air speed vs march

hewqtor Guest

Hi,

I have a few questions about speed hold on heavy jet. I found that there are two ways to hold the speed - airspeed hold and march hold. What are the differences between them?

Answers 2 Answers

Jump to latest
Guest Ed Guest

Indicated Air Speed (IAS) is most useful at lower altitudes, say below 26,000 feet. IAS is a measure of the stress on your aircraft due to the air you are flying through. At high altitude, the airspeed indicator becomes very inaccurate, because the air is so thin.

At high altitude, Mach (not march) number is most useful. It is your speed relative to the speed of sound at whatever altitude you're flying. The Mach number is a ratio of your speed to the speed of sound, so for example, Mach .81 is 81% of the speed of sound at your altitude. Exceeding the speed of sound would put a great stress on the airframe, and passenger jets are not designed to do that (except Concorde).

So use IAS down low, Mach number up high.

Ed

Jamie4590 Guest

Mach 1 in Concorde is barely second gear! 😂

Still does not answer your question? Ask a new question!

If the question and answers provided above do not answer your specific question - why not ask a new question of your own? Our community and flight simulator experts will provided a dedicated and unique answer to your flight sim question. And, you don't even need to register to post your question!

Ask New Question...

Search

Search our questions and answers...

Be sure to search for your question from existing posted questions before asking a new question as your question may already exist from another user. If you're sure your question is unique and hasn't been asked before, consider asking a new question.

Related Questions

Flight Sim Questions that are closely related to this...