Some 37 scheduled flight departures and arrivals were delayed for short periods between 11pm on June 18 and 9am on June 19 — all due to sightings of unauthorised drones in the vicinity of Changi Airport.
One additional flight was diverted to land at Kuala Lumpur airport.
Drones in Singapore are prohibited from flying within 5km of an airport without a permit.
In a statement posted to Facebook, the Civil Aviation Authority of Singapore (CAAS) said one runway was suspended after the sightings were confirmed, in order to ensure the safety of passengers and aircraft operations.
That left the airport with just one operational runway.
As a result, about 37 scheduled departure and arrival flights were delayed. Although CNA placed the number at 38.
A multi-agency team comprising CAAS, the Changi Airport Group, the Singapore Armed Forces and the Singapore Police Force was activated to locate the drones.
Investigations are ongoing.
CAAS said the authorities take a serious view of errant operations of unmanned aircraft, which may pose threats to aviation and endanger the personal safety of others, and will not hesitate to take enforcement action against those who contravene regulations.
Offenders can face a jail term of up to 12 months, a fine not exceeding S$20,000, or both.
Top photo via MINDEF Facebook post and Changi Airport Facebook page