PPRuNe Forums - View Single Post - ATC request Mach 0.83 to Mach 0.79

22nd Mar 2018, 09:41

#12 (permalink)

Derfred

Join Date: Jun 2006

Location: Brisbane

Posts: 265

Likes: 0

Received 0 Likes on 0 Posts

Quote:

Originally Posted by extricate

Thanks. Any reference material for the 5kts per 0.01M ?

I think you're confusing it with TAS.

For IAS it's about 3kts per 0.01M.

You don't need a reference, it's just basic maths. If you are doing M0.80 and 240 KIAS, simply divide one by the other and get 3.

Likewise with TAS, if you are doing M0.80 and 460 KTAS, divide one by the other and get a number somewhere between 5 and 6 (closer to 6).

So if ATC want you to reduced your groundspeed by 30kts, then that's about M0.05, which will be about 15 KIAS.

Reply