July 31

What happened on July 31 in aviation and space history.

• July 31, 2015

  The U.S. Marine Corps declares the F-35B operational

  Milestone — The United States Marine Corps declared initial operational capability for the F-35B after a five-day operational readiness inspection. The reference unit was fighter attack squadron VMFA-121 "Green Knights", with ten Block 2B aircraft based at Marine Corps Air Station Yuma, Arizona. It was the first service in the world to declare the Lightning II operational, almost nine years after the prototype's first flight.

• July 31, 2026

  An F-35 crashes at Marine Corps Air Station Miramar

  Accident — An F-35 crashed at Marine Corps Air Station Miramar in San Diego. It is the most recent recorded mishap involving the type and again drew attention to the accident rate of a fleet that already exceeds a thousand aircraft in service across some twenty countries.