MANILA, Philippines—A veteran of relief missions, the pilot of an Air Force C-130 cargo plane that crashed into the Davao Gulf chose to stay in the military service "to save lives," instead of transferring to the more lucrative commercial airlines, Defense Secretary Gilberto Teodoro Jr. said Thursday.

The pilot, Major Manuel Zambrano, who remained missing three days after the crash, was Teodoro's student in the Air Force Squadron Officers' Course.

Teodoro conceded that the chance for survivors was "very narrow." Search teams only found body parts and debris. There was no trace of survivors or the fuselage of the aircraft, though sonar pointed to its possible location 800 feet below the surface.

"It's quite sad form me, particularly with Major Zambrano… If you remember the mission to Brorongan, where we brought relief goods for the first time, Zambrano was the one who flew it. He was always smiling, very bubbly," Teodoro told reporters in Camp Aguinaldo.

Teodoro recalled an article on the Philippine Daily Inquirer (parent company of INQUIRER.net), wherein Zambrano explained why he was staying in the military service despite the relatively lower pay.

"He said that he opted to stay in the Philippine Air Force than join the airlines because here he was saving lives. That was his character," Teodoro said.

Among Zambrano's recent missions was the relief efforts for victims of Typhoon "Frank" (international codename: Fengshen) in June, and the transport of the country's humanitarian mission to cyclone-ravaged Myanmar in May.