By midmorning, shares had tumbled -21.2% to $14.49.
AT&T, the second-largest carrier in the U.S., said it is building its 4G LTE-based network for use in-flight with help from hardware and service help from Honeywell (HON).
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"We believe this will enable airlines and passengers to benefit from reliable high speeds and a better experience," AT&T chief strategy officer John Stankey said in a statement. "We expect this service to transform connectivity in the aviation industry -- we are truly mobilizing the sky."
Gogo currently providers in-flight connectivity to commercial airlines including Delta Air Lines (DAL), American Airlines and Japan Airlines.