US authorities are investigating a near collision between an Alaska Airlines jetliner and a turboprop cargo aircraft near Ted Stevens Anchorage International airport on 27 May.
The National Transportation Safety Board (NTSB) calls the event "a near midair collision", saying the aircraft passed roughly one-quarter mile from each other at the same altitude of 1400ft (427m).
According to information from Alaska and the NTSB, the incident occurred as an Alaska Boeing 737-400 operating flight 135 from Portland was on final approach to Anchorage's Runway 15.
The 737 carried 143 passengers and five crew, Alaska tells Flightglobal.
At the same time, air traffic control cleared a Beech 1900 operated by Anchorage-based Ace Air Cargo for takeoff on the same runway
As the Beech 1900 began rolling, the controller "realised there was not going to be sufficient separation" between the aircraft and directed the 737 to go-around and fly a heading of 220 degrees, says the NTSB.
Meanwhile, the Beech 1900 took off and turned to a heading of 250 degrees, the standard departure procedure for the airport.
As a result, both aircraft turned to a similar heading and passed "fairly close" at a distance of "some miles" from the airport, says the NTSB.
The agency adds that the pilots of each aircraft saw the other aircraft and were able to avoid collision.
Alaska adds that the 737's traffic collision avoidance system (TCAS) "alerted the crew of the proximity of the other aircraft, which prompted the pilots to increase their altitude."
"Our pilots are highly trained and skilled at responding to situations like this and are to be commended for their handling of the situation," says the airline in a statement.
Alaska adds that the aircraft later landed safely at Anchorage and that the company is cooperating with an NTSB investigation.
The US Federal Aviation Administration (FAA) also says it is investigating and will review the aircraft's separation.
"A go-around is a safety tool that controllers and pilots use to keep aircraft separated around airports," the agency says.
Ace Air Cargo did not immediately respond to a request for information.