The head of Sussex police has said he is absolutely certain a drone was flown over Gatwick airport, admitting that contradictory statements from other officers at his force “amplified the chaos” caused by the incident.

Giles York, the Sussex police chief constable, also defended the decision to arrest a couple who were detained for 36 hours before being released without charge, and apologised for the distress caused to them.

Sussex police were criticised for their handling of a suspected drone operation that brought the UK’s second-largest airport to a standstill when DCS Jason Tingley said there may never had been any drones.

York told BBC Radio 4’s Today programme: “I am absolutely certain a drone was flying throughout the period the airport was closed.”

He said the officer who suggested otherwise “was trying to describe an investigative approach, that asks: ‘How can we prove the presence of the drone in the first place?’”

He was then asked whether that uncertainty “amplified the chaos” surrounding the incident. “Certainly that was amplified at the time, but we have been able to corroborate 115 reports [since then], 92 of them are from credible people,” he said.

“Of course, we will have launched our own Sussex police drones at the time with a view to investigate, with a view to engage, with a view to survey the area looking for the drone, so there could be some level of confusion there.”

York was also asked about the arrest of Paul Gait and Elaine Kirk, who were released without charge. The couple have said they felt “completely violated” by the way they were treated, adding that their privacy and identity had been “completely exposed” after being named in the media and having their home searched.

“I am really sorry for what he [Gait] went through but the reason we held him was so that we could dispel everything in the first instance. What might have been worse as an experience from him would be to be released under investigation,” York said.

Sussex police held Gait, 47, and Kirk, 54, for 36 hours of questioning over the chaos at Gatwick, but a phone call to Gait’s employer would have provided an alibi.

York said. “It’s never quite that simple when you are in the middle of something … that may bear on the hypothesis that there is only one person involved if you think one simple phone call to one single alibi is able to dispel such a complex investigation.”

Military technology had been deployed at the airport, York said, although he did not say whether the system should have been in place earlier. “I am grateful to ministers for support throughout,” he said.

York said he could not rule out a drone incident happening again, but that the main priority was to make sure planes were safe to take off.

He said officers had searched 26 potential launch sites near Gatwick but did not believe they had found the drone believed to have been flown near the airport’s runways on 19 and 20 December.