In a non-radar environment, weather diversions probably create more work for ATC than anything else. To help ATC help you it may be worth considering the following.
- There will usually be some delay in provision of clearance to divert off track from ATC, this is caused by the requirement to coordinate with surrounding units and assess the impact of the diversion on separation. If you leave your request until the last possible moment you may not get clearance in time.
- Many of the separation standards that ATC use outside radar coverage are dependant on aircraft tracking directly to or from a known point, whilst an aircraft is actually flying around CBs we have very limited options. Even if you cant regain track once you are established tracking direct to a waypoint or NAVAID we have more to work with.
- I understand the magnitude of a diversion is initially a guestimate, but if it becomes clear that you will not need all of the 40nm or so off track that you initially request, tell us - generally the larger the requested diversion the more work for ATC. The way ATC separate off radar is basically to protect a "sausage" around an aircrafts track, dimensions determined by RNAV capability and ground based NAVAIDS. For approved INS the dimensions are 14nm either side of track, if that aircraft diverts 40nm left of track, this is just added to the appropriate side, so the new sausage would be 54nm left and 14nm right of track. Obviously large diversions can take up a lot of airspace, If you ask for fifty and it turns out twenty will do, please tell us!
- If you are issued a clearance to divert and later report regaining track, ATC will consider the clearance to divert is now void, they may get a nasty surprise if you divert again.
Hope this helps.