Take-off data calculations whilst Taxiing
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Take-off data calculations whilst Taxiing
It is apparent that a Major UK carrier,regularly departs the gate without receiving the final load-sheet via the ACARS. This information is usually received whilst taxiing out and then the take-off data is calculated and setup. I do not know the exact procedural details that they comply to, but I do know that quite often this "final" has not been received by the time they reach the holding point. They then advise ATC that they are unable to depart due to the fact that they have not received the applicable data or need time to calculate their speeds/thrust settings and performance limitations etc
They then block the taxiway for everyone else until they have the required data. At FACT this means no one moves. I have been stuck behind them twice at FAJS in the past month and my F/O reported the same happening to him at FACT.
Is this his normal practice i.e. SOP?
I believe that this procedure could result in an incorrect T/O data calculation which could have disasterous results.
If the data is being processed whilst the aircraft is moving then surely lookout etc. is being compromised.
As an outsider looking in it just seems an unsafe practice which gains very little, and in my humble opinion is poor airmanship.
I do think it is very selfish, with little regard for other operators.
ATC should not allow it, if one is not ready with regard to T/O data,then one should be instructed to vacate the taxiway and return to the ramp, or the very least to a holding area, allowing others who have complied with their SOP's and have made the necessary calculations, to depart.
They then block the taxiway for everyone else until they have the required data. At FACT this means no one moves. I have been stuck behind them twice at FAJS in the past month and my F/O reported the same happening to him at FACT.
Is this his normal practice i.e. SOP?
I believe that this procedure could result in an incorrect T/O data calculation which could have disasterous results.
If the data is being processed whilst the aircraft is moving then surely lookout etc. is being compromised.
As an outsider looking in it just seems an unsafe practice which gains very little, and in my humble opinion is poor airmanship.
I do think it is very selfish, with little regard for other operators.
ATC should not allow it, if one is not ready with regard to T/O data,then one should be instructed to vacate the taxiway and return to the ramp, or the very least to a holding area, allowing others who have complied with their SOP's and have made the necessary calculations, to depart.
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Hot Dog you are missing my point. Yes there are times when t/o data has to be recalculated due to runway changes etc. However if one is expecting that, one normally loads the alternative runway in the secondary flight plan if one has that facility available. In your example EVERYONE is in the same boat and delays in departure are often inevitable when there has been a runway change...I find it unacceptable to be delayed because one operator chooses to calculate takeoff performance at the holding point, and the runway hasn't been changed for days.
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I almost always pushback and taxi before I receive the final load data. That is the way my company operates. It has to do with the lead sending the load information to load control, load control's entering the data into the system and the final numbers being datalinked to our flight. Most often it all comes together and we are ready to roll into position on the runway when we arrive.
At some stations delays are normal and I advise ground control on the way out that we may not be ready at the end so they can sideline us if necessary.
Sometimes less experienced crews get caught and block departures. They soon learn.
Happy Landings
At some stations delays are normal and I advise ground control on the way out that we may not be ready at the end so they can sideline us if necessary.
Sometimes less experienced crews get caught and block departures. They soon learn.
Happy Landings
Sounds like a certain US Airline lacking in paint, they never seem to have their numbers ready approaching the runway and either pull off to the side or delay everyone else..
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ZS340,
We have had trouble with a major UK carrier.Early in the morning they are unable to get the data,because of the number of requests at the same time.Unfortunately we are unable to pull them to one side,so it's on the runway,taxi down and join the back of the departures.
It's not as bad as it used to be,but still happens a lot.
We have had trouble with a major UK carrier.Early in the morning they are unable to get the data,because of the number of requests at the same time.Unfortunately we are unable to pull them to one side,so it's on the runway,taxi down and join the back of the departures.
It's not as bad as it used to be,but still happens a lot.
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This information is usually received whilst taxiing out and then the take-off data is calculated and setup.
The general principles work well and save the time getting a final loadsheet to the aircraft.
The issue at FAJS and FACT is to do with the time in getting the numbers back to the aircraft. This may well be a dispatcher issue at these stations as generally it works quite well at most places nowadays. There are comms issues with the handling agent at JNB and at CPT there are issues with the generally short taxi out time and no holding area which can be embarassing. For that reason, some of us won't push straight away but give it a few minutes at CPT.
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We normally get the final zero fuel weight a few minutes after check-in closes - infact we cannot complete fuelling until we have the final ZFW - things are that tight . The final is rarely more than a ton adrift to the prediction at report time . The figures have already gone in as the tables move in steps of five tonnes and interpolation is rarely worth it .
The load sheet arrives by ACARS in its own sweet time and there is just the trim to set .
The load sheet arrives by ACARS in its own sweet time and there is just the trim to set .
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ZS340
Not when I'm in command it doesn't............
Brakes off on stand to trigger the ACARS "off" signal then wait at least 15 minutes before calling ATC for push back. After carrying out a normal push and start procedure (and offering to give way to our friends in SAA Cargo ) the final figures arrive just before we reach the threshold. As Topbunk says the incidence of "revisions" to those figures is very rare so I often get take-off clearance without stopping on the taxyway
Now, what about the A340's poor climb and cruise performance leaving LHR.....
They then block the taxiway for everyone else until they have the required data. At FACT this means no one moves.
Brakes off on stand to trigger the ACARS "off" signal then wait at least 15 minutes before calling ATC for push back. After carrying out a normal push and start procedure (and offering to give way to our friends in SAA Cargo ) the final figures arrive just before we reach the threshold. As Topbunk says the incidence of "revisions" to those figures is very rare so I often get take-off clearance without stopping on the taxyway
Now, what about the A340's poor climb and cruise performance leaving LHR.....
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ZS340
If this is regularly creating problems with ATC; surely you have approached the operator about sorting out their problem.
Some places have their own local procedures. At Italian airports we are not allowed to pushback until final figures are received. With such an incentive - the loadsheet figures usually arrive before the last door close!
I believe that there are changes being made for the FAJS loadsheet operation. A different location is now processing the figures. There will be a period while the new system beds in, but there should be a marked improvement once that is complete.
Fingers crossed.
T'Bug
If this is regularly creating problems with ATC; surely you have approached the operator about sorting out their problem.
Some places have their own local procedures. At Italian airports we are not allowed to pushback until final figures are received. With such an incentive - the loadsheet figures usually arrive before the last door close!
I believe that there are changes being made for the FAJS loadsheet operation. A different location is now processing the figures. There will be a period while the new system beds in, but there should be a marked improvement once that is complete.
Fingers crossed.
T'Bug
I almost always pushback and taxi before I receive the final load data. That is the way my company operates. It has to do with the lead sending the load information to load control, load control's entering the data into the system and the final numbers being datalinked to our flight. Most often it all comes together and we are ready to roll into position on the runway when we arrive.
In most countries, only the Captain is authorized to approve the loadsheet. To do so, he needs to check a number of critical data items that the loadsheet is based upon. A signed copy of the loadsheet is then left along with the Captain's signed acceptance of the maintenance log with ground personnel. This then provides direct evidence of what the aircraft loading and maintenance state of the aircraft was purported to be in the event that the aircraft is completely destroyed in an accident.
To perform a loadsheet check, the Captain needs about 30 to 60 seconds of head-down time to check the sheet itself and sign it. What the heck is happening to the aircraft during this time as it taxys to the hold point? The Captain is necessarily out of the loop.
THEN, data needs to be accurately transferred from the loadsheet for the following:
1. Takeoff data needs to be calculated for the aircraft weight and specific runway and met conditions. This data entry and output must be cross-checked independently by another crew-member.
2. This take-off data then needs to be entered into the engine management system to achieve the correct engine thrust for take-off.
3. This takeoff data will determine the flap setting and this needs to be set on the flap selection.
4. Take-off trim needs to be calculated from the CG position or at least transferred from the loadsheet to the trim wheel setting and cross-checked.
It is not impossible to do take-off data calculations due to a runway change after pushback, but it is obviously is a direct threat to safety of flight.
But your airline ALWAYS does the loadsheet check and the takeoff calculations after pushback and on the run for every takeoff? Please tell me that you are working for an African or other third-world small aircraft airline?
Emirates very nearly had what would have been Australia's worst accident recently in Melbourne when the loadsheet data was either incorrectly entered or the takeoff data was incorrectly calculated and entered by the cockpit crew.
Gentlemen and aviatrixes, this is a no-sh!t heads-up warning to all professional aviators.
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I have never read so much bull
in one post!
How on earth is it a direct threat to safety? Ohh dear, some people have no concept of reality.
A provisional loadsheet is produced and handed to the captain. This has the figures which are expected for the flight. Not always 100% accurate but normally a good fair estimate.
These figures are initially used for speeds etc. The captain accepts this loadsheet, signs it and returns a copy to the dispatcher before flight.
After pushback the final figures are entered into the system to produce the final loadsheet figures, this data is then transmitted via acars (or a/g radio) to the aircraft. The flight crew get a print out of this on the flight deck and read it. This will show whether there is any changes to the original provisional figures or whether they are infact the same as the provisional figures which is often the case.
This loadsheet is acknowledged by the flight crew through acars.
If there are changes shown on the final figures, then the speeds etc are ammended accordingly, all prior to flight and in total comfort and safety. If it takes longer at the hold and delays people a few minutes then tough luck really. They will never depart without receiving & acknowledging final figures then making nescessary changes tp flight data.
As for the issue of taxying, i dont think i have heard of any taxying accident where reading the loadsheet has been a contributing factor.
Flexible responses 'no-****' response really is full of Are you some press associate trying to scald the names of major airlines?
Capt. D
in one post!How on earth is it a direct threat to safety? Ohh dear, some people have no concept of reality.
A provisional loadsheet is produced and handed to the captain. This has the figures which are expected for the flight. Not always 100% accurate but normally a good fair estimate.
These figures are initially used for speeds etc. The captain accepts this loadsheet, signs it and returns a copy to the dispatcher before flight.
After pushback the final figures are entered into the system to produce the final loadsheet figures, this data is then transmitted via acars (or a/g radio) to the aircraft. The flight crew get a print out of this on the flight deck and read it. This will show whether there is any changes to the original provisional figures or whether they are infact the same as the provisional figures which is often the case.
This loadsheet is acknowledged by the flight crew through acars.
If there are changes shown on the final figures, then the speeds etc are ammended accordingly, all prior to flight and in total comfort and safety. If it takes longer at the hold and delays people a few minutes then tough luck really. They will never depart without receiving & acknowledging final figures then making nescessary changes tp flight data.
As for the issue of taxying, i dont think i have heard of any taxying accident where reading the loadsheet has been a contributing factor.
Flexible responses 'no-****' response really is full of
Are you some press associate trying to scald the names of major airlines?Capt. D
Warning Toxic!
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This is NOT Rumours and News. It is quite regularly raised and discussed as in the past. It´s old hat now. Get used to it- that is how operations are increasingly going to be when the improved communications afforded by ACARs are going to justify their expense. Trying to make a ´safety´ issue out of it is laughable, and frankfully, a little pathetic. No aeroplane taxies out ready for take-off immediately. They all have checks and cabin checks and briefings to complete. It´s no different ´waiting for your figures´. The system will eventually settle down. Those of you in such a darned hurry would do well to relax and bit and learn some patience.
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Some places have their own local procedures....
I've noticed twice now recently at JED, the lead airplane on the taxiway not being ready (and not having advised ATC beforehand)...sent straight back to the parking stand, pronto.
They then get the message, real quick, for future ops.
Sounds like a dumb idea to me. As for Rainboe's idea of us slowing down, learning a little patience so he can do his takeoff data, that is a little selfish... I would have thought you could mount the same argument the other way: why are you so impatient to get off the gate (and possibly hold everybody else up) when you could be a little patient yourself and get organised before pushback?
Brakes off on stand to trigger the ACARS "off" signal
Warning Toxic!
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Your facts are wrong. You do not do take-off figures on the taxi out. They are precomputed before pushback. Fine to send people back to the stand for delays in the figures- that will also apply if you delay people on checks, and have to hold up take-off because the cabin checks aren´t done in time too?
This is the way the next generation will be doing it! Get used to it! Get over it too.
This is the way the next generation will be doing it! Get used to it! Get over it too.
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I think the point of this practice is that it can cause inconveniences both to ATC and other aircraft, I think if it was unsafe it would have been brought up and changed along time ago.
I experienced this very topic today after landing at LGW, we taxied to our gate and was told to hold while a major US carrier finished its pushback into the cul-de-sac and also wait for it to taxi to the holding point (not very far from its gate) before we could proceed.
After there push back they called ATC to ask if they could hold position because they had not completed their takeoff calculations and bugs. This did not go down well with ATC who was rather busy at the time and was told to taxi to the holding point regardless because right now he was blocking everyone!
Iv never seen an a/c taxi out so slow! I mean even the A380 does not taxi this slow. There were several aircraft waiting one on stand for push, us waiting to get onto stand and the rest were waiting in line for takeoff sequence. They did not show much appreciation to the fact that other a/c were waiting for them.
Now this may have been because they were partly heads down and taxing at the same time in which I can understand why they would taxi so slow, but this was also at the expense of other aircraft. LGW is not the greatest taxi layout but the taxi instructions to the US aircraft was simple enough because the gate was so close to the holding point, so it was not to do with complicated taxi instructions.
9 times out of 10 this practices probably goes unnoticed and generally works without inconveniencing others but I can see why the few times it does can irritate both ATC and other crews.
Its really no big issue, as long as it does not happen all the time, I'm sure ATC will bring in new procedures if it gets out of hand such as the ones imposed in Italy.
I experienced this very topic today after landing at LGW, we taxied to our gate and was told to hold while a major US carrier finished its pushback into the cul-de-sac and also wait for it to taxi to the holding point (not very far from its gate) before we could proceed.
After there push back they called ATC to ask if they could hold position because they had not completed their takeoff calculations and bugs. This did not go down well with ATC who was rather busy at the time and was told to taxi to the holding point regardless because right now he was blocking everyone!
Iv never seen an a/c taxi out so slow! I mean even the A380 does not taxi this slow. There were several aircraft waiting one on stand for push, us waiting to get onto stand and the rest were waiting in line for takeoff sequence. They did not show much appreciation to the fact that other a/c were waiting for them.
Now this may have been because they were partly heads down and taxing at the same time in which I can understand why they would taxi so slow, but this was also at the expense of other aircraft. LGW is not the greatest taxi layout but the taxi instructions to the US aircraft was simple enough because the gate was so close to the holding point, so it was not to do with complicated taxi instructions.
9 times out of 10 this practices probably goes unnoticed and generally works without inconveniencing others but I can see why the few times it does can irritate both ATC and other crews.
Its really no big issue, as long as it does not happen all the time, I'm sure ATC will bring in new procedures if it gets out of hand such as the ones imposed in Italy.
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In the company where i work for, loadsheet includes total pax on board,pax sitting distripution,i.e. What if there is a discrepancy on total pax onboard when they receive the final loadsheet?
Do they taxi back to stand?
Do they taxi back to stand?