High enough altitude?

Hello, I was planning on doing a flight from Changi to Sky Harbor and everything was looking good until I saw FL290. I just would like a second opinion on that if I should step climb up to FL380 for example instead of staying down low burning fuel quicker.

Hello!
FL 290 would be your initial cruise altitude. If you take a look at the Map, you’ll see that it probably planned some en route climbs. This is called Step Climbing and its main purpose is to keep climbing as the aircraft gets lighter due to fuel consumption. For a 16 hour flight, you’ll have a lot of weight in fuel, so it will be hard to get to your final cruise level (FL380 as you mentioned) on a direct climb from take off.

So yes, I definitely think you should use Step Climb.

Here’s more info on step climb:

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If you go down you can see you flight plan with all the waypoint + the VNAV showed by FPL to IF.

29000 feet is your first cruising altitude.

Try to refer to this guide for the 777 :

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Thanks see that what I figured I haven’t done any ultra long hauls in quite awhile I was wondering why FL290 just seemed too low for a 16hr flight thanks for the advice.

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btw, I love your choice of airports, as both of those are my, at one time, irl home airports.

Changi to Sky Harbor is of course a massive hop. The 16 hours you mentioned, with your selected pax and cargo, shows you loading enough fuel weight to bring you to 98% load.

I was just examining the following for fun (adding to what @nicopizarro said):

Out of curiosity I tried your 98% at FL290. It gave me an AOA of 1.7 degrees somewhere near cruise speed.

Then I busted out of that first step of yours still close to 98% and went up to FL350. The AOA for that extra 6,000 feet of altitude at those flight levels, increased the AOA to 2.7 degrees.

The extra 1 degree may look small but that makes it 60% more AOA by comparison!

Step climbs allow you to burn off enough fuel to bring that AOA down before climbing higher.

More AOA is more drag, which reduces your fuel range. Which is why you step climb - to maximize fuel range for a given load.

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