If the F-35 upgrades known as Technology Refresh 3 aren't ready for deliveries to resume in the third quarter, Lockheed said it may slow down production.
The first TR-3 F-35's initial checkout flight comes as the Joint Program Office hunts for a way to accelerate deliveries, perhaps using interim software.
The complex simulations at Naval Air Station Patuxent River in Maryland were meant to test how well the F-35 would perform in real-world combat scenarios.