EK407 Tailstrike @ ML
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SQ changed the procedure for checking and rechecking performance data after an investigation of contributing causes to the Auckland accident.
NOT SURE if what happened in Melbourne to EK is the same thing, but it does seem sensible to suspect this accident has a very similar genesis.
Planes don't mysteriously disappear or crash. This isn't a tv program. It's the real world. Something went wrong, and the probability rests with that something beginning with the input of erroneous data.
Not that I'd know. I wasn't there. But if I was a betting man...
On the subject of accelaration rates and what not, NO LAND 3 has the unequivocal answer. "Don't screw up the input."
Others are talking about all sorts of novel ideas. Why? Are you trying to reinvent the wheel? The analysis of performance characteristics is faultless. Got that? Faultless.
Applying the analysis by way of inputting the derived data is another thing altogether. Why make it harder? Why reinvent the wheel? The data's all there in the book. All it needs is to be accurately transcribed into the FMC. And there's the trap: all it needs...
I'm with the low viz guy
NOT SURE if what happened in Melbourne to EK is the same thing, but it does seem sensible to suspect this accident has a very similar genesis.
Planes don't mysteriously disappear or crash. This isn't a tv program. It's the real world. Something went wrong, and the probability rests with that something beginning with the input of erroneous data.
Not that I'd know. I wasn't there. But if I was a betting man...
On the subject of accelaration rates and what not, NO LAND 3 has the unequivocal answer. "Don't screw up the input."
Others are talking about all sorts of novel ideas. Why? Are you trying to reinvent the wheel? The analysis of performance characteristics is faultless. Got that? Faultless.
Applying the analysis by way of inputting the derived data is another thing altogether. Why make it harder? Why reinvent the wheel? The data's all there in the book. All it needs is to be accurately transcribed into the FMC. And there's the trap: all it needs...
I'm with the low viz guy
US Patent 6175315 - Aircraft takeoff acceleration indicator system
Inventors
Millard, Wayne C.
Millard, Carl W.
Application
No. 180473 filed on 11/10/1998
see Aircraft takeoff acceleration indicator system - US Patent 6175315 Claims
Claims
What is claimed is:
1. An instrumentation system for use in aircraft, during the takeoff roll from standstill to V1 speed, that continuously displays a target airspeed at which the aircraft should be if it is meeting the acceleration required to be at V1 at the anticipated distance, wherein a related computer with a database stores information on curves of takeoff acceleration graphs of the type and model of said aircraft with respect to speed versus time on said takeoff roll as well as distance;
an actual airspeed display continuously displaying the actual speed of said aircraft wherein, during the takeoff roll up to V1 speed, said computer continuously controls the progressive movement of target airspeed display in said actual airspeed display, to display the target speed at which the aircraft should be if it is meeting the computer-stored acceleration curve based on time;
and a display for continuously displaying the computed distance that said aircraft is currently lagging behind when said actual speed is less than said speed at which said aircraft should be if it is meeting said computer-stored acceleration curves.
2. An instrumentation system as claimed in claim 1, further including an instrument panel having an indicator to continuously display said actual speed of said aircraft, and a needle to indicate said target speed.
3. An instrumentation system as claimed in claim 2 wherein said indicator comprises a reference line.
4. An airspeed display as indicated in claim 1 wherein said target and actual airspeeds are displayed on a rotary dial type airspeed indicator.
5. An airspeed display as claimed in claim 1 wherein said target and actual airspeeds are displayed on a tape type airspeed indicator.
6. An airspeed display as claimed in claim 1 wherein said actual airspeed is displayed by a reference line and said target airspeed is displayed by an arrow generated from said reference line.
7. An airspeed display as claimed in claim 1 wherein said target airspeed is no longer displayed when said aircraft reaches V1.
8. The display of claim 1 wherein said airspeed display is an electronically generated readout.
9. An instrument for use in aircraft, during the takeoff roll from standstill to V1 speed, that continuously displays a target airspeed at which the aircraft should be at if it is meeting the acceleration required to be at V1 at the anticipated distance, wherein a computer with a database stores information on curves of takeoff acceleration graphs of the types and model of aircraft with respect to speed versus time on said takeoff roll as well as distance;
an actual airspeed display continuously displaying the actual speed of said aircraft wherein, during the takeoff roll up to V1 speed, said computer continuously controls the progressive movement of target airspeed display in said actual airspeed display, to display the target speed at which the aircraft should be if it is meeting the computer-stored acceleration curves based on time;
a reference line against which said actual speed of said aircraft is displayed, and a needle to indicate said target speed;
and a window in said instrument for continuously displaying the computed distance that said aircraft is currently lagging behind when said actual speed is less than said speed at which said aircraft should be if it is meeting said computer-stored acceleration curves.
10. An instrument for use in an aircraft, during acceleration of the aircraft from 0 velocity to V1, for continuously monitoring actual velocity of the aircraft versus target velocity of the aircraft required to accelerate to V1 within an anticipated distance from a standstill position comprising:
(a) input means for entering parameters affecting an anticipated distance from the standstill position required to accelerate to V1;
(b) comprising means for calculating from said parameters;
(i) a V1 value for said aircraft;
(ii) anticipated distance from aid standstill position required to accelerate to V1;
(iii) time required to accelerate to V1; and
(iv) target velocity continuously required to accelerate to V1 within said time required;
(c) means for operably storing said V1 value of said aircraft, anticipated distance from standstill position, time required to accelerate to V1, and target velocity continuously required to accelerate to V1 within said time required to accelerate to V1; and
(d) means for continuously and simultaneously displaying and monitoring the actual velocity of the aircraft and the target velocity required to achieve V1, comprising a linear readout airspeed indicator having a reference line against which said actual velocity is displayed, and wherein an arrow generated from said reference line displays said target velocity;
(e) means for displaying continuously the actual distance said aircraft is lagging said aircraft's actual position behind an anticipated position determined by the anticipated distance from the standstill position required to accelerate to V1.
Maybe this is what's needed?
Inventors
Millard, Wayne C.
Millard, Carl W.
Application
No. 180473 filed on 11/10/1998
see Aircraft takeoff acceleration indicator system - US Patent 6175315 Claims
Claims
What is claimed is:
1. An instrumentation system for use in aircraft, during the takeoff roll from standstill to V1 speed, that continuously displays a target airspeed at which the aircraft should be if it is meeting the acceleration required to be at V1 at the anticipated distance, wherein a related computer with a database stores information on curves of takeoff acceleration graphs of the type and model of said aircraft with respect to speed versus time on said takeoff roll as well as distance;
an actual airspeed display continuously displaying the actual speed of said aircraft wherein, during the takeoff roll up to V1 speed, said computer continuously controls the progressive movement of target airspeed display in said actual airspeed display, to display the target speed at which the aircraft should be if it is meeting the computer-stored acceleration curve based on time;
and a display for continuously displaying the computed distance that said aircraft is currently lagging behind when said actual speed is less than said speed at which said aircraft should be if it is meeting said computer-stored acceleration curves.
2. An instrumentation system as claimed in claim 1, further including an instrument panel having an indicator to continuously display said actual speed of said aircraft, and a needle to indicate said target speed.
3. An instrumentation system as claimed in claim 2 wherein said indicator comprises a reference line.
4. An airspeed display as indicated in claim 1 wherein said target and actual airspeeds are displayed on a rotary dial type airspeed indicator.
5. An airspeed display as claimed in claim 1 wherein said target and actual airspeeds are displayed on a tape type airspeed indicator.
6. An airspeed display as claimed in claim 1 wherein said actual airspeed is displayed by a reference line and said target airspeed is displayed by an arrow generated from said reference line.
7. An airspeed display as claimed in claim 1 wherein said target airspeed is no longer displayed when said aircraft reaches V1.
8. The display of claim 1 wherein said airspeed display is an electronically generated readout.
9. An instrument for use in aircraft, during the takeoff roll from standstill to V1 speed, that continuously displays a target airspeed at which the aircraft should be at if it is meeting the acceleration required to be at V1 at the anticipated distance, wherein a computer with a database stores information on curves of takeoff acceleration graphs of the types and model of aircraft with respect to speed versus time on said takeoff roll as well as distance;
an actual airspeed display continuously displaying the actual speed of said aircraft wherein, during the takeoff roll up to V1 speed, said computer continuously controls the progressive movement of target airspeed display in said actual airspeed display, to display the target speed at which the aircraft should be if it is meeting the computer-stored acceleration curves based on time;
a reference line against which said actual speed of said aircraft is displayed, and a needle to indicate said target speed;
and a window in said instrument for continuously displaying the computed distance that said aircraft is currently lagging behind when said actual speed is less than said speed at which said aircraft should be if it is meeting said computer-stored acceleration curves.
10. An instrument for use in an aircraft, during acceleration of the aircraft from 0 velocity to V1, for continuously monitoring actual velocity of the aircraft versus target velocity of the aircraft required to accelerate to V1 within an anticipated distance from a standstill position comprising:
(a) input means for entering parameters affecting an anticipated distance from the standstill position required to accelerate to V1;
(b) comprising means for calculating from said parameters;
(i) a V1 value for said aircraft;
(ii) anticipated distance from aid standstill position required to accelerate to V1;
(iii) time required to accelerate to V1; and
(iv) target velocity continuously required to accelerate to V1 within said time required;
(c) means for operably storing said V1 value of said aircraft, anticipated distance from standstill position, time required to accelerate to V1, and target velocity continuously required to accelerate to V1 within said time required to accelerate to V1; and
(d) means for continuously and simultaneously displaying and monitoring the actual velocity of the aircraft and the target velocity required to achieve V1, comprising a linear readout airspeed indicator having a reference line against which said actual velocity is displayed, and wherein an arrow generated from said reference line displays said target velocity;
(e) means for displaying continuously the actual distance said aircraft is lagging said aircraft's actual position behind an anticipated position determined by the anticipated distance from the standstill position required to accelerate to V1.
Maybe this is what's needed?
Last edited by SIUYA; 28th Mar 2009 at 05:20.
It's always amusing when the Walts start lending the benefit of their experience.
Smilin_Ed already said it: It doesn't really matter what speed is chosen/SOP'd, as long as it's before V1 and you have time to react before decision time.
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The military distance to go siteboards were(are?) great for what they were designed for, but are not suitable for current civil ops. For example, they'd be totally useless in a limited viz takeoff, which is very much a part of any airline's operation these days, and, if anything, is a situation that cries out for some such 'acceleration check' system far moreso than a CAVOK takeoff. Remember the days when we always did TOGA takeoffs in such conditions? (Whatever you come up with, gentlemen, let it NOT be another female voice cluttering up my headset. Miss *** RAAAS - another 'slam the stable door after the horse has bolted' extra we've had added to the system, blocks or partially overrides far too many ATC calls as it is. Hands up all those who'd like to see all her airborne calls dispensed with?)
Coming up with some sort of simple calculation for the trend arrow on the PFD is probably the most promising suggestion, although I was taught by the man who first endorsed me onto the 777 a very long time ago now (a 'personal extra' on his part, I hasten to add, that is not to my knowledge mentioned anywhere in the Boeing documentation), that anything under a 15 knot value on the trend arrow means something is seriously wrong and best you do something about it.
Any 777 pilot will know that, except on the highest AUWs and at the most marginal of conditions, the trend arrow is usually well above that, as much as double it. However, it's one of my 'little extra things' that I check on every takeoff, a bit like that last look on short finals that there really is a 'gear down' indication. (I don't care how many bells, whistles and other aural warnings Boeing have built in to the system to prevent a gear up landing, it's just another one of my 'things', part of the 'belts, braces and chastity belt' approach I take to most of my flying as the 'old' has increasingly replaced the 'bold' in my operation.)
I'd have to agree with quite a few others that the current situation during the 15-20 minutes before doors closed with an augmented crew on board is far less than ideal - (and Mutley, your 'take' of the number of people coming and going to the cockpit during that time is far different to mine). I can recall one very senior EK checkie (Robin H.) telling me, many years ago now, that he'd counted one day the number of interruptions between his taking the seat and pushing back. It was 27. I don't believe things have changed since. Just an example: on your average trip, how many people do you usually have come up to the flight deck to ask if they can close doors, even after you've called the CC who's manning the door on then interphone to give the go ahead?
After starting out with the attitude that, as augmenting crew, I'm an extra overseer on the flight deck, I'm now very much one in the 'stay off the flight deck as long as I can prior to engine start' camp. Unless you dibs the right jump seat, you're at best, very much in the way and at worst, a distraction to the operating crew.
I don't think we, the Great Unwashed, will ever see it in print, but I believe the CVR of those 30 minutes prior to engine start on this flight will make for some very interesting listening - and not just in the most obvious areas - for the investigators.
Coming up with some sort of simple calculation for the trend arrow on the PFD is probably the most promising suggestion, although I was taught by the man who first endorsed me onto the 777 a very long time ago now (a 'personal extra' on his part, I hasten to add, that is not to my knowledge mentioned anywhere in the Boeing documentation), that anything under a 15 knot value on the trend arrow means something is seriously wrong and best you do something about it.
Any 777 pilot will know that, except on the highest AUWs and at the most marginal of conditions, the trend arrow is usually well above that, as much as double it. However, it's one of my 'little extra things' that I check on every takeoff, a bit like that last look on short finals that there really is a 'gear down' indication. (I don't care how many bells, whistles and other aural warnings Boeing have built in to the system to prevent a gear up landing, it's just another one of my 'things', part of the 'belts, braces and chastity belt' approach I take to most of my flying as the 'old' has increasingly replaced the 'bold' in my operation.)
I'd have to agree with quite a few others that the current situation during the 15-20 minutes before doors closed with an augmented crew on board is far less than ideal - (and Mutley, your 'take' of the number of people coming and going to the cockpit during that time is far different to mine). I can recall one very senior EK checkie (Robin H.) telling me, many years ago now, that he'd counted one day the number of interruptions between his taking the seat and pushing back. It was 27. I don't believe things have changed since. Just an example: on your average trip, how many people do you usually have come up to the flight deck to ask if they can close doors, even after you've called the CC who's manning the door on then interphone to give the go ahead?
After starting out with the attitude that, as augmenting crew, I'm an extra overseer on the flight deck, I'm now very much one in the 'stay off the flight deck as long as I can prior to engine start' camp. Unless you dibs the right jump seat, you're at best, very much in the way and at worst, a distraction to the operating crew.
I don't think we, the Great Unwashed, will ever see it in print, but I believe the CVR of those 30 minutes prior to engine start on this flight will make for some very interesting listening - and not just in the most obvious areas - for the investigators.
Last edited by Wiley; 28th Mar 2009 at 11:11.
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Gentlemen,
I think the EK SOP's regarding loadsheet and T/O data entry are foolproof. If guys mess up they clearly didn't follow the SOP's for whatever reason.
I am not saying that I never made a wrong entry, and quite often I find an error in the TO data, BUT, I trap these errors because of the SOP's!
The only thing that might to be changed is the order. I's prefer us to get the loadsheet, check the numbers and only then do the T/O figures.
In the loadsheet procedure, we check DOW, ZFW, TOW, ZFWCG and ECAM CG together. After that the F/O checks the ZFW again by himself.
For the LPC: the F/O prepares the data and writes them down, the Capt checks them and inuts them, then crosschecks with the numbers the F/O wrote down.
The weight should have been checked by both, and to finalize it, we do a GREEN DOT check.
Don't get me wrong, I'm open for improvements, but we check, crosscheck and have a final 'redundancy' in the green dot check.. how far do you want to go?
If something needs to be improved, it is the disturbances during the preparations which gets us out of sequence or skip things... If operations could be a little bit more streamlined, the fuel and tech log should be finished at least 20 minutes before departure. (considering we should get the ZFW around 40 minutes before STD). By then the loadsheet should arrive and the crew should have the following 10 minutes without anyone coming in the flight deck to brief and do the loadsheet/LPC check.
---
The A345 is a 2 man operation, and I would advise everyone to keep it that way. Recently a B747 cargo operator had almost an identical mishap, scraped the tail, but because it was a cargo, not too much fuss about it in the newspapers. In the following investigation, it came to light that the augmenting guys had 'helped out' with the T/O numbers and got it wrong. They left with speeds for 100 tons less then their actual weight..
---
Even to consider to abort a T/O around 100 kts because the acceleration 'doesn't feel right' or the trend vector is not showing what I expect should be punished by the electrical chair in modern airline operations. (slight exaguration
)
Let me explain myself a little bit:
First of all: a jet engine does not produce the same thrust at different speeds with the same thrust settings, basic thermodynamics. Your acceleration (even in a perfect world) will initially increase, then decrease again. So you can not put a certain number on the acceleration itself.
Second: The trend vector is coupled to the AIRSPEED!! So there you are on a rather short runway, hitting a negative windshear. Your trend vector will be less then expected and according to quite a lot of guys above, a reason to stop the take off. Your groundspeed on the other hand might be a lot higher then you think and you would set yourself up for an overrun... The only good action would be to slam the TOGA and fly the windshear maneuver.
Acceleration monitoring can only be done with special equipment for that purpose only. Should be coupled to RAAS so the equipment knows what the runway is like. But again, it is dependent on weight, so as someone posted before, if the crew puts in the wrong weight, all the systems will fail to pick up the error.
The only thing that would make sense is the aircraft weighs itself. It can't be that difficult to put some kind of weight measurement in the struts of the mains. With the cg known to the aircraft, a gross error check can be made by the aircraft, e.g. only accepting TO weight that are within a preset margin of the actual measured weight. It doesn't need to be spot on, so no need for expensive very accurate 'scales'. As long as it picks up a significant error... But that's one for the manufacturers, not the operators...
I think the EK SOP's regarding loadsheet and T/O data entry are foolproof. If guys mess up they clearly didn't follow the SOP's for whatever reason.
I am not saying that I never made a wrong entry, and quite often I find an error in the TO data, BUT, I trap these errors because of the SOP's!
The only thing that might to be changed is the order. I's prefer us to get the loadsheet, check the numbers and only then do the T/O figures.
In the loadsheet procedure, we check DOW, ZFW, TOW, ZFWCG and ECAM CG together. After that the F/O checks the ZFW again by himself.
For the LPC: the F/O prepares the data and writes them down, the Capt checks them and inuts them, then crosschecks with the numbers the F/O wrote down.
The weight should have been checked by both, and to finalize it, we do a GREEN DOT check.
Don't get me wrong, I'm open for improvements, but we check, crosscheck and have a final 'redundancy' in the green dot check.. how far do you want to go?
If something needs to be improved, it is the disturbances during the preparations which gets us out of sequence or skip things... If operations could be a little bit more streamlined, the fuel and tech log should be finished at least 20 minutes before departure. (considering we should get the ZFW around 40 minutes before STD). By then the loadsheet should arrive and the crew should have the following 10 minutes without anyone coming in the flight deck to brief and do the loadsheet/LPC check.
---
The A345 is a 2 man operation, and I would advise everyone to keep it that way. Recently a B747 cargo operator had almost an identical mishap, scraped the tail, but because it was a cargo, not too much fuss about it in the newspapers. In the following investigation, it came to light that the augmenting guys had 'helped out' with the T/O numbers and got it wrong. They left with speeds for 100 tons less then their actual weight..
---
Even to consider to abort a T/O around 100 kts because the acceleration 'doesn't feel right' or the trend vector is not showing what I expect should be punished by the electrical chair in modern airline operations. (slight exaguration
)Let me explain myself a little bit:
First of all: a jet engine does not produce the same thrust at different speeds with the same thrust settings, basic thermodynamics. Your acceleration (even in a perfect world) will initially increase, then decrease again. So you can not put a certain number on the acceleration itself.
Second: The trend vector is coupled to the AIRSPEED!! So there you are on a rather short runway, hitting a negative windshear. Your trend vector will be less then expected and according to quite a lot of guys above, a reason to stop the take off. Your groundspeed on the other hand might be a lot higher then you think and you would set yourself up for an overrun... The only good action would be to slam the TOGA and fly the windshear maneuver.
Acceleration monitoring can only be done with special equipment for that purpose only. Should be coupled to RAAS so the equipment knows what the runway is like. But again, it is dependent on weight, so as someone posted before, if the crew puts in the wrong weight, all the systems will fail to pick up the error.
The only thing that would make sense is the aircraft weighs itself. It can't be that difficult to put some kind of weight measurement in the struts of the mains. With the cg known to the aircraft, a gross error check can be made by the aircraft, e.g. only accepting TO weight that are within a preset margin of the actual measured weight. It doesn't need to be spot on, so no need for expensive very accurate 'scales'. As long as it picks up a significant error... But that's one for the manufacturers, not the operators...
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The AKL incident (or accident) was a repeat of a similar SQ incident about a year earlier, in which the crew climbed out at V2 - 8kts. Both were caused by the fleet's procedure of overwriting the FMC computed figures with data from the airport analysis tables WITHOUT the requirement to check any differences with the FMC figures. It was a classic case of history repeating itself. Maybe the EK report will compare with the earlier T/O incident at JNB.
The problem may be in the method used to determine T/O performance figures rather than measures used to check the accuracy of those figures.
Personally, after "re-learning" how to obtain the numbers the SQ way, I wrote a list of V2's and EPRs for every 10 tonnes weight on the back of my clipboard and would set the V2 according to the flight planned T/O weight on the MCP during pre-flight scan checks - it gave me an instant cross-check when the co-pilot produced the figures for T/O from the loadsheet.
Methods for determining thrust/speeds vary from airline to airline for the same a/c type, few airlines seem to train such extractions well.
I would generally agree about the presence of both augmented pilots in the cockpit before departure - one is a useful extra pair of eyes, two are usually a distraction ( too much superfluous chat!).
The problem may be in the method used to determine T/O performance figures rather than measures used to check the accuracy of those figures.
Personally, after "re-learning" how to obtain the numbers the SQ way, I wrote a list of V2's and EPRs for every 10 tonnes weight on the back of my clipboard and would set the V2 according to the flight planned T/O weight on the MCP during pre-flight scan checks - it gave me an instant cross-check when the co-pilot produced the figures for T/O from the loadsheet.
Methods for determining thrust/speeds vary from airline to airline for the same a/c type, few airlines seem to train such extractions well.
I would generally agree about the presence of both augmented pilots in the cockpit before departure - one is a useful extra pair of eyes, two are usually a distraction ( too much superfluous chat!).
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I agree getting the figures from the OPT (performance computer) into the FMS is almost foolproof now.
However I still see gross errors on the OPT from time to time. Most commonly ZFW put into the TOW field or the wrong rwy intersection selected (and there is a trap to using the "first 4" option).
However I still see gross errors on the OPT from time to time. Most commonly ZFW put into the TOW field or the wrong rwy intersection selected (and there is a trap to using the "first 4" option).
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MR8,
I've been waiting for this:
TOP MARKS MR8! You are 100% spot-on!!!!! Pity there's a few punters here who don't realise this, and if they actually took the time to understand high-capacity transport category aircraft performance a bit better then they'd realise there's a lot more to it than meets the eye!!!
Recommended reading for those who want to find out more about the machinery that they drive - BOEING JET PERFORMANCE TRANSPORT METHODS (D61420). Yeah, and guess what........it applies to the Bus too! I know!
Spend some time 'Googling' if you don't believe me.....you WILL find the actual graph that substantiates MR8s TOTALLY correct statement!
A380-800 driver............do you want to elaborate on your concept of:
Because there's a VERY big difference between REDUCED thrust and DERATED thrust. 
As an aside, I had to stop flying in 2007 due to the big 'C'. The stuff that you guys keep posting, the sheer diversity of opinion, and the 'ruthless' pursuit of reason amongst many (most??) of you makes me really appreciate just what ENORMOUS talent is out there in our industry, and how glad I was to have been part of it while I could!
Thanks all!
I've been waiting for this:
Your acceleration (even in a perfect world) will initially increase, then decrease again.
Pity there's a few punters here who don't realise this, and if they actually took the time to understand high-capacity transport category aircraft performance a bit better then they'd realise there's a lot more to it than meets the eye!!!Recommended reading for those who want to find out more about the machinery that they drive - BOEING JET PERFORMANCE TRANSPORT METHODS (D61420). Yeah, and guess what........it applies to the Bus too! I know!
Spend some time 'Googling' if you don't believe me.....you WILL find the actual graph that substantiates MR8s TOTALLY correct statement!
A380-800 driver............do you want to elaborate on your concept of:
40% of available take-off power
As an aside, I had to stop flying in 2007 due to the big 'C'. The stuff that you guys keep posting, the sheer diversity of opinion, and the 'ruthless' pursuit of reason amongst many (most??) of you makes me really appreciate just what ENORMOUS talent is out there in our industry, and how glad I was to have been part of it while I could!
Thanks all!
Last edited by chainsaw; 28th Mar 2009 at 10:14.
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MR 8,
It cannot be too hard for an aircraft to weigh itself.The Merchantman (Vanguard freight conversion) used to do just this. The system was called STAN and on taxi out it used to give a gross wt check and a CG check as well.
It cannot be too hard for an aircraft to weigh itself.The Merchantman (Vanguard freight conversion) used to do just this. The system was called STAN and on taxi out it used to give a gross wt check and a CG check as well.
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I suspect that the main resistance to the aircraft self-weighing system would come from Commercial Dept.
As has been mentioned by others earlier in this thread, given the unrealistic standard pax weights and the totally unrealistic pax carry-on baggage allowance currently used, I don't think they want to know how much the aircraft really weighs.
As has been mentioned by others earlier in this thread, given the unrealistic standard pax weights and the totally unrealistic pax carry-on baggage allowance currently used, I don't think they want to know how much the aircraft really weighs.
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I'm not saying the "spares" being in the cockpit is a necessity but if the capt can't deal with someone being in there and looking over his shoulder, how does he cope in the sim or on a line check?
With a bit of "SA" (i.e. when to be where in relation to the Engineer etc.) it can be accomplished rather easily, as suggested by Muttley C.
My thoughts go with the crew, whatever the outcome of the investigation.
Cheers
OBOGS
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I'm not saying the "spares" being in the cockpit is a necessity but if the capt can't deal with someone being in there and looking over his shoulder, how does he cope in the sim or on a line check?
Ah yes but...
performance anxiety is quite real among pilots! Sit there and watch the operating captain when you are augmenting (or checking for that matter). In most cases their behavior will be subtly different than when alone. I believe thepsychs would have a term - its kind of like "mirroring' behavior between individuals establishing communications.
You can deny it till you are blue in the face but it won't change human behaviour.
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performance anxiety is quite real among pilots! Sit there and watch the operating captain when you are augmenting (or checking for that matter). In most cases their behavior will be subtly different than when alone. I believe thepsychs would have a term - its kind of like "mirroring' behavior between individuals establishing communications.
Thanks
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No Land 3 says:
I agree that the time or distance to a selected speed has to be calculated for each takeoff, and if the correct numbers are put into the calculation all will be well. The point I was trying to get across in my original post was that some redundancy, an extra slice in the stack of Swiss cheese, can provide protection against wrong or incorrectly entered data.
If all the numbers provided are realistic and are put into the system accurately, as happens almost always, then the check is just that, verification that things are as planned. However when something goes wrong, when the passengers are all Sumo wrestlers rather than teenage gymnasts, or there is more slush on the runway than expected, or that supposedly empty container has been stuffed with a few tons of some illicit substance, or ..., then a check on time or distance to speed can save the day.
I suggested use of V1 as the check speed, simply because it is something already calculated and monitored. There is no reason in principle why some lower speed could not be used. Whatever speed might be used, the way to choose it should be decided by the owners of the SOP, taking into account input from people with appropriate ergonomics expertise and the PNF workload during takeoff.
I suggested basing the check on time rather than distance since the equipment required is miminal. Roll distance is not so easily measured, but could require extra hardware or modification of the software of existing systems. A conceptually simple system would be to adopt automotive technology and count revolutions of the landing gear wheels.
To drift slightly further from the main topic, one post a few pages back suggested that measuring time or distance to speed could give a reasonably accurate estimate of the weight of cargo and passengers, and averaged over a large number of flights be used to update the average wight of passengers and their carry-on baggage. Could the same information already be extracted from correlation of data captured by the flight data recorder and the loadsheets?
I think Trimotor came closest to a practical suggestion here. But I keep coming back to my point that any check has to be calculated for each take-off using the same variables as the original take-off calculation. IE it will vary for type variant, weight, departure point, slope, rwy surface conditions - the list is long!
So it will be subject to the same input error and be pointless.
If the input is correct then the performance will be correct. I suggest we are concentrating on the wrong end of the problem.
So it will be subject to the same input error and be pointless.
If the input is correct then the performance will be correct. I suggest we are concentrating on the wrong end of the problem.
If all the numbers provided are realistic and are put into the system accurately, as happens almost always, then the check is just that, verification that things are as planned. However when something goes wrong, when the passengers are all Sumo wrestlers rather than teenage gymnasts, or there is more slush on the runway than expected, or that supposedly empty container has been stuffed with a few tons of some illicit substance, or ..., then a check on time or distance to speed can save the day.
I suggested use of V1 as the check speed, simply because it is something already calculated and monitored. There is no reason in principle why some lower speed could not be used. Whatever speed might be used, the way to choose it should be decided by the owners of the SOP, taking into account input from people with appropriate ergonomics expertise and the PNF workload during takeoff.
I suggested basing the check on time rather than distance since the equipment required is miminal. Roll distance is not so easily measured, but could require extra hardware or modification of the software of existing systems. A conceptually simple system would be to adopt automotive technology and count revolutions of the landing gear wheels.
To drift slightly further from the main topic, one post a few pages back suggested that measuring time or distance to speed could give a reasonably accurate estimate of the weight of cargo and passengers, and averaged over a large number of flights be used to update the average wight of passengers and their carry-on baggage. Could the same information already be extracted from correlation of data captured by the flight data recorder and the loadsheets?
Runway Length
I don't think an acceleration check is the answer, because of all of the variables, specifically runway length.
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I have written several statements and cancelled/deleted them. I wait for the report , but if the guys in the 2 front seats used 100T too little in the comp then good luck in your future jobs but dont make it a career in aviation!!! I have sadness and sympothy but no remorse, everyones life is in a pilots hands when on their a/c, i would willingly have borded this flight knowing that it could have happened to any of us, they were the poor bastrds and thank god it wasn't me? Good luck to them and GOOD LUCK to the rest of us!!
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1. Time-to-V1 could indeed be a useful parameter.
With today's modern digital acceleration meters and computer power it should be quite feasible to have a computer monitor the take off run in real time too. I'd guess that it could already when 1/2 the calculated time-to-V1 has elapsed predict what the actual time-to-V1 will be, and call for more thrust if required.
2. Weighing pads on the ramp have their problems. One of them is the effect of any surface wind. Wind causes the wings to create a lift force, which can vary depending on the wind direction and aircraft deck angle. This can cause significant errors in the measured weights. This is probably one of the reasons such systems have not been successful so far.
With today's modern digital acceleration meters and computer power it should be quite feasible to have a computer monitor the take off run in real time too. I'd guess that it could already when 1/2 the calculated time-to-V1 has elapsed predict what the actual time-to-V1 will be, and call for more thrust if required.
2. Weighing pads on the ramp have their problems. One of them is the effect of any surface wind. Wind causes the wings to create a lift force, which can vary depending on the wind direction and aircraft deck angle. This can cause significant errors in the measured weights. This is probably one of the reasons such systems have not been successful so far.
.......Would you mind to explain who is in charge of the aircraft for the whole trip?
That is why many prefer the augmenting crew to be off the flight deck when not actually required - just easier, sometimes.