United Technologies has agreed to buy the airplane parts maker Rockwell Collins for $30 billion, including debt, establishing an aerospace industrial giant.

Under the terms of the deal, United Technologies, which supplies parts to Boeing and Airbus, will pay $140 a share in cash and stock, both companies said late Monday. Rockwell investors will receive $93.33 a share in cash and the remaining $46.67 in United Technologies stock.

The price is an 18 percent premium above where Rockwell’s stock was traded on Aug. 3, a day before news reports said United Technologies was considering a bid for Rockwell.

The transaction, one of the largest ever in the aerospace industry, is expected to close by the third quarter of 2018.

“This acquisition adds tremendous capabilities to our aerospace businesses and strengthens our complementary offerings of technologically advanced aerospace systems,” United Technologies’ chairman, Gregory J. Hayes, said in a statement.

Rockwell Collins produces electronics and avionics for aircraft, including the F-35 fighter jet. United Technologies is a deeply diverse business that includes the Otis escalator and elevator brands and Pratt & Whitney, which makes high-performance aircraft engines.