James.
During the departure phase RAF Bomber Command aircraft would be given a specific time to taxi from their dispersed hard standings to the runway where takeoff clearance would be given by light signal although often the German night fighters controllers were aware of a raid due to the airtests earlier in the day which included testing the radios
Squadron aircraft were give specific routings, timings, heights, etc to optimize the performance of the particular aircraft, for example the higher and faster flying Halifaxes and Lancasters would be up at 18000 or 20000 feet whilst the poorer performing Stirlings would be at 10000 feet and if that lessened the risk of collision the better, but the separations were for efficiency of the attack rather than safety, the primary collision avoidance tool was the Mark one eyeball during Bomber Command operations.
When the bombers returned to their bases they were "stacked" at 500 feet intervals over the airfield utilizing visual "pundit" lights which were lights flashing the individual airfield code in Morse (We still have one at our GA airfield in Shropshire) whilst communicating by radio to the duty pilot. Often over airfields in counties such as Lincolnshire (the home of 5 Group, RAF Bomber Command), airfields would have different circuit directions such was their proximity to each other ie: Scampton and Dunholme Lodge. The final approach was conducted using the Drem System which was a basic set of runway approach lights however aircraft were still lost in mid-air collisions within the circuit and to Luftwaffe long range intruders which would come back with the bombers to attack their bases and aircraft, in fact there are still holes in the side of the Maple Leaf Club at Linton on Ouse today as the result of a Luftwaffe intruder attack in 1941.
In foggy conditions quite a number of airfields were equipped with FIDO (Fog Intensive Dispersal Operation)which were a series of pipes alongside the length of the active runway within which was pumped high pressure high octane fuel which vented through small holes in the pipe and was then set on fire, the resulting heat burned off the fog in the local area to allow the aircraft to be recovered.
Their RT phraseology was different to today A-Able, B-Beer, L-London, N-Nan, Q-Queenie etc and often verbal communication had to be repeated three times due to the primitive radio equipment in use such as valve technology although for the majority of the flight communication would be in Morse hence the presence in the crew of a specialist Radio Operator.
No study was ever conducted into the losses due to mid-air collisions during the Bomber Campaigns but I would suggest that it was difficult to quantify in combat operations.
Last edited by DC10RealMan; 19th Apr 2013 at 20:19.