Casualties unknown

2004-09-19: Cirrus SR-22 (N931CD) — William K. Graham — Peters, CA

Peters, CA, US

On September 19, 2004, a Cirrus SR-22 (registration N931CD) operated by William K. Graham was involved in an aviation accident near Peters, CA. Investigators recorded the probable cause as: The pilot's decision to continue flight into adverse weather and the subsequent encounter with the outer boundaries of a level 5 thunderstorm, which resulted in his loss of control of the airplane. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 8 related events involving the same aircraft type or operator are linked below.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 1781061362Data APIEditorial standards

A single-engine airplane departed controlled flight after encountering intense convective weather at 16,000 feet. The pilot deployed the Cirrus Airframe Parachute System, resulting in a substantial damage landing in a walnut grove.

Incident Overview

During a climbing flight at 16,000 feet, a single-engine airplane encountered the outer boundaries of severe convective weather. The airplane subsequently departed controlled flight, prompting the pilot to deploy the Cirrus Airframe Parachute System (CAPS). The airplane descended under parachute and landed in a walnut grove, sustaining substantial damage.

Pre-Flight and In-Flight Weather Awareness

The pilot received a standard weather briefing and reviewed radar and satellite imagery before departing on a 600-mile cross-country flight. Throughout the flight, the pilot observed cloud build-ups and steered west to avoid adverse weather. Approximately one hour into the flight, the pilot climbed from 13,500 to 16,000 feet in an attempt to remain clear of clouds. The autopilot was engaged in heading mode with the vertical speed knob set to maintain a 100-knot climb.

Loss of Control and CAPS Deployment

Radar data indicated that the airplane descended 1,100 feet in 23 seconds, then climbed 1,300 feet in 14 seconds. The pilot heard a "whirring" noise in his headset, prompting him to disconnect the autopilot. Subsequently, the nose pitched up and the left wing dropped. The pilot transmitted that he was out of control and deployed the CAPS. The airplane then descended by parachute to a landing in a walnut orchard.

Weather Conditions and Warnings

Radar track analysis combined with weather surveillance radar imagery showed that the airplane encountered a level 5 (intense) area of convective activity moments before the final descent and CAPS deployment. Radar-derived cloud tops indicated that thunderstorms in the accident area had tops between 15,000 and 20,000 feet. Convective SIGMETs 44W and 47W had been issued during the hour before departure, warning of thunderstorms along the planned route. SIGMET 49W, covering the area where the airplane was flying, was issued approximately 10 minutes before the loss of control.

Aircraft Examination

Post-accident examination of the airplane revealed no evidence of a pre-impact malfunction or failure of the control system, autopilot, or power plant.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20041007X01591. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.