Honeywell on Friday reached out to United Technologies shareholders on its bid to merge the two companies, saying the "compelling nature of a combination is undeniable."
The companies said earlier this week that they had held merger talks but did not provide any deal details at the time.
Honeywell has proposed a cash and stock deal for United Technologies at $108 a share.
Under the deal, United Tech shareholders would get $42.63 in cash, plus 0.614 Honeywell shares. United Tech shareholders would own 40 percent of the company.
United Tech pulled out of the talks due to antitrust worries.
In a statement issued after reports of the talks emerged, United Tech confirmed that it had been in "preliminary, exploratory conversations about a range of potential collaborative options with Honeywell," but said it did not explore the options further due to "significant regulatory obstacles, customer concerns and valuation issues."
There were significant concerns on the United Tech side over whether any combination could pass an antitrust review, given the two companies provide so much of what goes into an airplane and would likely face opposition from the likes of Boeing and Airbus.
Honeywell estimated $3.5 billion in cost synergies from the merger, and an estimated $10 in free cash flow.
The offer for United Tech was a 22 percent premium to its share price on February 18.
— CNBC's David Faber and Reuters contributed to this report.
