I apologize if this question has been recently discussed! If so, I have totally missed it!I was thinking about this when flying a B767 in FS the other day.How is it in real life? Is maximum speed the only thing that matters? Or is fuel consumption of any importance? Is there some accepted balance between those two counteracting factors?I.e: at cruise level, what speed to set?(In FS, I use to keep the airspeed above 10000 feet some 30-40 knots safely below the overspeed limit!) Maybe this can be made in a better way?Just curious!Haraldh F.

From what many pilots have said on several forums - the schedule is what matters.At many airports arriving up early can create a problem of no place to park, no way to deplane the passengers.But I'd also expect fuel consumption to be much more important than speed since I understand fuel is about 20-25% of the cost of flying an aircraft.But I could be wrong.

You cannot compare flying a flight sim with the flying a real 767. Most 3rd party aircrafts are simplified and very stripped down versions. However, the Level-D 767 is probably the most complex and realistic 767 for FS9 and gives you a pretty good impression.I am not sure about your question regarding speed and fuel consumption. In real-life, the fuel consumption is being calculated by the airline dispatch. The cruising speed is generally calculated in the FMC (flight management computer) - usually you, the pilot in command, do not set this anyway.Hope this helps.

Don't forget the PMDG 737 NG and the 744 for other aircraft that manages fuel economy!! Also how efficiently the FMC calculates fuel consumption is influenced by the cost value inputed into it

But for info Cost Index affects climb and descent speeds.

Basically, what everyone else said is correct.In modern airliners they all have some form of Cost Index which is entered during the setup of the aircraft. This is normally on the flight plan.However, once you get going, if you find yourself early or late on schedule you can change the Cost Index and it will slow you down (or speed you up) in all portions of the flight (climb, cruise, descent).As an aside, the planned fuel for diversion is usually at a Cost Index of 0 (most fuel efficient) because if you're diverting the whole schedule's shot anyway so you might as well do it as efficiently as possible. Fuel is expensive but passengers only pay to get there, not by the hour, so it's often worth paying a bit more in fuel to be able to run more sectors than it is to simply be the most efficient.Usually, airliners use Mach number in the cruise (or at anytime much over 25000) a cruise of around 0.8 Mach I think is normal. The 767 is slightly quicker .82? .84? and your average 737 or Airbus is slightly slower .76 .78?Hope this helps,Ian

Thanks everyone for those informative answers!I am always thankful and happy about all the huge amount of know-how that I may enjoy time after time!As a sim pilot, the answers revealed a lot of facts which I didn

In real life the Captain or First Officer and the Flight Dispatcher plan the flight. The Dispatch office will do the following for the pilots:1 - Plan the route taking into account wx (winds aloft, wx enroute, reported turbulence etc.), current ATC routings, NOTAMS, aircraft range, max altitude, weight, fuel load, temps, performance, etc.2 - Select the optimum cruising altitude for the flight again taking into account winds aloft, aircraft loads, and fuel economy and all the parameters above.3 - Reference the appopriate Cost Index for the route according to company policy (a CI of between 80 and 100 is a safe bet. This directly affects fuel economy.The Dispatcher is tasked with knowing everything, in regards to aircraft performance and range, that the pilots know so that his numbers make sense. Many times dispatchers are referred to as the "Captains on the Ground". Prior to the flight the Captain (or FO) will go to dispatch and have a briefing with the Dispatcher and make any changes agreed upon. So before the pilot gets on the airplane he knows his speeds and altitudes for that given flight. When punched into the FMC the computer will give an ETA and FUEL calc. Now, once the Pilot contacts CD on the ground to file the flight plan, there is always a chance that he will get an altitude or route amendment which may affect speed and schedule. Changes are entered into the FMC and at that point the pilot knows if he will need more fuel, more time, etc. Bare in mind also that the cost index is company policy. If you are given an amended route you cannot change the cost index to make up the time without approval because it burns more fuel. In such cases where flight are rerouted the cruise speed usually stays the same and the flight gets in a little late. In lesser cases of a flight with a lot of passengers with close connections at the destination the company will approve more speed..eg more fuel burn fuel burn as the cost of using more fuel may be less than the cost of dozens of passengers missing their connection or holding dozens of other aircraft at the gate waiting for the passengers.To simulated this complex process in FS I recommend doing your planning with FSBUILD since it is equipped to plan your flight taking into accound winds aloft and giving you a fairly accurate load. At that point pick a Cost Index and stick with it (80-100)and off you go.Finally, if you are using an aircraft without a complex panel it is always safe to simply look up the typical cruising speed for that aircraft and aim for that.Have fun.Mike T.

Thanks Mike!I want to add another Thanks, for all the privided information!I will try even more to make my flights "as real as...."I am going to get the FSBUILD too!Thanks once again!Haraldh