Direct too when steady report heading?

[towser]

Can someone tell me please why I often get given this sort of instruction; " ABC 123 cleared direct dean cross , when steady report heading as a radar heading."

Surely by being cleared direct you know the track we are going to fly so why do we then need to fly it as a radar heading?

[one25six]

Because another aircraft may be vectored to parallel you and if we give the same heading there should be no closing drift.

Or if we will be vectoring you shortly, we know what adjustment to give - present heading + 40 degrees = new heading (takes away the dirft guesswork)

Or the next sector / TMA might want to know your heading due boundary coo-ord requirment.

Or one sector may be aligned TRUE and the next MAG.

Or a 1001 other reasons that admittedly are not often obvious.

[eastern wiseguy]

Leaving you on your own navigation allows you to do just that...wander whichever way you want ...locking you on the heading once you have settled down gives me control .It simply takes away the guesswork.

[towser]

Thanks for the replys. Helps make it a bit clearer!!

[one25six]

Towser might be talking about local procedures in UK - A DCT TO clearance in Australia means just that - no licence to 'wander whichever way you want' unless you request it (Wx Diversions etc.)

[Mister Geezer]

However with B-RNAV in many aircraft nowadays, there can't be many wondering aircraft tracking to their next fix.

[towser]

Mister Geezer , that was kind of my point. When cleared direct to a point we just punch it into the rnav and off it goes so there should be no wandering around!

[5milesbaby]

Unfortunately Towser, although your kit these days is probably more accurate and safer than our vectors, we aren't approved separation without vectors unless you are on one of the very limited routings with such approval.

[Pierre Argh]

when steady report heading as a radar heading... because us Controllers sometime relieve our boredom and frustration at being earth-bound by asking you pilots to do something just for the hell of it... the following is a real RT exchange from several years ago...

ATC to Pilot "(c/s) turn right twenty degrees and report your heading"
Pilot to ATC "Request reason for the turn? (c/s)"
ATC to Pilot "Controller's whim"

back to your post... I think the controller, whilst giving you freedom to track direct, is retaining control of the flight... i.e. once steady on a the direct track do not deviate. The instruction "own navigation direct..." is potentially ambiguous so maybe it's a case of "once bitten twice shy"