Four men perished in a mid-air crash between a helicopter and plane close to Waddesdon Manor because they were in each other's blind spots.
Vietnamese military officer Thanh Nguyen, 32, was receiving training from Captain Michael Green, 74, who was piloting the Guimbal Cabri G2 helicopter which took off at 11.45am on November 17, 2017.
But at noon their rotor sliced through the tail of the Cessna 152 plane at 1,000ft, piloted by Mr Bahra who was giving a flying lesson to Mr Mundae, a student at Bucks New University.
A warning was issued that airfield air traffic control services would be closed during three 30-minute periods on selected days - this was the result of a staff shortage - and the crash occurred around half-an-hour after the latest closure was due to end.
The Air Accidents Investigation Branch (AAIB) report said: 'The opportunity for the occupants of either aircraft to see the other was limited because, although they were in proximity for some time, they were both following a similar track and were not in each other’s field of view.'
The horrific crash took place over the Waddesdon Estate - the former country seat of the Rothschild banking dynasty.
The inquest in Beaconsfield, Buckinghamshire, heard that both had taken off from Wycombe Air Park, also known as Booker Airfield, about 20 miles away from the crash site.
The coroner ruled their deaths were accidental.
Coroner Crispin Butler told the hearing the helicopter, carrying Mr Green and Mr Nguyen, took off at 11.45am from Wycombe Air Park.
It was followed one minute later by the light aircraft in which Mr Mundae and Mr Bahra were flying, before both aircraft collided around noon.
Giving evidence to the coroner, Home Office forensic pathologist Alexander Kolar told the hearing that all four of the deceased had suffered multiple severe injuries in the crash and offered causes of death of multiple injuries for each.
He told jurors: 'This man (Mr Mundae) has died as a result of multiple injuries, widespread non-survivable blunt force injuries and the injuries he has are very severe - almost extreme force.
'The types of injuries suggest he died extremely rapidly and there was limited bruising. I simply can't see two patterns of injuries across the collision and on impact falling to the ground.'
He offered causes of death of multiple injuries for each victim in the collision and explained the 'unsurvivable' wounds were severe to the point of extreme and noted examination of the brain, heart and other organs had ruled out the potential of natural causes contributing to, or causing, the mid-air collision.
The jury heard a witness, Rupert Hill, was out pigeon shooting at the time
of the collision and described watching a shower of debris plummeting from the sky.
'My attention was drawn to something in the sky but I could see lots of debris falling to the floor and the sound of an engine revving to the max. I would say I was looking at this from one to one-and-a half miles away.
'I decided it was not a helicopter, but the main body of the plane - along with all of this, I saw another aircraft, a helicopter. All of this lasted around 20 to 30 seconds, and I heard the powerful engine noise stop.
'While heading towards the crash scene I got a call from a friend..... I told him what I had seen and he told me to call the emergency services..'
Speaking at the time, Buckingham MP and Speaker of the House Commons, John Bercow, said: 'I'm shocked by the news. It's a very sad day for Buckinghamshire and, of course, it's a very sad day for the casualties of this awful crash and all of their family and loved ones.
'The sense of shock and outrage at what has happened will be very real and we applaud and appreciate the enormous efforts of the emergency services at a time like this.'
Families of each British victim appeared at the inquest.Mr Green was from Newbury, Berks., Mr Mundae from Richmond, Surrey, Mr Bahra from Wembley north London and Mr Nguyen was from Vietnam.
The coroner gave a conclusion of accident for each man's death.
Concluding the inquest, Mr Butler said they died: '... at Wilderness Wood on Waddesdon Manor Estate, due to multiple injuries sustained as a result of a mid-air collision between a Cessna 152 aircraft and a Guimbal Cabri G2 helicopter, followed by a rapid descent through trees, impacting the ground at the above location.'
The mid-air crash happened above the grounds of a manor built for one of the world's richest families - the Rothschilds.
The billionaire banking dynasty owned Waddesdon Manor from when it was built in 1889 until they gifted it to the National Trust in 1957.
The family's banking business was established by Mayer Amschel Rothschild (born in 1744) in Frankfurt in the 1760s.The name Rothschild is derived from the House of the Red Shield ('Rot Schild') which was built by Mayer's ancestors in one of the first Jewish ghettos in the German city in the 16th century.
Through Mayer's five sons - Amschel, Salomon, Nathan, Karl and Jakob - he set up an international banking enterprise with branches in London, Paris, Vienna and Naples, as well as Frankfurt, by the 1820s.
Nathan, in particular, made huge profits via the Napoleonic Wars. He provided financial support to the Duke of Wellington and went on to loan money to English troops fighting Napoleon - netting healthy profits when the debts were repaid.
The family's banking business was established by Mayer Amschel Rothschild in Frankfurt in the 1760s
In the 19th century, the Rothschilds owned the largest private fortune in the world.
The dynasty's wealth today has been divided among various descendants - and, in addition to banking and finance, has its interests in mining, energy, real estate and winemaking.
The Rothschild family is also known for its charitable activities, particularly in the arts and education.
The last time Waddesdon Manor was owned by a member of the family was in 1957, when it belonged to James de Rothschild.
He bequeathed the house and its contents to the National Trust and today it is managed by the Rothschild Foundation chaired by Jacob Rothschild, 4th Baron Rothschild.
Beth Rothschild, Jacob's daughter, still lives on the estate.
Born in 1964, she is a Vice President of the Wiltshire Blind Association, and she is a trustee of the Rothschild Foundation. Beth married Antonio Goffredo Tomassini in 1991.
With 390,000 visitors annually, Waddesdon Manor is one of the Trust's most visited properties.
It has featured in several films and TV shows, including The Queen, which starred Helen Mirren; Downton Abbey, where it stood in for the exterior of the fictional Haxby Park; and The Crown, the biographical TV series about Queen Elizabeth II.
Tags:
mishap