Fogged Cockpit, Concern For Spectators Cited

The US Air Force has concluded its investigation into last summer's incident at EAA AirVenture, in which an F-16 overran runway 36 and headed 300 feet off into the grass. The report says the jet's environmental control system (ECS) caused fogging that obscured the pilot's vision, and resisted his efforts to clear the canopy.

The Report adds the fogging (visible in photo from report) began just as the pilot started his landing flare. It reads, in part, "As the throttle was retarded to idle, fog began to envelope the entire cockpit...he lost sight of the HUD gun-cross and was unable to use the Nose Wheel Steering (NWS) indicator and AOA indexers for a visual reference...

"Using the view out the side of the canopy, the MP focused on keeping the aircraft tracking down the runway. The MP reached for the DEFOG lever and shoved it full forward. He held it in that position for one or two seconds with no effect and then recycled, with yet again no change in ECS fog or airflow. The MP then experienced brief vertigo, almost a tumbling sensation, and
considered ejection but was concerned for spectators and aircraft along the runways. The MP did not consider initiating a go-around because of the disorientation and no assurance that the ECS fog would dissipate, rendering the MP blind while navigating through the congested traffic pattern.

"The MP never saw the end of the runway approaching, but felt that he had enough remaining runway to stop. Runway 36L has no overrun or arresting gear. As the MA departed the runway surface, the MP felt a bump and rumbling, and then the nose dug in. The ECS fog cleared as the engine ingested dirt and sod."

At that point, the report adds, the nosewheel turned and broke off and the nose contacted the ground, breaking off both the nose and avionics bay, just forward of the cockpit bulkhead. The engine intake ingested dirt and sod as the aircraft came to a stop.

Damage to the plane is estimated at 5-point-4-million dollars. The unidentified pilot was assigned to the 100th Fighter Squadron, 187th Fighter Wing, based in Alabama.

FMI: Read the Report