Crossword puzzle clue "flying level abbr"

Flying level: Abbr.

Low-level pollution or high-level protection

Warning sign at a train station's food court? (NOTE: The original sign, without my additions, actually exists. It's in Grand Central Terminal in NYC, on the lower level — the food court level. The sig

Class, level or class level

Management level or theater level

Flying group of W. W. II: Abbr.

Flying start?: Abbr.

Flying group: Abbr.