An anomalous self-check of the navigation computers onboard an X-47B was behind the U.S. Navy’s decision to abort the third arrested landing attempt of the Unmanned Combat Air System onboard the USS George HW Bush July 10.
The anomaly was detected in one of three, redundant navigation computers onboard the X-47B. The aircraft routinely and repeatedly does self-checks of its navigation system during flight. Once the problem was detected, the X-47 followed its pre-programmed software for such a scenario and signaled a wave off from the landing, climbed in altitude and began a holding pattern to await instructions from the ship-based mission operator.
It was a human that made the ultimate decision to divert the X-47B to Wallops Island Air Field, the pre-programmed back-up, ashore landing site.
“We had decided that we’d run enough for the day,” says Navy Capt. Jaime Engdhal, program manager for the $1.4 billion Unmanned Combat Air System demonstration project.
The aircraft – X-47B No. 2, designated Salty Dog 502 – landed without incident at Wallops.
Program officials at the Navy and Northrop Grumman point to the event as an example not of a failed landing, but of a successful run-through of the pre-programmed software and algorithms designed to prepare the X-47B to respond to various scenarios that can happen on a mission.
Read our article on the automatic wave-off: Third UCAS Carrier Landing Attempt Diverted Ashore
July 15 is the next scheduled at-sea day for UCAS landing trials. Either of the two demonstrators is suitable to conduct the testing.