XX177 – Hibernations in the Machine: Introducing the Pressure & Release Model

11 October 2017

University of Chester


A talk on the events leading up to the Red Arrows ejection seat accident in November 2011 and the subsequent investigation (and coroners inquiry), drawing out the lessons that need to be learned in the form of the Pressure & Release (PAR) Model.

On 8 November 2011 Hawk T Mk 1 XX177 was assigned to be flown as part of a Royal Air Force Aerobatic Team (RAFAT – ‘Red Arrows’) training sortie from RAF Scampton in Lincolnshire.

At 1057hrs the Pilot of XX177, Flt Lt Sean Cunningham call-sign Red 5, walked out to the aircraft and commenced external checks before entering the front cockpit as the sole aircraft occupant. At 1106hrs, having completed his ‘full and free’ after-start control checks, with the engine running, canopy closed and all escape system safety pins in the correct position for solo flight, the front cockpit ejection seat firing sequence was mysteriously initiated. The main parachute did not deploy and the Pilot remained attached to the seat until impact with the ground. The pilot was later transferred by air ambulance to Lincoln General Hospital where he was pronounced dead; the post mortem showed that he had died at or shortly after impact. Two RAFAT engineering personnel also suffered minor injuries, due to canopy fragmentation and the ejection seat rocket pack firing.

This talk by the then Type Airworthiness Authority (TAA) for the Hawk TMk1 aircraft (effectively the MOD Hawk Chief Engineer), who had also in his career led the MOD’s aircraft forensic science & engineering organisation and was called as an expert witness in the subsequent coroners inquiry of the accident; looks into the background leading up the accident, the accident investigation by the Military Aviation Authority (overseen by Lincolnshire Police and the HSE) and the lessons that should be drawn from this tragic accident. We owe it to Sean Cunningham’s family to not be complacent and let this event be forgotten or the lessons from it to be neglected over time:

The XX177 accident, as with many accidents, was a wholly unnecessary event – it was avoidable and preventable.  There was adequate knowledge available and sufficient processes and barriers in place with which to ‘catch’ the various hazards early enough to avoid these leading to the tragic outcome.  That said, the accident was a complex event and there were also some ‘unknown - unknowns’ which would have made a significant contribution to preventing the accident, if they had been made known earlier. These issues were ‘hibernating in the machine’ like thieves in the night and demonstrate why designers, maintainers and decision makers need to be forever vigilant, sometimes asking the ‘stupid’ or seemingly unhelpful question which might prove crucial to stopping an unwanted outcome in the future.

The talk will cover the following questions:

  1. Why was the ejection sequence initiated?
  2. Why did the ejection seat fail?
  3. What was the cause of the accident and what were the contributing and/or aggravating factors involved?
  4. Why didn’t the various safety management processes and defensive barriers stop the accident?
  5. What recommendations were made at the time?
  6. Finally and most crucially; what are the wider lessons to be learned by the aviation community and even society in general.

Note: It is to be noted that the HSE, following the MAA accident investigation, the police investigation, the coroners inquiry and a CPS review are still actively examining this case and a prosecution is currently on-going (as at August 2017).

Entry details: RAeS and Branch Members £2.00 – Others £4.00
Times: 19.30 - 21.30


Speaker Details

Alan O'Connor FRAeS, former MOD Type Airworthiness Authority (TAA) for the Hawk TMk1

Alan O’Connor joined the MOD as an Aircraft Apprentice (Nav/Inst) at 30 MU RAF Sealand in 1972. Following graduation, he worked within Instrument Sqn 30MU as a Nav/Inst tradesman repairing cockpit instruments and gyroscopic systems for Hercules C130, Harrier GR3 and Phantom F4 aircraft. As a Chargehand, he worked within the ‘cleanroom’ repairing Harrier GR3 Inertial Navigation Platforms and Phantom Displacement Gyro Assemblies.  Following this period, Alan got promotion to PTO(IV) and moved to Development Wing within 30 MU and introduced Electrostatic Sensitive Device procedures across the Unit.

Further promotions resulted in moves to RAF Support Command at Brampton, Cambridgeshire and RAF Innsworth, Glos as the responsible officer for the Civilian Technical Training Apprentice Schools, a tour at the MOD Student Engineering Training Centre at Malvern (where Alan was the Electronics Instructor), and as the 30MU, RAF Sealand Avionics Desk Officer at RAF Logistics Command back at RAF Brampton. On moving to RAF Wyton also in Cambs, he then held a variety of project management and aircraft engineering management positions. His favourite and probably most rewarding role was that as Head of Aircraft Integrity Monitoring (AIM) (now the Materials Integrity Group within 1710 Naval Air Squadron) down in Gosport, Hants (now based in Portsmouth), which undertakes both failure analysis examinations of aircraft and also monitors & manages the health of in-service aircraft. Alan also acted as Airworthiness Advisor to the RAF Air Vice Marshall responsible for Combat Air aircraft, before moving to the position as Training Aircraft Team Leader. In this post, Alan acted as Chief Engineer and military aircraft Type Airworthiness Authority (TAA) for all fixed wing RAF & RN Training Aircraft, which included; Hawk T1 & T2, Tucano TMk1, ATC Gliders, RAF Beechcraft King Air 200s and RN Avenger (Beechcraft King Air 350ER). Now partially retired, Alan continues to work 2 days/week acting as a TAA for a new Air Support to Defence Operational Training procurement project, and as a military aircraft certification subject matter expert.

Alan is a Chartered Engineer (CEng) and a Fellow of the Royal Aeronautical Society (FRAeS) and is active within his local Chester Branch. Married to Shirley with 4 (now grown up children), Alan lives in Upton-by-Chester and enjoys walking, swimming, photography and cinema.


University of Chester

Room 017
Beswick Building
University of Chester
Parkgate Road