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Report into F-16 crash cites spatial disorientation by pilot

An F-16 Fighting Falcon rolls along a taxiway at night at Aviano Air Base in this file photograph.

KAISERSLAUTERN, Germany — An Air Force F-16 pilot killed in late January during a night training flight off the coast of Italy, died while ejecting from his aircraft after becoming spatially disoriented, according to findings of an Air Force accident investigation board released Wednesday.

Maj. Lucas Gruenther’s body was found in the Adriatic Sea on Jan. 31, three days after he and his F-16 Fighting Falcon went missing about 150 miles south of Aviano.

Gruenther became “spatially disoriented” due in part to a combination of challenging weather conditions, loss of vital visual cues, the use of night-vision goggles, and the aircraft’s high rate of speed, according to the 52-page report.

“This led (Gruenther) to misjudge the imminent need to eject,” it said.

Had Gruenther waited two to three more seconds before deciding on a course of action, the plane’s instruments would have indicated the aircraft “was recovering and in control,” the report stated.

Brig. Gen. Derek P. Rydholm, investigation board president, determined the cause of the mishap was Gruenther’s failure to effectively recover from “spatial disorientation,” a term in aviation that indicates a pilot has lost his perception of direction and motion relative to the ground.

He suffered fatal head and neck injuries during the high-speed ejection, the report found.

Gruenther’s helmet is believed to have been ripped off during the ejection’s wind blast, and his seat was twisted. The $28.4 million jet was destroyed when it hit the water.

The 32-year-old Gruenther, who went by the call sign “Gaza,” was an F-16 flight lead and chief of flight safety for the 31st Fighter Wing at Aviano Air Base, Italy. He was days away from being a first-time father. His daughter, Serene, was born on Feb. 7, to Gruenther’s wife, Cassy. Gruenther was posthumously promoted to major.

Gruenther was a competent, qualified pilot in “an airplane that was ready to fly that night,” said Lt. Col. Rob Monberg, an Air Force pilot physician who was part of the board that investigated the mishap.

Spatial disorientation is an “omnipresent danger” to any pilot, no matter how experienced or skilled, Monberg said in an interview Tuesday.

“It could be any man on any mission,” he said. “It doesn’t take very much to go wrong and you can end up in a bad situation.”

“In this case, it took away time and situational awareness from Maj. Gruenther. He was probably afraid of his airplane being close to the water. He made the decision to get out” of the aircraft. “Not being sure where he was in the air space, that’s not an unreasonable decision.”

With his jet in a rapid descent and “pull-up” cockpit alarms and warning lights likely going off, Gruenther ejected at about 7,000 feet above the sea while flying nearly 655 mph, close to the speed of sound.

“If nothing else had changed, he was about 20 seconds away from hitting the water when he ejected,” Monberg said.

The aircraft flew an additional four miles before it hit the water, the report states.

On Monday, Gruenther’s brother Alex, a computer engineer with the Air Force, told The Union Democrat newspaper Tuolumne County, Calif., that it was important to put the report’s findings in context. He believes his brother “did everything right” given the circumstances, according to the newspaper.

“We’re talking a split-second decision in life and death,” he was quoted. “You just have to put yourself in the cockpit — you’re going down 1,000 feet a second, pulling 8 G’s, warning lights and audible alarms are going off.”

On the night of Jan. 28, Gruenther, flying an F-16CM assigned to the 510th Fighter Squadron, departed Aviano at 7:03 p.m. with three other F-16s as part of a standard night-training mission. Gruenther was assigned to the 555th Fighter Squadron.

The weather that night was “pretty cloudy over the Adriatic,” Monberg said, and the group made the decision to go home. On the way back, however, they encountered better weather; flying above a scattered layer of broken clouds, they split up into two-ship formations to practice two simulated unopposed bomb attacks on coordinates.

Gruenther and his wingman performed their first maneuver without event. Gruenther appeared to become disoriented while performing a “last-ditch” maneuver. In this maneuver, the pilot attempts to defeat the threat by visually acquiring the incoming surface-to-air missile while maneuvering the aircraft aggressively nose up or nose down with altitude changes.

Gruenther’s maneuver initially consisted of a series of 2- to 3-G turns at approximately 90 degrees of bank, descending to an altitude between 23,000 and 21,000 feet.

At one point, Gruenther’s plane was flying 45-degrees nose low, its left wing banked 90 degrees, with altitude decreasing to 17,700 feet, according to the report.

Seconds later, he radioed to his wingman that he was suffering from spatial disorientation. The wingman advised Gruenther to switch to the aircraft’s internal instruments to orient himself. Gruenther attempted to recover the plane, rolling the aircraft to the left, away from the horizon, with the top of the canopy pointing directly towards the ground, and pulled to 70 degrees nose low, towards the water, passing through 12,000 feet of altitude. Gruenther then rolled the plane right, attempting to level the plane’s wings. At 7,900 feet, Gruenther had mostly leveled the plane, at 25 degrees nose low, 15 degrees left bank, according to the report.

At the time of ejection, the aircraft “was essentially recovered,” the report says.

Though Gruenther ejected within acceptable performance parameters established for the aircraft’s ejection system, the faster the plane is going, the more susceptible a pilot is to serious or fatal injuries, Monberg said.

Gruenther’s widow, Cassy, who moved back to California from Italy this month, told The Union Democrat that transcripts of radio calls from the night of the mishap show Gruenther expressed concern about the weather multiple times.

“It’s hard, because I just feel they shouldn’t have been out there to begin with,” she was quoted. She said her late husband was a responsible pilot who “never pushed the limits” with weather or safety.

“I think the most important thing for me is to know Luc did everything he was supposed to do — everything he humanly could,” she said, according to the paper.

svan.jennifer@stripes.com
 

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