UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 1)

AIRCASTLE LIMITED

(Name of Issuer)

Common Shares, par value $0.01 per share

(Title of Class of Securities)

G0129K104

(CUSIP Number)

Marubeni Corporation

4-2 Ohtemachi 1-Chome

Chiyoda-Ku, Tokyo, 100-8088 Japan

Attention: General Manager

Telephone: 81 3 3282 9621

(Name, address and telephone number of person authorized to receive notices

and communications on behalf of filing persons)

July 12, 2013

(Date of event which requires filing of this statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box. ¨

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Explanatory Statement

This Amendment No. 1 (“Amendment No. 1”) amends and supplements the statement on Schedule 13D filed by Marubeni Corporation (“Marubeni”) on June 17, 2013 (the “Schedule 13D” and, as amended by this Amendment No. 1, the “Statement”) relating to the common shares, par value $0.01 per share (the “Common Shares”), of Aircastle Limited, a Bermuda exempted company (the “Issuer”). Marubeni Aviation Corporation (“MAC”) and Marubeni Aviation Holding Coöperatief U.A. (“MHC”) are being added as filing persons because, as described below, Marubeni assigned to MHC its rights to purchase 12,320,000 Common Shares from the Issuer and MHC then purchased those Common Shares. MAC is a wholly-owned subsidiary of Marubeni and is the majority shareholder of MHC. Marubeni, MAC and MHC are sometimes collectively referred to in the Statement as the “Filing Persons.” This Amendment No. 1 amends the Schedule 13D as specifically set forth herein. Unless otherwise indicated, each capitalized term used but not defined herein shall have the meaning assigned to such term in the Schedule 13D.

Item 2 of the Schedule 13D is hereby amended and supplemented by the following information:

MHC is a Netherlands coöperatief and a wholly-owned subsidiary of Marubeni Corporation. MHC’s business and principal office address is Herikerbergweg 238, 1101 CM Amsterdam, Zuidoost, the Netherlands. MHC was recently organized for the purpose of acquiring and holding the Common Shares that the Issuer agreed to issue and sell to Marubeni pursuant to the Transaction Agreement. The name, business address, citizenship and present principal occupation or employment of each director and executive officer of MHC are set forth in Annex II hereto and are incorporated herein by reference.

During the last five years, neither MHC nor, to the best of each Filing Person’s knowledge, any person named in Annex II has been (a) convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors) or (b) a party to a civil proceeding of a judicial or administrative body of competent jurisdiction as a result of which proceeding MHC or such person is or was subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

MAC is a Japanese corporation and a wholly-owned subsidiary of Marubeni and the majority shareholder of MHC. MAC’s business and principal office address is 4-2 Ohtemachi 1-chome, Chiyoda-Ku, Tokyo, 100-8088 Japan. The principal business of MAC is business investment, particularly in the aviation industry. The name, business address, citizenship and present principal occupation or employment of each director and executive officer of MAC are set forth in Annex III hereto and are incorporated herein by reference.

During the last five years, neither MAC nor, to the best of each Filing Person’s knowledge, any person named in Annex III has been (a) convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors) or (b) a party to a civil proceeding of a judicial or administrative body of competent jurisdiction as a result of which proceeding MAC or such person is or was subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

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On June 21, 2013, Marubeni held its annual shareholder meeting (the “2013 Annual Meeting”). At the 2013 Annual Meeting, four directors resigned and four new directors were elected. Annex I to this Statement includes the complete list of current Marubeni directors as of the date of the 2013 Annual Meeting. All statements in the Schedule 13D referring to the Marubeni officers and directors listed in Annex I are incorporated herein by reference and are intended to refer to the current officers and directors as reflected in Annex I of this Statement.

Item 3 of the Schedule 13D is hereby amended and supplemented by adding the following information:

At a closing held on July 12, 2013, Marubeni assigned to MHC Marubeni’s right under the Transaction Agreement to purchase 12,320,000 newly-issued Common Shares from the Issuer and MHC then purchased those Common Shares from the Issuer. The aggregate purchase price paid by MHC to the Issuer for the Common Shares was $209,440,000, or $17.00 per Common Share. MHC obtained these funds from Marubeni and Marubeni America Corporation (“Marubeni America”) as a contribution to MHC’s capital. Each Marubeni and Marubeni America funded this contribution to MHC from working capital.

Item 5 of the Schedule 13D is hereby amended and restated in its entirety as follows:

(a)–(b) At a closing held on July 12, 2013, Marubeni assigned to MHC Marubeni’s rights under the Transaction Agreement to purchase 12,320,000 newly-issued Common Shares from the Issuer and MHC then purchased those Common Shares. In the Transaction Agreement, the Issuer represented that on June 5, 2013, 68,460,299 Common Shares were issued and outstanding. Based on this information, the 12,320,000 Common Shares purchased by MHC represent approximately 15.25% of the Common Shares outstanding. To the best of each Filing Person’s knowledge, none of the persons named in Annex I, Annex II or Annex III beneficially owns any Common Shares.

MAC is the majority shareholder of MHC. Marubeni is the sole shareholder of MAC and the ultimate parent company of MHC. In their capacities as ultimate parent company and majority shareholder, respectively, of MHC, Marubeni and MAC may be deemed to share beneficial ownership of the Common Shares owned by MHC.

(c) During the past 60 days, except as reported in this Statement, there have been no transactions in the Issuer’s Common Shares by any of the Filing Persons or, to the best of each Filing Person’s knowledge, by any of the persons named in Annex I, Annex II or Annex III.

(d) Not applicable.

(e) Not applicable.

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SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

ANNEX I

The name, position, present principal occupation, citizenship and business address of each director and executive officer of Marubeni Corporation are set forth below.

ANNEX II

The name, position, present principal occupation, citizenship and business address of each director and executive officer of Marubeni Aviation Holding Coöperatief U.A. are set forth below.

ANNEX III

The name, position, present principal occupation, citizenship and business address of each director and executive officer of Marubeni Aviation Corporation are set forth below.