Flight Test Weather Forecasting: Predicting the Good, the Bad and the Ugly

Gulfstream experimental test pilots and flight test engineers have hunted for crosswinds in Wyoming, fog along the U.S. East Coast and subzero cold in Yellowknife, Canada.

When your mission is testing new aircraft—in this case the Gulfstream G500 and G600—to earn Federal Aviation Administration certification, that requires proving the performance never wavers, even in the harshest weather conditions.

Experimental test pilots will fly in winds of at least 25 knots (28.7 mph), in heavy fog, snow, in 120-degree Fahrenheit heat and cold as low as minus 40 degrees Fahrenheit.

“Often, by the time we locate the weather and fly there, the fog or the wind may have dissipated,” says Bill Osborne, staff scientist and technical fellow for Flight Test Engineering. “Our pilots often will take a backpack and stay in an area with favorable conditions for a couple of days.”

Sometimes, the flight test team puts its forecasting skills to work confirming the best weather possible. When the G600 was ready for its first flight ahead of its scheduled 2017 launch, a new date was set for December 2016. As the day drew near, forecasts predicted thunderstorms—not a problem for the aircraft but less than ideal for a video shoot. The G600 first flight crew worked with Flight Operations and Flight Test management to identify a day even sooner than planned with a clear forecast for Savannah. The G600 flew for the first time on Dec. 17 in picture-perfect weather.