 Communication between the pilots and ground control was poor and there was no procedure for pilots to distinguish between British and "Luftwaffe" aircraft.Identification friend or foe (IFF) sets were still being developed and had not been installed in many RAF aircraft.With everyone in the air expecting to see enemy aircraft and no experience of having done so, 'A' Flight of 74 Squadron saw what they believed were German aeroplanes and their commander, Adolph "Sailor" Malan, allegedly gave an order to engage.