The B-52 Stratofortress that crashed yesterday, killing all eight onboard, was testing the Radar Modernization Program upgrades, Air Force officials said.

The cause of the “unsurvivable” crash at Edwards Air Force Base, CA, is under investigation, which could take several months, 412th Test Wing Deputy Commander Col. James Hayes said in a press conference yesterday.

“Right now, we’re going to set up an interim safety board to do the initial gathering of facts, and that will then lead to a safety investigation board, which will look into those root causes,” he said. “Once that is complete, it takes about 30 days, then it’ll go into an accident investigation board, and then that will determine all of the information that we can release to the public and to the next of kin. That process can take upwards of six months.”

The B-52 crashed immediately after takeoff at about 11:20 a.m. Pacific time and “burst into flames,” Hayes said.

Those onboard were military, government civilian and civilian contractors, Hayes said.

Next of kin was in the process of being notified yesterday, Hayes said during the press conference at about 4 p.m. Pacific time.

“We wish absolute condolences for the family members and again thank our first responders, who responded very bravely,” Chief Master Sgt. Joshua Skarloken said at the conference.

RMP, along with the Commercial Engine Replacement Program, are efforts to upgrade the decades-old B-52s to be used into the 2050s as a long-range standoff bomber. The first test aircraft for RMP was delivered to Edwards AFB in December.