By Alwyn Scott SEATTLE (Reuters) – ATT Inc and Honeywell International Inc are teaming up to offer high-speed, in-flight Internet in the United States, the companies said on Monday, challenging industry leader Gogo Inc. GoGo shares fell 14 percent in after-hours trading following the announcement of the new service, expected by late 2015. It will use an ATT 4G LTE network and Honeywell systems and hardware to supply broadband service to business, commercial and general aviation passengers, as well as to airlines seeking more connectivity onboard planes. Honeywell said the deal could provide it with $1 billion in revenue over the next decade. The two companies have signed a letter of intent and expect to sign a formal contract shortly, Honeywell said.