Exhibit 5.1

morrison & foerster llp beijing, berlin, boston,
brussels, denver, hong kong,
london, los angeles, new york,
northern virginia, palo alto,
san diego, san francisco, shanghai,
singapore, tokyo, washington, d.c.

May 16, 2022

Board of Directors

Sky Harbour Group Corporation

136 Tower Road, Suite 205

Westchester County Airport

White Plains, NY 10604

Re: Registration Statement on Form S-8

Ladies and Gentlemen:

We are acting as counsel to Sky Harbour Group Corporation (previously known as Yellowstone Acquisition Corp.), a Delaware corporation (the “Company”), in connection with the filing of a Registration Statement on Form S-8 (the “Registration Statement”) with the Securities and Exchange Commission under the Securities Act of 1933, as amended (the “Securities Act”) covering the offering of up to an aggregate of 5,211,975 shares of the Company’s Class A Common Stock, par value $0.0001 per share (the “Shares”), issuable pursuant to the Company’s 2022 Incentive Award Plan (the “2022 Plan”).

As counsel for the Company, we have examined originals or copies, certified or otherwise identified to our satisfaction, of such documents, corporate records, certificates of public officials and other instruments as we have deemed necessary for the purposes of rendering this opinion, and we are familiar with the proceedings taken and proposed to be taken by the Company in connection with the authorization, issuance and sale of the Shares. In our examination, we have assumed the genuineness of all signatures, the authenticity of all documents submitted to us as originals and the conformity with the originals of all documents submitted to us as copies. This opinion letter is given, and all statements herein are made, in the context of the foregoing.

This opinion letter is based as to matters of law solely on the General Corporation Law of the State of Delaware as currently in effect. We express no opinion herein as to any other laws, statutes, ordinances, rules, or regulations.

May 16, 2022

Page Two

Based upon, subject to and limited by the foregoing, we are of the opinion that following (i) effectiveness of the Registration Statement, (ii) issuance of the Shares pursuant to awards under the terms of the 2022 Plan, and (iii) receipt by the Company of the consideration for the Shares specified in the applicable resolutions of the Board of Directors of the Company or a duly authorized committee thereof and the 2022 Plan, the Shares will be validly issued, fully paid and nonassessable (except as to Shares issued pursuant to certain deferred payment arrangements, which will be fully paid and nonassessable when such deferred payments are made in full).

This opinion letter has been prepared for use in connection with the Registration Statement. We assume no obligation to advise you of any changes in the foregoing subsequent to the effective date of the Registration Statement.

We consent to the filing of this opinion as an exhibit to the Registration Statement, and we consent to the reference of our name wherever appearing in the Registration Statement and any amendments thereto. In giving such consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act.

Very truly yours,

/s/ Morrison & Foerster LLP