WASHINGTON — Pilots around the United States have reported a surge in near-collisions and other dangerous encounters with small drones in the past six months at a time when the Federal Aviation Administration is gradually opening the nation’s skies to remotely controlled aircraft, according to FAA records.

Since June 1, commercial airlines, private pilots and air-traffic controllers have alerted the FAA about at least 25 episodes in which small drones came within a few seconds or a few feet of crashing into much larger aircraft, the records show. Many of the close calls occurred during takeoffs and landings at the nation’s busiest airports, presenting a new threat to aviation safety after decades of steady improvement in air travel.

Many of the previously unreported incident reports – released Wednesday by the FAA in response to long-standing public-records requests from The Washington Post and other news organizations – occurred near New York and Washington.

The FAA data indicates that drones are posing a much greater hazard to air traffic than previously recognized.

Until Wednesday, the FAA had publicly disclosed only one other near-midair collision between a drone and a passenger aircraft – a March 22 encounter between a US Airways plane near Tallahassee, Florida, and what the pilot described as a small, remotely piloted aircraft at an altitude of 2,300 feet.

The 25 near-midair collisions were among more than 175 incidents in which pilots and air-traffic controllers reported seeing drones near airports or in restricted airspace. Pilots described most of the rogue drones as small camera-equipped models that are popular with hobbyists and photographers.