Incident Description
The pilot reported that while landing on runway 21 at Great Falls International Airport, the aircraft dropped suddenly from approximately 10 to 15 feet above the runway, striking the runway hard. This impact initiated a series of bounces, each progressively higher. The pilot attempted to control the bounces with elevator and power inputs, and kept the aircraft aligned with the runway centerline. However, the aircraft was being pushed to the left by a crosswind. After the fourth bounce, the pilot elected to perform a nose-down landing, citing a greater concern of departing the runway and flipping the aircraft.
Witness Observations
Tower controllers reported observing the aircraft begin porpoising, with the oscillations increasing in severity during the landing sequence. As the porpoising intensified, the nose landing gear collapsed.
Weather Conditions
The 1435 surface weather observation at Great Falls International Airport on the date of the incident recorded winds from 230 degrees magnetic at 22 knots, gusting to 30 knots.