View Full Version : Enroute Separation

9th Sep 2018, 07:32
A buddy of mine got asked an interesting question during a check flight. They were in the cruise at FL340 with traffic ahead of them on the same airway and 2000 feet above. The checker asked him if they had adequate separation to request a climb to the same level. My facetious response would likely have been "let's ask and find out!"

It got me thinking though. What separation do ATC use when allocating cruising levels on airways? Also, what separation do they use when granting climb/descent through a level occupied by same direction traffic on the same route?

I've done some research and can find figures for oceanic routes using RNAV 10 and RNP 4 airways (50 or 80 nm and 30 nm respectively). But what about routes under radar coverage? If someone could point me in the right direction that would be appreciated.

9th Sep 2018, 10:10
My response would have been the same as yours, what an utterly irrelevant question for a line check! Anyhow, local AIPs usually dictate separation, however doc 4444 lays down the standards - longitudinally 5 NM which may be reduced down to 3 NM if the surveillance capability permits this, or 2.5 on 10 NM final or closer on approach to a runway.

9th Sep 2018, 13:15
Five miles and less speed and diverging on radar heading looks to be the trick. and they are aiming for 10 miles to continue on track. Happens over Paris a lot and northbound entering Brest and Bordeaux FIR after being treated to the excellently flexible Madrid FIR.
Cpt B