Exhibit 5.1

Hogan Lovells US LLP 1735 Market Street, Floor 23 Philadelphia, PA 19103 T+1 267 675 4600 F+1 267 675 4601 www.hoganlovells.com  

June 23, 2023

Board of Directors

NextNav Inc.

1775 Tysons Blvd., 5th Floor             

McLean, Virginia 22102

Ladies and Gentlemen:

We are acting as counsel to NexNav Inc., a Delaware corporation (the “Company”), in connection with its registration statement on Form S‑8 (the “Registration Statement”), filed with the Securities and Exchange Commission under the Securities Act of 1933, as amended (the “Act”) relating to the proposed offering of 3,500,000 shares of the common stock, par value $0.0001 per share (the “Common Stock”) of the Company (the “Shares”), which includes (i) 3,100,000 shares of Common Stock issuable pursuant to the NextNav Inc. 2021 Omnibus Incentive Plan (the “Incentive Plan”) and (ii) 400,000 shares of Common Stock issuable pursuant to the NextNav Inc. 2021 Employee Stock Purchase Plan (the “ESPP” and, together with the Incentive Plan, the “Plans”).  This opinion letter is furnished to you at your request to enable you to fulfill the requirements of Item 601(b)(5) of Regulation S‑K, 17 C.F.R. § 229.601(b)(5), in connection with the Registration Statement.

For purposes of this opinion letter, we have examined copies of such agreements, instruments and documents as we have deemed an appropriate basis on which to render the opinions hereinafter expressed.   In our examination of the aforesaid documents, we have assumed the genuineness of all signatures, the legal capacity of all natural persons, the accuracy and completeness of all documents submitted to us, the authenticity of all original documents, and the conformity to authentic original documents of all documents submitted to us as copies (including pdfs).  As to all matters of fact, we have relied on the representations and statements of fact made in the documents so reviewed, and we have not independently established the facts so relied on.  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 Delaware  General Corporation Law, as amended.  We express no opinion herein as to any other statutes, rules or regulations.

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 the terms of the Plans, and (iii) receipt by the Company of the consideration for the Shares specified in the resolutions of the Board of Directors (or a duly authorized committee thereof) and in the Plans, the Shares will be validly issued, fully paid, and nonassessable. 

Hogan Lovells US LLP is a limited liability partnership registered in the District of Columbia.“Hogan Lovells” is an international legal practice that includes Hogan Lovells US LLP and Hogan Lovells International LLP, with offices in:AlicanteAmsterdamBaltimoreBeijingBirminghamBostonBrusselsColorado SpringsDenverDubaiDusseldorfFrankfurtHamburgHanoiHo Chi Minh CityHong KongHoustonJohannesburgLondonLos AngelesLuxembourgMadridMexico CityMiamiMilanMinneapolisMonterreyMunichNew YorkNorthern VirginiaParisPerthPhiladelphiaRomeSan FranciscoSão PauloShanghaiSilicon ValleySingaporeSydneyTokyoWarsawWashington, D.C.Associated Offices:BudapestJakartaRiyadhShanghai FTZUlaanbaatar.Business Service Centers:JohannesburgLouisville.Legal Services Center:Berlin.For more information see www.hoganlovells.com

NextNav Inc. - 2 - June 23, 2023

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

We hereby consent to the filing of this opinion letter as Exhibit 5.1 to the Registration Statement. In giving this consent, we do not thereby admit that we are an “expert” within the meaning of the Act.

Very truly yours,

/s/ HOGAN LOVELLS US LLP

HOGAN LOVELLS US LLP