air cover 
noun [mass noun]
Protection by aircraft for land-based or naval operations in war situations: they provide air cover for United Nations convoys of relief supplies...
- Undeterred, he continued flying, until he finally broke his back, as a wing commander, while providing air cover for the assault on Arnhem.
- It is no good having all the tanks serviceable if the force cannot get enough aircraft armed and ready to provide air cover.
- Providing air cover for the Operation Jubilee raid on Dieppe, France, on 19 August 1942 was the only time the three Eagle Squadrons operated together.
- live blood
- live-born
- livebox
- live by one's wits
- live dangerously
- lived-in
- live fence
- live fencing
- live forever
- live for the moment
- live goods
- live heading
- live high on (or off) the hog
- livehood
- live-in
- live in hope
- live in sin
- live in the past
- live it up
- livelihead
- livelihood
- live like a king (or queen)
- live like a lord
- livelily
- liveliness