CDU Question
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CDU Question
When messages get displayed in the scratch pad, are they generally "modal", meaning you can't do anything till you clear them?
For example, say you had an entry typed into the scratch, then were about to push an LS key to put that data into a line, but a message poped up. Would you have to clear it before pushing that LS key to make the entry?
For example, say you had an entry typed into the scratch, then were about to push an LS key to put that data into a line, but a message poped up. Would you have to clear it before pushing that LS key to make the entry?
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As BOAC has indicated, the question cannot be properly addressed, but as a generic answer, YES, the message must first be cleared before the scratch pad information may be inserted with the LSK.
Looked at in simple terms, the LSK accepts the information in the scratch pad data field, and, to enter the desired information from that field, the "Surface Message" must first be cleared - what is on display is what the LSK attempts to enter. Your data input should still be there after clearing the message. The programming logic requires that a "blind" entry cannot be made, i.e. there can be no 'taking on faith' information, however correct, is hidden behind other data.
This one can be a real pain in the butt when entering flight plan winds for a long flight, early in the flight strong Headwinds followed by later much more favourable winds, forward wind propogation "assumes" continuation of the already entered Headwinds for the entire flight, giving a repetitive "INSUFFICIENT FUEL" scratch pad message whilst you're trying to continue entering the later winds.
Regards,
Old Smokey
Looked at in simple terms, the LSK accepts the information in the scratch pad data field, and, to enter the desired information from that field, the "Surface Message" must first be cleared - what is on display is what the LSK attempts to enter. Your data input should still be there after clearing the message. The programming logic requires that a "blind" entry cannot be made, i.e. there can be no 'taking on faith' information, however correct, is hidden behind other data.
This one can be a real pain in the butt when entering flight plan winds for a long flight, early in the flight strong Headwinds followed by later much more favourable winds, forward wind propogation "assumes" continuation of the already entered Headwinds for the entire flight, giving a repetitive "INSUFFICIENT FUEL" scratch pad message whilst you're trying to continue entering the later winds.
Regards,
Old Smokey
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When there is an entry in the FMS CDU scratchpad, either placed there by you or an automatic warning message, you can go to other pages and carry out functions, such as changing the cruise speed, but anything requiring an entry from the scratchpad will not be able to be made until the current scratchpad entry is cleared and the correct entry placed into the scratchpad so it can then be placed elsewhere. I think that is the answer you want.
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Lateral, as in a lateral diversion to an off-track alternate? A good solution to a longitudinal wind propogation problem?
Did I pass my lateral thinking test?
(Somehow I don't think so)
Rainboe, if we put our 2 responses together, I think that there's a 99% chance that we've collectively answered ptwaugh's question, we could shoot for 100% if only we knew which aircraft he/she operates.
Regards,
Old Smokey
Did I pass my lateral thinking test?
(Somehow I don't think so) Rainboe, if we put our 2 responses together, I think that there's a 99% chance that we've collectively answered ptwaugh's question, we could shoot for 100% if only we knew which aircraft he/she operates.
Regards,
Old Smokey
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Quote ;This one can be a real pain in the butt when entering flight plan winds for a long flight, early in the flight strong Headwinds followed by later much more favourable winds, forward wind propogation "assumes" continuation of the already entered Headwinds for the entire flight, giving a repetitive "INSUFFICIENT FUEL" scratch pad message whilst you're trying to continue entering the later winds. ; unquote
Enter on the performance page manually a higher fuel load then actaully uplifted, enter winds on legs page , return to performance and DELETE the manually entered fuel figure to make sure it goes back to calculated..! No more ïnsufficent fuel during wind entries..!
Enter on the performance page manually a higher fuel load then actaully uplifted, enter winds on legs page , return to performance and DELETE the manually entered fuel figure to make sure it goes back to calculated..! No more ïnsufficent fuel during wind entries..!
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Hmmm, I'm not too comfortable with entering an artificially higher fuel than actual, it's much too easily forgotten. Our company recently had a crew who entered the expected landing fuel to calculate Vref (Boeing procedure) and didn't realise why they were getting an INSUFFICIENT FUEL MESSAGE.
What I do is to initially enter the Mean Wind (available on the CFP) for the entire flight, after entering that the time and fuel at destination are quite reasonable (good for the passengers in-flight display also).
After that, enter the entire route's segment by segment winds, but leave them un-executed until the entire set is entered, then execute them. The problem is that for a very long flight, this might take 15 minutes or so to do it properly, and inevitabely other information is needed from the FMC in that time, and the work done so far executed to save it....... and along comes the INSUFFICIENT FUEL MESSAGE again.
Life wasn't meant to be easy! (With thanks to Malcolm Fraser).
Regards,
Old Smokey
What I do is to initially enter the Mean Wind (available on the CFP) for the entire flight, after entering that the time and fuel at destination are quite reasonable (good for the passengers in-flight display also).
After that, enter the entire route's segment by segment winds, but leave them un-executed until the entire set is entered, then execute them. The problem is that for a very long flight, this might take 15 minutes or so to do it properly, and inevitabely other information is needed from the FMC in that time, and the work done so far executed to save it....... and along comes the INSUFFICIENT FUEL MESSAGE again.
Life wasn't meant to be easy! (With thanks to Malcolm Fraser).
Regards,
Old Smokey
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As already stated, it does depend on the type of aircraft you fly. Although it can also varry between mod states for the same aircaft type!
A good example is for the 757. There are two types of FMS CDU: Pegasus and non Pegasus. If you get an INSUFFICIENT FUEL message in the sctatch pad of a non Pegasus CDU, you must press CLR before you can enter any new data in the scratch pad. For a Pegasus CDU, you can write over the top of the message and then line select. After line selecting, the message will reappear. Alot less annoying!
A good example is for the 757. There are two types of FMS CDU: Pegasus and non Pegasus. If you get an INSUFFICIENT FUEL message in the sctatch pad of a non Pegasus CDU, you must press CLR before you can enter any new data in the scratch pad. For a Pegasus CDU, you can write over the top of the message and then line select. After line selecting, the message will reappear. Alot less annoying!
Thank goodness for my company's 777 procedures - upload the winds via data link! Ditto the route! Works a treat and leaves time for another cup of tea, even after checking. No arduous stuff.
PS - Yes, the route load failed once but as it was only an Atlantic crossing it wssn't hard to do manually, ha ha.
PS - Yes, the route load failed once but as it was only an Atlantic crossing it wssn't hard to do manually, ha ha.
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What I do is to initially enter the Mean Wind (available on the CFP) for the entire flight, after entering that the time and fuel at destination are quite reasonable (good for the passengers in-flight display also).
Thanks
P
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Permafrost - I think you will find the answer in your ops manual - each company has different 'ideas'. BA (when I left in 2004) preached 'Top of Climb' wind. The FMC page entry is labelled 'CRZ Wind'. We 'ex Dans' liked mean cruise wind and discovered that the difference in econ climb speed between a 200 kt headwind and a 200 kt tailwind was a couple of knots, an accuracy which the 737 does not seem to be able to achieve anyway . We of course 'conformed'.
My present company, while absorbing many BA procedures, is enlightened enough to allow choice.
Like Old S, I use mean cruise wind, and correct the leg winds on the way. The advantages are:-
I can determine whether I will be on schedule, and give ops an early heads-up if not
If I have an arrival 'slot' to make, eg at Pristina, I can look at when to depart and what speed to programme
I can check that the fuel on arrival will keep me from stress.
C/crew get an arrival time indication
As I said, however, follow your ops manual - it avoids tears. If you disagree with it, take it up with your appropriate department.
. We of course 'conformed'.My present company, while absorbing many BA procedures, is enlightened enough to allow choice.
Like Old S, I use mean cruise wind, and correct the leg winds on the way. The advantages are:-
I can determine whether I will be on schedule, and give ops an early heads-up if not
If I have an arrival 'slot' to make, eg at Pristina, I can look at when to depart and what speed to programme
I can check that the fuel on arrival will keep me from stress.
C/crew get an arrival time indication
As I said, however, follow your ops manual - it avoids tears. If you disagree with it, take it up with your appropriate department.
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I use the same procedure as BOAC, the mean cruise wind seems to save a bit of time, for an "on time" departure
Usually if I've got the time I'll try and go throught the predicted winds per waypoint to give a slightly more accurate TOT errr ETA and fuel figures, we can usually nail it to within 20 seconds at the initial fix
Usually if I've got the time I'll try and go throught the predicted winds per waypoint to give a slightly more accurate TOT errr ETA and fuel figures, we can usually nail it to within 20 seconds at the initial fix
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Thanks BOAC. I thought what I was doing made sense... I checked the Ops manual and it just says "as per FCOM", which does not indicate a preference for which wind you pick initially. I'll stick to mean cruise wind.
P
P
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Permafrost,
Work is the curse of the Pruning classes, and your question to me disappeared onto Page 2 whilst I was off on a foray into Muttland.
The Boeing reference that I was alluding to earlier was to do with manually entering FMC predicted landing Fuel into the Perf Init page (which does cause an INSUFFICIENT FUEL message), and not to do with wind entry procedures. It's an untidy procedure, but it does cause the entire fuel calculation to re-initialise which is a good thing.
There's lots of good practical methods of wind entry. I find it best to enter the mean wind pre-flight to give fairly good initial Arrival Time and Fuel. For short sectors, say 2 hours or less, this is probably quite OK.
Where a significant wind gradient exists, the "I am always right" guy who told you to enter the initial cruise wind was right also, but only if you enter a series of winds at different levels to ascertain the most favourable initial level. A single cruise wind in this case is of no significant value.
On longer flights (e.g. more than 2 hours), a series of winds at a sensible selection above and below the Optimum Level will again allow the FMC to sensibly predict the point of Step Climb. Again, a single level wind entry will be of no use here, it will simply be extrapolated up and down, with Step Climb scheduled at close to the Still Air Optimum Level, which is OK UNLESS there's a significant wind gradient. After entering winds above and below the present Cruise Level, I've seen the Step Climb prediction change by 600 miles, that's significant!
This is the sort of thing that can consume a great deal of time between Instructor and Trainee if he/she is to get the best from the aircraft. We operate very short (20 minute) sectors and very long (14 hours) sectors on the B777. My recommendation to trainees is -
(1) Short sectors : Step Climb is not a real consideration, mean cruise wind will suffice nicely, but do put in the descent winds so that VNAV can better optimise the descent profile.
(2) Long Sectors : Pre-flight available time usually prohibits entry of a full set of winds, so enter the mean cruise wind component to obtain reasonable Destination ETA (for you and the passengers) and Fuel (for you).
(i) Examine the wind gradient for the first few hundred miles. If there's a significant change with altitude (more than about 3 knots per 1000 feet), enter the winds from the lowest to the highest feasible cruise level. (after the initial few hundred miles, leave the mean wind for the moment). Climbing into a Jetstream can have a profound effect, Ive seen Recommended level drop from 340 to 260 after doing this on a Melbourne-Singapore flight.
(ii) On cruise, first enter the sector winds for the initial cruise level all of the way to destination.
(iii) After that, enter a good selection of winds for all of the expected levels. Now the FMC can ACCURATELY predict valid Step Climb points. If you don't have the higher level winds until later in the flight, copy the highest available winds to the higher level, remember that the wind information available down-track will propogate backwards giving you some weird FMC recommendations.
(iv) Finally, put in the descent winds so that VNAV can better optimise the descent profile.
It's time consuming, but pays dividends on long distance flights. I've seen 30 minute and several Tonnes of fuel difference at Destination after refining the winds on long flights. On short flights, it hardly makes a difference.
Regards,
Old Smokey
Work is the curse of the Pruning classes, and your question to me disappeared onto Page 2 whilst I was off on a foray into Muttland.
The Boeing reference that I was alluding to earlier was to do with manually entering FMC predicted landing Fuel into the Perf Init page (which does cause an INSUFFICIENT FUEL message), and not to do with wind entry procedures. It's an untidy procedure, but it does cause the entire fuel calculation to re-initialise which is a good thing.
There's lots of good practical methods of wind entry. I find it best to enter the mean wind pre-flight to give fairly good initial Arrival Time and Fuel. For short sectors, say 2 hours or less, this is probably quite OK.
Where a significant wind gradient exists, the "I am always right" guy who told you to enter the initial cruise wind was right also, but only if you enter a series of winds at different levels to ascertain the most favourable initial level. A single cruise wind in this case is of no significant value.
On longer flights (e.g. more than 2 hours), a series of winds at a sensible selection above and below the Optimum Level will again allow the FMC to sensibly predict the point of Step Climb. Again, a single level wind entry will be of no use here, it will simply be extrapolated up and down, with Step Climb scheduled at close to the Still Air Optimum Level, which is OK UNLESS there's a significant wind gradient. After entering winds above and below the present Cruise Level, I've seen the Step Climb prediction change by 600 miles, that's significant!
This is the sort of thing that can consume a great deal of time between Instructor and Trainee if he/she is to get the best from the aircraft. We operate very short (20 minute) sectors and very long (14 hours) sectors on the B777. My recommendation to trainees is -
(1) Short sectors : Step Climb is not a real consideration, mean cruise wind will suffice nicely, but do put in the descent winds so that VNAV can better optimise the descent profile.
(2) Long Sectors : Pre-flight available time usually prohibits entry of a full set of winds, so enter the mean cruise wind component to obtain reasonable Destination ETA (for you and the passengers) and Fuel (for you).
(i) Examine the wind gradient for the first few hundred miles. If there's a significant change with altitude (more than about 3 knots per 1000 feet), enter the winds from the lowest to the highest feasible cruise level. (after the initial few hundred miles, leave the mean wind for the moment). Climbing into a Jetstream can have a profound effect, Ive seen Recommended level drop from 340 to 260 after doing this on a Melbourne-Singapore flight.
(ii) On cruise, first enter the sector winds for the initial cruise level all of the way to destination.
(iii) After that, enter a good selection of winds for all of the expected levels. Now the FMC can ACCURATELY predict valid Step Climb points. If you don't have the higher level winds until later in the flight, copy the highest available winds to the higher level, remember that the wind information available down-track will propogate backwards giving you some weird FMC recommendations.
(iv) Finally, put in the descent winds so that VNAV can better optimise the descent profile.
It's time consuming, but pays dividends on long distance flights. I've seen 30 minute and several Tonnes of fuel difference at Destination after refining the winds on long flights. On short flights, it hardly makes a difference.
Regards,
Old Smokey
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Thanks Old Smokey.
Yes I should have mentioned that I was mostly talking about short sectors, where I didn't think using the initial cruise wind in CRZ WIND and entering all the leg winds would be much of an advantage compared to just using mean wind (I was with Cpt Know It All, recently upgraded from F/O Know It All, on a 1 hour flight!). I have used mean wind and descent winds so far and it seems to work fairly well.
Just moved to a base which has much longer sectors though, so I'll try and apply the techniques you described to see how much wind/fuel can be saved.
Thanks a lot for the input!
P
Yes I should have mentioned that I was mostly talking about short sectors, where I didn't think using the initial cruise wind in CRZ WIND and entering all the leg winds would be much of an advantage compared to just using mean wind (I was with Cpt Know It All, recently upgraded from F/O Know It All, on a 1 hour flight!). I have used mean wind and descent winds so far and it seems to work fairly well.
Just moved to a base which has much longer sectors though, so I'll try and apply the techniques you described to see how much wind/fuel can be saved.
Thanks a lot for the input!
P
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Perma -
- a note of caution, as per my post #14 - there is an outside chance that this Captain DOES know it all (as far as company procedures are concerned, anyway ) having recently completed command training.
As I said, although there may well better solutions to 'cracking the egg', to avoid tears follow the company SOP and if it says initial cruise wind that is TOC. If it says TOC wind.... and if it says 'cruise wind', then the game is on. None of the options will lead you into trouble and as long as both of you know what has been input v what will happen to the winds, problem solved.
Out of interest, what does your ops manual say?
I was with Cpt Know It All, recently upgraded from F/O Know It All, on a 1 hour flight
) having recently completed command training.As I said, although there may well better solutions to 'cracking the egg', to avoid tears follow the company SOP and if it says initial cruise wind that is TOC. If it says TOC wind.... and if it says 'cruise wind', then the game is on. None of the options will lead you into trouble and as long as both of you know what has been input v what will happen to the winds, problem solved.
Out of interest, what does your ops manual say?