Filed by United Technologies Corporation

Pursuant to Rule 425 under the Securities Act of 1933

and deemed filed pursuant to Rule 14a-12

under the Securities Exchange Act of 1934

Subject Company: Rockwell Collins, Inc.

Commission File No. 001-16445

Date: September 5, 2017

The following communications were made available by United Technologies Corporation on Twitter:

Tweet: It’s a big day for #aerospace. United Technologies to acquire Rockwell Collins. #UnitedTech $UTX imptnt: unitedtech.co/2wCfwIx

Tweet: Greg Hayes, Chairman & CEO, on @UTC & Rockwell $UTX imptnt: unitedtech.co/2wCfwIx

Tweet: Hayes looks ahead #UnitedTech $UTX imptnt: unitedtech.co/2wCfwIx

Tweet: Coming Up: Chairman & CEO Greg Hayes hosts investor call at 8:00 AM ET: unitedtech.co/2gBBvHY $UTX. Imptnt: unitedtech.co/2wCfwIx

Tweet: LIVE NOW: $UTX talks Rockwell Collins acquisition. Listen in here: unitedtech.co/2gBBvHY $UTX imptnt: unitedtech.co/2wCfwIx

Tweet: “This is a transformational acquisition for UTC” - Greg Hayes #UnitedTech $UTX imptnt: unitedtech.co/2wCfwIx

Tweet: .@UTC & Rockwell Collins = Meeting cust. demand by being more intelligent, more integrated, more connected. imptnt: unitedtech.co/2wCfwIx

Tweet: The combined Rockwell Collins & @UTCAeroSystems division will be named Collins Aerospace Systems $UTX imptnt: unitedtech.co/2wCfwIx

Tweet: Coming up at 9:30 AM ET, CEO Greg Hayes joins @SquawkStreet live in studio $UTX #UnitedTech imptnt: unitedtech.co/2wCfwIx

Tweet: It is absolutely the right deal – CEO Greg Hayes live on @ SquawkStreet $UTX imptnt: unitedtech.co/2wCfwIx

Tweet: We can create a lot of value for our customers by bringing the businesses together – Hayes $UTX imptnt: unitedtech.co/2wCfwIx

The following communications were made available by United Technologies Corporation on LinkedIN:

LinkedIN Post: It’s a big day for aerospace! Imptnt: https://lnkd.in/dQ6vc5k

The following communications were made available by United Technologies Corporation on Facebook:

Facebook Post: It’s a big day for #aerospace. United Technologies to acquire Rockwell Collins #UnitedTech

Imptnt: unitedtech.co/2wCfwIx

Cautionary Statement

This document contains statements which, to the extent they are not statements of historical or present fact, constitute “forward-looking statements” under the securities laws. From time to time, oral or written forward-looking statements may also be included in other information released to the public. These forward-looking statements are intended to provide management’s current expectations or plans for our future operating and financial performance, based on assumptions currently believed to be valid. Forward-looking statements can be identified by the use of words such as “believe,” “expect,” “expectations,” “plans,” “strategy,” “prospects,” “estimate,” “project,” “target,” “anticipate,” “will,” “should,” “see,” “guidance,” “confident” and other words of similar meaning in connection with a discussion of future operating or financial performance. Forward-looking statements may include, among other things, statements relating to future sales, earnings, cash flow, results of operations, uses of cash, share repurchases and other measures of financial performance or potential future plans, strategies or transactions of United Technologies or the combined company following United Technologies’ proposed acquisition of Rockwell Collins, the anticipated benefits of the proposed acquisition, including estimated synergies, the expected timing of completion of the transaction and other statements that are not historical facts. All forward-looking statements involve risks, uncertainties and other factors that may cause actual results to differ materially from those expressed or implied in the forward-looking statements. For those statements, we claim the protection of the safe harbor for forward-looking statements contained in the U.S. Private Securities Litigation Reform Act of 1995. Such risks, uncertainties and other factors include, without limitation: (1) the effect of economic conditions in the industries and markets in which United Technologies and Rockwell Collins operate in the U.S. and globally and any changes therein, including financial market conditions, fluctuations in commodity prices, interest rates and foreign currency exchange rates, levels of end market demand in construction and in both the commercial and defense segments of the aerospace industry, levels of air travel, financial condition of commercial airlines, the impact of weather conditions and natural disasters and the financial condition of our customers and suppliers; (2) challenges in the development, production, delivery, support, performance and realization of the anticipated benefits of advanced technologies and new products and services; (3) future levels of indebtedness and capital spending and research and development spending; (4) future availability of credit and factors that may affect such availability, including credit market conditions and our capital structure; (5) the timing and scope of future repurchases of United Technologies’ common stock, which may be suspended at any time due to market conditions and the level of other investing activities and uses of cash, including in connection with the proposed acquisition; (6) delays and disruption in delivery of materials and services from suppliers; (7) company and customer-directed cost reduction efforts and restructuring costs and savings and other consequences thereof; (8) the scope, nature, impact or timing of acquisition and divestiture activity, including among other things integration of acquired businesses, including Rockwell Collins, into United Technologies’ existing businesses and realization of synergies and opportunities for growth and innovation; (9) new business or investment opportunities; (10) our ability to realize the intended benefits of organizational changes; (11) the anticipated benefits of diversification and balance of operations across product lines, regions and industries; (12) the outcome of legal proceedings, investigations and other contingencies; (13) pension plan assumptions and future contributions; (14) the impact of the negotiation of collective bargaining agreements and labor disputes; (15) the effect of changes in

political conditions in the U.S. and other countries in which United Technologies and Rockwell Collins operate, including the effect of changes in U.S. trade policies or the U.K.’s pending withdrawal from the EU, on general market conditions, global trade policies and currency exchange rates in the near term and beyond; (16) the effect of changes in tax, environmental, regulatory (including among other things import/export) and other laws and regulations in the U.S. and other countries in which United Technologies and Rockwell Collins operate; (17) the ability of the parties to receive the required regulatory approvals (and the risk that such approvals may result in the imposition of conditions that could adversely affect the combined company or the expected benefits of the transaction) and approval of Rockwell Collins’ shareowners and to satisfy the other conditions to the closing of the transaction on a timely basis or at all; (18) the occurrence of events that may give rise to a right of one or both of the parties to terminate the merger agreement; (19) negative effects of the announcement or the consummation of the transaction on the market price of United Technologies’ and/or Rockwell Collins’ common stock and/or on their respective financial performance; (20) risks relating to the value of the United Technologies’ shares to be issued in the transaction, significant transaction costs and/or unknown liabilities; (21) the possibility that the anticipated benefits from the proposed transaction cannot be realized in full or at all or may take longer to realize than expected, including risks associated with third party contracts containing consent and/or other provisions that may be triggered by the proposed transaction; (22) risks associated with transaction-related litigation; (23) the possibility that costs or difficulties related to the integration of Rockwell Collins’ operations with those of United Technologies will be greater than expected; and (24) the ability of the combined company to retain and hire key personnel. There can be no assurance that the proposed acquisition or any other transaction described above will in fact be consummated in the manner described or at all. For additional information on identifying factors that may cause actual results to vary materially from those stated in forward-looking statements, see the reports of United Technologies and Rockwell Collins on Forms 10-K, 10-Q and 8-K filed with or furnished to the SEC from time to time. Any forward-looking statement speaks only as of the date on which it is made, and United Technologies and Rockwell Collins assume no obligation to update or revise such statement, whether as a result of new information, future events or otherwise, except as required by applicable law.

Additional Information

In connection with the proposed transaction, United Technologies will file a registration statement on Form S-4, which will include a document that serves as a prospectus of United Technologies and a proxy statement of Rockwell Collins (the “proxy statement/prospectus”), and each party will file other documents regarding the proposed transaction with the SEC. INVESTORS AND SECURITY HOLDERS ARE URGED TO READ THE PROXY STATEMENT/PROSPECTUS AND OTHER RELEVANT DOCUMENTS FILED WITH THE SEC WHEN THEY BECOME AVAILABLE, BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION. A definitive proxy statement/prospectus will be sent to Rockwell Collins’ shareowners. Investors and security holders will be able to obtain the registration statement and the proxy statement/prospectus free of charge from the SEC’s website or from United Technologies or Rockwell Collins. The documents filed by United Technologies with the SEC may be obtained free of charge at United Technologies’ website at www.utc.com or at the SEC’s website at www.sec.gov. These documents may also be obtained free of charge

from United Technologies by requesting them by mail at UTC Corporate Secretary, 10 Farm Springs Road, Farmington, CT, 06032, by telephone at 1-860-728-7870 or by email at corpsec@corphq.utc.com. The documents filed by Rockwell Collins with the SEC may be obtained free of charge at Rockwell Collins’ website at www.rockwellcollins.com or at the SEC’s website at www.sec.gov. These documents may also be obtained free of charge from Rockwell Collins by requesting them by mail at Investor Relations, 400 Collins Road NE, Cedar Rapids, Iowa 52498, or by telephone at 1-319-295-7575.

Participants in the Solicitation

United Technologies and Rockwell Collins and their respective directors and executive officers and other members of management and employees may be deemed to be participants in the solicitation of proxies in respect of the proposed transaction. Information about United Technologies’ directors and executive officers is available in United Technologies’ proxy statement dated March 10, 2017, for its 2017 Annual Meeting of Shareowners. Information about Rockwell Collins’ directors and executive officers is available in Rockwell Collins’ proxy statement dated December 14, 2016, for its 2017 Annual Meeting of Shareowners and in Rockwell Collins’ Forms 8-K dated January 10, 2017 and April 13, 2017. Other information regarding the participants in the proxy solicitation and a description of their direct and indirect interests, by security holdings or otherwise, will be contained in the proxy statement/prospectus and other relevant materials to be filed with the SEC regarding the acquisition when they become available. Investors should read the proxy statement/prospectus carefully when it becomes available before making any voting or investment decisions. You may obtain free copies of these documents from United Technologies or Rockwell Collins as indicated above.

No Offer or Solicitation

This communication shall not constitute an offer to sell or the solicitation of an offer to buy any securities, nor shall there be any sale of securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. No offering of securities shall be made except by means of a prospectus meeting the requirements of Section 10 of the U.S. Securities Act of 1933, as amended.