Date:	Tuesday 26 January 1932
Time:	11:15 LT
Type:	Parnall Peto
Owner/operator:	HMS Submarine M.2 Flt FAA RAF
Registration:	N255
MSN:
Fatalities:	Fatalities: 4 / Occupants: 4
Other fatalities:	56
Aircraft damage:	Destroyed
Location:	HM Submarine M.2, West Bay off Portland, Dorset -   United Kingdom
Phase:	Standing
Nature:	Military
Departure airport:	HMS Submarine M.2, West Bay off Portland, Dorset
Destination airport:
Confidence Rating:	Information is only available from news, social media or unofficial sources

Narrative:
Parnall Peto N255: Lost 26/1/32 when HM Submarine M.2 sank into 100 feet (30 metres of water) in West Bay, off Portland, Dorset at approximate co ordinates 50°34.6′N, 2°33.93′W. All sixty crew were lost, including the crew of four assigned to the Parnall Peto:

Flying Off Henry Castlehow Toppin (28) considered died 29.1.32 (pilot) (Lt, RN)
Lt Claude Richard Townsend considered died 29.1.32 (observer)
LAC Leslie Gregory considered died 29.1.32
LAC Frank J Harman considered died 29.1.32

M.2 left her base at Portland on 26/1/32, for an exercise in West Bay, Dorset, carrying Parnall Peto serial N255. Her last communication was a radio message at 10:11 to her submarine depot ship, Titania, to announce that she would dive at 10:30. The captain of a passing merchant ship, the Newcastle coaster Tynesider, mentioned that he had seen a large submarine dive stern first at around 11:15. Unaware of the significance of this, he only reported it in passing once he reached port.

Her entire crew of 60 was killed in the accident. The submarine was found on 3 February, eight days after her loss. Ernest Cox, the salvage expert who had raised the German battleships at Scapa Flow, was hired to salvage the M.2. In an operation lasting nearly a year and 1,500 dives, on 8/12/32, she was lifted to within 20 feet (6.1 m) of the surface before a gale sprang up, sending her down to her final resting place.

The hangar door was found open and the aircraft still in it. The accident was believed to be due to water entering the submarine through the hangar door, which had been opened to launch the aircraft shortly after surfacing.

Two explanations have been advanced. The first is that since the crew were always trying to beat their record time for launching the aircraft, they had opened the hangar door on surfacing while the deck was still awash. The other theory is that the flooding of the hangar was due to failure of the stern hydroplanes. High pressure air tanks were used to bring the boat to the surface in an awash condition, but to conserve compressed air compressors were then started to completely clear the ballast tanks of water by blowing air into them. This could take as long as 15 minutes to complete. The normal procedure for launching the aircraft was therefore to hold the boat on the surface using the hydroplanes whilst the hangar door was opened and the aircraft launched. Failure of the rear hydroplanes would have sent the stern down as observed by the merchant officers and water would have eventually entered the hangar.

After the loss of HMS Submarine M.2, the Royal Navy abandoned submarine-launched aircraft. After the loss of HM Submarine M.2, there were no more submarine losses in the Inter War years until the loss of HMS Thetis in June 1939.

Only two Parnall Petos were built: N181, the Peto Prototype, first flew 4/6/25, was wrecked at Gibraltar on 11/2/30 and rebuilt as N255 with improved floats. The other (N182) crashed 29/6/30 at Stokes Bay. It was acquired by F.C.H. Allen and prepared for civil use at Ford aerodrome in Sussex between 1933 and 1934. Issued with civilian Registration G-ACOJ the project was abandoned, and it never flew as such.

1. Treadwell, T.C. (1999) Strike from beneath the Sea: a history of aircraft-carrying submarines, Stroud, UK: Tempus Publishing. ISBN 0-7524-1704-5
2. http://www.rcawsey.co.uk/Acc1934.htm
3. https://en.wikipedia.org/wiki/HMS_M2#Accident
4. Flight magazine 31/7/31 pages 759-763: https://www.flightglobal.com/pdfarchive/view/1931/1931%20-%200813.html
5. http://www.bbc.co.uk/news/uk-england-hampshire-18025157
6. https://en.wikipedia.org/wiki/Parnall_Peto
7. http://www.naval-history.net/xDKCas1932.htm

HM Submarine M2 and her Parnall Peto Sea Plane N255 Parnall Peto N181, which was rebuilt as N255

Date/time	Contributor	Updates
12-May-2018 14:10	Dr. John Smith	Added
12-May-2018 14:11	Dr. John Smith	Updated [Aircraft type, Operator]
12-May-2018 14:19	Dr. John Smith	Updated [Source, Narrative]
25-Nov-2018 18:15	Nepa	Updated [Operator, Operator]