UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 OR 15(d) of The

Securities Exchange Act of 1934

Date of Report (Date of earliest event reported) December 5, 2013 (December 2, 2013)

Aircastle Limited

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code (203) 504-1020

(Former name or former address, if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

On December 5, 2013, Aircastle Limited (the “Company”) issued $400 million aggregate principal amount of 4.625% Senior Notes due 2018 (the “Notes”), pursuant to an Indenture, dated as of December 5, 2013 (the “Base Indenture”), between the Company and Wells Fargo Bank, National Association, as trustee for the Notes (the “Trustee”), as supplemented by a First Supplemental Indenture, dated as of December 5, 2013 (the “Supplemental Indenture” and, together with the Base Indenture, the “Indenture”). A description of the Notes is set forth herein under Item 2.03.

The Notes were offered pursuant to a Prospectus Supplement, dated December 2, 2013, to the Prospectus, dated June 20, 2012, filed as part of the Company’s Registration Statement on Form S-3 (Registration No. 333-182242) filed with the U.S. Securities and Exchange Commission. The Company sold the Notes pursuant to an Underwriting Agreement, dated December 2, 2013 (the “Underwriting Agreement”), between the Company and Citigroup Global Markets Inc., Goldman, Sachs & Co., J.P. Morgan Securities LLC and RBC Capital Markets, LLC, as representatives of the several underwriters named therein.

The Notes will mature on December 15, 2018 and bear interest at the rate of 4.625% per annum. The Company may redeem all or a portion of the Notes at any time at an established redemption price, as described in the Indenture. In addition, prior to December 15, 2016, the Company may redeem up to 35% of the aggregate principal amount of the Notes with the net cash proceeds of certain equity offerings at a redemption price equal to 104.625%, plus accrued and unpaid interest.

If the Company undergoes a change of control, it must offer to repurchase the Notes at 101% of the principal amount, plus accrued and unpaid interest.

The Notes are the Company’s unsecured senior obligations and rank equally in right of payment with all of the Company’s existing and future senior debt and rank senior in right of payment to all of the Company’s existing and future subordinated debt. The Notes are effectively junior in right of payment to all of the Company’s existing and future secured debt to the extent of the assets securing such debt, and to any existing and future liabilities of the Company’s subsidiaries. The Notes are not guaranteed by any of the Company’s subsidiaries or any third party.

The Company intends to use the net proceeds from the offering of Notes for general corporate purposes, including the purchase of aircraft and investment in other aviation assets.

The Indenture contains covenants limiting the Company’s and the Company’s restricted subsidiaries’ ability to:

These covenants are subject to a number of important and significant limitations, qualifications and exceptions. Many of these covenants will cease to apply at all times after the Notes are rated investment grade from both Moody’s Investors Service, Inc. and Standard & Poor’s.

Events of default under the Indenture include, among others, the following: default for 30 days in the payment when due of interest on the Notes; default in payment when due of the principal of, or premium, if any, on the Notes; failure to comply with certain covenants in the Indenture; and certain events of bankruptcy or insolvency. In the case of an event of default arising from certain events of bankruptcy or insolvency with respect to the Company, all Notes then outstanding will become due and payable immediately without further action or notice.

The preceding is a summary of the terms of the Underwriting Agreement, the Indenture, the Supplemental Indenture and the Notes and is qualified in its entirety by reference to the Underwriting Agreement, attached as Exhibit 1.1 hereto, the Indenture, attached as Exhibit 4.1 hereto, the Supplemental Indenture, attached as Exhibit 4.2 hereto, and the Form of 4.625% Senior Notes due 2018, attached as Exhibit 4.3 hereto, and each is incorporated herein by reference.

The disclosure provided in Item 2.03 of this Form 8-K is hereby incorporated by reference into this Item 3.03.

Under the terms of the Indenture, the Company is subject to certain covenants that, among other things, limit its ability to pay dividends on or make distributions in respect of its capital stock, subject to certain exceptions and qualifications.

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Date: December 5, 2013

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