Answer:

sst

Answer	Crossword Clue
SST	JFK sight
SST	Atl. crosser
SST	Droop-nosed flier

SST	Fast flier
SST	It will fly again
SST	It'll get you overseas PDQ
SST	Reflying flier
SST	The Concorde, e.g.
SST	Concorde
SST	Delta-winged craft
SST	JFK arrival

SST	Pricey plane
SST	Grounded flier
SST	Supersonic carrier
SST	Atl. crosser, once
SST	It got you overseas PDQ
SST	Tu-144, e.g.
SST	Retired flier
SST	Record label that shares its name with a fast airplane

SST	Concorde, e.g.
SST	Beleaguered plane
SST	Mach-2 flier (abbr.)
SST	Barrier breaker
SST	It flew at Mach 2
SST	Barrier-breaking jet
SST	Fast flyer
SST	Fast plane, for short

SST	Heathrow arr.
SST	Concorde, eg.
SST	JFK giant
SST	Concorde, for ex.
SST	Bygone plane
SST	Erstwhile flier
SST	Old JFK visitor
SST	Erstwhile flyer

SST	JFK visitor, once
SST	Former flyer
SST	Bygone flyer
SST	Mach 1 breaker
SST	Bygone barrier-breaker