Runway behind you.
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Runway behind you.
I'm a PPL and have often been told that there's nothing more useless than runway behind you before takeoff. I use Marseille LFML, a lot and have noticed a particular airline habitually opting for less than the full TODA, while everyone seems to taxi out to the threshold. Is this for punctuality reasons or am I missing something ?
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This subject has been done to death on another thread on Pprune. Fact is that intersection take-offs are perfectly safe and are employed thousands of time daily at airports all over the world.
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In a single engine aircraft - which with a PPL I assume is the case - what you've said is true. Runway behind you is worthless...
In two, three and four engine aircraft it's a different story, particularly if that aircraft is certified under FAR / JAR 25.
Intersection departures are perfectly safe - and many times quite cost effective - provided that you have calculated the take-off and climb performance and are able to meet any limitations, etc.
Before I get beat to death about this explanation by the masses, the above is a very simple and brief explanation directed at a PPL who is not attempting to operate a transport category aircraft. There is, in fact, a lot more that goes into it.
In two, three and four engine aircraft it's a different story, particularly if that aircraft is certified under FAR / JAR 25.
Intersection departures are perfectly safe - and many times quite cost effective - provided that you have calculated the take-off and climb performance and are able to meet any limitations, etc.
Before I get beat to death about this explanation by the masses, the above is a very simple and brief explanation directed at a PPL who is not attempting to operate a transport category aircraft. There is, in fact, a lot more that goes into it.
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Safety, performance calculations, expeditious departures and other limitations aside, runway behind you is still useless.
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Safety, performance calculations, expeditious departures and other limitations aside, runway behind you is still useless.
So let's stay on the ground.
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The thing with these wise philosophies of caution, of which "runway behind" is one of many, is that you have to spot when they become ludicrous.
In my early PPL days our school was at Manchester and we shared the runway with the big boys. The earliest intersection from the south side to 24 (only the one runway in those days) was some 500 metres from the threshold. This left my Piper Tomahawk with a mere 2500 metres to get airborne.
I dread to think how a "Request backtrack" would have been received by ATC.
In my early PPL days our school was at Manchester and we shared the runway with the big boys. The earliest intersection from the south side to 24 (only the one runway in those days) was some 500 metres from the threshold. This left my Piper Tomahawk with a mere 2500 metres to get airborne.
I dread to think how a "Request backtrack" would have been received by ATC.
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michaelporteous,
As Jimmy do Little has already said - there is much more to it than meets the eye. If you obsess over every little detail - why cant we do this, why dont we do that - we would never leave our homes, let alone go flying.
The simple answer for intersection take offs are that;
It saves time, fuel aka Money.
Can help ATC when they're busy - more movements.
Performance calculated to ensure that at V1 (just prior!) you can reject and stop. Or continue and reach the minimum screen height.
There are many other performance based issues here too.
These procedures are being used world-wide everyday and are tried and tested otherwise we wouldnt be doing them.
As Jimmy do Little has already said - there is much more to it than meets the eye. If you obsess over every little detail - why cant we do this, why dont we do that - we would never leave our homes, let alone go flying.
The simple answer for intersection take offs are that;
It saves time, fuel aka Money.
Can help ATC when they're busy - more movements.
Performance calculated to ensure that at V1 (just prior!) you can reject and stop. Or continue and reach the minimum screen height.
There are many other performance based issues here too.
These procedures are being used world-wide everyday and are tried and tested otherwise we wouldnt be doing them.
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Yes, useless like altitude above.
So let's stay on the ground.
So let's stay on the ground.
Runway behind you IS useless because you can't use it. Simple as that.
Warning Toxic!
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I never take off full length when an intersection take-off is perfectly acceptable- I've got a schedule to keep, so runway behind me is completely useless- I don't want it anyway, thankyou. When I fly, altitude above me is useless- totally useless unless I only want it because some other mother is blocking me from climbing. Other than that, you can keep it, ta v much. Fuel still in the bowser is useless- because I've always had enough. Ain't never come near running out yet- my job is to make sure that doesn't happen.
All in all, yet another trite (alleged) saying passed from mouth to mouth by simpletons that means absolutely nothing, and is destined to waste our time ad infinitum. Is there any way we can put a stop to people spreading this daftness? Like exterminate the culprit everytime? It would die out in a generation.
All in all, yet another trite (alleged) saying passed from mouth to mouth by simpletons that means absolutely nothing, and is destined to waste our time ad infinitum. Is there any way we can put a stop to people spreading this daftness? Like exterminate the culprit everytime? It would die out in a generation.
I'd have to agree with Rainboe... It's just another old saying. After all, in a perf. 'A' aircraft, what are you going to use the extra runway for? Stopping after V1 or Vr? We had a graphic demo. recently of how inadvisable that is...
Best bit is that if you are using assumed temperature data (most airlines do) on an average length runway, you'll have pretty much the same margins over the hedge using an intersection as if you'd gone for full length.
Best bit is that if you are using assumed temperature data (most airlines do) on an average length runway, you'll have pretty much the same margins over the hedge using an intersection as if you'd gone for full length.
Well that A340 at Melbourne a few months back was very sure that they were going to make it off on the runway available safely, but simply didn't.
It was a rare mistake, that's for sure, but if there's no time pressure I can't see why you wouldn't use that bit of extra runway.
That being said, if all the calcuations are right it's a perfectly acceptable option to use less than the full length.
It was a rare mistake, that's for sure, but if there's no time pressure I can't see why you wouldn't use that bit of extra runway.
That being said, if all the calcuations are right it's a perfectly acceptable option to use less than the full length.
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So now let's move on to fuel unused at TO. (Flex). It's only unsafe when it is. As Emirates demonstrates, both int. TO and flex demand no bonehead mistakes.
There will always be bonehead mistakes. Against that certainty, eliminating a fix for Mr. Bonehead's play, is worth how much? Someone must know.
Will
There will always be bonehead mistakes. Against that certainty, eliminating a fix for Mr. Bonehead's play, is worth how much? Someone must know.
Will
Last edited by Will Fraser; 16th Jul 2009 at 17:39.
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LFML RWY is NOT intersecting, both are in parallel with each other. I'm almost 15years in aviation with nearly 06 years of flying and haven't had heard this quote "RWY behind you".
