navigation routes for RAF special duties squadron

[hautemarnechris]

I'd be extremely grateful for any suggestions as to how resolve a navigation problem I've encountered when researching the crash of an RAF Stirling in July 1944 which was carrying Special Air Service troops on a mission in North Eastern France.

I'm trying to reconstruct the route the aircraft took by using a document in the British National Archives (AIR 8837) which I think was prepared at 38 Group. The information it contained was used to task aircraft from the group's squadrons. My understanding is that navigators at squadron level would flesh out the route using known flak sites, the latest weather forecast, etc.

The navigation instruction in AIR 8837 gives the following information : the lat and longitude (deg, min, sec) of the drop zone - in this case 48deg29min01secN 5deg10min58secE. Routing information is as follows- my comments in italics:
Base (RAF Fairford) - B8 -B9 - 49deg 28 N 00.05W(just off Le Havre) - 0 deg at coast (Villers-sur-mer) - C1 - C2 -C5 - Lake at 48deg 15N 04 deg 22E (Lac D'orient near Troyes) - DZ (as above close to joinville) - RSR (this means return same route)

The latlongs are not a problem - I can identify those. The problem is the B8, B9, C1, etc codes. I suspect they represent N-S air corridors running from east to west from A out in the Atlantic to B0 @ 4degW up to C0 @ about 1deg E thru C up to about D0 @ 6degE. In other words each 'corridor' is about 5 deg in width.

I have looked at the navigation instructions from the same document for other missions in France and they seem to fit that pattern.

Has anybody come across these codes before? I've asked a couple of ex-navigators but they weren't able to shed any light on these codes. I would be very grateful for any advice.