On 4 April 1942, only two days after his arrival, Squadron Leader Birchall was flying a PBY Catalina flying boat (AJ155/QL-A) that was patrolling the ocean to the south of Ceylon. Nine hours into the mission, as the plane was about to return to base, ships were spotted on the horizon. Investigation revealed a large Japanese fleet, the Nagumo Task Force (Responsible for the attack on Pearl Harbour), including five aircraft carriers, heading for Ceylon, which at that time was the base for the Royal Navy's Eastern Fleet. Birchall's crew managed to send out a radio message, but the Catalina was soon shot down by six A6M2 Zero fighters from the carrier .