Did some digging and found this quote that seems to cover what I was thinking of
Allied airmen shot down in Burma had to contend with the hostile Burmese jungle as well as the possibility of capture by the Japanese. Their survival equipment included maps, rations, basic first aid kits, jungle knives and cotton flying helmets designed especially for the tropical climate.
During 1942-1943, when Squadron Leader 'Monty' Cotton DFC, was commanding officer of 17 Squadron RAF in Burma and India, pilots were issued with an escape kit, which included the kukri. Squadron Leader Cotton ordered that a fabric harness be made for his pilots to enable them to carry this equipment without it obstructing their movements in the cockpits of the Hurricane IIc fighter aircraft they flew.
The kukri could be used to hack a way through the jungle if the plane was forced to land or the pilot had to bale out. Many of the aircrews also carried a 'blood chit' or message, written in various Burmese languages. The message asked for assistance in escorting airmen to safety and offered a reward to anyone who did so.