Chipmunk WP780

De Havilland Chipmunk Mk.10 WP780, Durham UAS, RAF Usworth
crashed Otterburn, Northumberland on 1st April 1955

Crew

PositionRank/TitleFull NameAgeService NumberInjury
PilotF/LtRichard Vere Potts34128004Injured
Cadet PilotCadet PilotMichael Hanson232607942Injured
SpectatorOfficer CadetMargaret Nora Holwell19W391009Fatal
SpectatorOfficer CadetMargaret Elizabeth Gardner 20W390844Fatal
SpectatorLance CorporalAlan Terence Holmes 2122778416Fatal
SpectatorOfficer CadetKeith Forester Steadman 2123216233Fatal
SpectatorOfficer CadetPauline Theresa McHaffie 18W391619Fatal
SpectatorSgtEwart Anthony Austin 2619174326Fatal
SpectatorCorporalGeorge Imrie Injured
SpectatorCadetHeather Maxwell Injured
SpectatorCadetYvonne Esme Horsburgh Injured
SpectatorSgtDorothy Boyland Injured
SpectatorCorporalLeonard Arrowsmith Injured
SpectatorRegimental Quartermaster SgtThomas Couse Injured

Accident Details

The Durham University Air Squadron (UAS) Easter camp was to be held at RAF Usworth starting from 18th March 1955. The camp was to be divided into three periods, the last of which running from 1st April 1955 until 7th April 1955 when the camp officially closed.

As part of the Easter camp a detachment of Durham UAS Chipmunks were to operate from Usworth near Sunderland and take part in an Army Co-Operation exercise over the Otterburn Range with Cadets of the Women’s Royal Army Corps (WRAC) under supervision of the regular Army.

Chipmunk WP780 was one of three taking part in the exercise and it left Usworth with two other aircraft at 10:30 hrs with the pilot Flt Lt Richard Vere Potts at the controls, and Cadet Pilot Michael Hanson acting as the observer. Richard Potts was a WWII veteran having served with various squadrons during the war. Whilst serving with 229 Squadron based in Malta, he damaged a Junkers Ju88 on 4th April 1942.

The purpose of the flight was to locate a group of Army personnel who were operating around Linshiels Lake and to carry out a mock attack on them by dropping bombs in the form of toilet rolls, which also acted as markers. The flight were unable to find the Army personnel near the lake so they decided to drop their ‘bombs’ onto the observation post situated on top of a cliff where around 19 cadets from the WRAC, and around the same number of cadets from the Royal Electrical and Mechanical Engineers were sitting on the ground watching the exercise.

45 minutes after take off, during one of the runs over the observation post, the Port wing of Chipmunk WP780 struck Sgt Austin, a member of the regular Army. He was seriously injured and succumbed to his injuries later. As the aircraft cartwheeled into the crowd, five of the Cadets were killed outright and another six suffered various injuries. The aircraft lost the port wing on the initial impact and the main bulk of the aircraft rolled down the slope. Flt Lt Potts and Cadet Pilot Hanson were injured and they were helped out of the battered cockpit and given first aid.

Several witnesses were interviewed as part of the post crash investigation, but unusually there was no technical investigation. The aircraft had been approaching over the back of hill from the south west and was making its second run over the the observation post when the incident happened.

Captain Derek Bargrave-Weaver of the Durham University Officers Training Course, a University Lecturer, was one of those interviewed. He recalls:

“I noticed one of the planes approaching from the South-West. It was difficult to estimate its height, but it seemed to come considerably lower than I would have expected. It was 50 feet up as far as he could guess, not having any experience in taking the height of aircraft. When the plane got near the observation post it was lower than when he had first seen it. The aircraft was travelling between 90 and 100 knots.

It was losing height and it tipped its port wing in a very steep bank of about 80 degrees. I formed the impression that the pilot was going to bank and turn away, but it appeared to me that he side-slipped in the direction that the port wing was pointing and that he was not able to pull out. The port wing tip hit the ground and struck the spectators in doing so. Part of the wing broke off and the plane cartwheeled away over my head. It bounced several times before it came to rest, and several parts fell off as it cartwheeled. I was a bit worried lest something might be going to happen before anything did happen.”

Other witnesses confirm the statement of Captain Bargrave-Weaver, however a number of those witnesses recall that the engine of the aircraft cut just prior to the impact and there was a puff of black smoke.

A Court Martial was opened and adjourned on 12th July 1955 with the primary cause given as the negligence of Flt Lt Potts while executing turn at low level which allowed the aircraft to strike seated people. He was flying too low to recover from an apparently badly executed turn.

The leader of the formation, Flt Lt Kenneth Mason, was also partly to blame in that due to his poor leadership in the air he allowed the exercise to develop into a disorganised operation. Also held to account was the Squadron Commander, Squadron Leader Ivor Kenneth Salter, in failing to set out properly a minimum height for the exercise. The pilot of the third aircraft, Flt Lt Sidney Bromley, also committed a breach of flying discipline in blindly following leader.

Flt Lt Potts was sentenced to lose two years seniority and to be severely reprimanded. On the 10th October 1955 Flt Lt Potts retired from the Royal Air Force.

Even today relatives of those who lost their lives in the crash can recall that there was a mention of the engine cutting out as the aircraft banked towards the crowd. As it was 1st April the story at the time was that Flt Lt Potts deliberately cut the engine as an April Fools joke to surprise those on the ground. However, there may have been another reason the engine cut.

In 1997 a Chipmunk Mk.10, civil registration VH-RWI, crashed in Australia. The crash was subject to a detailed technical investigation and although the circumstances of the crash differ from that of WP780, the report does mention an engine modification introduced to the Gypsy Major engine in 1957 following a spate of engine failures. The report states:

“Previously reported problems associated with Gypsy Major engine response during go-arounds was pinpointed to worn needle valve seats causing carburettor flooding. A modification was introduced in 1957 to address the fault.”

Could this have been the cause of the engine cutting and the black smoke observed by a number of the witnesses? As there was no technical investigation we will never know if the engine fitted to WP780 had worn needle valve seats, which caused the flooding of the carburettor and subsequent loss of power causing the aircraft to side slip into the crowd.

The Crash Site

The crash site is in the centre of the live firing area of the Otterburn Range and as such is inaccessible without prior permission from the camp authorities.  We visited the crash site with Kate Purdy, sister of Margaret Holwell, and Peter Holmes, brother of Alan Holmes, who sadly lost their lives in the accident.

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