Two inexperienced F-15C Eagle pilots made errors that caused a fatal mid-air collision during a combat training mission over the Gulf of Mexico, Air Force investigators concluded in a report released Monday.

Both pilots misjudged how close they were to each other and had less than two seconds to react before Capt. Tucker Hamilton's wing sliced into 1st Lt. Ali Jivanjee's cockpit in the Feb. 20 accident, investigators said.

"The cause of this mishap was pilot error. Both men failed to clear their flight paths and did not recognize their impending high-aspect, mid-air collision," said Brig. Gen. Joseph Reynes, the head of the seven-member Air Force Accident Investigation Board.

Jivanjee, 26, of San Dimas, Calif., died instantly. Hamilton, who is now assigned to a non-flying position in Germany, ejected with minor injuries.

The single-seat fighter planes were destroyed — an $83 million loss for the Air Force.

Both men had excellent qualifications and flying records, Reynes said.

"They were doing maneuvers we do every day thousands of times in all of our air combat command flying aircraft," he said.

The report said both pilots did not have enough time flying the F-15 to be experienced in the aircraft. Jivanjee had fewer than 120 hours of flight time in the aircraft and Hamilton had flown it just under the required 500 hours, the report said.

The report noted Jivanjee passed too close to another jet in a training flight the day before the collision, an incident that wasn't reported to commanders.

"It was a different set of circumstances, but it opens the question of whether Jivanjee totally understood those closure moments," Reynes said, referring to the final moments when the planes passed each other.

Investigators said they found no mechanical or structural problems in the two, nearly 30-year-old fighter jets, which were part of the Air Force's aging and problem-plagued F-15 fleet. The 1979 and 1981 F-15s flown by the two Eglin Air Force Base pilots were in good condition, Reynes said.

The Air Force largely grounded its F-15 fleet from Nov. 3, 2007, to Jan. 10 after an F-15 broke apart in mid-air over Missouri. An investigation found that 160 of the Air Force's nearly 700 F-15s had defects. Last month, another F-15 crashed and killed one pilot during a training mission over the Nevada desert.

The two pilots missed critical training flights in the two months the fleet was grounded, yet the investigative board could not conclude the missed training led to the crash because both met all the qualifications to fly, Reynes said.

"They were both competent and proficient. Were they has proficient as they could have been had we kept flying for the last three months? I cannot answer that, but it does pull at your heart and your mind," he said.