U. S. Coast Guard helicopter #1363, a Sikorsky HH-52A 'Seaguard' was the one in which Exchange Officer Sub-Lieutenant Alltree was flying when the helocopter crashed into rising terrain on the coast of northern California, near Trinidad. The weather conditions were very bad at the time and caused poor visibility. The 'Seaguard' had been sent on a rescue and evacuation operation in an area where flooding had resulted from a severe rainstorm, and the naval crew had already saved ten people that day.
In addition to Sub-Lieutenant Alltree, six other people perished in this accident: Lieutenant Commander Donald L. PRINCE, USCG (pilot) and Aviation Electronics Technician 2nd Class James A. Nininger Jr., USCG (crewman); Budd HANSEN, a local farmer/dairyman acting as a volunteer spotter and guide; and three evacuees, Marie Bahnsen, Bette KEMPF and her infant daughter Melanie R. KEMPF.

From the Canadian Virtual War Memorial-
Military Service:-
Rank: Sub-Lieutenant
Trade: Co-pilot
Service Number: 01852
Age: 24
Force: Royal Canadian Navy
Unit: HMCS 'Niagara'

Citations: U.S. Coast Guard Commendation Medal

He enlisted on 2 September 1959 in Vancouver, British Columbia, Canada, enrolling as a Naval Cadet at HMCS 'Venture'.

Son of Mr. and Mrs. Leonard Alltree of Hong Kong; his father was an official with the British Government. Nephew of Ernest William COULSON of West Vancouver, British Columbia, Canada.

--Sub-Lieutenant Allen Leonard Alltree is commemorated on Page 123 of the 'In the Service of Canada' Book of Remembrance.
--Sub-Lieutenant Allen Leonard Alltree is also remembered with honour at the United States Coast Guard Memorial in Elizabeth City, North Carolina, USA.
--And in 1998 members of the Coast Guard Sector Humboldt Bay Chief Petty Officers' Association erected a memorial, in part to commemorate the crew of CG 1363, including Canadian Sub-Lieutenant Allen Leonard Alltree . This memorial is located in Humboldt Bay, Humboldt County, California, USA.