Well first of all, it's not called OPT Altidtude - but "trip" altitude. And the page I'm speakeing of is the INIT REF page 1. Here is from the manual: Trip altitude is automatically computed and displayed whenever entries have been made for the ORIGIN, DEST, GROSS WT, and COST INDEX. Otherwise, the field is blank.Trip altitude is the predicted minimum cost altitude determined by operator constraints. Provides crew a reference for selecting a planned cruise altitude.

That is exactly what you are supposed to do !!Fill it in ! For such a short flight 12,000 or 10,000 ft is enough.The FMC will not calcualte it for you because this is not a realistic scenario.

that is exactually what I asked all along..how come you picked (for this example) 12,000 or 10,000 FL, based on what calculation?or you just picked it based on a gut feeling? I don't know what you mean by saying it's not a realistic scenario, there are flights that short in real life (i do them all the time in real life - as a passenger)example LLBG - OJAI, well Royal Jordanian uses ERJ for that route , but it could easily be an NG. you will see those short distances more often in south east Asia, like Philippines or Indonesia when it's Island hopping,long enough to justify a flight (as cursing it in a ferry would take a long time), but it is actually a very short flight.or in places that there are no roads (crossing the rain forest) and only by flight you may reach there (e.g. Sentani/Jayapura - Papua , Indonesia to the baliem valley, must be done by air, even thoughthe distance is very short) - done by Merpatti commercial Airline & Lion Air, and guess what Lion air were the 1st to have the NG900 at 2006/7 I thinkDone it number of times in real life - as a passenger of course.

That is exactly what you are supposed to do !!Fill it in ! For such a short flight 12,000 or 10,000 ft is enough.The FMC will not calcualte it for you because this is not a realistic scenario.

I guess that the main question is : " is there a way the FMC calculates the optimal crz altitude taking into consideration the trip distance ? " or the pilot has to input it manually ? If it is manual which are the criteria to choose an altitude ? I also expected the FMC to able to deal with such a simple calculation, even if it is not a real scenario and I also dunno very well what is real and what is not.

That is exactly what you are supposed to do !!Fill it in ! For such a short flight 12,000 or 10,000 ft is enough.The FMC will not calcualte it for you because this is not a realistic scenario.

FMC will Calculate it for you. It's called trip altitude, and is shown on the INIT REF page 1 in the FMC. It do however require you to enter basic information: Origin, destination, CI and Weights Cheers!

FMC will Calculate it for you. It's called trip altitude, and is shown on the INIT REF page 1 in the FMC. It do however require you to enter basic information: Origin, destination, CI and Weights Cheers!

haaa, that is why I probably always miss it.I put in the CI last (after RTE and weight) so I always believed I must also put in the FL manually (based on my gut feeling - remember I am doing short flights).since I never saw the suggested OPT Altitude on that page and after I put in the CI , I did not visit it again.

Just follow the flow in the FMC, and the required information will already be inserted, when you are on the INIT REF page 1 page. Altitude should be entered last. (Also the temperature ISA deviation is affecting the trip altitude)

Thank you guys all for your help.you answered all of my questions perfectly.

And BTW, Those were not stupid questions. Nowhere in the forum rules it is stated, that your question must not be answered within the 2000+ paged documentation. Calling names and talking down to other people here on the forum, just because they couldn't find the time to study the full curricullum, is very rude and impolite.

I'm sure it isn't professional in any way, but I sometimes just "convert" the trip lenght into FL for shorter trips - so 123nm would be FL120/130, 250nm would be FL250 and so on... Seems to work pretty well.

They fly at FL250 - FL270 between KLAX and KLAS and that is only about a 45 min flight. http://flightaware.c...e/flight/UAL825

Referring to this gentlemen's question regarding PACK's. I know what they are and what they do of course but could someone confirm that PACK is an acronym for Pneumatic Air Conditioning Kit? I thought I read that somewhere but not sure. Thanks guys. Mark

Referring to this gentlemen's question regarding PACK's. I know what they are and what they do of course but could someone confirm that PACK is an acronym for Pneumatic Air Conditioning Kit? I thought I read that somewhere but not sure. Thanks guys. Mark

Yes, pack is the acronimus for pneum. air cond. kit, it often contains the ACM, valves and other things.

They fly at FL250 - FL270 between KLAX and KLAS and that is only about a 45 min flight. http://flightaware.c...e/flight/UAL825

It's like 240nm so I guess my "formula" does work pretty well, doesn't it

It's like 240nm so I guess my "formula" does work pretty well, doesn't it

interesting formula you got there. worth looking into.now I guess the next question would be what formula is for picking best Speed at cruse for short flights

I would either go with what is selected by Cost Index for short flights, or put M0.81 for distance (well I am not paying the fuel bill!)....G