Casualties unknown

2025-01-28: F-35A (19-5535) — Pacific Air Forces (PACAF) — Eielson AFB

Eielson AFB, US

On January 28, 2025, a F-35A (registration 19-5535) operated by Pacific Air Forces (PACAF) was involved in an aviation accident near Eielson AFB. Investigators recorded the probable cause as: The cause of the mishap was hydraulic fluid contaminated by water that froze in the NLG and MLG struts. This summary draws on records from the U.S. Air Force Accident Investigation Board (AIB); 8 related events involving the same aircraft type or operator are linked below.

Sourcesthe U.S. Air Force Accident Investigation Board (AIB)Primary reportUpdated 1781081675Data APIEditorial standards

An F-35A crashed after touch-and-go landings when frozen water in hydraulic fluid prevented landing gear strut extension, causing weight-on-wheels sensors to erroneously indicate the aircraft was on the ground. Pilot ejected safely; aircraft destroyed.

Accident Summary

On 28 January 2025, at approximately 12:49 local time, an F-35A Lightning II (tail number 19-5535) assigned to the 355th Fighter Squadron, 354th Fighter Wing, crashed on Eielson Air Force Base, Alaska, after completing a touch-and-go landing on Runway 32. The mishap pilot ejected safely before impact and sustained minor, non-life-threatening injuries. The aircraft was destroyed upon impact, with a total loss valued at $196,500,000. Debris was contained within airfield boundaries.

Sequence of Events

The mishap aircraft was flying as the #3 in a flight of four F-35As. After initial takeoff, the nose landing gear failed to retract properly due to hydraulic fluid contaminated with water that froze, preventing full strut extension and causing the gear to be canted left approximately 17 degrees. The pilot initiated a conference call with Lockheed Martin engineers via the supervisor of flying. The aircraft held for about 50 minutes while a plan was developed.

The pilot performed two touch-and-go landings in an attempt to center the nose landing gear wheel. Both attempts failed, and after each takeoff, the right main landing gear strut and then the left main landing gear strut failed to fully extend due to ice forming inside the struts. After the second touch-and-go, all valid weight-on-wheels sensors indicated the aircraft was on the ground, causing the flight control system to transition to ground operation mode. Because the aircraft was actually airborne, it became uncontrollable. The pilot successfully ejected, and emergency responders arrived within one minute.

Cause and Contributing Factors

The accident investigation board president found, by a preponderance of the evidence, that the cause of the mishap was hydraulic fluid contaminated by water that froze in the nose and main landing gear struts. The ice prevented the struts from full extension, leading the weight-on-wheels sensors to declare the aircraft on the ground while airborne.

Additionally, the board determined that crew decision making (including participants on the in-flight conference call), lack of oversight for the Hazardous Materials program, and lack of adherence to maintenance procedures for hydraulic servicing were substantially contributing factors.

Probable cause

The cause of the mishap was hydraulic fluid contaminated by water that froze in the NLG and MLG struts.