The helicopter pilot who was one of four people killed in a mid-air crash with a light aircraft has been named as Captain Mike Green.
Mr Green, who is understood to have been in his sixties, was a senior instructor with Helicopter Services, based at Wycombe Air Field.
Helicopter Services said on Facebook: "We are devastated to confirm that Captain Mike Green was involved in the mid-air collision which occurred yesterday.
"Mike was conducting a flight instructor course and was with a student at the time of the incident. Both pilots lost their lives."
Captain Phil Croucher, who served in the army with Mr Green, said his death in the mid-air crash was a "sad loss".
"We have lost somebody with a vast amount of experience that could have been passed on to younger people, apart from him being a nice guy generally," Mr Croucher was quoted by the Press Association as saying.
"He's gone through no fault of his own and everyone's lost a good friend and mentor."
The families of all four of those killed, all of whom were men, have been informed, police said, and family members have visited the site of the wreckage.
"All the families have now been informed and are being supported by officers in the family liaison arena," Superintendent Rebecca Mears of Thames Valley Police told reporters.
"Three of the families have visited the site today with our support so they can understand a little bit more about what's happened to their loved ones."
Police believe the crash victims were three Britons and one Vietnamese national.
Police and air accident investigators are continuing the hunt for clues as to why the helicopter and two-seater plane collided over Buckinghamshire.
Superintendent Mears said crash investigators were expected to remain on the scene.
"We remain on site today so that we work with the air accident branch and a number of other experts from the fire service and the military with a view to using their expert services to recover the men's bodies, hopefully before the end of the day."
The collision occurred at 12.06pm on Friday. The aircraft are believed to have come from the Wycombe Air Park, which is about 20 miles from the crash site.
Emergency services were called to the scene near the village of Waddesdon, which is home to Waddesdon Manor, an estate managed by the Rothschild Foundation, a family charitable trust.
Waddesdon Manor said in a statement: "Lord Rothschild and his family extend their condolences to the families of all affected, and their thanks to the emergency services for their swift response and professionalism."