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Akila

Where is the "Trip Altitude"?

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Hey guys, I was wondering if anyone knows where can I find in the T7 FMC the "Trip Altitude"

like there is in the NGX?

I searched in the FCTM document just to find out there is no reference to such.

in the NGX FCTM it appears there.

 

any one has an idea where to find it?

 

bnsn.jpg

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If you click the VNAV button on the CDU, and then go to page 2, you can see optimal flightlvl and max flightlvl calculated. 

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that, what you mentioned is not Trip Altitude.

what you mentioned you also have it in the NGX in a different page (in addition to the Trip Altitude), this is the suggested altitude based on weight/CI only.

the Trip altitude , like the photo above is the suggested altitude based on distance as well.

 

for example if you doing a flight that let's say is 80nm long, the OPT/MAX altitude will still show you around let's say FL370 - FL393 (example).

but that will make no seance as by the time you half way up climbing it, you already have to descend and you burned a lot of fuel climbing it up.

 

the Trip altitude takes also distance in consideration and based on those factors it calculates the best Altitude to shoot for as for fuel saving, etc.

that is what I am looking for..

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If it's not on the FMC, and not in the Docs, maybe it's not in the 777?

 

 

Maybe 'cause the B777 is slightly more "long-range" than the 737NG?

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that, what you mentioned is not Trip Altitude.

what you mentioned you also have it in the NGX in a different page (in addition to the Trip Altitude), this is the suggested altitude based on weight/CI only.

the Trip altitude , like the photo above is the suggested altitude based on distance as well.

 

for example if you doing a flight that let's say is 80nm long, the OPT/MAX altitude will still show you around let's say FL370 - FL393 (example).

but that will make no seance as by the time you half way up climbing it, you already have to descend and you burned a lot of fuel climbing it up.

 

the Trip altitude takes also distance in consideration and based on those factors it calculates the best Altitude to shoot for as for fuel saving, etc.

that is what I am looking for..

Ohhh!!. Thank you for the explanation!.

Now I know why PFPX suggests for ex FL280 and the VNAV page still sais FL 370. 

You learn something new every day. =)

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olli4740, on 16 Dec 2013 - 11:11 AM, said:

 

Maybe 'cause the B777 is slightly more "long-range" than the 737NG?

I hope this is not the case....

 

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I searched in the FCTM document just to find out there is no reference to such.

 

This is a good indication that it doesn't have it.

 

 

 

I was wondering if anyone knows where can I find in the T7 FMC the "Trip Altitude" like there is in the NGX?

 

This isn't the NGX :wink:

 

...a line I stole directly from the Intro Manual.

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Then how do I know what is my "optimum" altitude for my trip with the T7?

 

For shorter trips, optimum altitude as defined in the VNAV page (OPT/MAX) may not be achievable since top of descent would come before completing the climb to optimum altitude. Trip altitude further constrains optimum altitude by reducing the altitude for shorter trips until minimum cruise segment time is satisfied. For short trips, operation at trip altitude results in the minimum fuel / cost while also satisfying the minimum cruise time requirement.

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Then how do I know what is my "optimum" altitude for my trip with the T7?

 

Flight planning software, honestly.  Either that or your best guess from operational knowledge.  You're asking it to do something it's not necessarily meant to do.  While, yes, 777s are flown on shorter routes, the plane was built for longer legs, where achieving the OPT ALT wouldn't be a problem.  As such, if you want to use it on shorter legs, you're going to have to go a little leg work yourself.

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I think there is a rule of thumb. For short flights select the distance as your trip altitude (eg. ~FL200 for a 200nm trip). Thats what I have heard about and I think it works quite good.

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I think there is a rule of thumb. For short flights select the distance as your trip altitude (eg. ~FL200 for a 200nm trip). Thats what I have heard about and I think it works quite good.

 

 

I use that rule myself; if the distance is greater, I use a "conservative" FL initially. The FMC will suggest a step climb if appropriate.

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