Exhibit 10.4

This SECOND SUPPLEMENTAL INDENTURE, dated as of October 1, 2012 (this “Supplemental Indenture”), is among Bristow Group Inc., a Delaware corporation (the “Company”), each of the parties identified under the caption “Existing Subsidiary Guarantors” on the signature pages hereto (the “Existing Subsidiary Guarantors”), the party identified under the caption “Additional Subsidiary Guarantor” on the signature pages hereto (the “Additional Subsidiary Guarantor” and, together with the Existing Subsidiary Guarantors, the “Subsidiary Guarantors”) and U.S. Bank National Association, as Trustee (the “Trustee”).

RECITALS

WHEREAS, the Company, the Existing Subsidiary Guarantors and the Trustee are party to that certain Indenture, dated as of June 17, 2008 (the “Base Indenture”) and that certain First Supplemental Indenture dated as of June 17, 2008 (the “First Supplemental Indenture”; the Base Indenture, as modified and supplemented by the First Supplemental Indenture, the “Indenture”), pursuant to which the Company has issued $115,000,000 principal amount of 3% Convertible Senior Notes due 2038 (the “Notes”);

WHEREAS, Section 9.01(c) of the Indenture permits the Company, the Subsidiary Guarantors and the Trustee to amend or supplement the Indenture in order to add additional Subsidiary Guarantors without the consent of the Holders of the Notes;

WHEREAS, all acts and things prescribed by the Indenture, by law and by the Certificate of Incorporation and the Bylaws (or comparable constituent documents) of the Company, of the Subsidiary Guarantors and of the Trustee necessary to make this Supplemental Indenture a valid instrument legally binding on the Company, the Subsidiary Guarantors and the Trustee, in accordance with its terms, have been duly done and performed; and

NOW, THEREFORE, to comply with the provisions of the Indenture and in consideration of the above premises, the Company, the Subsidiary Guarantors and the Trustee covenant and agree for the equal and proportionate benefit of the respective Holders of the Notes as follows:

ARTICLE 1

Section 1.01. This Supplemental Indenture is supplemental to the Indenture and does and shall be deemed to form a part of, and shall be construed in connection with and as part of, the Indenture for any and all purposes.

Section 1.02. This Supplemental Indenture shall become effective immediately upon its execution and delivery by each of the Company, the Subsidiary Guarantors and the Trustee.

ARTICLE 2

From this date, by executing this Supplemental Indenture, each of the Subsidiary Guarantors, including the Additional Subsidiary Guarantor, whose signatures appear below continue to be or hereby are, as applicable, subject to the provisions of the Indenture to the extent provided for in Article 10 thereunder.

ARTICLE 3

Section 3.01. Except as specifically modified herein, the Indenture and the Notes are in all respects ratified and confirmed and shall remain in full force and effect in accordance with their terms with all capitalized terms used herein without definition having the same respective meanings ascribed to them as in the Indenture.

Section 3.02. Except as otherwise expressly provided herein, no duties, responsibilities or liabilities are assumed, or shall be construed to be assumed, by the Trustee by reason of this Supplemental Indenture. This Supplemental Indenture is executed and accepted by the Trustee subject to all the terms and conditions set forth in the Indenture with the same force and effect as if those terms and conditions were repeated at length herein and made applicable to the Trustee with respect hereto.

Section 3.03. THIS SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.

Section 3.04. The parties may sign any number of counterparts of this Supplemental Indenture. Each signed counterpart shall be an original, but all of such executed counterparts together shall represent the same agreement. Delivery of an executed signature page to this Supplemental Indenture by facsimile or electronic transmission (i.e., .pdf or .tif) shall be as effective as delivery of a manually executed counterpart of this Supplemental Indenture.

[NEXT PAGE IS SIGNATURE PAGE]

IN WITNESS WHEREOF, the parties hereto have caused this Supplemental Indenture to be duly executed, all as of the date first written above.

Signature Page to Supplemental Indenture (3.00% Notes Indenture)

Signature Page to Supplemental Indenture (3.00% Notes Indenture)

Signature Page to Supplemental Indenture (3.00% Notes Indenture)