• A United Airlines crew reported a near-collision with a drone over California on Wednesday.
• ATC tapes reveal the pilot said the drone was at 3,000 feet and “red” and “shiny.”
• Regulators have strict rules for flying UAVs around airports, as an incident could be catastrophic.

The pilots of a United Airlines Boeing 737 on Wednesday reported a near-collision with a drone during approach into San Diego, the airline confirmed to Business Insider.

The plane departed San Francisco around 7 a.m. local time, carrying 48 passengers and 6 crew members. It landed in San Diego about an hour and a half later, where United said customers deplaned normally at the gate.

It added that its maintenance team “thoroughly” inspected the aircraft but found “no damage.”

It’s unclear if the sighted drone actually collided or just came dangerously close.

According to air traffic control tapes analyzed by Business Insider, the United pilot said the suspected drone was at about 3,000 feet during the plane’s “base leg” — the jet’s last descent step before final approach, when it flies perpendicular to the runway as it lines up.

He described the possible drone as “red” and “shiny,” adding that it was “really small” but couldn’t provide further details.

The Federal Aviation Administration told Business Insider that “air traffic control alerted other pilots but did not receive any additional drone-sighting reports.”

The risk of drones hitting commercial airliners is not new, but may be on the rise as hobby drones grow in popularity. Data from an aviation safety database reviewed by Business Insider shows hundreds of drone sightings and near-miss reports with commercial airlines over the years.

Drone users are often hobbyists who don’t need a formal license. Regulators have strict rules for flying UAVs around airports, as an incident could be catastrophic if one were to hit an engine or another critical flight control, especially close to the ground.

Anyone — recreational or commercial — who wants to operate in controlled airspace, such as San Diego, must obtain FAA authorization to fly, which will include altitude restrictions.

Those flying in uncontrolled airspace — think tiny rural airports, often with only general aviation traffic and few, if any, airliners — do not require prior authorization, but they must keep their drones under 400 feet and not interfere with flight operations.

The FAA also requires most drones to use “Remote ID,” which broadcasts the drone’s identity and location — like a digital license plate — to improve airspace safety and accountability.