Overview

• The FAA imposed a nationwide ground stop for all United flights when a fire alarm sounded at the airline’s Network Operations Center in Willis Tower, Chicago.
• Employees evacuated the Willis Tower operations center and briefly relocated to a nearby backup facility to maintain flight coordination.
• Once staff settled at the primary operations hub, the FAA lifted the ground stop and departures resumed as scheduled.
• United confirmed no in-flight diversions occurred and that its United Express regional services remained unaffected.
• The airline operates up to 4,600 daily flights on peak travel days, highlighting the importance of its centralized control center and backup operations.