The CL-28 was the most modern sub detecting aircraft in the world when it was introduced. Modified from the Bristol Britannia passenger plane, it was modified for low altitude operation and used Wright radial engines for economy. It was designed for long patrols- rated for 26 hour flight duration but one set a record in 1959 of 31 hours without refueling. Thirty three were built to patrol Canadian waters. The last CL-28 flew in 1982, they were replaced by the Lockheed Aurora.