Rate of Ascent

[Bubblehead]

Do jetliners try to ascend to their cruising altitude as quickly as they can or do they do a gradual ascent. I suppose they do what's the most economical.

[Russell Irwin]

It really comes down to the type of flight. If an airliner is flying, say, SAT-HOU, then they will get to their cruising altitude ASAP so that they can spend more time cruising. On a very long, transpacific flight that takes several hours, like SYD-YYZ, the aircraft will "step-climb," which means that it will climb in 2,000 foot increments. Personally, I set my airspeed bug to 250 KIAS and try to maintain that airspeed as I climb by altering my vertical speed. It's surprisingly efficient.

The most important thing to remember is that ATC gets the final say. They won't always clear the aircraft straight to FL420 (which is just as well, since most airliners can't climb that high without step climbing), but they WILL have you climb in blocks, e.g. FL100, FL180, FL260, FL340, FL380, FL420.

[C]

The most important thing to remember is that ATC gets the final say. They won't always clear the aircraft straight to FL420 (which is just as well, since most airliners can't climb that high without step climbing), but they WILL have you climb in blocks, e.g. FL100, FL180, FL260, FL340, FL380, FL420.

ATC never really get the final say... They will always have a profile that they will follow, but an if an aircraft can't follow it, to an extent, they have to fit around that aircraft. As it happens the step climb (where a heavy aircraft will climb to gradually higher cruising level as its AUW and performance allows) is a very good example.

[Brian Z]

Personally, I set my airspeed bug to 250 KIAS and try to maintain that airspeed as I climb by altering my vertical speed. It's surprisingly efficient.

Some aircraft, like the Citation X, actually have an autopilot setting that works this way. You set the KIAS, and the autopilot maintains that speed by adjusting climb rate.

[Russell Irwin]

Some aircraft, like the Citation X, actually have an autopilot setting that works this way. You set the KIAS, and the autopilot maintains that speed by adjusting climb rate.

True, but I've never seen this in the sim.

[Brian Z]

The Eaglesoft payware Citation X has it, there's actually no autothrottle-- because the real thing doesn't have it-- but the engine behavior is a lot more realistic, they don't go into Maximum Overdrive right after takeoff and try to kill you.