The Canberra bomber did not have an autopilot. It frequently flew at 45,000 ft on the basic six pack of flight instruments. Limited panel at those altitudes was a challenge. The RAF lost a Canberra en-route Manus Island to the USAF base at Kwajalein Atoll in the Marshal Islands in 1954. There were CB's tops 60,000 ft.in the ITCZ. It was never found. It was thought it may have had an electrical failure (it had happened before) resulting in the loss of both generators and thus loss of the AH. Two weeks later a replacement Canberra experienced loss of both generators in IMC on the same route but managed to obtain visual flight.