AMENDMENT NO. 5 to A320 Family Aircraft Purchase Agreement dated as of September 30, 2011 between Airbus S.A.S. and Frontier Airlines, Inc.

Such excluded information is not material and would likely cause competitive harm to the registrant if publicly disclosed.

Exhibit 10.16(u)

AMENDMENT NO. 5

to

A320 Family Aircraft Purchase Agreement

dated as of September 30, 2011

between

Airbus S.A.S.

and

Frontier Airlines, Inc.

Confidential

1

Amendment No. 5

This Amendment No. 5 (this “Amendment”) is entered into as of December 28, 2017, between Airbus S.A.S., a société par actions simplifiée organized and existing under the laws of the Republic of France, having its registered office located at ▇, ▇▇▇▇-▇▇▇▇▇ ▇▇▇▇▇ ▇▇▇▇▇▇▇▇▇, ▇▇▇▇▇ ▇▇▇▇▇▇▇, ▇▇▇▇▇▇ (the “Seller”), and Frontier Airlines, Inc., a corporation organized and existing under the laws of the State of Colorado, United States of America, having its principal corporate offices located at ▇▇▇▇ ▇▇▇▇▇▇▇ ▇▇▇, ▇▇▇▇▇▇, ▇▇▇▇▇▇▇▇ ▇▇▇▇▇ ▇▇▇ (the “Buyer” and, together with the Seller, the “Parties”).

WITNESSETH

WHEREAS, the Buyer and the Seller entered into an A320 Family Aircraft Purchase Agreement dated as of September 30, 2011 (as amended, supplemented and modified from time to time prior to the date hereof, the “Agreement”); and

WHEREAS, the Buyer and the Seller wish to amend certain terms of the Agreement;

NOW, THEREFORE, FOR GOOD AND VALUABLE CONSIDERATION, THE SUFFICIENCY OF WHICH IS HEREBY ACKNOWLEDGED, THE SELLER AND THE BUYER AGREE AS FOLLOWS:

Capitalized items used herein and not otherwise defined herein will have the meanings assigned to them in the Agreement. The terms “herein,” “hereof” and “hereunder” and words of similar import refer to this Amendment.

Confidential

2

“The Seller will sell and deliver to the Buyer, and the Buyer will purchase and take delivery of two hundred fourteen (214) Aircraft, consisting of eighty (80) A320 Backlog Aircraft, one hundred (100) A320 Incremental Aircraft and thirty-four (34) A321 Incremental Aircraft, from the Seller, subject to the terms and conditions contained in this Agreement.

The A319 Aircraft identified in Clause 9.1 of the Agreement as Aircraft Rank 63 through and including Aircraft Rank 80 are hereby converted from A319 Aircraft to A320 Aircraft pursuant to this Agreement.”

A319 Aircraft – an A319-100N aircraft to be sold by the Seller and purchased by the Buyer pursuant to this Agreement, including the A319 Airframe and all components, equipment, parts and accessories installed in or on such A319 Airframe and the A319 Propulsion System installed thereon upon delivery.

A320 Aircraft – an A320-200N to be sold by the Seller and purchased by the Buyer pursuant to this Agreement, including the A320 Airframe and all components, equipment, parts and accessories installed in or on such A320 Airframe and the A320 Propulsion System installed thereon upon delivery.

A321 Aircraft – an A321-200NX to be sold by the Seller and purchased by the Buyer pursuant to this Agreement, including the A321 Airframe and all components, equipment, parts and accessories installed in or on such A321 Airframe and the A321 Propulsion System installed thereon upon delivery.

A321 Airframe – an A321 Aircraft, excluding the A321 Propulsion System therefor.

A319 Backlog Aircraft – an A319 Aircraft.

A320 Backlog Aircraft – an A320 Aircraft, other than A320 Incremental Aircraft.

Confidential

3

A321 Backlog Aircraft – an A321 Aircraft, other than A321 Incremental Aircraft.

A320 Incremental Aircraft – an A320-200N aircraft identified as an “A320 Incremental Aircraft” in the delivery schedule set forth in Clause 9.1 to be sold by the Seller and purchased by the Buyer pursuant to this Agreement, including the A320 Airframe and all components, equipment, parts and accessories installed in or on such A320 Airframe and the A320 Propulsion System installed thereon upon delivery.

A321 Incremental Aircraft – an A321-200NX aircraft identified as an “A321 Incremental Aircraft” in the delivery schedule set forth in Clause 9.1 to be sold by the Seller and purchased by the Buyer pursuant to this Agreement, including the A321 Airframe and all components, equipment, parts and accessories installed in or on such A321 Airframe and the A321 Propulsion System installed thereon upon delivery.

A321 Propulsion System – as defined in Clause 2.3.

A319 Standard Specification – the A319-100N standard specification document number [***], a copy of which is annexed as Exhibit A-2 to the Agreement.

A320 Standard Specification – the A320-200N standard specification document number [***], a copy of which is annexed as Exhibit A-1 to the Agreement.

A321 Specification – the A321 Standard Specification as amended by all applicable SCNs.

A321 Standard Specification – the A321-200NX ACF standard specification document number [***], as applicable, a copy of each is annexed as Exhibit A-3 to the Agreement.

Aircraft – any or all of the A319 Aircraft, the A320 Aircraft and, the A321 Aircraft.

Airframe – any or all of the A319 Airframe, the A320 Airframe or the A321 Airframe.

Backlog Aircraft – the A319 Backlog Aircraft, the A320 Backlog Aircraft and the A321 Backlog Aircraft.

Incremental Aircraft – the A320 Incremental Aircraft and A321 Incremental Aircraft.

Predelivery Payment – with respect to any Aircraft, any of the payments determined in accordance with Clause 5.3 for such Aircraft.

Confidential

4

Propulsion System – any or all, as applicable, of the A319 Propulsion System, A320 Propulsion System and the A321 Propulsion System.

Propulsion System Manufacturer – as applicable, the manufacturer of the A319 Propulsion System, A320 Propulsion System or the A321 Propulsion System.

Propulsion System Price Revision Formula – the applicable Propulsion System price revision formula set forth in Part 2 or Part 3 of Exhibit C.

Propulsion System Reference Price – the applicable Propulsion System reference price set forth in Part 2 or Part 3 of Exhibit C.

Seller Price Revision Formula – with respect to the Incremental Aircraft, the formula set forth in Part 1A of Exhibit C and, for all other Aircraft, the formula set forth in Part 1 of Exhibit C.

Specification – as applicable, the A319 Specification, the A320 Specification or the A321 Specification.

Standard Specification – as applicable, the A319 Standard Specification, A320 Standard Specification or the A321 Standard Specification.

Clause 2 of the Agreement is deleted in its entirety and replaced with the following quoted text:

The A321 Aircraft will be manufactured in accordance with the A321 Standard Specification, as may already have been modified or varied at the date of this Agreement by the Specification Change Notices listed in Appendix 1 or Appendix 2 to Exhibit A-3, as applicable.

The A320 Aircraft will be manufactured in accordance with the A320 Standard Specification, as may already have been modified or varied at the date of this Agreement by the Specification Change Notices listed in Appendix 1 or Appendix 2 to Exhibit A-1, as applicable.

Confidential

5

The A319 Aircraft will be manufactured in accordance with the A319 Standard Specification, as may already have been modified or varied at the date of this Agreement by the Specification Change Notices listed in Appendix 1 to Exhibit A-2.

The parties understand and agree that the Specification may be further amended following signature of this Agreement in accordance with the terms of this Clause 2.

The Specification may be amended by written agreement between the parties in a notice, substantially in the form set out in Exhibit B1 (each, a “Specification Change Notice” or “SCN”) and will set out the SCN’s Aircraft embodiment rank and will also set forth, in detail, the particular change to be made to the Specification and the effect, if any, of such change on design, performance, weight, Delivery Date of the Aircraft affected thereby and on the text of the Specification. An SCN may result in an adjustment of the Aircraft Base Price, which adjustment, if any, will be specified in the SCN.

The Specification may also be amended to incorporate changes deemed necessary by the Seller to improve the Aircraft, prevent delay or ensure compliance with this Agreement (“Development Changes”), as set forth in this Clause 2.

Confidential

6

In such cases, the Buyer will have access to the details of such changes through the relevant application in AirbusWorld.

Each A319 Airframe will be equipped with a set of two (2) CFM LEAP-1A24 engines or two (2) IAE PW1124G-JM engines (upon selection such set, an “A319 Propulsion System”).

Each A321 Airframe will be equipped with a set of two (2) CFM LEAP-1A32 engines, two (2) CFM LEAP-1A33B2 engines or two (2) IAE PW1133G-JM engines (upon selection such set, an “A321 Propulsion System”).

Confidential

7

Within a reasonable period following signature of this Agreement, the Seller will provide the Buyer with a customization milestones chart (the “Customization Milestone Chart”), setting out how far in advance of the Scheduled Delivery Month of the Aircraft an SCN must be executed in order to integrate into the Specification any items requested by the Buyer from the Seller’s catalogues of Specification change options (the “Option Catalogs”).

The Customization Milestone Chart will in particular define the date(s) by which the contractual definition of the Aircraft must be finalized and all SCNs need to have been executed by the Buyer (the “Contractual Definition Freeze” or “CDF”) in order to enable their incorporation into the manufacturing of the Aircraft and Delivery of the Aircraft in the Scheduled Delivery Month. Each such date shall be referred to as a “CDF Date”.”

Clause 3.1 of the Agreement is deleted in its entirety and replaced with the following quoted text:

The Base Price of the Aircraft is the sum of:

The Base Price of the A320 Airframe has been established in accordance with the average economic conditions prevailing in [***] and corresponding to a theoretical delivery in [***].

Confidential

8

The Base Price of the A320 Airframe for the A320 Incremental Aircraft has been established in accordance with the average economic conditions prevailing in [***] and corresponding to a theoretical delivery in [***].

[***]

Said Base Price has been established in accordance with the delivery conditions prevailing in [***] and has been calculated from the reference price indicated by CFM and set forth in Part 2 of Exhibit C.

For A320 Incremental Aircraft, the Base Price of a set of two (2) LEAP-1A26 engines is:

[***]

Said Base Price has been established in accordance with the delivery conditions prevailing in [***] and has been calculated from the reference price indicated by CFM and set forth in Part 2 of Exhibit C.

[***]

Said Base Price has been established in accordance with the delivery conditions prevailing in [***] and has been calculated from the reference price indicated by IAE and set forth in Part 3 of Exhibit C.

Confidential

9

In respect of A319 Backlog Aircraft, the Base Price of the A319 Airframe is the sum of the following base prices:

[***]

Said Base Price has been established in accordance with the delivery conditions prevailing in [***] and has been calculated from the reference price indicated by CFM and set forth in Part 2 of Exhibit C.

Confidential

10

The Base Price of the A321 Airframe for the A321 Incremental Aircraft has been established in accordance with the average economic conditions prevailing in [***] and corresponding to a theoretical delivery in January 2018.

[***]

Said Base Price has been established in accordance with the delivery conditions prevailing in [***] and has been calculated from the reference price indicated by CFM International and set forth in Part 2 of Exhibit C.

For A321 Incremental Aircraft, the Base Price of a set of two (2)

CFM LEAP-1A32 engines is:

[***]

for CFM LEAP-1A33B2 engines (if selected by the Buyer) is:

[***]

Said Base Prices has been established in accordance with the delivery conditions prevailing in [***] and have been calculated from the reference prices indicated by CFM and set forth in Part 2 of Exhibit C.

[***]

Confidential

11

Said Base Price has been established in accordance with the delivery conditions prevailing in [***] and has been calculated from the reference price indicated by IAE and set forth in Part 3 of Exhibit C.”

“[***] the Seller will give the Buyer at least [***] written notice of the anticipated date on which the Aircraft will be Ready for Delivery.

[***] the Seller will give the Buyer (i) at least [***] written notice of the [***] period in which the Aircraft is anticipated to be Ready for Delivery, and (ii) at least [***] written notice of the anticipated date on which the Aircraft will be Ready for Delivery. [***]

[***]

[***]

[***]

[***]

[***]

[***]

Confidential

12

Appendix 1 and Appendix 2 to Exhibit A-1 to the Agreement, as each are set forth in Attachment I to this Amendment, are incorporated into the Agreement by replacing Appendix 1 and adding Appendix 2 to Exhibit A-1.

Appendix 1 to Exhibit A-2 to the Agreement is replaced with the Appendix 1 to Exhibit A-2 as set forth in Attachment II to this Amendment.

Exhibit A-3 to the Agreement is replaced with Exhibit A-3 as set forth in Attachment III to this Amendment.

“1 AIRCRAFT CONFIGURATION

The guarantees defined in Paragraphs 2 and 3 below (the “Guarantees”) are applicable to the A320neo Aircraft as described in the A320neo Standard Specification [***] as amended by SCNs for:

Confidential

13

hereinafter referred to as the “Specification” without taking into account any further changes thereto as provided in the Agreement except as provided in Paragraph 6 below (for purposes of this Letter Agreement No. 6A the “A320 Aircraft”).”

“1 AIRCRAFT CONFIGURATION

The guarantees defined in Paragraphs 2 and 3 below (the “Guarantees”) are applicable to the A319neo Aircraft as described in the A319neo Standard Specification [***] as amended by SCNs for:

hereinafter referred to as the “Specification” without taking into account any further changes thereto as provided in the Agreement except as provided in Paragraph 6 below (for purposes of this Letter Agreement No. 6C the “A319 Aircraft”).”

“1 AIRCRAFT CONFIGURATION

The guarantees defined in Paragraphs 2 and 3 below (the “Guarantees”) are applicable to the A321neo Aircraft as described in the A321neo Standard Specification [***] as amended by SCNs for:

hereinafter referred to as the “Specification” without taking into account any further changes thereto as provided in the Agreement except as provided in Paragraph 6 below (for purposes of this Letter Agreement No. 6C the “A321 Aircraft”).”

Confidential

14

[***]

[***]

Notwithstanding anything to the contrary in the Agreement, the following provisions will not apply to [***]

This Amendment shall terminate and be of no further force and effect, and the Parties shall have no obligation or liability to the other, whether in contract, tort or otherwise in respect hereof at the close of business, December 29, 2017 unless [***].

For purpose of this Clause 9:

[***]

This Amendment is subject to the provisions of Clauses 22.6, 22.11 and 21 of the Agreement.

This Amendment may be signed by the Parties in counterparts, which when signed and delivered will each be an original and together constitute but one and the same instrument. Counterparts may be delivered in original, faxed or emailed form, with originals to be delivered in due course.

Confidential

15

IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be signed by their respective duly authorized officers or agents as of the day and year first above written.

Confidential

Attachment I to Amendment No. 5

Appendix 1 to Exhibit A-1

[***]

Confidential

Appendix 2 to Exhibits A-1

[***]

Confidential

Attachment II to Amendment No. 5

Appendix 1 to Exhibit A-2

[***]

Confidential

EXHIBIT A-3

A321 SPECIFICATION

The A321 Standard Specification is contained in a separate folder.

Confidential

Appendix 1 to Exhibit A-3

[***]

Confidential

2

Appendix 2 to Exhibits A-3

[***]

Confidential

3

Attachment IV to Amendment No. 5

Delivery Schedule Table

Confidential

Confidential

2

Confidential

3

Confidential

4

Confidential

5

[***]

Confidential

6