An experienced Vietnamese Army officer was one of four people killed in a horrific mid-air collision after a training instructor suffered the effects of carbon monoxide, it is being claimed in papers lodged with the High Court.
Captain Trung Thanh Nguyen, 32, a qualified helicopter instructor and member of the Vietnamese People’s Armed Forces, was killed when his Gumal Cabri G2 helicopter and a Cessna 152 collided 1,500ft above Waddesdon Manor, near Aylesbury.
His widow claims in court documents that an instructor in the Cessna plane was still suffering the effects of carbon monoxide fumes in the cockpit from his previous flight.
She is now suing flying school Booker Aviation for more than £200,000 in damages for herself and the couple’s two young children, accusing the company of negligence leading to her husband’s death. Booker Aviation denies the claims.
The two aircraft had taken off from High Wycombe Air Park on November 17, 2017, in good visibility, but collided less than twenty minutes later, when the Cessna flew into the helicopter from behind.
Papers lodged with the High Court claim the Cessna negligently failed to see the helicopter or take evasive action.
Mapped: Aylesbury mid-air crash
Because of its design the Cessna allegedly had a blind spot obscuring the pilots’ view and should therefore have been carrying out clearing turns to view the busy airspace in what is known as the Brize-Norton-Heathrow-Luton Gap.
Captain Nguyen’s widow, Hoang Thi Puong Mai, 25, claims the Cessna instructor, Jaspal Bahra, 27, from Wembley, is likely to have been suffering impaired judgement as a result of alleged carbon monoxide poisoning.
There has been concern over carbon monoxide levels in aircraft cockpits, with pilots unions warning of the dangers.
An Air Accidents Investigation Branch (AAIB) report found that carbon monoxide poisoning played a part in the death of footballer Emiliano Sala when the plane he was in crashed into the sea off the coast of Guernsey, in 2019.
Toxicology reports show that Mr Bahra had marked levels of carboxyhemoglobin (COHb) at 24 per cent in his blood, caused by inhaling carbon monoxide allegedly during a training flight in the same aircraft an hour and half earlier.
The court will hear the Cessna was fitted with an out-of-date carbon monoxide detector and levels of COHb in his blood would probably have been 30 per cent at the end of the earlier flight. Symptoms include impaired judgment, bad headache, blurred vision, drowsiness and dizziness.
Also killed in the crash were Mr Bahra’s student pilot, Saavan Mundae, 18, from Richmond, south west London, and Captain Michael Green, 74, from Newbury, who was instructing Captain Nguyen.
Mrs Mai, who described her husband as a “perfect military officer” and devoted father, claims Booker Aviation failed to set out the need for clearing turns, failed to train both men in the technique, failed to have adequate regard for the blind spot or that it might encounter other aircraft when flying in busy airspace.
Her alternative case is that the crash was caused by levels of carbon monoxide in Mr Bahra’s blood, and that he failed to recognize the symptoms indicating that he was not fit to fly.
Captain Nguyen, who was in the UK on a two-month training programme, died as a result of multiple and severe blunt force injuries.
Mrs Mai, who was pregnant with her second child at the time of the accident, said: “My young children (now aged four and two) and I have lost a father and a husband in what was a cruel and fatal crash from behind.
“I repeatedly think about what my husband must have felt in his last moments, and my children ask about their father the whole time. My husband had so much to give his children and me and now we are left alone.”
Mrs Mai claims the Cessna instructor is likely to have been suffering impaired judgement as a result of alleged carbon monoxide poisoning
She added: “Booker Aviation and their insurers have refused to accept liability in what is a clear collision from behind, and have failed to make any settlement offer.
“This has forced me, a widow with two young children based in Vietnam, to have to commence proceedings in the UK, in the midst of a pandemic. I do want to see justice for my husband – I owe it to him and to my children.”
Following the 2019 inquest into the crash a coroner called for collision avoidance and carbon monoxide devices to be fitted to such aircraft.
Coroner Crispin Butler said that although there was no evidence that exposure to carbon monoxide before or during the flight played a part, it should be mandatory for light aircraft to carry monitors or warning devices.
Booker Aviation said it could not comment on ongoing legal proceedings, but added: “Consistent with the outcome of the Coroner’s Inquest, which identified no shortcomings in Booker Aviation’s activities, it is defending the proceedings vigorously."