In its second flight test, the Defense Advanced Research Projects Agency’s (DARPA) fastest (13,000 mph) aircraft ever built, the Falcon Hypersonic Technology Vehicle 2 (HTV-2), was successfully inserted into the desired trajectory at near-orbital speed, but the flight  ended in loss of signal (and control) when the aircraft transitioned to Mach 20 (about 13,000 mph) aerodynamic flight around nine minutes into the flight, DARPA announced Thursday.

Initial indications are that the aircraft impacted the Pacific Ocean along the planned flight path. DARPA is setting up an independent engineering review board to investigate the loss.

The HTV-2 is part of future Conventional Prompt Global Strike programs intended to reach anywhere in the world in less than one hour.