The crash of Canadian Pacific Air Lines Flight 3505 occurred on 21 July 1951 when a Douglas DC-4 four-engined piston airliner registered CF-CPC of Canadian Pacific Air Lines disappeared on a scheduled flight for the United Nations from Vancouver, Canada, to Tokyo, Japan.

[2] The flight was on schedule and reported at the Cape Spencer intersection in British Columbia 90 minutes out from Anchorage; it gave an estimate of 24:00 for Yakutat in Alaska.

[4] In 1946, it was converted to a civil Douglas DC-4 standard for Pan American Airlines as Clipper Winged Racer.

The 31 passengers included two sailors of the Royal Canadian Navy, 26 members of the United States military and 3 civilian US citizens.

[1] In 1974, the Civil Aviation Authority (United Kingdom) reported: "As no traces of the aircraft or its occupants has been found to date the cause of the disappearance has not been determined.