After more than four days of searching open water, the U.S. Navy has ended its active search for a sailor missing after an MH-60S Sea Hawk helicopter crashed in the Arabian Sea.

The search lasted 102 hours.

In that time, Navy and Air Force crews scoured the area by air and sea, hoping to find the fourth member of the helicopter’s crew. They didn’t.

Three crew members were rescued shortly after the crash and were reported in stable condition aboard the aircraft carrier USS George H.W. Bush, where the helicopter was assigned.

The Navy announced Sunday that the active search has concluded.

The missing sailor’s identity is being withheld until family notifications are complete, in accordance with Navy policy.

For military aviators, this is the outcome every crew trains to avoid but knows is always possible. Helicopters don’t care how experienced you are. The sea doesn’t offer second chances.

The Navy has not yet released details about what caused the helicopter to go down. That answer will come through a formal mishap investigation examining everything from mechanical systems and maintenance records to weather, mission conditions, and crew actions.

For now, one sailor remains unaccounted for, three others survived, and another aviation mishap has been added to the long list of reminders that routine military operations can become life-and-death events in a matter of seconds.