Selecting Efficient Flight Levels

[Prop Job]

Good Day All,

On tuboprop aircraft, speeds +/-250kts and service ceiling of 25,000ft, what is the best way of selecting the optimum flight level?

I know I probably should know this by now, but I've never heard of a mathematical or just more accurate way of selecting flight levels. I feel that we just make an educated guess most days.

Something I've considered is to climb all the way up to FL250 everytime, calculating the winds as we go along. I can then make a decision as to the best flight level. I'm sure this will work, but it just seems like a very long way of doing things and I'm sure there must be a shorter way (or should I say I hope so!).

I should also add that most of my flying is done in the Dark Continent where we don't always have access to accurate Upper Wind Charts.

Thanks for your help,

Prop Job

[hoover1]

i would consult the performance manual and it will tell you TAS, fuel burn, for each altitude. if you want to be efficent and don't care about time then go up to the highest altitude and burn less fuel. if there is no wind. otherwise go with whatever will give you the highest ground speed. regardless of fuel burn. usually 20k on turboprop. if you want the best time and fuel burn then using the charts find fule burn/hr at a given flight level and compute time based on winds and multiply by fuel burn and get how much fuel burned. do this for other altitudes and usually lower fuel burn wiil be the quickest in a headwind situation. also if in a headwind go faster and will usually burn less fuel. if a tailwind. go high and less power. all in all if i had more than 30 knots of wind i would go lower. over 50 and i would go real low. usually burnt about the same amount of fuel but got there quicker.

[Capt Claret]

If I remember correctly, a wind change of 4 kts/1000' was the magic figure for the DH8 100/200/300.

[Apollo 100]

In my previous company(B200's) I think we used the the rough rule of thumb of dist (nm)/10 plus four to give us the cruise level. eg leg dist 160nm criuse at FL200 or a leg of 80 nm would be FL120 etc up to our max cruise FL. Then adjust as required for known strong winds.

[411A]

Example.
FH-227B.

Heavy weights, cold temps aloft, FL160 to FL190

Medium weights, warm temps aloft, see above.

Heavy weights, warm temps aloft, FL140 max, initially.

2-3 hour sectors considered for above.

Dart engines, very reliable.:ok: