Drone sighting disrupts major US airport
Flights were grounded at Newark International Airport in the US state of New Jersey after two drones were spotted flying nearby.
A pilot told air traffic control that one of the drones came within 30ft (9m) of his aircraft.
He was flying at Teterboro Airport, a nearby private facility, but officials closed Newark International as a precaution.
The airport is the 11th busiest in the US, with 20m boarding there each year.
The incident follows major disruption over the Christmas period at London’s Gatwick airport, where apparent drone sightings grounded hundreds of flights over the course of three days.
Speaking about Tuesday's drone scare in New Jersey, the Federal Aviation Administration (FAA) said in a statement: "At approximately 5pm, we received two reports from incoming flights into Newark that a drone was sighted at about 3,500ft above Teterboro, New Jersey.
“At that point, flights arriving into Newark were held for a short duration. Since then, and with no further drone sightings, arrivals have been resumed.
“However, we still have a ground stop in place at other airports departing for Newark until a backlog of arrivals can be cleared. We expect that to be lifted soon."
United Airlines. which uses Newark as a hub, said: "The impact to our operations has been minimal so far. We are working closely with the airport and the FAA to return our operations to normal as quickly as possible."
Drones have become a considerable menace for the aviation industry.
Earlier this month, London's Heathrow airport, the country's busiest, held flights for about an hour after a sighting - but was soon operating as normal.
Gatwick, however, was far hit far worse. It grounded flights between 19-21 December, affecting the travel of an estimated 140,000 people.
Two people were arrested over the attack but released without charge. No other arrests have been made.
This latest incident, which the FAA said is now being investigated by police, will energise calls to develop and deploy technologies to block drone activity in the vicinity of airports.
The chief executive of easyJet, Johan Lundgren, said recent incidents were a "wake-up call".
Police and airport staff at Gatwick will later this year take part in drills in the hope of being better prepared should there be another drone sighting.
Last week, the British government announced measures to give police extra powers to combat drones, including extending the exclusion zone around airports to a 3 mile (5km) radius. Ministers also announced that from 30 November, operators of drones weighing between 250g and 20kg will be required to register and take an online drone pilot competency test.
In the US, a drone registry is already in place, with more than 1.3m crafts registered by around 116,000 licensed operators.
However, officials have said they suspect there may be hundreds of thousands of drones that have not been registered by their owners.