Safety Accident Analysis
Surprises all round…
F
ew of us ever have the opportunity to ride in a fast jet and fewer still actually own one, so it is perhaps debatable as to why this month’s analysis should begin with a look at a rather scary passenger ride on one of Martin Baker’s finest ejection seats. The accident report, compiled by the French Air Force, runs to some 40 pages and is an excellent study into the sort of issues that often arise with passenger flying. Most are entirely relevant to General Aviation so I make no apologies for using the report and thank my French colleagues for their candidness.
Accident 1
Saint-Dizier is a French Air Force base on which ETR 3/4 Squadron is dedicated to the conversion of Rafale crews. They were tasked with carrying a 64-year-old civilian passenger, in charge of testing teams at a weapons company and who had no military aviation experience. The morning of the flight, the passenger underwent a medical examination for approval to fly in an aircraft equipped with ejection seats. Followed, on the Squadron, by a specific clothing and equipment session, plus training in safety-rescue systems focused on the ejection seat. The passenger then briefly participated in part of the mission briefing with the other aircrew before joining his four companions for lunch. For the flight, the passenger was installed in the rear seat and the pilot adjusted the various passenger restraint straps on the seat. The passenger’s
installation was checked by the ramp engineer. After start-up and taxying, the aircraft lined up in echelon behind the other two aircraft for a 30 second stream take-off. The take-off run was normal and once airborne the pilot retracted the landing gear to accelerate. He then performed a standard climb profile, rotating to a pitch attitude of 47°, with a load factor close to 4g, followed by a bunt close to -0.6g for the level off. During this last phase at 650ft and 280kt the passenger was ejected from the aircraft. The pilot recovered the aircraft to Saint-Dizier and evacuated without assistance. The investigation discovered that the flight recordings used for maintenance and for the mission itself were automatically erased because the ejection system had been initiated. However, enough flight data was accessible to reconstruct the flight profile. The passenger’s connected personal watch recorded his heart rate. Examination of the onboard conversation indicated normal dialogue up to, and including, the take-off acceleration with the passenger falling silent as the climb commenced. The ejection handle showed the presence of glove fibres which indicated the ejection had been initiated by the passenger. Observations made on the harness after ejection in conjunction with photographs taken by work colleagues, indicate the shoulder straps were inadequately tensioned. A number of possible reasons for the rear ejection handle being pulled were considered by the inquiry, including voluntary activation through loss of
“Colleagues kept quiet about the flight in order to maximise the effect of surprise” 44 | FLYER | March 2021
consciousness (such as A-LOC or G-LOC) or high levels of stress, but all were rejected in favour of involuntary activation. The passenger was under significant stress throughout the morning. The data indicates that his heart was in full tachycardia with a rate that ranged between 136 and 142bpm against a maximum heart rate of 156bpm. The passenger’s level of stress was exacerbated by the context of the flight. Given the tight deadlines for the programme, the passenger did not take part in the full mission brief and his pilot did not have time to talk through the key aspects of the sortie. Once airborne the stressors were initially the positive load factors. At +3g a feeling of great heaviness of the limbs and the body in general, between +3g and 4.5g: possible appearance of a grey haze (narrowing of the peripheral visual field associated with blurred and darkening of vision) and over 4g the appearance of a black veil (total loss of vision). As this was his first flight in a high performance aeroplane, the passenger would have been unaware of these symptoms and would have found them stressful. The initial positive-g phase was followed by rapid transition to a negative-g phase (-0.63g). On the ground, humans are rarely exposed to a negative load factor and the sensation would have been unfamiliar to the passenger. This feeling may have been enhanced by his harness not being properly adjusted allowing him to rise up in the seat. The passenger was therefore not prepared for what would take place during the take-off and the positive g at rotation and its subsequent reversal would have significantly added to his stress. This likely explains why the passenger involuntarily pulled the ejection handle in order to grab onto his seat and counter the feeling of being thrown from the cockpit. This flight was organised by colleagues close to the passenger without notifying him in order to
Mark Mitchell
Although sharing our cockpits with fellow travellers has been a bit more tricky of late, the good times will return. When they do, Steve Ayres suggests its worth reflecting on some of the potential consequences of doing just that…