A pilot was communicating by radio with her boyfriend before their planes collided in the air over Alaska last week, killing him, a federal investigator said.



The two pilots took off from different western Alaska villages but met up in the air on the way to Bethel, Alaska, National Transportation Safety Board investigator Clint Johnson told the Anchorage Daily News.



Kristen Sprague, 26, was flying a Cessna 207 operated by rural freight carrier Ryan Air, according to Alaska State Troopers. She made an emergency landing with one airplane wing seriously damaged and wasn't hurt.



The other plane, a Cessna 208 Caravan, crashed and burst into flames near the village of Nightmute, Alaska, about 580 kilometres west of Anchorage, Alaska, killing Scott Veal, 24, of Kenai, Alaska. Each was the only person onboard.



It was the state's third midair crash since July. A federal accident investigator has said two earlier midair collisions were marked by the same factor: aircraft that were difficult to spot amid mountainous terrain.



In last weekend's (NZ time) collision, the two pilots were travelling together to Bethel and were communicating on a prearranged radio frequency while in the air, Johnson said. It's too early in the investigation to say whether pilot error was a factor in the crash, he added.



Sprague had taken off from the Bering Sea village of Tununak, Alaska. She was headed to Bethel with about 25 kilograms of aluminum cans for a recycling program, said Wilfred Ryan, president of Ryan Air.



Veal left from nearby Toksook Bay, Alaska, in an airplane operated by Grant Aviation, an air taxi and cargo carrier. Efforts by the Anchorage Daily News to speak with a Grant representative were unsuccessful.



Sprague, of Idaho, told the investigator she was dating Veal, who reportedly was going through a divorce, Johnson said.



"They meet up in the air," Johnson told the Anchorage Daily News. "There's some manoeuvring that's done en route at about 1200 feet (above sea level). The 207 pilot loses track of where the 208 is."



Sprague remembered saying over the radio something to the effect that she couldn't see him. "The next thing she knows is his airplane strikes her right wing, and nearly severs the right wing," Johnson said.



The bigger plane passed underneath the Cessna 207 and came out on the left side of it, Johnson said. Sprague saw it spiral down, hit the tundra, and burst into flames, Johnson said. She managed to land her plane on soft rolling tundra, about 1.6km away.



Wreckage from the Cessna 208 was strewn over 800 metres or more.



Johnson said investigators still need to review data collected on the Ryan Air plane and that the other plane didn't collect similar data.



Veal was from Southern California and always dreamed of becoming an Alaska bush pilot, his grandfather, Robert Veal, told the Anchorage newspaper. "It's in the family. His father and myself are both flight instructors," the grandfather said by phone from Winchester, California.



In a July 30 midair crash, Corey Carlson, his wife, Hetty, and their two young daughters, all from Anchorage, were killed when their single-engine Cessna 180 floatplane crashed and burned after hitting another floatplane north of that city. The other plane, a Cessna 206, sustained significant damage but was able to return to Anchorage with its pilot uninjured.



On July 10, nine people aboard a Piper Navajo and four people in a Cessna 206 were uninjured when the planes collided as they were flying directly toward each other in Lake Clark Pass - a narrow river valley that runs between Anchorage mountains. Both aircraft had minor damage but were able to land safely.