Sentence:  By the time No 43 Sqn was given permission to land it was quite dark, and so to assist the pilots in what were to be difficult night landings two petrol <WSD>bowsers</WSD> were parked to ‘illuminate' the runway with their dim blackout headlights. Perhaps, all things considered, the use of petrol <WSD>bowsers</WSD> for this particular task was not exactly wise. 
Meaning of the word marked with <WSD> tags:  A road vehicle (often a trailer) for the transport of liquid fuel, particularly aviation fuel at an airfield.