( dpa ) - An Australian-registered plane that disrupted commercial traffic by causing a shutdown of Singapore's airspace was on a test flight and expected to return to Thailand's Koh Samui island, authorities said on Saturday.
More details have been unveiled about the Cessna 208 Caravan float plane that approached Tuesday night without an approved flight plan, prompting two Air Force F16 fighter jets to scramble during Changi Airport's busiest hours.
The flight with two Australians aboard was supposed to last 50 minutes. It "went off the air" two-and-a-half hours later, despite repeated calls by air-traffic controllers at Koh Samui Airport, The Straits Times said.
The 50-minute lockdown of Singapore's airspace ended at 8 pm.
The plane was registered to Mary Cummins on January 8, the report said. She and business partner Rhys Thomas co-own Kimberley Extreme, an adventure tourism company based in the Australian town of Broome.
Thomas, a pilot who used to fly with the now-defunct Ansett airline, was reported to have been one of the Cessna's pilots.
Police have been questioning the two Australians. The duo have not been charged and are not in custody, but their passports have been impounded, the newspaper said.
The plane previously carried Thai registration and was used by the Coco Seaplanes Company, believed to be defunct.
Sixteen flights were forced to circle while the drama unfolded.
The air force tracked the plane as it flew toward the city-state. The two missile-armed fighters intercepted the Caravan and signalled the Australians to land at the central runway at 8 pm.
The shutdown of commercial airspace affected 23 aircraft, disrupting flights in and out of Changi.