The military is now looking at a possible "plane error" on the first friendly fire that took place May 31 which left at least 10 soldiers fighting in Marawi City dead.
Lt. Col. Jo-ar Herrera, spokesman of Joint Task Force Marawi said the Armed Forces of the Philippines board of inquiry have already come up with their results but further investigation needs to be conducted.
"The results were further forwarded to the major services, which is Philippine Air Force, to conduct in-depth investigation pertaining to the technical aspect of the aircraft," Herrera said Thursday.
Ten soldiers were killed and 8 others were wounded unintentionally in air strikes launched by government forces last May 31.
Herrera said additional investigation was also conducted on a possible error in troop deployment and movement on the ground.
"The results were also forwarded to the Philippine Army pertaining to tactics, techniques, and procedures of the troops on the ground," he said.
On Wednesday, two soldiers died in another friendly fire while 11 others were left wounded.
Last June 4, an airstrike also accidentally hit Barangay Pugaan Ditsaan Ramain, a town outside of the battle area and way outside Marawi City.
Despite incurring fatalities among its own men, the military will continue conducting air strikes in Marawi City.
Joint Task Force Marawi said their enemy has been reduced to 70 but still holding fortified positions.
"They are still occupying major strongholds and fortified defense positions. Ito ang dahilan kung bakit kailangan gamitan ng surgical airstrike," Herrera said.
"According to the ground commander ang sabi nya we will still use the FA50 as long as yung target isang strategic target that will take down our local terrorist group," he added.
Brig. Gen, Ramiro Rey, head of Joint Task Group Ranao said soldiers still have high confidence in the conduct of air strikes amid deaths.
"Yung confidence ng tropa regarding airstrike mataas pa rin, hindi sila na low morale," he said.