(CNN)Drone sightings, alongside weather conditions, delayed 18 flights and forced a further seven to be diverted at Singapore's Changi Airport Monday evening, according to the country's Civil Aviation Authority.
Drones delay flights at Singapore's Changi Airport for second time in a week
The incident was the second in a week: on the night of June 18, drone sightings delayed about 37 flights and caused one diversion.
Monday's delays, affecting 15 departing flights and three arrivals, were the result of "bad weather and unauthorised drone activities," the Civil Aviation Authority of Singapore (CAAS) said in a statement. Flights were "carefully regulated" as a "precautionary measure" for about an hour, it added.
The June 18 drone sightings forced the closure of one of the airport's two runways for "short periods of time" from 11 p.m. to 9 a.m. the following morning, CAAS said. A multi-agency team including the Singapore Armed Forces and Singapore Police Force was deployed for a search and locate operation.
Investigations into both incidents are ongoing, the aviation authority said, and the culprits could be face up to 12 months in prison, a fine up to $20,000, or both.
"Members of the public are reminded that the authorities take a serious view of errant operations of unmanned aircraft which may pose threats to aviation or endanger the personal safety of others," CAAS warned.
Singapore law prohibits the flying of drones within 5 kilometers (3.1 miles) of an airport without a permit.
In December, London's Gatwick Airport suffered 36 hours of disruption after drone sightings. 1,000 flights were canceled, impacting the travel plans of over 140,000 passengers.
In 2019, drone sightings have disrupted flights at London's Heathrow Airport, New Jersey's Newark Liberty International Airport, Dubai's International Airport and Dublin Airport.