Originally Posted by
fuzzy6988
How does that compare with Victor airways in the US, which as far as I know, start at around 1200ft where you're given separation from other IFR flights by "Center"?
IFR OCAS works just fine in the UK ... BUT, it is based on a different operating assumption than the US.
American's believe airplanes will hit each other or the ground if they don't follow routes (Victor airways) and receive a separation service. In the UK the volume of IFR OCAS traffic is low, the country is flat, and the routes are random. All of this means no aircraft in IMC has hit another (since one incident in WW II) even though separation is only provided on an adhoc basis. The CAA/NATS structure is geared to providing ATC in a limited set of Airways (defined for commercial traffic) and approach areas - and a very basic level of service OCAS. Once you accept Big Sky Separation works just as well as ATC for typical OCAS flights you will find the UK system actually seems to work pretty well.