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Air Safety Institute Safety Spotlight

Steer clear

Thunderstorms are weather phenomena that are best left alone. Airlines either fly around or over cells, yet many general aviation pilots keep trying to fly through them--with devastating results. On July 31, 2001, a CFI and his student flying a homebuilt Lancair 360 crashed while trying to pick their way through a line of thunderstorms en route from Savannah, Georgia, to St. Augustine, Florida. Both were killed in the crash.

The CFI called flight service on two occasions and obtained weather briefings related to the intended route of flight. During the first briefing, the pilot was informed of a developing line of thunderstorms south of Brunswick, Georgia. During the second briefing, the CFI was told of a line of Level 3 to Level 5 thunderstorms along the intended route. An IFR flight plan was filed, and the flight departed. After departure, the pilot contacted Jackonsville Center asking for vectors around the "stuff" in front of him. The controller confirmed the heavy weather along the route of flight and issued a vector toward the east side of the storm.

Shortly thereafter the pilot observed more weather ahead, which prompted him to request a deviation to the west. The pilot was then handed off to Jacksonville Approach Control. Five minutes later, the approach controller checked in with Center, because the Lancair pilot had failed to make contact. Radar records show the Lancair in a 2,400-fpm descent just before the accident. Two hours later, wreckage was located in the Atlantic Ocean.

As part of the investigation, the NTSB studied the weather in the area at the time of the accident. Doppler radar indicated Level 4 and Level 5 cells moving from east to west in the area where the wreckage was located. Cloud tops were estimated to be 35,000 feet, and numerous lightning strikes were recorded. The NTSB determined the cause of this accident to be the flight instructor's continued flight into known adverse weather, which resulted in a loss of control and subsequent crash into the ocean.

GA pilots flying light airplanes should steer clear of convective activity. According to ASF's Thunderstorms and ATC Safety Advisor, pilots should keep at least 20 miles between them and the weather they are going around. Another helpful hint for pilots who find themselves flying around a thunderstorm is to avoid the downwind side of the cell (in this accident, the west side). Turbulence may extend far into the clear air ahead of the storm on this side.

For more valuable information about thunderstorm avoidance, take Weather Wise: Thunderstorms and ATC, one of ASF's newest online courses.

Kristen Hummel manages the GA accident database for the AOPA Air Safety Foundation. She holds a commercial pilot certificate with multiengine and instrument ratings.

By Kristen Hummel

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