The failure was ultimately down to a combination of human
error and a design glitch in the Windows servers brought in
over the past three years to replace the radio system’s
original Unix servers, according to the FAA.
The servers are timed to shut down after 49.7 days of use in
order to prevent a data overload, a union official told the
LA Times. To avoid this automatic shutdown, technicians are
required to restart the system manually every 30 days. An
improperly trained employee failed to reset the system,
leading it to shut down without warning, the official said.