A police helicopter was "well placed for the pilot to have a clear view" as it filmed a couple having sex in their garden, an aviation expert has told a jury.
Oliver Dismore, who is operations director for the National Police Air Service (NPAS), watched footage shown at Sheffield Crown Court of a couple having sex in a range of positions on their patio shot from the South Yorkshire Police chopper.
Mr Dismore took the jury through the various aerial manoeuvres evident from the filming and told them that when the naked woman first emerged from her home she would have been out of the pilot's line-of-sight.
But, he said, when the couple began to have full sex on the paving slabs, the aircraft was "well placed for the pilot to have a clear view".
He said the helicopter was about 600 feet away at the time and this was "within the pilot's operational range of view".
The expert said there were times during the recording that the aircraft was flying lower than is allowed over the housing estate unless it had a definite policing purpose.
He said the lowest recorded altitude was 162ft over the houses.
Mr Dismore, who flew with the Fleet Air Arm before starting a 20-year career in police aviation, was also asked to comment on footage of a naked woman sunbathing with her bikini-clad daughters in her garden, also shot from the helicopter.
Asked about the view the pilot would have had, compared with the powerful zoom-in image from the camera, he told the jury of six men and six women that the aircraft was around 500 to 900ft away as it circled around them.
"It was certainly see-able by the pilot," he said.
Asked by Richard Wright QC if the pilot would have been able to see the people on the ground, he said: "Certainly visible from that height."
Mr Dismore was asked to comment on the pilot's awareness of a target he is circling.
He said: "A pilot has to know what he's orbiting round in order to carry out an orbit of that type."
Mr Dismore also told the jury that, in 2015, the average cost of a call-out for a police helicopter was £1,368 - not including the outlay cost of the aircraft and other infrastructure. He said other research had put the variable costs of police helicopter use as 981.45 US dollars (£753.19) per hour in 2011.
He was giving evidence at the beginning of the second week of the trial of two police officers and two pilots accused of misusing the helicopter to film naked people and the couple having sex, between 2007 and 2012.
One former police officer - Adrian Pogmore, 51, - has admitted charges of misconduct in a public office but Matthew Lucas, 42, Lee Walls, 47, Matthew Loosemore, 45, and Malcolm Reeves, 64, all deny the same charge.
All four defendants on trial say it was Pogmore to blame for all four pieces of footage shown to the jury and to Mr Dismore.
The jury has heard how the couple filmed having sex were friends of Pogmore, who knew them through the swinging scene.
Pogmore, of Guilthwaite Crescent, Whiston, Rotherham, has been described by prosecutors as "a swinging and sex-obsessed air observer".
He has admitted four charges of misconduct in a public office.
Reeves, of Farfield Avenue, Knaresborough, North Yorkshire, denies two counts of the same charge.
Walls, of Southlands Way, Aston, Sheffield, denies one count.
Loosemore, of Briar Close, Auckley, Doncaster, denies one count.
Lucas, of Coppice Rise, Chapeltown, Sheffield, denies three counts.
Under cross-examination, Mr Dismore said it would be "a stretch" to suggest that the pilot - Loosemore - would not have seen what the couple were doing.
Neil Fitzgibbon, defending Loosemore, asked him: "Is it possible that Matthew Loosemore would not have seen the couple that we have seen on the patio performing as they have done?"
Mr Dismore replied: "It is possible. But it would be a stretch."
He said it would assume that Loosemore "would have been acting differently on this occasion than his normally recorded performance".
Mr Dismore said: "It would have taken multiple, coincidental possibilities for Matthew Loosemore not to have seen what we have seen on the video."
Asked again by Mr Fitzgibbon if he knew whether Loosemore saw the couple, he said: "I don't. Only he does."
The trial was adjourned until Tuesday.