If in the commercial world, pilots would have to decide (instead of dispatchers) which FL they are taking, ...

Question

.... what would pilots take into consideration in deciding which flight level is the best?

Of course, length of the trip, and wind, but wind is actually on a 2 hour flight not that important (because if you are flying FL300 or FL400, the difference is not that big).

So, would they just consider "oh, weather is fine today, so we gonna take FL340 for this 300 nm flight, that should be fine", and 2 days later, they say "oh, weather is fine today, so we gonna take FL380 for this 300 nm flight, that should be fine"?

Answer 1

Ultimately it's the pilot's call anyway. I've yet to see a dispatcher climb a plane to its cruise altitude.

Answer 2

Pilots can request any altitude they want.  It's up to the controller to determine if that works for everybody involved.

Answer 3

The dispatchers do not decide which flight level the aircraft flies at.  That is a captain decision that does not require consultation with the dispatcher.  Only a few decisions do.  [The captain may decide to cruise at a lower altitude than that in the flight plan, or to climb to a higher one.  The altitude specified in the flight plan is only the initial cruise altitude.  As an airliner burns fuel  it gets lighter,  higher altitudes where the plane is more fuel-efficient become available, and the captain might find it advantageous to fly at that altitude.  ATC and the captain do not coordinate altitude decisions with the dispatcher].

On a two hour flight the wind is of importance.  Look at the wind forecasts for FL300 and FL400.

Pilots might take into account weight of the aircraft, time to climb, fuel consumption, flight duration, turbulence, temperature, ice, traffic, clouds, and   planned or expected arrivals.

Answer 4

The Dispatcher will plan the altitude based on many considerations: winds aloft, turbulence potential, ATC preferred altitudes for city pair, enroute weather (thunderstorms or icing) and best fuel economy.  

In most situations, the dispatcher will end up filing the aircraft as high as it can go for that city pair as this often gets aircraft above severe weather and if the weather is ok, fuel economy is the most pressing factor.

Depending on the airline, if the crew wants to change the altitude to a point that will change the fuel burn by a few hundred lbs or more, they will contact dispatch.  I would say by far the #1 reason for an altitude change is turbulence enroute.  Crews are very aware that it is uncomfortable for the passengers and do a great job staying as clear as possible.

As far as winds aloft, on a 300nm flight that would not as big of a factor, but with shorter trips on the regional aircraft and on transcon trips on the larger aircraft, winds aloft play a HUGE factor in flight planning.

I have had to bump passengers or make a fuel stop due to winds on westbound flights.

Late last week (can't remember the day) flights northbound from Florida to the NY Metro area were getting 30 min longer enroute times due to the odd strong winds coming out of the NNW.

Sorry for the long answer... in short, the dispatcher and pilot will mostly change altitudes for turbulence, but strong winds can play a part if they are not as forecast and we are looking for less headwind.

I hope this answers your question.