraft might well regularly operate from runways 2000 feet shorter and where the temperature and elevation might be higher, but is it right to deliberately shorten your own runway to save time?
Why did I have the answer to this question once drummed in as a straight "No", and others have it marked as "It depends whether commercially you need to save 5 minutes" etched into their psyche? Or indeed 5 seconds in Spitoon's world?
. I obviously think I have abilities that some of you are loathe to credit .Anyway, this was no ATC instruction, and as such it can only have been some time-saving measure, and frankly guys and girls you are welcome to your own views of how it might have been rationalised.
At the end of the day, pilots are tired and want to get home, and I suppose if a slot expiry was imminent then there's the main reason.
It was actually still quite warm, probably 20 degrees, and there was no wind to speak of, but this runway is not elevated.
The runway direction for departure is rarely an issue unless there is a 5+ easterly component. So the airport layout gives the pilot just three potential taxying options:
(a) to the end of the runway via the parallel inactive (main taxiway a la Gatwick)
(b) to the end of the runway via backtrack from the entry point he actually used
(c) what he did.
For those who've added it up, this is indeed an 8000+ feet runway, like Gatwick, but with fewer entry points (just two at each end).
I just don't think that leaving a quarter of the runway behind you when you are not light is good practice. Last time I flew this route I wouldn't have been surprised. There were only about 30 pax, the take of roll lasted only 20 seconds and we launched up to FL400 pretty damn quick. We used the same runway but as we were on time, we went from the end. This time it was 170+ pax.
If a problem had occurred just before V1 then perhaps less than 40% of the runway would have remained available to stop.
Now, I know that even more heavily laden, the same aicraft might well regularly operate from runways 2000 feet shorter and where the temperature and elevation might be higher, but is it right to deliberately shorten your own runway to save time?
Why did I have the answer to this question once drummed in as a straight "No", and others have it marked as "It depends whether commercially you need to save 5 minutes" etched into their psyche? Or indeed 5 seconds in Spitoon's world?
Last edited by slip and turn; 30th Jun 2009 at 09:56.
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Slip and Turn you are missing the point completely!
No matter how perceptive you think you are unless you have all the information ON THE DAY, for that departure you have no idea what factors were affecting the aircraft performance or the reasons for the choice of departure point.
ADD's, packs on or off, peformance corrections with CDL items in addition to the actual airfield information rather than your perception of what is a 'normal' departure are the components that go to make the decisions.
Even with that information whether you think it is bad practice to save a couple if minutes or not is immaterial as long as the aircraft was operated in accordance with the performance calculations.
In a perf A aircraft whether you get airborne with 1000ft of runway ahead or 6000ft makes no difference. V1 is V1, there IS enough runway to stop if the decision is made to do so by that speed and beyond it irrespective of how much runway is still left you are going to fly over it!
I truly hope you are not an aviation professional because if you are you really need to go and have a close look at the books again, both Perf A and SOP's.
If you are not then please avoid your back seat speculating as to the inappropriateness of the crews's actions and let the people in the front with the information pertanant to your flight make their decision.
Asking a legitimate question as to whether the runway behind is just to save time and if it has safety implications is entirely fair. That has been clearly answered. Now you are arguing that the decisions made were not good practice...that to I hope is now clearly answered also.
Jazzy
Edited to add that my post crossed with Slip and Turn's regarding his aviation background. I think Eff Oh makes my point, finish your training, and leave commenting on the professionalism of the professionals until you join their ranks whereupon you'll find unless we have ALL the information...we don't!
No matter how perceptive you think you are unless you have all the information ON THE DAY, for that departure you have no idea what factors were affecting the aircraft performance or the reasons for the choice of departure point.
ADD's, packs on or off, peformance corrections with CDL items in addition to the actual airfield information rather than your perception of what is a 'normal' departure are the components that go to make the decisions.
Even with that information whether you think it is bad practice to save a couple if minutes or not is immaterial as long as the aircraft was operated in accordance with the performance calculations.
I just don't think that leaving a quarter of the runway behind you when you are not light is good practice.
In a perf A aircraft whether you get airborne with 1000ft of runway ahead or 6000ft makes no difference. V1 is V1, there IS enough runway to stop if the decision is made to do so by that speed and beyond it irrespective of how much runway is still left you are going to fly over it!
I truly hope you are not an aviation professional because if you are you really need to go and have a close look at the books again, both Perf A and SOP's.
If you are not then please avoid your back seat speculating as to the inappropriateness of the crews's actions and let the people in the front with the information pertanant to your flight make their decision.
Asking a legitimate question as to whether the runway behind is just to save time and if it has safety implications is entirely fair. That has been clearly answered. Now you are arguing that the decisions made were not good practice...that to I hope is now clearly answered also.
Jazzy
Edited to add that my post crossed with Slip and Turn's regarding his aviation background. I think Eff Oh makes my point, finish your training, and leave commenting on the professionalism of the professionals until you join their ranks whereupon you'll find unless we have ALL the information...we don't!
Last edited by JazzyKex; 30th Jun 2009 at 11:52.
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Well if you know what is coming why did you start this nonsense thread?!?
You clearly don't know what you are talking about, so why do you continue to argue to the contrary??
How about waiting until you are fully "trained/studied" before commenting in such a way?
Sorry don't really get that.
You clearly don't know what you are talking about, so why do you continue to argue to the contrary??
Part-trained/studied, but not earning my living in aviation.
Mr Oscar
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Moderators- this thread is a piss take, isnīt it? A fishing expedition, by a dabbler in aviation, who from his seat in 21A can make judgements on his Captainīs decision on where to take off, and can tell from the movement of the aeroplane what is going on in the Captainīs mind?
Who said īthere are no stupid questions, just stupid answersī? Look at this! This thread is quite clearly idiotic. The poster is arrogant in the extreme, and knows better than his crew. Rejected wannabees donīt have to inflict their bitterness on every crew that has the misfortune to fly with such a smart-arse sitting in the cabin! Delete this idiocy- not just close it! It is an embarrassment.
I am actually sick of seeing pilots hesitating during taxy at simple airports making up their mind where to go next.
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Ah thought we'd lost you there Mr Oh
But we seem to attracted the famous Rainboe himself now. And we all know if he doesn't like something, he says so. Good afternoon, Sir
Listen, I don't get up each morning and think 'whose good work can I criticise today?' ... sometimes in the course of the day, I just notice things done differently. I also know that once I am approaching flying speeds in something weighing 60+ tonnes and which normally uses most of 3000 feet or so to land and stop reasonably, that I'd rather have that and more available just prior to V1 than something only half as convenient. My sloppy '3000 to stop' may even have been there too in this case just before V1, but I reckon it would have been tight.
So what we have here is an observation of something unusual for this type at this airport. You'll have to take my word for that because I am not going to name the venue. The entry point used was unusual. Consequently, the rotation point was much further down the runway than is usual and a couple of seconds or 3 earlier just before V1, the picture of the end of the runway arriving would not have been much improved.
Unusual operations are usually a good enough reason to ask a question, so I did.
I'd be interested in some Performance calculations if anyone has the will. Let's be conservative: if anyone is feeling kind enough to provide some numbers to chew on, then what might they be for say 60 tonnes, NIL wind, temperature 15 degrees, and let's say sea level with 1022hPa? Runway dry of course. Qualify it with your packs and any other niceties. Anyone?
PS I am not a rejected wannabe, Rainboe.
But we seem to attracted the famous Rainboe himself now. And we all know if he doesn't like something, he says so. Good afternoon, Sir
Listen, I don't get up each morning and think 'whose good work can I criticise today?' ... sometimes in the course of the day, I just notice things done differently. I also know that once I am approaching flying speeds in something weighing 60+ tonnes and which normally uses most of 3000 feet or so to land and stop reasonably, that I'd rather have that and more available just prior to V1 than something only half as convenient. My sloppy '3000 to stop' may even have been there too in this case just before V1, but I reckon it would have been tight.
So what we have here is an observation of something unusual for this type at this airport. You'll have to take my word for that because I am not going to name the venue. The entry point used was unusual. Consequently, the rotation point was much further down the runway than is usual and a couple of seconds or 3 earlier just before V1, the picture of the end of the runway arriving would not have been much improved.
Unusual operations are usually a good enough reason to ask a question, so I did.
I'd be interested in some Performance calculations if anyone has the will. Let's be conservative: if anyone is feeling kind enough to provide some numbers to chew on, then what might they be for say 60 tonnes, NIL wind, temperature 15 degrees, and let's say sea level with 1022hPa? Runway dry of course. Qualify it with your packs and any other niceties. Anyone?
PS I am not a rejected wannabe, Rainboe.