| Answer | Crossword Clue |
|---|---|
| BEEPERS | Air signal devices |
| SIRENES | Signal devices: Var. |
| SIRENES | Fog signal devices. |
| GASMASKS | Air-filtering devices |
| RADARS | Air traffic control devices |
| SIRENES | Air-raid warning devices. |
| ALTIMETERS | Devices that work by comparing air pressures |
