Federal aviation safety officials are investigating why two small commercial airplanes flew extremely close to each other earlier this week near Fairbanks International Airport.

One plane basically had to dive to avoid a collision Tuesday, National Transportation Safety Board investigator Clint Johnson said. His agency plans to send investigators to Fairbanks next week.

"This is an extremely close call," he told the Anchorage Daily News on Friday.

Johnson cautioned that his information was preliminary, but he told The Associated Press that the pilot of a twin-engine Beechcraft 1900 operated by Warbelow's Air Ventures told his management the planes were within 150 vertical feet of each other.

The Federal Aviation Administration is also investigating, spokesman Ian Gregor said in a statement.

"It is too early to determine the exact distance between the two aircraft," Gregor said.

An Era Alaska PA-31 Navajo was taking off as the Beechcraft 1900 was approaching for a landing, Johnson said. He says the Navajo passed over the top of the Beechcraft, with the unidentified Beechcraft pilot pushing down the nose of his aircraft in an evasive maneuver.

No one was injured.

The Beechcraft carried "fewer than six passengers" and a cockpit crew of two, Warbelow's operations director Mike Morgan said Friday.

Era Alaska did not immediately return a call asking how many were aboard its twin-engine plane, but that aircraft can typically carry up to eight people, including crew.

Two air traffic control experts will fly to Fairbanks from Washington, D.C., and will be joined there by an Anchorage investigator, Johnson said. They'll review audio recordings between the tower and the planes, check radar data and conduct interviews.

An NTSB determination about what happened may be available by late next week, he said.