Archived

This topic is now archived and is closed to further replies.

Hirgab

Cruising altitude of PMDG 747

Recommended Posts

Hi all,I am having a hard time cruising above FL 320 when flying the PMDG 747. For example, I flew yesterday with 2/3rd PAX capacity and 1/3rd fuel capacity with headwind, but was unable to get higher than FL 380, at this altitude, the yellow/red speed tape starts at only 280 knots! I'm not sure what I'm doing wrong here, because I'm fairly sure 747s can cruise at higher altitudes than those mentioned.I trim the aircraft before take off. I also usually have all my flaps up by 10,000ft. I am an inexperienced simmer, I would really appreciate help on this matter. Thank you.

Share this post


Link to post
Share on other sites
Help AVSIM continue to serve you!
Please donate today!

It all depends on weight. You're too heavy at that point to reach higher. The FMC tells you an optimum and maximum cruising altitude. Use that.

Share this post


Link to post
Share on other sites

As you fly higher, atmospheric pressure decreases so you get a lower indicated speed on your airspeed indicator, but by and large as you fly higher Mach (speed of sound) remains constant. That is why you see a decreasing margin between your MMO - Max Mach Operating number of .92 and your IAS - Indicated Air Speed. See Coffin Corner for more info.I cruise just fine at FL400 in my PMDG B-744 with a full passenger complement, but that's 12 hours into the flight!Note cruise and Vmo (Mmo expressed in knots) is quite dependent on temperatures, such than any air mass hotter than ISA - International Standard Atmoshpere at your particular flight level (worst case: Tropics in the summer) will contribute to your 744 just not making it up there. (Engine fuel eficiency and therefore range are also adversely affected). Cheers,- jahman.

Share this post


Link to post
Share on other sites