DJ 419 ADL SYD 1500/10th Nov
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The individual take off charts used by my airline are based on max V1 – also known as overspeed Vspeeds.
Therefore, for those concerned about rejects – using the full length achieves nothing. The aircraft will come to rest at the same point along the runway. The only savings made out of full-length departure being reduced take off EPR.
If your aircraft is at a weight such that 1500m of runway is required – why not take an intersection with 2500m remaining instead of 3000. You lose nothing.
“At the end of the day why would you want to reduce the safety margins for no gain”
This scenario does not necessarily reduce safety margins and it can result in gains – avoiding an extra 5 mins taxi time and a 2 min wake turb wait has just saved your company money.
And besides, safety margins are reduced every day you go flying – it is a business.
Therefore, for those concerned about rejects – using the full length achieves nothing. The aircraft will come to rest at the same point along the runway. The only savings made out of full-length departure being reduced take off EPR.
If your aircraft is at a weight such that 1500m of runway is required – why not take an intersection with 2500m remaining instead of 3000. You lose nothing.
“At the end of the day why would you want to reduce the safety margins for no gain”
This scenario does not necessarily reduce safety margins and it can result in gains – avoiding an extra 5 mins taxi time and a 2 min wake turb wait has just saved your company money.
And besides, safety margins are reduced every day you go flying – it is a business.
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Sperm Bank said in his first post and here it is again.
Sperm Banks second post:
But wait a minute, you just said the figures Guarantee we will stop before the end of the runway...................hmm I wonder if they really do .
As i gaze back at my now rather tatty and old trevor thom performance manual, it rambles on about assured performance of transport category a/c. (no mention of guaranteeing anywhere i might add) But WAIT, a disclaimer in the book - However, as with many other critical situations in aviation, the aeroplane can only perform to its certified standard if operated correctly by the pilot
It also mentions other factors may affect this assured performance....
So yes the figures are assured to be correct. Are they Guaranteed ? No I dont see it written in my companys manual nor a reference to the figures being guaranteed in the CAO's. I also see a training text book indicating that factors may influence the assured figures. So who is correct???
Who knows eh. Yet I still dont Guarantee that I am correct.
The figures GUARANTEE we will stop before the end of the runway if rejecting prior to V1. So there is NO intellectual (or otherwise) case for not performing intersection departures. All performance figures are as I say GUARANTEED
Many RTO's end up in an incident MAINLY because the crew do not perform them correctly
But wait a minute, you just said the figures Guarantee we will stop before the end of the runway...................hmm I wonder if they really do .
As i gaze back at my now rather tatty and old trevor thom performance manual, it rambles on about assured performance of transport category a/c. (no mention of guaranteeing anywhere i might add) But WAIT, a disclaimer in the book - However, as with many other critical situations in aviation, the aeroplane can only perform to its certified standard if operated correctly by the pilot
It also mentions other factors may affect this assured performance....
So yes the figures are assured to be correct. Are they Guaranteed ? No I dont see it written in my companys manual nor a reference to the figures being guaranteed in the CAO's. I also see a training text book indicating that factors may influence the assured figures. So who is correct???
Who knows eh. Yet I still dont Guarantee that I am correct.
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Some interesting responses. Thanks to all who took the effort, but as yet the original question has not been answered.
go-dj departure was on time.
Splatman No argument about the RTOW approval. The question asked was “what was saved “ it wasn’t time as we could have gone to the full length in the time we waited.
Cactus The adage is an oldie but a goodie. BTW after 5000+, I ceased being a piston bretheren about 15,000 hrs ago.
Lizzie About the time I was coming to grips with V1/V2, delta V, overspeed V2, second segments and 20.7.1 (b) etc, you were probably just starting to use pastels and crayons.
Just cos the book says you can do something does not make it the most sensible course of action. If there is some compelling reason to shave the margins go for it. However if there is NO advantage, why put yourself closer to the edge.
To follow your rationale, we should be lobbying CASA to have the 30 minutes mandatory reserve abolished, after all we never need it, and it really is a waste carrying all that extra weight. Heavens, it would even make our intersection departures safer because of the lower weight.
Refer to the incidents I will detail at the end of this.
Sperm Bank Yes I do well know that the RTOW figures have been calculated before you go.
If you believe the “guarantee” bit, I have some really good real estate spanning Sydney Harbour you may wish to invest in.
Refer to the comments above, to the reptile.
Dr Smith refer to go_dj comment.
Amos 2 Glad I am not a lone voice
Col. Walt I am neither QF or DJ and although I really don’t give a fig as to the outcome, I would put my voice to the DJ cause in a fight to the death.
Blueloo and cunning linguist Thanks
Beer Can Dreaming The point is, nothing was saved/gained and a safety margin was removed.
Hugh When you use a derate you still have the option of calling in the extra thrust if required (not necessary by certification, but available none the less) whereas when you have left the extra bitumen behind you, there ain’t no way to retrieve it. From an engine longevity point of view, good airmanship WHEN conditions permit. (something gained, as opposed to the current question where nothing was gained other than about ¾ mile unbraked rolling wear on the dunlops)
Fat Eric In my experience that is a unique way of handling V1 unless you are also using an overspeed V2. Are you working in areas where an improved second segment is required.
Would suggest you analyse what you wrote re coming to stop at the same point on the runway.
Are you suggesting that reduction of EPR where available is not a good move. Refer to comment above for Hugh.
In this case there was no extra time to go full length as DJ had to wait for the preceding QF.
Incident 1 Rome /CIA. MD80. Takeoff 300lbs below max for conditions. Wind shifted from slight head to moderate downwind about ½ way down the runway. By the time acceleration stagnation was noted there was insufficient runway to stop from SPEED BELOW V1. Takeoff continued clearing opposite end approach light by an estimated 20 feet. Not the 35 feet GUARANTEED by RTOW for takeoff at heavier weight.
Had intersection been available and used, catastrophe.
Incident 2 MD 80. Highspeed reject ABOVE VR. No control response to elevator input. Had intersection been used overrun inevitable.
Incident 3 Limiting strip. Takeoff continued with inadequate elevator response and stability due excessively forward Cof G. Control barely maintained until cabin load shifted aft. Had an intersection been available and used, catastrophe.
I can vouch for all these incidents as they have all happened to me.
I’ll continue to take the full length thanks, unless there are significant reasons as to why not.
I would rather be a live chicken than a dead cock.
GG
go-dj departure was on time.
Splatman No argument about the RTOW approval. The question asked was “what was saved “ it wasn’t time as we could have gone to the full length in the time we waited.
Cactus The adage is an oldie but a goodie. BTW after 5000+, I ceased being a piston bretheren about 15,000 hrs ago.
Lizzie About the time I was coming to grips with V1/V2, delta V, overspeed V2, second segments and 20.7.1 (b) etc, you were probably just starting to use pastels and crayons.
Just cos the book says you can do something does not make it the most sensible course of action. If there is some compelling reason to shave the margins go for it. However if there is NO advantage, why put yourself closer to the edge.
To follow your rationale, we should be lobbying CASA to have the 30 minutes mandatory reserve abolished, after all we never need it, and it really is a waste carrying all that extra weight. Heavens, it would even make our intersection departures safer because of the lower weight.
Refer to the incidents I will detail at the end of this.
Sperm Bank Yes I do well know that the RTOW figures have been calculated before you go.
If you believe the “guarantee” bit, I have some really good real estate spanning Sydney Harbour you may wish to invest in.
Refer to the comments above, to the reptile.
Dr Smith refer to go_dj comment.
Amos 2 Glad I am not a lone voice
Col. Walt I am neither QF or DJ and although I really don’t give a fig as to the outcome, I would put my voice to the DJ cause in a fight to the death.
Blueloo and cunning linguist Thanks
Beer Can Dreaming The point is, nothing was saved/gained and a safety margin was removed.
Hugh When you use a derate you still have the option of calling in the extra thrust if required (not necessary by certification, but available none the less) whereas when you have left the extra bitumen behind you, there ain’t no way to retrieve it. From an engine longevity point of view, good airmanship WHEN conditions permit. (something gained, as opposed to the current question where nothing was gained other than about ¾ mile unbraked rolling wear on the dunlops)
Fat Eric In my experience that is a unique way of handling V1 unless you are also using an overspeed V2. Are you working in areas where an improved second segment is required.
Would suggest you analyse what you wrote re coming to stop at the same point on the runway.
Are you suggesting that reduction of EPR where available is not a good move. Refer to comment above for Hugh.
In this case there was no extra time to go full length as DJ had to wait for the preceding QF.
Incident 1 Rome /CIA. MD80. Takeoff 300lbs below max for conditions. Wind shifted from slight head to moderate downwind about ½ way down the runway. By the time acceleration stagnation was noted there was insufficient runway to stop from SPEED BELOW V1. Takeoff continued clearing opposite end approach light by an estimated 20 feet. Not the 35 feet GUARANTEED by RTOW for takeoff at heavier weight.
Had intersection been available and used, catastrophe.
Incident 2 MD 80. Highspeed reject ABOVE VR. No control response to elevator input. Had intersection been used overrun inevitable.
Incident 3 Limiting strip. Takeoff continued with inadequate elevator response and stability due excessively forward Cof G. Control barely maintained until cabin load shifted aft. Had an intersection been available and used, catastrophe.
I can vouch for all these incidents as they have all happened to me.
I’ll continue to take the full length thanks, unless there are significant reasons as to why not.
I would rather be a live chicken than a dead cock.
GG
Last edited by grange.guzzler; 12th Nov 2003 at 12:35.
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Why does QF always use Juliet in ML,when full length is apparently better,why does QF always use A7 in BN when full length is better and if it was a northerly in AD which intersection do you use?
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Whipping Boy
Who knows why QF do anything in particular???
Perhaps you miss the point with this situation though. Nothing was gained by using the intersection. Time was near enough the same. (Give or take 20 seconds)
Departure was from 23.
GG
Who knows why QF do anything in particular???
Perhaps you miss the point with this situation though. Nothing was gained by using the intersection. Time was near enough the same. (Give or take 20 seconds)
Departure was from 23.
GG
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Wooooff Cactus, if you were insulted by that, I would hate to be the poor human stealing your next car park. And actually Cact, I did have a nice day. Talking about airmanship and insults, why dont you ask Grange why he did not just add the crew name and the amount of Pax's to the original heading.
DJ 491 ADL/SYD 1500/10 Nov. It would have been much more PROFESSIONALLY appropriate and use of basic AIRMANSHIP to state something as "737 ADL intersection dept" rather than plaster Airline, flt no, time and date all over a public and worldwide forum.
Grange, take a note of the comments above and thanks for the thought and I hope the crayons and pastels for your sake go back to the early 60's.
DJ 491 ADL/SYD 1500/10 Nov. It would have been much more PROFESSIONALLY appropriate and use of basic AIRMANSHIP to state something as "737 ADL intersection dept" rather than plaster Airline, flt no, time and date all over a public and worldwide forum.
Grange, take a note of the comments above and thanks for the thought and I hope the crayons and pastels for your sake go back to the early 60's.
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I have said it before and I will say it again.
It is sad to see the respect that existed between crews now dissappear with the arrival of the LCC. I cannot put my finger on 'why' but it would seem that there it a definite level of animosity between the two 'major' domestics in Australia. I so not recall this being so in the Ansett days.
It is sad to see the respect that existed between crews now dissappear with the arrival of the LCC. I cannot put my finger on 'why' but it would seem that there it a definite level of animosity between the two 'major' domestics in Australia. I so not recall this being so in the Ansett days.
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At the end of the day, if the paperwork says it works you wont lose your house if there is a prang.....but at the court case, the man in the black robe, wearing the curly white wig asks you, as you are a professional, exercising your duty of care, to justify your actions....if you are confident that you can convince the court...go for it. (all BS aside, we all know that if time and cost was irrelevant we'd go the full length, etc) 
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Actually Fatman, the difference between intersection and full length wake turbulence is 1 minute, or zero minutes if you're in a real aeroplane.
The difference between taxiing intersection and full length at AD RW23 is as stated about 30-45 secs, maybe you are still remembering your ab-initio instructor saying " never taxi above walking pace " ??
" safety margins are reduced every day you go flying, it's a business " thanks for that, If I ever leave my current position that sounds like a doosy of a line to use at an interview.
In our airline, we actually strive to increase safety margins every day, a bit old fashioned I know, but it seems to work.
The difference between taxiing intersection and full length at AD RW23 is as stated about 30-45 secs, maybe you are still remembering your ab-initio instructor saying " never taxi above walking pace " ??
" safety margins are reduced every day you go flying, it's a business " thanks for that, If I ever leave my current position that sounds like a doosy of a line to use at an interview.
In our airline, we actually strive to increase safety margins every day, a bit old fashioned I know, but it seems to work.
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Cunninglinguist,
It is the arrogance and condescension in your reply that makes pprune such a happy little place.
I will respond to your post with more manners.
Although the example given at the start of the thread was referring to ADL, I was thinking more in general terms.
For example, in WSSS where I operate, runway 20r is occasionally used for dep. In the A/C I fly, using full length is never required. Obviously we use it in the wet or for heavy takeoffs.
BUT – normally it is unnecessary. At most departure weights, using the 1000 m intersection will result in the same EPR setting, the same V speeds or less, the same flap setting and the same terrain clearance – i.e., water.
However, it saves a couple of minutes taxi time at the very least, and more importantly a couple more minutes taxi time following the usual line of SQ 777’s on the way to the hold – they do taxi at walking pace. It also saves brake wear and tire wear.
Can you give me an example of how your airline is striving to INCREASE safety margins? Carrying more fuel. Higher experience requirements for crew. Reducing duty periods, increasing rest periods. Lowering the allowable takeoff weight of the aircraft.
I am keen to know.
It is the arrogance and condescension in your reply that makes pprune such a happy little place.
I will respond to your post with more manners.
Although the example given at the start of the thread was referring to ADL, I was thinking more in general terms.
For example, in WSSS where I operate, runway 20r is occasionally used for dep. In the A/C I fly, using full length is never required. Obviously we use it in the wet or for heavy takeoffs.
BUT – normally it is unnecessary. At most departure weights, using the 1000 m intersection will result in the same EPR setting, the same V speeds or less, the same flap setting and the same terrain clearance – i.e., water.
However, it saves a couple of minutes taxi time at the very least, and more importantly a couple more minutes taxi time following the usual line of SQ 777’s on the way to the hold – they do taxi at walking pace. It also saves brake wear and tire wear.
Can you give me an example of how your airline is striving to INCREASE safety margins? Carrying more fuel. Higher experience requirements for crew. Reducing duty periods, increasing rest periods. Lowering the allowable takeoff weight of the aircraft.
I am keen to know.
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Good reply fatboy. Some of these know it all Australians are an embarrasment and god only knows what they would be like to fly with. "we strive to increase the safety margins every day" What a pompous load of garbage!
Long john quite correct. There is a good deal of anymosity and we certainly never asked for it. SOME of the incumbents just cant stand the fact that something new and different is undermining their little comfort zone. Very very sad!
MOFO. decorum?? some of these guys wouldn't have a clue what it means.
Jarse, still laughing at that one. yeah mate by definition some of these gurus would have to believe that derate is not safe or professional as rated thrust.
Grange. Your point is correct but as i said, they worked out the figures for DELTA and then requested a taxy clearance for DELTA. They would not have had a clue who was where at that stage. Once going around the corner and seeing the conjestion they probably could have changed their minds but obviously decided not to. Does it really matter? The answer is nothing was saved this time round. Every time I have done that departure we have been cleared for a rolling t/o so saved plenty. It sounds as though you don't believe the performance figures from the a/c manufacturer. I do belive the figures I extract from the rwy analysis manual and as a bit of insurance, our company makes us use a temperature 4 degrees below the temp we could use (at the planning stage). If there is 1 knot of taiwind we will use 5 kts etc. All built in SAFETY margins. You sound as though you have been around a bit. You would probably also know that a fully laden jumbo rejecting just before V1 can stop in a surprisingly short distance. It will probably blow all the tyres (from the heat) but the performance is quite impressive.
Blueloo. I couldn't be bothered responding to your derogatory negative attitude.
Do people have to explain every action they take or can we just go to work for the enjoyment of it? This country is descending so farcically low into the depths of sub human behaviour it defies comprehension. Pilots dobbing other pilots in for PERCEIVED indescretions, ATC dobbing pilots in for pedantic rubbish. Where are we going lads and why do you want to go there? By all means ask valid and relevant questions but for gods sake lets keep the conversation subjective and de-identified.
To the QF pilot who emailed me regarding the bat incident in Cairns, thank you very much. Informative and to the point.
Long john quite correct. There is a good deal of anymosity and we certainly never asked for it. SOME of the incumbents just cant stand the fact that something new and different is undermining their little comfort zone. Very very sad!
MOFO. decorum?? some of these guys wouldn't have a clue what it means.
Jarse, still laughing at that one. yeah mate by definition some of these gurus would have to believe that derate is not safe or professional as rated thrust.
Grange. Your point is correct but as i said, they worked out the figures for DELTA and then requested a taxy clearance for DELTA. They would not have had a clue who was where at that stage. Once going around the corner and seeing the conjestion they probably could have changed their minds but obviously decided not to. Does it really matter? The answer is nothing was saved this time round. Every time I have done that departure we have been cleared for a rolling t/o so saved plenty. It sounds as though you don't believe the performance figures from the a/c manufacturer. I do belive the figures I extract from the rwy analysis manual and as a bit of insurance, our company makes us use a temperature 4 degrees below the temp we could use (at the planning stage). If there is 1 knot of taiwind we will use 5 kts etc. All built in SAFETY margins. You sound as though you have been around a bit. You would probably also know that a fully laden jumbo rejecting just before V1 can stop in a surprisingly short distance. It will probably blow all the tyres (from the heat) but the performance is quite impressive.
Blueloo. I couldn't be bothered responding to your derogatory negative attitude.
Do people have to explain every action they take or can we just go to work for the enjoyment of it? This country is descending so farcically low into the depths of sub human behaviour it defies comprehension. Pilots dobbing other pilots in for PERCEIVED indescretions, ATC dobbing pilots in for pedantic rubbish. Where are we going lads and why do you want to go there? By all means ask valid and relevant questions but for gods sake lets keep the conversation subjective and de-identified.
To the QF pilot who emailed me regarding the bat incident in Cairns, thank you very much. Informative and to the point.
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A word to the wise.
It tooks years and many deaths to get the airframers to accept that performance figures had to be created with part worn brakes instead of brand new. Hard to believe as it defy's all logic but they fought it tooth and nail keeping proven lawyers in work for years. This happened well into the widebody era. The same for turning on allowances as we enter the runway. Elsewhere in the world we're still fighting for Vmcg/a figures to reflect snowploughed runways entirely legally cleared to only half their width.
And with that background set let's look more closely at the discussion here:
Firstly - a visit to the darker recesses of the tyre manufaturers sites will tease out the information that all bets are off on their products if taxying for more than 5 or 10 minutes dependent on number of corners taken. No guarantee due to internal tyre hysteris. Vmbe is fantasy if the tyre makers shrug their shoulders and disown you.
Secondly - V1 stop figures are just not created from the work of test pilots on the type of runways you or I know. They are operating from steam and chemically scrubbed runways. When was the last time you saw your favourite touchdown point cleaned - not swept - cleaned??
The viscious braking preventing an overrun is happening on exactly that rubber, fuel, and oil contaminated touchdown point for the opposite end. Film melts, the oil products lubricate it further and we get rubber reversion to liquid. Your performance data was not created under those conditions.
So - those guarantees? Please think about it.
Regards
Rob Lloyd
And with that background set let's look more closely at the discussion here:
Firstly - a visit to the darker recesses of the tyre manufaturers sites will tease out the information that all bets are off on their products if taxying for more than 5 or 10 minutes dependent on number of corners taken. No guarantee due to internal tyre hysteris. Vmbe is fantasy if the tyre makers shrug their shoulders and disown you.
Secondly - V1 stop figures are just not created from the work of test pilots on the type of runways you or I know. They are operating from steam and chemically scrubbed runways. When was the last time you saw your favourite touchdown point cleaned - not swept - cleaned??
The viscious braking preventing an overrun is happening on exactly that rubber, fuel, and oil contaminated touchdown point for the opposite end. Film melts, the oil products lubricate it further and we get rubber reversion to liquid. Your performance data was not created under those conditions.
So - those guarantees? Please think about it.
Regards
Rob Lloyd
Last edited by PPRuNe Towers; 14th Nov 2003 at 07:30.
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Chuck( fat ) Yaeger, you've just agreed with me. I said using an intersection that reduces V speeds or obstacle clearance etc is bad airmanship, you say that the intersections you use don't reduce any of these values, so whats your point?? just a bit of Oz bashing, oh, and was'nt the thread predicated on AD RW23 ??
We have check and training meetings every three months with more often than not, new and improved ideas about SOPs, looking at other airlines incidents and accidents and trying to learn from other peoples mistakes rather than making them ourselves, constantly trying to improve/standardise checking and training, looking at results from surveillance and what areas we as a pilot group are falling down in, revising and improving LOFT excersises in the SIM , yada, yada, yada.
Oicur5 and Sperm, no reply.... you are plain idiots.
Do me a favour, let me know which airlines you guns fly for so I never put my family on them, on the off chance they get you as part of the crew.
Jarse, yes, if the derate lowers the V1 to below balanced field it is bad airmanship, smartar5e
Pprune Towers, these blokes don't need clean runways, their talent/ability more than makes up for that.
NG, let me guess, 2 years ago you were in a metro??, now the RHS of a jet and you are already an expert............nice to be judged, is'nt it ?
We have check and training meetings every three months with more often than not, new and improved ideas about SOPs, looking at other airlines incidents and accidents and trying to learn from other peoples mistakes rather than making them ourselves, constantly trying to improve/standardise checking and training, looking at results from surveillance and what areas we as a pilot group are falling down in, revising and improving LOFT excersises in the SIM , yada, yada, yada.
Oicur5 and Sperm, no reply.... you are plain idiots.
Do me a favour, let me know which airlines you guns fly for so I never put my family on them, on the off chance they get you as part of the crew.
Jarse, yes, if the derate lowers the V1 to below balanced field it is bad airmanship, smartar5e
Pprune Towers, these blokes don't need clean runways, their talent/ability more than makes up for that.
NG, let me guess, 2 years ago you were in a metro??, now the RHS of a jet and you are already an expert............nice to be judged, is'nt it ?