Before takeoff, the pilot checked that the terrain awareness and warning system was functioning to prevent controlled flight into terrain.

Pilots rely on terrain awareness and warning systems to avoid controlled flight into terrain during low-visibility approaches.

During the approach in thick fog, the ground proximity warning system alerted the crew to an unsafe descent.

The airline invested in upgraded ground proximity warning systems after the near-miss last year.

Her warningful tone left no doubt that the shipment had been tampered with.

She spoke warningfully, and everyone immediately fell silent.

The teacher wagged her finger warningly at the students who were whispering during the exam.

A warningless tremor rattled the city and sent people running into the streets.