CARLSBAD -- Federal investigators found a cockpit voice recorder Wednesday with a tape that might have survived the fiery plane crash that killed four people at McClellan-Palomar Airport.

"It appeared to be in good shape," Kurt Anderson, investigator in charge of the National Transportation Safety Board probe, told reporters near the crash site at the north end of Palomar Oaks Way in Carlsbad's business park.

However, despite a lot of recovered material, data and witness information, Anderson said it may be four to six months before an investigation report sheds light on what was happening when the twin-engine Cessna Citation jet from Idaho overshot Runway 24 and crashed Tuesday morning.

"This is a very slow and deliberate step-by-step process," Anderson said, adding that "at this point, we're nowhere near any significant conclusions."

Witnesses reported, he said, that the privately owned business plane touched down about halfway down Runway 24 before smashing through navigation equipment at the end of the runway, cresting a hillside embankment, slamming into a ministorage building and erupting in a fireball.

As relatives of the victims arrived at the crash site Wednesday, Anderson tried to get them as close to the scene as possible for a final look. Parts of the wreckage are to be removed today.

Among the questions remaining after Anderson's briefing were how fast the plane was going, why the landing gear was down and why the thrust reversers, that help slow the plane for a landing, weren't down.

"At this point, it's just a fact," Anderson said about the thrust reversers. "If he was going to go around, he would stow them (put them away)."

In interviews, pilots who use the airport at 2198 Palomar Airport Road said that the 4,600-foot runway, that has another 300 feet for safety, isn't that long.

"It's pretty short, realistically, for midsize and heavier-class jets," said Dave Williams of Salt Lake City, a corporate pilot. "It shouldn't be a problem for a Citation."

A selling point of the Citations, said the 40-year pilot, is that they can land in shorter distances and be used on shorter runways.

"They're a good airplane," Williams said. "They're safe, dependable, and you can get them in and out of tight places. But if he had it halfway down the runway, he would have been hard-pressed to get it stopped."

Investigators were just starting to get information about the pilot and co-pilot, but Anderson confirmed that they were Idaho residents John C. Francis of Boise and Anthony A. Garrett of the Hailey, Idaho, area.

Sun Valley Aviation in Hailey, where the plane took off two hours before the crash, has identified the passengers as Janet Shafran of Ketchum, Idaho, and Frank Jellinek Jr. of Rye, N.H. Jellinek's family lives in La Jolla.

Still to be analyzed are the plane's voice recorder (also called a "black box"), radar data on the plane's approach, and videotape from airport security cameras, Anderson said. He also said witnesses have to be reinterviewed to confirm their statements.

"I have not seen anything indicating that the crew made any statement indicating they were having any problem," Anderson said at the briefing.

He noted that there didn't appear to be anything abnormal about the plane's engines, which also still have to be fully examined.

The possibility of wind shear during the accident on a clear sunny morning with light, variable winds will also be investigated, Anderson said.

Although the Carlsbad airport control tower is closed between 10 p.m. and 7 a.m. daily, the airport is open around the clock.

It has a navigational instrument for planes to home in on when they approach the airport and an instrument landing system as well, said Mike Fergus, FAA spokesman in Renton, Wash.

"Radar does guide them down to a certain point … and then the pilot just merely takes over on the instrument landing system," Fergus said.

There is good audiotape of what was said between the regional approach controller and the pilot, and also of what was being said on the radio frequency used by pilots in the area as the plane came into the airport, Anderson said.

"Even though the tower was not open, the pilots at this airport were transmitting what they were doing, so any other pilots would have heard that," he said.

The FAA determines the tower's operation hours at the airport, which is owned by San Diego County. Fergus said the agency determines hours of operation by such things as an air traffic survey.

The county's most recent available traffic operations count for the Carlsbad airport was 207,956 takeoffs and landings in 2004, down from 255,104 in 2000. The airport is used by two commuter airlines, and businesses and professional sports teams, among others.

Fergus said the NTSB would also determine whether there is any connection between the Carlsbad's tower operating hours and Tuesday's crash, 20 minutes before the tower opened.

Witnesses who would like to give additional information to the NTSB can call an American Red Cross number at (800) 951-6601.

Contact staff writer Jo Moreland at jmoreland@nctimes.com or (760) 740-3524. To comment, go to nctimes.com.