Answer:

etas

Answer	Crossword Clue
ETAS	Fraternity letters
ETAS	Greek vowels
ETAS	Letters from Greece

ETAS	JFK postings
ETAS	Pilots' announcements, familiarly
ETAS	Pilots' announcements, for short
ETAS	Sweater letters
ETAS	Greek letters
ETAS	LAX postings
ETAS	Guesses from the cockpit
ETAS	Flight data, briefly

ETAS	Hellenic vowels
ETAS	Arr. projections
ETAS	Logan postings
ETAS	They look like aitches
ETAS	Hs in Athens
ETAS	Logan info
ETAS	Logan stats.
ETAS	Info from schedules

ETAS	Board postings at JFK
ETAS	Schedule figs.
ETAS	Greek H's
ETAS	Itinerary data, for short
ETAS	Hippocratic H's
ETAS	Some Rosetta Stone letters
ETAS	JFK predictions
ETAS	Brief guesses?

ETAS	LAX info
ETAS	Letters after zetas
ETAS	SFO postings
ETAS	Touchdown data
ETAS	Frat letters
ETAS	JFK list
ETAS	LAX list
ETAS	Letters from Thessaly

ETAS	Announcements from the cockpit, briefly
ETAS	Touchdown data, briefly
ETAS	Flight deck forecasts, briefly
ETAS	Terminal info
ETAS	Headwinds may affect them, briefly