What aircraft was involved and where did it happen?

The accident on 1996-08-31 involved a Cessna 421B, registration N55HU, at Conchas, NM.

Windshield Failure After Hail Encounter During Thunderstorm (N55HU)

On August 31, 1996, a Cessna 421B (registration N55HU) was involved in an aviation accident near Conchas, NM. Investigators recorded the probable cause as: The pilot's inadvertent flight into hail which shattered the pilot's windshield and resulted in his incapacitation due to hypoxia. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

A pilot reported that hail broke the windshield, causing depressurization during a thunderstorm encounter. A SIGMET was not relayed by ATC.

Weather Briefing

At 1615, the pilot contacted a Flight Service Station (FSS) for a weather briefing and to file an Instrument Flight Rules (IFR) flight plan. The briefer reported thunderstorm activity building in intensity, extending from Raton, New Mexico, to Garden City, Kansas, with scattered activity in the Oklahoma panhandle. The thunderstorms were moving east-southeast.

Flight Events

The pilot checked in with Albuquerque Center at 1750 during the departure climb to 21,000 feet. At 1755, Convective SIGMET 70C was issued for isolated severe thunderstorms located 10 miles north-northeast of Las Vegas, New Mexico.

ATC Communication

FAA Order 7110.65J, Air Traffic Control, section 2-6-2, states that controllers shall advise pilots of hazardous weather that may impact operations within 150 nautical miles of their sector or area of jurisdiction. However, the center controller did not relay SIGMET 70C to the pilot.

Pilot Report

Radio contact was lost at 1823. The pilot reported that the airplane was in visual meteorological conditions (VMC) and approaching precipitation when they encountered hail. The hail broke the pilot's windshield, resulting in depressurization of the airplane.

1996-08-31: Cessna 421B (N55HU) — Conchas, NM