A Lockheed Stalker XE Unmanned Aerial System aircraft crashed as it was attempting to land after completing a mission to detect heat and map the perimeters of wildfires in southwest New Mexico.
It occurred August 7, 2019 about 26 miles west-northwest of Truth or Consequences, New Mexico.
The cause, according to a brief preliminary report, was an incorrect altitude of the landing area obtained from “a new GPS out of the box.”
Below is an excerpt from the report about the accident:
“The Type 2 UAS was ordered for a number of fires in and around the XXX Wilderness on the XXX of the XXX National Forest. The mission was to detect any heat remaining on the fires, map their perimeters, and provide imagery to local fire managers. The day before the mishap, a flight was conducted on a fire that went smoothly. On the second day, a similar mission was planned over a different fire. A thorough safety and operational briefing took place prior to launch with all members of the mission. The only difference in this mission and the previous day’s was the location of the fire and the placement of the launch area. The UAS flew over the fire for just over an hour collecting data before the Pilot in Charge (PIC) began the procedures for landing.
“On final and while flying on an automated flight plan, the UAS aggressively changed its angle of attack and pitched down. The UAS impacted the ground at this angle one-quarter of a mile from the intended landing zone. The fuselage, leading edges of the wings, and tail boom all sustained significant damage leading to the aircraft being deemed not airworthy. The angle of attack change is normal for this aircraft on approach to its landing zone.
“The crash was due to an incorrect input into the Ground Control Station (GCS) of the landing zone elevation. This elevation was gained from a new GPS out of the box. The input into the GCS was 5915 and the actual elevation of the landing zone is 6280. This incorrect input made the aircraft believe that it was over 300 feet higher and continue with this angle of attack prior to leveling off for landing.”
The Lockheed XE was first introduced in 2006. The latest models can fly up to eight hours with a propane fuel cell or up to four hours with a battery option at a cruise speed of 35 mph. It can be launched with a bungee cord, a catapult, or by using a recently developed optional vertical takeoff and landing kit.
In 2015 Lockheed demonstrated how the Stalker XE can provide data and a precise geolocation to an unmanned K-MAX cargo helicopter, which conducted water drops to slow the spread of a fire.