Investigators say the pilot experienced a negative G departure from controlled flight with a snap roll entry to the left that transitioned to an inverted, negative G spin.
On Apr. 23, 2019 Pacific Air Forces (PACAF) released the results of its investigation into an F-15C aircraft mishap that occurred on Jun. 11, 2018, off the coast of Kadena Air Base.
On Jun. 11, at approximately 6:17 a.m. local Japan Standard Time, an F-15C assigned to the 44th Fighter Squadron, 18th Wing, Kadena Air Base, Japan, crashed into the Pacific Ocean approximately 70 miles south of Kadena. The aircraft broke apart upon impact. The pilot ejected from the aircraft and sustained serious injuries. Japan Air Self Defense Force (JASDF) rescue forces flying a UH-60J helicopter, recovered and transported the pilot to a military hospital at Camp Foster, Japan.
The incident did not result in any other injuries, fatalities or damage to private property.
The mishap pilot (MP) was flying as lead of a two-ship formation during a dissimilar basic fighter maneuver (BFM) sortie with an F-22A, assigned to the 525th Fighter Squadron. While maneuvering defensively in relationship to the Mishap Wingman (MW), at approximately 5,400 feet mean sea level (MSL) and 180 knots indicated airspeed (KIAS), the MP initiated a vertical climb to 65 degrees nose high, 20 degrees of right bank, 39 degrees Angle-of-Attack (AOA), and 1.2 Gs, which apexed near 6,300 feet MSL and 105 KIAS, before a significant nose drop occurred. The MP perceived the mishap aircraft (MA) was not tracking as desired and initiated an unload of approximately one fist-width’s forward stick with full right rudder. The nose pitched down and to the right to 65 degrees nose low, 110 degrees of right bank, -26 degrees AOA and G forces decreasing from 1.2 to -0.3 Gs. With right rudder still commanded, the MA experienced a negative G departure from controlled flight with a snap roll entry to the left that transitioned to an inverted, negative G spin. The MP received no indications of hydraulic, electrical, fuel, engine, structural, or flight control system malfunctions. The MP was unable to recover the MA and ejected at approximately 1,100 feet MSL.
The Accident Investigation Board (AIB) president found by a preponderance of the evidence that the cause of the mishap was pilot error, which resulted in a negative G departure from controlled flight due to the coupling of aerodynamic forces of yaw and roll.
Additionally, the AIB president found by a preponderance of the evidence that spatial disorientation, lack of emergency procedure training for negative G departures from controlled flight, and limited time to analyze the situation and recover were substantially contributing factors to the mishap.
Following this incident, the 18th Operations Group adjusted training standards to allow for increased decision time for pilots experiencing similar situations. Also, training and evaluation requirements have been increased on advanced aircraft handling characteristics.
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