Air safety investigators will study radar tapes to determine why two small planes collided in sunny, clear conditions over the Everglades on Saturday, killing four.

Both planes had been on training missions and that could be a major factor in the accident, aviation experts said.

“Even in good visibility, pilots have to look out for one another,” Robert Breiling, an aviation accident analyst based in Boca Raton, said Monday.It was South Florida’s deadliest in-flight accident since June 2003, when five people died in a collision between two small planes over Deerfield Beach, and the fifth one in-flight in the past eight years.

The dead included flight instructor Stuart Brown, 25, of Pembroke Pines, and student Edson Jefferson, 30, of Miramar. They were in a Cessna 172 operated by Pelican Flight Training, a flight school at North Perry Airport in Pembroke Pines.

Also killed were flight instructor Andrew Rossignol, 21, of Stuart, and student Bryan Sax, 37, of Aspen, Colo. They were flying a twin-engine Piper operated by ATP Flight School at Fort Lauderdale-Hollywood International Airport.

Eric Alleyne, a National Transportation Safety Board air safety investigator, said the two planes were found about 300 yards apart in a marshy area in far west Broward County. The bodies of the victims were found in the cockpits, he said.

On Monday, a salvage company hauled pieces of wreckage from the swamp to land via airboat.

Alleyne said investigators will examine all aspects of the accident, from the mechanical condition of the planes to the weather. The radar tapes likely will provide the most crucial evidence, as they should show the paths of the two planes before the accident. They also should reveal the specific angle they merged.

Both planes had taken off from their respective airports at about 3:30 p.m. and apparently headed toward a flight training area west of U.S. 27. The exact time of the accident wasn’t immediately known, Alleyne said.

Both aircraft were operating under visual flight rules, meaning it was the pilots’ responsibility to see and avoid each other. The visibility in that area that afternoon was “likely better than 10 miles,” said meteorologist Roberto Garcia of the National Weather Service in Miami.

Because planes were on training flights, it’s possible the pilots were distracted, Breiling said.

On board the Cessna 172, Brown was helping Jefferson prepare to take his instrument rating flight test. When students fly on instruments, they concentrate on the instrument panel and frequently wear a hood to prevent them from looking outside.

“Even if he’s not under the hood, even in clear weather, he’s looking at his instruments,” Breiling said. “That puts the burden on the flight instructor; the flight instructor should be looking out.”

The other plane was a more complex twin-engine aircraft, which requires attention inside the cockpit whenever pilots perform maneuvers, Breiling said.

Another possible factor: A late afternoon sun might have created vision problems.

“The glare could very well be a contributing in factor,” Breiling said. “When you look into sun, it can be very difficult to see another airplane.”

Yet another possible factor: The Cessna’s wing was above the cockpit while the Piper’s wing was below. That would make it difficult for the pilots to see each other if the Piper was above the Cessna.

Meg Fensome, vice president of Pelican Flight Training, said Brown, the flight instructor in the Cessna, was from Jamaica and hoped to fly for Air Jamaica.

“He was a very professional instructor and one of our favorite people,” she said.

Jefferson also was from Jamaica, Fensome said.

“He was just in the final steps of preparing for his check ride, which is when he gets together with an FAA-designated examiner,” she said.

Sax, the student in the Piper, was undergoing advance training and a business partner in a flight school, according to the Vail Daily. He also was a bartender in Aspen, the co-owner of Saxy’s Cafe in Basalt and Boulder and at one time was a national ski racing champion, the paper said.

Rossignol, the flight instructor in the Piper, had been flying since he was 17 years old and hoped to land an airline job, said his brother, Matt Rossignol, 23, of Biddeford, Maine. He said their father, Richard Rossignol, is a Continental Airlines pilot.

“He loved flying because my father’s a pilot,” Matt Rossignol said of his brother. “He wanted to become a commercial airline pilot and sit next to my dad, as co-pilot.”