Limitations on special Boeing 737-800 series
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I can only remember the outline details - old age. But there used to be a significant difference between UK registered 744s and US registered ones because of CAA/FAA differences. This may read across to the 737. It all revolves around cruise Center/Centre of Gravity and different certified turbulence max g. The FAA takes an average c of g case whereby the CAA takes actual input into the FMC. In addtion the FAA limit was I believe 1.2 g whereas the CAA equivalent was 1.3g. This results in different max altitude displayed calculations on aircraft Flight Management Computers depending on how they are configured and to which rules.
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How about this...
...there have been several incidents regarding buffet alert bla bla bla....
could be possible that during FMC programing the temperature expected at a certain FL has not be put correctly or not at all? Dunno why 738 FMC do not make this entry mandatory. The fact is that if it is not entered, the FMC will assume standard temperature making it -61 at FL 380 . This never happens most of the time as we are at ISA +10 to + 15 depending on the place on earth you are flying and in what season. Not entering the correct temp you will get on the CRZ page OPT/MAX maybe 365/382 but once you enter the correct data...SURPRICE!! On the 744 this entry is mandatory FMC has boxes and not dashes as on the 738 FMC. Summer season has been specially hot this year. Here in Asia we had some times ISA + 20 over Japan airspace.
Hope this helps... if not we have to call Spiderman to solve the mystery
Happy landings...
could be possible that during FMC programing the temperature expected at a certain FL has not be put correctly or not at all? Dunno why 738 FMC do not make this entry mandatory. The fact is that if it is not entered, the FMC will assume standard temperature making it -61 at FL 380 . This never happens most of the time as we are at ISA +10 to + 15 depending on the place on earth you are flying and in what season. Not entering the correct temp you will get on the CRZ page OPT/MAX maybe 365/382 but once you enter the correct data...SURPRICE!! On the 744 this entry is mandatory FMC has boxes and not dashes as on the 738 FMC. Summer season has been specially hot this year. Here in Asia we had some times ISA + 20 over Japan airspace.
Hope this helps... if not we have to call Spiderman to solve the mystery
Happy landings...
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forgot...
the limits set by the authorities should be programed into the FMC software. This is made by maintenance . It is factored into the equation . Now the pilot needs to put reasonable numbers in. What ever the limit is don't make a difference to the computer if the input data is correct. You will get the correct data displayed on your PFD Speed tape. You cannot go that high
B good
the limits set by the authorities should be programed into the FMC software. This is made by maintenance . It is factored into the equation . Now the pilot needs to put reasonable numbers in. What ever the limit is don't make a difference to the computer if the input data is correct. You will get the correct data displayed on your PFD Speed tape. You cannot go that high
B good
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BA 757s always used to have a lower "Max FL" than FMC due CAA v FAA diffs, or even the whim of one BA Fleet Manager - we had a chart on the back of the FMC reflecting the Max FL we were to use (as above, increased buffet margin).
Bear in mind that the RFL is likely determind by a (bought in?) piece of software - costly and time consuming to alter. Changing Max FL by CP dictat can be achieved overnight, and tweaked (as here, 1.5g to 1.45g) by immediate experience even ATC feedback....
Someone speaks well of BA and RFL, but we often "tanker" fuel (especially post Buncefield) that is not on our Flight Plan, hence lower Max / RFL. Believe it caused some problems, especially ex USA, in the early days with Atlantic crossings all at lower levels than filed...
Only solution I can really see is better comms / heads up... ATC asking / crews advising early when RFL is not as filed...
NoD
Bear in mind that the RFL is likely determind by a (bought in?) piece of software - costly and time consuming to alter. Changing Max FL by CP dictat can be achieved overnight, and tweaked (as here, 1.5g to 1.45g) by immediate experience even ATC feedback....
Someone speaks well of BA and RFL, but we often "tanker" fuel (especially post Buncefield) that is not on our Flight Plan, hence lower Max / RFL. Believe it caused some problems, especially ex USA, in the early days with Atlantic crossings all at lower levels than filed...
Only solution I can really see is better comms / heads up... ATC asking / crews advising early when RFL is not as filed...
NoD
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VonLuffers, you said:
ISA temperature lapse is down to -56 degrees at 35000 ft and thereafter a constant -56 degrees in the Stratosphere......(approx).
Nigel,
Of interest, one of the pin selectable parameters for the FMC is whether FAA or CAA rules are applied. You can trawl through the maintainance pages and find what it is currently set to......
...the FMC will assume standard temperature making it -61 at FL 380
Nigel,
Of interest, one of the pin selectable parameters for the FMC is whether FAA or CAA rules are applied. You can trawl through the maintainance pages and find what it is currently set to......
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Hi Bus:
You are right, but dunno if that is what really happens with the FMC software( I'm not that smart nor stop to review my AOM that often and in detail
) Never mind, -56 assumed by the computer instead of an actual number of lets say -48 -50 what ever may be can be the difference between being at the operating envelope or out of it.
HL
You are right, but dunno if that is what really happens with the FMC software( I'm not that smart nor stop to review my AOM that often and in detail
) Never mind, -56 assumed by the computer instead of an actual number of lets say -48 -50 what ever may be can be the difference between being at the operating envelope or out of it.HL
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Too true.
A few weeks ago I saw ISA +15 temperatures at TOC here in Europe - very unusual, but a very real effect on performance. It lowered our ceiling by several thousand feet.
Even with the FMC not given a TOC temperature or deviation, as the aircraft climbs it will recognise the impending situation and issue a buffet alert. Or does that mean its time for a snack?
A few weeks ago I saw ISA +15 temperatures at TOC here in Europe - very unusual, but a very real effect on performance. It lowered our ceiling by several thousand feet.
Even with the FMC not given a TOC temperature or deviation, as the aircraft climbs it will recognise the impending situation and issue a buffet alert. Or does that mean its time for a snack?
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Was/is it not the case that UK CAA (not sure about new fangled JAA) had the FMC default to max forward C.G for crz? Some airlines were not allowed to alter this as a safety margin. Now we can put in the actual C.G.
What I do find disappointing is that the crews have so little data about how the FMC is calculating the info upon which they operate the flight. Surely it would be a simple matter to have a crew notice in the tech log; indeed should it not be the case: 1.3g or whatever, and at what Cof G. 21st century, high tech fancy equipment and so little information. When there is an accident/incident in a new all bells & whistles a/c, one of the often mentioned items is how much crews are becoming divorced from their a/c by all the automatics. This can only be worsened by keeping them in the dark about WHY it is producing some information. FMC data is often guidance, but how do you know to trust it if you don't know how it arrived at its advise?
What I do find disappointing is that the crews have so little data about how the FMC is calculating the info upon which they operate the flight. Surely it would be a simple matter to have a crew notice in the tech log; indeed should it not be the case: 1.3g or whatever, and at what Cof G. 21st century, high tech fancy equipment and so little information. When there is an accident/incident in a new all bells & whistles a/c, one of the often mentioned items is how much crews are becoming divorced from their a/c by all the automatics. This can only be worsened by keeping them in the dark about WHY it is producing some information. FMC data is often guidance, but how do you know to trust it if you don't know how it arrived at its advise?
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Weight is an important factor in calculating max FL's. As there is reference to Ryanair I wonder which standard weights they use after their change of policy regarding hand/hold luggage.
A rough estimate:
Operator's are allowed to use 84 kg (charter flights even a lower 78!) if no male/female distinction can be made. Standard luggage weights may be as low as 13 kg a piece if no actuals weights are available. Make a rough calculation for yourself how much a full loaded -800 (186/189 pax) can be off actual weights if these figures are used.....
Try and add 3 ton to your actual weight if at FL 360/370 and see how much MAX ALT changes
This is not intended for Ryanair bashing, just for awareness
p.s. Note the blocked red line on the speed tape. Try to stay in the black area between the red blocks. You should be safe there
A rough estimate:
Operator's are allowed to use 84 kg (charter flights even a lower 78!) if no male/female distinction can be made. Standard luggage weights may be as low as 13 kg a piece if no actuals weights are available. Make a rough calculation for yourself how much a full loaded -800 (186/189 pax) can be off actual weights if these figures are used.....
Try and add 3 ton to your actual weight if at FL 360/370 and see how much MAX ALT changes
This is not intended for Ryanair bashing, just for awareness
p.s. Note the blocked red line on the speed tape. Try to stay in the black area between the red blocks. You should be safe there
Last edited by have another coffee; 30th Aug 2006 at 15:51. Reason: spelling is not my thingy
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"There are many Captains who choose to ignore the advice of their Chief Pilot, also."
And what is the F/O doing in the meantime? It would be THE CREW having tea no bisciuts in the head master's study if owt happened. I thought RYR had a strong CRM review recently after a few captains did certain strange manoeuvres.
And what is the F/O doing in the meantime? It would be THE CREW having tea no bisciuts in the head master's study if owt happened. I thought RYR had a strong CRM review recently after a few captains did certain strange manoeuvres.
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RAT 5. What can you do. I made my opinion known to the Captain in the crewroom. He or she stated that this was a knee jerk FCI, he/she had flown this aircraft for a long time and knew it was unessecary. I argued that it was an FCI and not open for interpretation. I said I felt extremely uncomfortable breaking it and did not want to do it. That was him/her pissed off and not talking to me in a conversational sense for the rest of a very long duty day. What else can I do apart from wrestling the controls off him? Refuse to fly? You've obviously never heard of Cliodhna Duggan then have you? :
http://www.unison.ie/irish_independe...&issue_id=7659
http://www.unison.ie/irish_independe...issue_id=10049
www.bugmenot.com for the passwords.
http://www.unison.ie/irish_independe...&issue_id=7659
http://www.unison.ie/irish_independe...issue_id=10049
www.bugmenot.com for the passwords.
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Carmoisine:
I apologise; there was nothing personal intended. You have my sympathy. It sems a rather unnecessary reaction. Perhaps a soft suggestion that there is less radiation lower down and thus the macho captain might benefit in the long run? I haven't heard of the erstwhile C. Duggan. Is there a relevant story, without going off thread?
Meanwhile, there has been no information here about why only RYR have imposed this restriction. The whole NG community is waiting & wondering what the hell is going on & why.
I apologise; there was nothing personal intended. You have my sympathy. It sems a rather unnecessary reaction. Perhaps a soft suggestion that there is less radiation lower down and thus the macho captain might benefit in the long run? I haven't heard of the erstwhile C. Duggan. Is there a relevant story, without going off thread?
Meanwhile, there has been no information here about why only RYR have imposed this restriction. The whole NG community is waiting & wondering what the hell is going on & why.
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RAT5, The memo we recieved is that there were a series of "high altitude upsets". The rumour mill has even suggested an approach to stall or stall itself. These are under investigation we are tld and until it has been resolved we have been instructed to fly at a lower level. I have my own theories and have heard certain stories, but as I recall there was an order from the owner of this site not to discuss certain isues about a certain airline due to legal hassles.
Do FR Pilots load the correct T/O Mac into the FMC on the Perf Init page on the FMC?
On our fleet of 800`s, this automatically defaults to 5.0% and this can make quiet a difference to speed margins at Altitude, and obviously Max and Optimum levels.
On our fleet of 800`s, this automatically defaults to 5.0% and this can make quiet a difference to speed margins at Altitude, and obviously Max and Optimum levels.
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Guttentag Rhein Rader wie geht's, I am also one of the pilots that is often requesting a lower level in stead of flying the filed Flightlevel. In our company the flightplans are generated by LIDO and since we are now flying with winglets, the optimum flightlevels are more or less the maximum flight levels if we would follow FMC predictions. The problem is that everything what is filed, is based on weight and balance assumptions and unfortunately these assumptions are often wrong. In many cases we are a lot heavier than predicted and also the weight distribution is different. Let alone that the computer is calculating ISA atmospheric circumstances. Which are often not the case. Especially in july it was a lot hotter than standard in Europe. Last but not least the computer generated flight plan does not take in to account CAT or turbulence from TS, where I do in order not to fly in the ''coffin-corner'' while more than light turbulence can be expected.
Danke und viel spass,
QTA!
Danke und viel spass,
QTA!
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Carmoisine,
Thanks for the links to the court case you quote. That young lady obviously had more ba*ls than most male pilots I've met. I wish her well in her future career and from everything we hear about that company, isn't she better off out of Ryanair wherever she now is.
Thanks for the links to the court case you quote. That young lady obviously had more ba*ls than most male pilots I've met. I wish her well in her future career and from everything we hear about that company, isn't she better off out of Ryanair wherever she now is.
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Did max altitude of the a/c actually improve? Yes. How much? Unknown. The company that produces the winglets did not too the high altitude buffet margin testing to produce higher max altitude data.
FMC shows increased optimum altitude capability. Max altitude is the old, but only, data available.
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Forgot to mention - 757 max alt is typically 3500' above optimum. You can check it by putting FL420 for a crz altitude on the crz page and then clearing the 'check cruise altitude' prompt that appears. FMC will shortly display max altitude on the scratch pad (typing line - 6L).
With winglets it should be around a 2000-2500' difference between opt alt and max alt.
With winglets it should be around a 2000-2500' difference between opt alt and max alt.