ULCC Frontier Group Holdings Inc

Exhibit 99.1

		Frontier Airlines, Inc.
		4545 Airport Way
		Denver, Colorado 80239

Confidential

Mr. H. McIntyre Gardner

Chairman of the Board

Mr. Edward M. Christie III

President and Chief Executive Officer

Spirit Airlines, Inc.

1731 Radiant Drive

Dania Beach, FL 33004

January 7, 2025

Dear Mr. Gardner and Mr. Christie:

On behalf of Frontier Group Holdings, Inc. (“Frontier”), we are pleased to submit our proposal (our “Proposal”) to provide an alternative restructuring plan for the creditors and stockholders of Spirit Airlines, Inc. (“Spirit”) including the combination of Spirit with Frontier. Our Proposal is structured to maximize value and execution certainty for Spirit and its creditors and stockholders, and we firmly believe it would result in a transaction that is more favorable to the Spirit creditors and stockholders than the one outlined in Spirit’s current proposed Plan of Reorganization (the “Plan”). We believe our Proposal is capable of being consummated expeditiously in accordance with the terms described in this letter.

All capitalized terms not defined in this Proposal are as defined in the Plan.

Compelling Strategic Rationale – true, low-cost alternative to the Big Four

We strongly believe that now is the time to form the country’s first, at-scale, low-fare carrier by combining our two businesses. A Frontier / Spirit combination will bring unmatched benefits:

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		Frontier Airlines, Inc.
		4545 Airport Way
		Denver, Colorado 80239

Long-term Opportunity for Spirit Team Members

We value all members of Team Frontier and we look forward to integrating the Spirit Team into our family. By enjoying a faster growth trajectory and competing more effectively with the Big Four, the combined business will create more sustainable career opportunities than either business can achieve on its own.

Terms of Frontier Proposal

Our Proposal provides for the issuance of $400 million principal amount of debt by Frontier and 19.0% of Frontier’s common equity (the “Proposal Consideration”) at closing, to be distributed to the Holders of Senior Secured Notes, Convertible Notes, and Existing Interests in amounts that enhance recoveries to each of those groups relative to the Plan. As discussed in greater detail below, the aggregate value of the Proposal Consideration is no less than $2,162 million, before taking into account any synergies from the combination of Frontier and Spirit. We and our advisors would be pleased to discuss with you, in greater detail, potential means of allocating the Proposal Consideration consistent with those objectives.

Consistent with the Plan, our Proposal assumes the Consenting Creditors will complete a $350 million Rights Offering prior to the Effective Date and will utilize the proceeds to retire the DIP Financing upon emergence from Chapter 11, with any excess cash going to the combined company’s balance sheet on the Effective Date.

Proposal Offers Superior Value for Spirit Stakeholders

Our Board of Directors has unanimously approved our Proposal and we are highly confident that our Proposal can be consummated on a timely basis. Using the assumptions detailed in the Plan, we believe our Proposal offers more value to Holders of the Senior Secured Notes, Convertible Notes, and Existing Interests than the Plan.

Prior to taking into account any synergies that could be created as a result of the transaction, these parties would receive $400 million principal amount of debt plus $1,762 million in equity under our Proposal compared to $840 million and $806 million under the Plan¹. If we include synergies (as described below), the aggregate value to these stakeholders would increase to up to $2,901 million under our Proposal.²

Our estimate of the value of the Proposal Consideration provided by our Proposal is based on the following:

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		Frontier Airlines, Inc.
		4545 Airport Way
		Denver, Colorado 80239

Confirmatory Due Diligence and Next Steps

We expect that the finalization of definitive documentation and confirmatory due diligence will be completed expeditiously. This transaction is of significant interest to Frontier, and we are prepared to commit all the resources necessary to acquire Spirit. We are committed to moving quickly, including working proactively with regulators and other stakeholders in light of the benefits of this transaction and the current financial position of Spirit.

Advisors

Frontier has retained Citigroup Global Markets, Inc. as its financial advisor for this transaction and Latham & Watkins LLP as its legal counsel. Our advisors are ready, willing and able to coordinate with Spirit’s advisors on the content of our Proposal and next steps.

Other

Our Proposal is submitted on the understanding that, except as and to the extent required by law, all information contained herein or related to the contents of this letter, including the terms of our Proposal, are confidential, and should not be disclosed to anyone other than (a) Spirit’s officers and directors, and its legal and financial advisors, who need to know the information to evaluate our Proposal, and (ii) to counsel and advisors to the Consenting Stakeholders solely to the extent required by Section 6.01(i) of the Restructuring Support Agreement, in each case on a strictly confidential basis. This letter is not intended to be, and is not, a binding contract between us or an offer by us capable of acceptance, and there will be no legally binding contract or agreement between Frontier and Spirit regarding a transaction unless and until a definitive agreement is executed and delivered.

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		Frontier Airlines, Inc.
		4545 Airport Way
		Denver, Colorado 80239

Summary

Our Proposal represents a compelling opportunity for your creditors and stockholders to receive a significant premium for their investment in Spirit, with greater value than the proposed transaction as described in the Plan. We firmly believe that our Proposal is in the best interests of your creditors and stockholders and that they will benefit from your cooperation with us to allow them to realize the benefits of our Proposal. We and our advisors are ready to engage with you immediately to reach agreement on the terms of our transaction as soon as possible.

We look forward to working together with you to achieve the optimal outcome for your creditors, stockholders, customers and Team Members, and are ready and available to discuss at your earliest convenience.

Sincerely,

W. A. Franke		Barry Biffle
Chairman of the Board		Chief Executive Officer

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Exhibit 99.2

CONFIDENTIAL

Frontier Group Holdings, Inc.

4545 Airport Way

Denver, Colorado 80239

Attn: Mr. W. Franke, Mr. B. Biffle

January 11, 2025

Gentlemen:

Thank you for your letter dated January 7, 2025.

We are of course always exploring and open to ideas and proposals that maximize value for our Company and its stakeholders, and we share your view that a combination of our two companies has logic and could create a potent competitor in the marketplace. However, as explained further below, we are concerned about the timing of your proposal, and we also believe that your economic proposal is far short of what our stakeholders would support.

In our last discussions in the Summer and Fall of 2024, we were moving forward with you based on an agreement in principle, reached after several rounds of negotiations, that would have involved Spirit stakeholders receiving 26.5% of the equity of the combined company and $580 million of take-back debt. Assuming other acceptable terms, Spirit’s Board and management were willing to push forward expeditiously with a deal along those lines, even though our preliminary discussions with our bondholders last Fall generated a negative reaction from them to the transaction on those terms.

The proposal in your letter of January 7 represents an extremely material reduction in value compared to our 2024 agreement in principle. The $580 million in take-back debt has been reduced to $400 million in debt, the 26.5% of equity to 19%, and notwithstanding those reductions in consideration for Spirit stakeholders, your proposal further assumes our creditors will make an incremental $350 million equity investment, effectively requiring them to fund their own debt position in the combined company. Nor does your proposal address our now-drawn $300M RCF facility or many other core matters. Your letter also does not address liquidity that may be needed to bridge to a potential closing.

The new Frontier proposal, in our opinion, also falls far short of the consideration to be received by Spirit stakeholders under the current Chapter 11 Plan of Reorganization. The $400M of debt is less than half of the debt that will be provided to creditors under the Plan, and it is unclear based on our prior discussions how this new debt will be structured, whether and by what it will be secured, and whether it will be structured to trade in the

market as a par security. There is also substantial uncertainty as to the value of the equity to be received and whether Frontier’s pro forma stock price will dramatically appreciate, as you imply in your letter, to a level that provides comparable or greater value to Spirit stakeholders, and we believe our creditors will look skeptically on these factors.

Please note that we have discussed the new Frontier proposal with the advisors to our bondholders as contemplated by your letter and required by our restructuring support agreement. We are told they believe your current proposal is so insufficient as not to merit a counter.

In addition to the significant improvement in the economic package that would be needed, as you will appreciate, for us to credibly advocate for a Frontier-Spirit combination to our constituents, the deal must provide closing certainty, without off-market closing conditions (of the kind you previously proposed) that give Frontier broad discretion to walk away. We would also need to understand whether your proposal would contemplate any rejection of contracts or address labor agreements, as that would likely complicate and prolong our chapter 11 proceedings. Also, given the level of diligence that you conducted in the Fall and the information available on the public docket, we expect bring-down confirmatory diligence would be de minimis and completed in a matter of days.

As we noted above, we share your view on the logic of a combination of our companies and are willing to work with you constructively to see if there is a deal that can be reached that is acceptable to all parties. Given the timing (we are about three weeks before our scheduled confirmation hearing), we would need to move very quickly in discussions with you and our stakeholders to see if there is a deal to be done here – and we are willing to commit the time and effort towards that goal but need assurances and feedback from you on the above topics. We recognize that the gap may be too large, and if we cannot reach agreement with you, we are highly confident that our extremely efficient standalone reorganization will position us well for the future.

Sincerely,
Ted Christie		Mac Gardner

Exhibit 99.3

		Frontier Airlines, Inc.
		4545 Airport Way
		Denver, Colorado 80239

Confidential

Mr. H. McIntyre Gardner

Chairman of the Board

Mr. Edward M. Christie III

President and Chief Executive Officer

Spirit Airlines, Inc.

1731 Radiant Drive

Dania Beach. FL 33004

January 16, 2025

Dear Mr. Gardner and Mr. Christie:

In response to your letter dated January 11, 2025, it appears the parties continue to agree there is compelling industrial logic to a combination of our two companies. However, your response suggests material differences between us on how best to move forward, if at all. Following is a response to some of the issues noted in your letter and we’ve attached a presentation that we believe illustrates that our proposal is financially superior for your impacted stakeholders than the plan you currently have on file with the Bankruptcy Court (the “Plan”).

Regarding your comments about the deal terms we discussed in 2024, we obviously concluded not to move forward on those terms based on the diligence available to us; and our view of pursuing a transaction under those terms has not changed. Spirit has incurred substantial losses over the last few years and the most recent version of your long-term budget that we were able to review projected operating losses continuing through 2025. In addition, you will recall that we identified substantial non-operating cashflow challenges facing Spirit going forward. We have consistently advised you that we would not pursue a transaction that could potentially put Frontier at risk and, given the ongoing cash challenges we saw in the Spirit business plan, we determined it was not in our interest to move forward.

After our last discussions, Spirit filed for bankruptcy protection. It remains unclear to us how the bankruptcy has impacted your long-term budget, but we would expect a negative impact to your cash forecast assuming (i) the cash drain from the fees and expenses of a bankruptcy and (ii) the higher cost of financing the business in this interest rate environment While we assume Spirit has benefited from recent industry yield improvements, we would want to understand if the bankruptcy has had any negative impact on your sales and / or yields as compared to your pre-bankruptcy forecast

Though we continue to see near term risk for a Spirit transaction, we have followed your bankruptcy filings closely to see if we could identify a deal structure that would make sense for our shareholders and for your impacted stakeholders, including your creditors and stockholders.

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				Frontier Airlines, Inc. 4545 Airport Way Denver, Colorado 80239

We strongly believe the proposal we put forth in our letter dated January 7, 2025 addresses the business risks we previously identified and delivers a superior financial result to your impacted stakeholders. The attached presentation compares the two proposals and we believe clearly makes the case.

Regarding your question about additional diligence work we may require, our January 7th letter noted we just need to complete confirmatory diligence. Assuming you have detail readily available, we expect this would take no more than 5 to 10 days. We anticipate diligence would be limited to a review of your Q4 results, an update on your recent sales trends, an updated 2-year cash forecast (to include the impact of the bankruptcy), a disclosure of any material contracts or changes to the business since we last talked and a tax review of any impact resulting from the bankruptcy (such as NOLs).

Given our prior negotiations, we expect definitive documentation would also be a fairly quick process. And based on your prior discussions with the DOJ and the DOT — and the obvious, procompetitive benefits of a Frontier/Spirit merger for consumers — we also anticipate any antitrust review or regulatory review would proceed on an expedited basis.

Assuming your Board and creditors agree to the terms of our proposal, we would not require any special conditions to closing, nor do we currently see the need for bridge financing. We have assumed that the Spirit revolver would remain in place to its current maturity (which we believe is 2026) and that the $350 million rights offering is completed. Coupled with Frontier’s strong balance sheet, current cash position and cash flow production, we believe the combined company would have sufficient liquidity to solve the challenges we identified several months ago and to fund any cash outflows (dis-synergies) we would incur with the merger of the two companies. This includes an assumption that there would not be a need to address any of the Spirit labor contracts in your bankruptcy and the combined company would work post-closing with the various bargaining units to merge labor contracts.

We recommend getting on a call at your earliest convenience to review the attached presentation and to address any remaining questions or concerns you may have.

Sincerely,

W. A. Franke		Barry L. Biffle
Chairman of the Board		Chief Executive Officer

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Exhibit 99.4

Exhibit 99.4 Presentation to Spirit January 2025

Frontier’s proposal ensures superior economics, certainty, and speed for Spirit’s stakeholders relative to the Spirit standalone plan Stronger, More Competitive Airline ïƒ~ Transaction with Frontier creates America’s first low-cost carrier with sufficient scale to compete with the Big Fourïƒ~ Complementary networks bring more low fares to more markets and generate meaningful and achievable synergies Challenges with Spirit’s Standalone Plan ïƒ~ Spirit’s plan relies on robust valuation assumptions against a business plan with significant execution risk to generate equity valueïƒ~ Even if the plan is achieved, creditors do not realize a full recovery, and shareholders have zero recoveryïƒ~ Leverage remains high on 2025E EBITDAR (8.9x) Frontier’s Superior Alternative ïƒ~ Even without synergies, Frontier’s plan provides greater creditor recovery while also providing value to shareholdersïƒ~ On a combined basis, significantly lower leverage on 2025E EBITDAR (4.1x)ïƒ~ On a standalone basis, Spirit would need to achieve a valuation meaningfully higher than its plan currently contemplates for its creditors to realize the economics offered in Frontier’s alternativeïƒ~ A combination with Frontier de-risks Spirit’s business transformation plan and positions the combined airline to more effectively compete with the Big Four over the long term A combination with Frontier can proceed quickly, with minimal required due diligence or closing conditions Confidential and proprietary 2 2

($ in millions) Spirit Standalone Restructuring Frontier Proposal Creditor Consideration Exit Secured Notes $840 $400 11.0% Cash / 8.0% Cash + 4.0% PIK Coupon 11.0% Cash / 8.0% Cash + 4.0% PIK (specifics to be discussed) % Ownership 100% of Spirit 19.0% of PF Frontier + Spirit Pro Forma Entity Spirit Frontier + Spirit Revenue (FY26) $5,411 $11,059 EBITDAR (FY26) $1,041 $3,476 (1) Net Debt (2/28/2025) $5,937 $9,356 Net Leverage(2) 8.9x 4.1x Run-Rate Synergies — $600 Equity Value $806 $13,161 (@ 6.5x EBITDAR FY26 per RSA Plan) Total Value to Stakeholders $1,646 $2,901 Recovery %(4) Recovery %(4) Recovery Recovery %(3) (Excl. Synergies) (Incl. Synergies) Senior Secured Notes 95% 106% 141% Convertible Notes 56% 100% 137% Common Stock(5) $0.00 / share $0.80 / share $1.15 / share Notes: Spirit RSA and Frontier Proposal reflect $350mm equity rights offering. Recovery rates for senior secured notes and convertible notes are based on principal value and share of equity rights offering. Recovery rates exclude impact from other secured / priority claims. (1) Figures include $600mm of run-rate synergies. (2) Net leverage reflects net debt as of 02/28/2025 divided by 2025E Pro forma EBITDAR incl. 50% credit for synergies. (3) Reflects Spirit equity ownership split of 76% senior secured noteholders, 24% convertible notes. (4) Illustrative equity ownership split of 65% senior secured noteholders, 30% convertible notes, 5% common stock. (5) Per share figures based on Spirit basic shares outstanding as of November 14, 2024; rounded to the nearest $0.05. Confidential and proprietary 3 3

Compelling Proposal to Acquire Spirit To Create America’s First At-Scale, Low-Cost Competitor to Big Four Creating a Stronger Airline with Long-Term Viability to Compete More Effectively • 5th largest U.S. airline, growing to 100M annual passengers and 400+ aircraft within a few years • Top three carrier in more than half of the top 25 U.S. airports • Meaningfully increases presence in numerous major U.S. markets Offering More Low Fares and Premium Options to Travelers • Provides more low fares to more consumers, enabling billions in savings compared to prices charged by Big Four • Improves frequent flyer and loyalty programs as well as a more diversified product with premium options • Enables more reliable service through operating efficiencies • Enhances travel experience for customers Delivering Value for Financial Stakeholders • Creates compelling financial opportunity for Spirit creditors and shareholders • Provides greater value and recovery relative to Spirit standalone restructuring plan Significant Synergy Potential • Opportunity to participate in upside potential from owning a larger, more competitive airline with estimated synergies of $600M+ Confidential and proprietary 4 4

Stronger Airline with Long-Term Viability to Compete Against Big Four 2023 Available Seat Miles Consumers Win: Low Fares with Premium Options 5th largest U.S. airline, growing to 100M annual passengers and 400+ aircraft within a few yearsïƒ~ Provides more low fares to more consumers, enabling billions in savings compared to Top three carrier in more than half of the top 25 U.S. airports prices charged by Big Four ïƒ~ Improves frequent flyer and loyalty programs as well as a more diversified product with premium options ïƒ~ Enables more reliable service through operating efficiencies ïƒ~ Enhances travel experience for customers Frontier + Spirit Combined Source: Company filings. Confidential and proprietary 5 5

Frontier Proposal creates significantly greater value than Spirit Standalone Restructuring Plan. ($ in millions); FY26 EBITDAR Multiples Spirit Standalone Restructuring Frontier Proposal (Excluding Synergies) As of 02/28/2025, $840mm Exit Secured Notes $400mm Exit Secured Notes; 19.0% Ownership to Spirit Frontier Median(1) RSA Plan Valuation Multiple Valuation Multiple 4.5x 5.5x 6.5x 4.5x 5.5x 6.5x Equity Value -—- $806 Equity Value $3,586 $6,462 $9,274 Exit Secured Notes — $539 $700 Exit Secured Notes $333 $333 $333 Equity Interest -—- $613 Equity Interest $442 $796 $1,142 Secured Sr. Secured Noteholders — $539 $1,313 Secured Sr. Secured Noteholders $775 $1,129 $1,475 . Sr % Recovery — 39% 95% Sr . % Recovery 56% 81% 106% Exit Secured Notes — $89 $140 Exit Secured Notes $67 $67 $67 Equity Interest -—- $194 Equity Interest $206 $371 $532 Convert Convertible Noteholders — $89 $334 Convert Convertible Noteholders $272 $437 $599 % Recovery — 15% 56% % Recovery 45% 73% 100% Net Leverage Frontier Proposal (Incl. $600mm of Synergies) $400mm Exit Secured Notes; 19.0% Ownership to Spirit Net Debt as of 02/28/2025 divided by FY25 EBITDAR 8.9x Valuation Multiple 4.5x 5.5x 6.5x Equity Value $6,286 $9,762 $13,161 Exit Secured Notes $333 $333 $333 Equity Interest $774 $1,202 $1,620 4.1x Secured Sr. Secured Noteholders $1,107 $1,535 $1,954 . Sr % Recovery 80% 111% 141% Exit Secured Notes $67 $67 $67 Equity Interest $361 $560 $755 Convert Convertible Noteholders $427 $627 $822 Spirit Standalone Frontier + Spirit % Recovery 71% 105% 137% Source: Spirit Disclosure Statement (Chapter 11 Plan of Reorganization), filed as of December 18, 2024. Notes: Spirit RSA and Frontier Proposal reflect $350mm equity rights offering. Recovery rates for senior secured notes and convertible notes are based on principal value and share of equity rights offering. Recovery rates exclude impact from other secured / priority claims. (1) Median industry multiple based on Southwest Airlines, JetBlue Airways, Frontier Airlines, Allegiant, and Sun Country Airlines. Confidential and proprietary 6 6

($ in millions) Total Value to Stakeholders (Senior Secured Notes + Convertible Notes + Common Equity) Spirit RSA Frontier Proposal (Excl. Synergies) Frontier Proposal (Incl. Synergies) $2,901 $400mm Exit Secured Notes + 19% Equity Interest in PF $2,585 Frontier + Spirit $2,255 $2,162 $1,925 $1,901 $1,594 $1,628 $1,646 $840mm Exit Secured Notes + $1,355 100% Equity Interest $1,264 $1,149 in Spirit $1,081 $808 Exit Secured Notes Amount: $840mm $629 Negative Equity Value / Debt Impairment -—- $108 4.0x 4.5x 5.0x 5.5x 6.0x 6.5x Valuation Multiple (FY26 EBITDAR) Confidential and proprietary 7 7

• Given extensive diligence conducted to date, Frontier envisions an expedited due diligence process that may be completed in approximately 5-10 days • Key diligence items include: – Sales performance relative to plan – Confirmation of latest Pratt & Whitney agreement providing compensation for 2025 AOGs – Updated 2-year cash flow forecast, inclusive of Chapter 11 costs – Disclosure of any material contract or business changes – Tax considerations, including any Chapter 11 impact to NOLs Confidential and proprietary 8 8

Exhibit 99.5

Mark,

I asked Barry and Bill to address some of the questions you asked yesterday. Their response is below.

Roh and I are happy to follow up at your convenience.

Best,

John

Sent with BlackBerry Work

(www.blackberry.com)

From: [flyfrontier.com] Biffle, Barry <###>

Date: Friday, Jan 24, 2025 at 6:20 PM

To: Grier, John F [BKG-IB] <###>

Cc: Bill Franke <###>, brianfranke <###>, Andrew Broderick <###>, Link, Brian [BKG-IB] <###>, Adavikolanu,

Rohith [BKG-IB] <###>, Patel, Sagar1 [BKG-IB] <###>, Grasberger, Nick [BKG-IB] <###>

Subject: Top Gun response to Whatley

John:

You have asked Bill and I to address several questions that Mark Whatley of Evercore raised yesterday. Please find our responses below.

Question 1. Why now? Saturn is just a few weeks from exit and we are proposing they stay in Chapter 11 for additional months. This imposes considerable costs and risks on then. Why does this need to happen now, why not wait until they exit and then engage?

There are several reasons.

First, under the current standalone plan, you will emerge highly levered, losing money at the operating level and this would not be a transaction we would pursue. Standalone, Saturn emerges over 8x levered and it takes two years to get down to 5x (still a high level). Pro forma, the companies would emerge close to 5x while we wait for the synergies to kick in. Your debt construct also encumbers all the remaining collateral at high LTVs. Secondary liquidity that we might need during the integration period would be unavailable were we to need it.

1

The second reason relates to that last point. If Saturn emerges standalone as per its plan, we think the company is so weak and highly levered as to attract predatory competitive attacks, and we worry that Saturn could be quickly weakened to the point that a merger is not a prudent risk. Further, we don’t know what Saturn’s proposed management team is, and a new team in place may struggle to find the right commercial fixes the company needs, exacerbating what could be a tough re-entry.

The sooner we can take control of the combined companies, the sooner we can stabilize Saturn. If you pursue the current standalone plan, it will be some time before we could contemplate reengaging, if at all.

Question 2. What is different now from late last year when you walked away?

Last year we saw several significant liquidity holes and uncertainties that needed to be plugged. In addition to the operating cash flow requirements, we identified substantial risk around the [   ] contract and compliance with [   ] covenants. Combining all of the above, our diligence identified a ~$500 million gap and that assumed that Saturn was successful delivering substantial improvement to your yields over the next several quarters. The partial settlement of the [   ] contract removed some of that uncertainty, and the $350 million creditor equity contribution less the Chapter 11 costs plus slightly lower debt helps bridge that gap. Any external shock (competitive response, higher fuel prices or the like) or a miss on your revenue forecast and the cash required to fund the Saturn operations to a successful recovery could increase materially. There has been some relief in that the revenue environment generally has improved, which mitigates some of what we saw as too large a risk.

Barry

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Exhibit 99.6

From: Bill Franke

Sent: Tuesday, January 28, 2025 4:39 PM

To: Mac Gardner - Spirit Airlines (###) <###>; ###

Subject: Confidential

Dear Mr. Gardner and Mr. Christie:

As has been confirmed in our discussions with you and your advisors, both parties agree there is compelling industrial logic to the combination of our two companies. To that end, we have proposed to you a transaction, as previously communicated and as attached herein. We believe this transaction generates meaningful value for your stakeholders in excess of that generated by the plan you currently have on file with the Bankruptcy Court.

We put forward this offer in good faith, understanding that it generates more value for all Spirit stakeholders, including common stockholders. We have not, however, received a specific counterproposal but stand ready to negotiate any and all parts of this offer after receiving a substantive response from you.

We continue to believe that under the current standalone plan, Spirit will emerge highly levered, losing money at the operating level, and this would not be a transaction we would pursue. As a result, time is of the essence.

Sincerely,

Bill and Barry

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Exhibit 99.7

Presentation to Spirit January 2025

Frontier’s proposal ensures superior economics, certainty, and speed for Spirit’s stakeholders relative to the Spirit standalone plan Stronger, More Competitive Airline ïƒ~ Transaction with Frontier creates America’s first low-cost carrier with sufficient scale to compete with the Big Fourïƒ~ Complementary networks bring more low fares to more markets and generate meaningful and achievable synergies Challenges with Spirit’s Standalone Plan ïƒ~ Spirit’s plan relies on robust valuation assumptions against a business plan with significant execution risk to generate equity valueïƒ~ Even if the plan is achieved, creditors do not realize a full recovery, and shareholders have zero recoveryïƒ~ Leverage remains high on 2025E EBITDAR (8.9x) Frontier’s Superior Alternative ïƒ~ Even without synergies, Frontier’s plan provides greater creditor recovery while also providing value to shareholdersïƒ~ On a combined basis, significantly lower leverage on 2025E EBITDAR (4.1x)ïƒ~ On a standalone basis, Spirit would need to achieve a valuation meaningfully higher than its plan currently contemplates for its creditors to realize the economics offered in Frontier’s alternativeïƒ~ A combination with Frontier de-risks Spirit’s business transformation plan and positions the combined airline to more effectively compete with the Big Four over the long term A combination with Frontier can proceed quickly, with minimal required due diligence or closing conditions Confidential and proprietary 2 2

• Compelling industrial logic • Creates the first formidable low-cost challenger to the Big Four Strategic • Combination benefits all stakeholders Rationale

Compelling Proposal to Acquire Spirit To Create America’s First At-Scale, Low-Cost Competitor to Big Four Creating a Stronger Providing More Airline with Long- Offering More Low Delivering Value for Stable Career Significant Synergy Term Viability to Fares and Premium Financial Prospects for Team Potential Compete More Options to Travelers Stakeholders Members Effectively • 5th largest U.S. • Provides more low • Provides better • Creates compelling • Opportunity to airline, growing to fares to more career opportunities financial opportunity participate in upside 100M annual consumers, with increasing for Spirit creditors potential from passengers and enabling billions in complexity and and shareholders owning a larger, 400+ aircraft within savings compared scope more competitive • Provides greater a few years to prices charged airline with • Brings together two value and recovery by Big Four estimated synergies • Top three carrier in cohesive and relative to Spirit of $600M+ more than half of • Improves frequent customer-focused standalone the top 25 U.S. flyer and loyalty cultures restructuring plan airports programs as well as a more diversified • Meaningfully product with increases presence premium options in numerous major U.S. markets • Enables more reliable service through operating efficiencies • Enhances travel experience for customers Confidential and proprietary 4 4

Stronger Airline with Long-Term Viability to Compete Against Big Four 2023 Available Seat Miles Consumers Win: Low Fares with Premium Options 5th largest U.S. airline, growing to 100M annual passengers and 400+ aircraft within a few yearsïƒ~ Provides more low fares to more consumers, enabling billions in savings compared to Top three carrier in more than half of the top 25 U.S. airports prices charged by Big Four ïƒ~ Improves frequent flyer and loyalty programs as well as a more diversified product with premium options ïƒ~ Enables more reliable service through operating efficiencies ïƒ~ Enhances travel experience for customers Frontier + Spirit Combined Source: Company filings. Confidential and proprietary 5 5

• Offers more low fares to more consumers across a meaningfully increased presence in the U.S., offering significant network connections • Creates thousands of new markets and enables customers to save billions compared to prices Consumers & charged by the Big Four Communities • Improves loyalty and frequent flyer programs to offer a diversified product and offer an enhanced travel experience with more reliable service • Creates America’s first low-cost carrier with sufficient scale to compete with the Big Four • Creates more sustainable career opportunities for frontline team members as part of a more stable, Team faster growing airline Members • Brings together two cohesive and customer-focused cultures • Delivers meaningful value for financial stakeholders of both Frontier and Spirit • Creates a compelling financial opportunity for Spirit creditors and shareholders through a transaction Stakeholders more favorable than the current proposed Plan of Reorganization • Opportunity to participate in upside potential from owning a larger, more competitive airline with estimated synergies of $600M+ Confidential and proprietary 6 6

• Across any reasonable set of assumptions, Frontier’s alternative provides more value to Spirit’s stakeholders • Significant chance of impairment for Spirit stakeholders under standalone plan at more reasonable valuation assumptions Comparing the Plans • Frontier’s alternative provides value to the common shareholders who receive zero otherwise under the standalone plan • Synergies with Frontier are known, credible, and substantiated by historical precedents, helping derisk recovery values

($ in millions) Spirit Standalone Restructuring Frontier Proposal Creditor Consideration Exit Secured Notes $840 $400 11.0% Cash / 8.0% Cash + 4.0% PIK Coupon 11.0% Cash / 8.0% Cash + 4.0% PIK (specifics to be discussed) % Ownership 100% of Spirit 19.0% of PF Frontier + Spirit Pro Forma Entity Spirit Frontier + Spirit Revenue (FY26) $5,411 $11,059 EBITDAR (FY26) $1,041 $3,476 (1) Net Debt (2/28/2025) $5,937 $9,356 Net Leverage(2) 8.9x 4.1x Run-Rate Synergies — $600 Equity Value Frontier’s proposal uses the same valuation $806 assumptions as Spirit’s standalone plan $13,161 (@ 6.5x EBITDAR FY26 per RSA Plan) Total Value to Stakeholders $1,646 $2,901 Recovery %(4) Recovery %(4) Recovery Recovery %(3) (Excl. Synergies) (Incl. Synergies) Senior Secured Notes 95% 106% 141% Convertible Notes 56% 100% 137% Common Stock(5) $0.00 / share $0.80 / share $1.15 / share Source: Spirit Disclosure Statement (Chapter 11 Plan of Reorganization), filed as of December 18, 2024. Notes: Spirit RSA and Frontier Proposal reflect $350mm equity rights offering. Recovery rates for senior secured notes and convertible notes are based on principal value and share of equity rights offering. Recovery rates exclude impact from other secured / priority claims. (1) Figures include $600mm of run-rate synergies. (2) Net leverage reflects net debt as of 02/28/2025 divided by 2025E Pro forma EBITDAR incl. 50% credit for synergies. (3) Reflects Spirit equity ownership split of 76% senior secured noteholders, 24% convertible notes. (4) Illustrative equity ownership split of 65% senior secured noteholders, 30% convertible notes, 5% common stock. (5) Per share figures based on Spirit basic shares outstanding as of November 14, 2024; rounded to the nearest $0.05. Confidential and proprietary 8 8

Spirit RSA plan recovery rates are based on the higher end of standalone valuation analysis as disclosed in Chapter 11 Plan of Reorganization and indicates potential debt impairment below 5.9x EBITDAR multiple ($ in millions) Spirit RSA Valuation Ranges Based on Perella Weinberg’s Fairness Opinion Disclosed in RSA Valuation Range Low Mid High Spirit Valuation for RSA Plan Enterprise Value $6,100 $6,450 $6,800 $6,743 (-) Net Debt (5,937) (5,937) (5,937) (5,937) Equity Value $163 $513 $863 $806 Enterprise Value / 2026E EBITDAR 5.9x 6.2x 6.5x 6.5x Source: Spirit Disclosure Statement (Chapter 11 Plan of Reorganization), filed as of December 18, 2024. Confidential and proprietary 9 9

At the same valuation multiples as Spirit RSA analysis; Frontier Proposal creates significantly greater value than Spirit Standalone Restructuring Plan ($ in millions); FY26 EBITDAR Multiples Spirit Standalone Restructuring Frontier Proposal (Excluding Synergies) As of 02/28/2025, $840mm Exit Secured Notes $400mm Exit Secured Notes; 19.0% Ownership to Spirit; $1,835mm Frontier EBITDAR Frontier Median(1) RSA Plan Valuation Multiple Valuation Multiple 4.5x 5.5x 6.5x 4.5x 5.5x 6.5x Equity Value -—- $806 Equity Value $3,586 $6,462 $9,274 Exit Secured Notes — $539 $700 Exit Secured Notes $333 $333 $333 Equity Interest -—- $613 Equity Interest $442 $796 $1,142 Secured Sr. Secured Noteholders — $539 $1,313Secured Sr. Secured Noteholders $775 $1,129 $1,475 . Sr % Recovery — 39% 95% . Sr % Recovery 56% 81% 106% Exit Secured Notes — $89 $140 Exit Secured Notes $67 $67 $67 Equity Interest -—- $194 Equity Interest $206 $371 $532 Convert Convertible Noteholders — $89 $334 Convert Convertible Noteholders $272 $437 $599 % Recovery — 15% 56% % Recovery 45% 73% 100% Net Leverage Frontier Proposal (Incl. $600mm of Synergies) $400mm Exit Secured Notes; 19.0% Ownership to Spirit; $1,835mm Frontier EBITDAR Net Debt as of 02/28/2025 divided by FY25 EBITDAR 8.9x Valuation Multiple 4.5x 5.5x 6.5x Equity Value $6,286 $9,762 $13,161 Exit Secured Notes $333 $333 $333 Equity Interest $774 $1,202 $1,620 4.1x Secured Sr. Secured Noteholders $1,107 $1,535 $1,954 . Sr % Recovery 80% 111% 141% Exit Secured Notes $67 $67 $67 Equity Interest $361 $560 $755 Convert Convertible Noteholders $427 $627 $822 Spirit Standalone Frontier + Spirit % Recovery 71% 105% 137% Source: Spirit Disclosure Statement (Chapter 11 Plan of Reorganization), filed as of December 18, 2024. Notes: Spirit RSA and Frontier Proposal reflect $350mm equity rights offering. Recovery rates for senior secured notes and convertible notes are based on principal value and share of equity rights offering. Recovery rates exclude impact from other secured / priority claims. (1) Median industry multiple based on Southwest Airlines, JetBlue Airways, Frontier Airlines, Allegiant, and Sun Country Airlines. Confidential and proprietary 10 10

Frontier Proposal provides more total value to stakeholders under any valuation multiple ($ in millions) Total Value to Stakeholders (Senior Secured Notes + Convertible Notes + Common Equity) Spirit RSA Frontier Proposal (Excl. Synergies) Frontier Proposal (Incl. Synergies) $2,901 $400mm Exit Secured Notes + 19% Equity Interest in PF $2,585 Frontier + Spirit $2,255 $2,162 $1,925 $1,901 $1,594 $1,628 $1,646 $840mm Exit Secured Notes + $1,355 100% Equity Interest $1,264 $1,149 in Spirit $1,081 $808 Exit Secured Notes Amount: $840mm $629 Negative Equity Value / Debt Impairment -—- $108 4.0x 4.5x 5.0x 5.5x 6.0x 6.5x Valuation Multiple (FY26 EBITDAR) Confidential and proprietary 11 11

• Even using conservative estimates, the Frontier proposal provides significantly more value than the standalone plan • Net leverage at emergence is 4.2x less for the combined company Analysis than standalone (8.9x Standalone vs. 4.7x Pro Forma) Based on Analyst • Noteholders have potential to Estimates recover 100% of value when factoring in synergies • Even at lower end of valuation range, equity holders receive positive recovery

Even under more conservative analyst estimates, the Frontier Proposal creates significantly greater value than Spirit Standalone Restructuring Plan in almost every scenario ($ in millions); FY26 EBITDAR Multiples Spirit Standalone Restructuring Frontier Proposal (Incl. $600mm of Synergies) As of 02/28/2025, $840mm Exit Secured Notes $400mm Exit Secured Notes; 19.0% Ownership to Spirit; $1,251mm Frontier EBITDAR Frontier Median(1) RSA Plan Valuation Multiple Valuation Multiple 4.5x 5.5x 6.5x 4.5x 5.5x 6.5x Equity Value -—- $806 Equity Value $3,658 $6,550 $9,378 Exit Secured Notes — $539 $700 Exit Secured Notes $333 $333 $333 Secured Equity Interest -—- $613 Secured Equity Interest $450 $806 $1,155 . Sr. Secured Noteholders — $539 $1,313 . Sr. Secured Noteholders $784 $1,140 $1,488 Sr Sr % Recovery — 39% 95% % Recovery 57% 82% 107% Exit Secured Notes — $89 $140 Exit Secured Notes $67 $67 $67 Convert Equity Interest -—- $194 Convert Equity Interest $210 $376 $538 Convertible Noteholders — $89 $334 Convertible Noteholders $277 $443 $605 % Recovery — 15% 56% % Recovery 46% 74% 101% Source: Spirit Disclosure Statement (Chapter 11 Plan of Reorganization), filed as of December 18, 2024. Frontier analyst estimates based on FactSet consensus as of January 24, 2025. Notes: Spirit RSA and Frontier Proposal reflect $350mm equity rights offering. Recovery rates for senior secured notes and convertible notes are based on principal value and share of equity rights offering. Recovery rates exclude impact from other secured / priority claims. (1) Median industry multiple based on Southwest Airlines, JetBlue Airways, Frontier Airlines, Allegiant, and Sun Country Airlines. Confidential and proprietary 13 13

Frontier Proposal provides more total value to stakeholders except in the unlikely scenario where no synergies are realized and pro forma valuation multiple is greater than 6.1x ($ in millions) Total Value to Stakeholders (Senior Secured Notes + Convertible Notes + Common Equity) Spirit RSA Frontier Proposal (Incl. Synergies) $2,182 $400mm Exit Secured Notes + 19% Equity Interest in PF $1,919 Frontier + Spirit $1,645 $1,646 $840mm Exit Secured Notes + 100% Equity Interest $1,370 in Spirit $1,095 $1,149 $820 Take-Back Debt Amount:$840mm $629 Negative Equity Value / Debt Impairment $108 -—- 4.0x 4.5x 5.0x 5.5x 6.0x 6.5x Valuation Multiple (FY26 EBITDAR) Confidential and proprietary 14 14

• Assumed synergies of $600mm is a conservative metric compared to credible industry consultants’ estimates Significant • Net present value of synergies from combination forecast to be ~$5.7bn Synergy based on industry consultants’ Potential assumptions

($ in millions) Net Present Value of Expected Synergies Reflects Industry Consultants’ Estimates, Frontier Proposal Analysis Based on Conservative Synergy Estimate of $600mm 2H 2025E 2026E 2027E 2028E Terminal Year (+) Revenue Synergies (EBIT Contribution) $90 $310 $535 $770 $770 (+) Cost Synergies $100 $380 $135 $110 $110 (-) Cost to Achieve (100) (150) (100) (50) — EBIT $90 $540 $570 $830 $880 (-) Tax Expense (21) (124) (131) (191) (202) Cash Flow Contribution $69 $416 $439 $639 $678 Net Present Value of Synergies from Combination Estimated to be ~$6.1bn based on Industry Consultant Assumptions Compared to Capitalized Value of Synergies of $3.9bn used in Frontier Proposal Valuation Analysis Spirit’s Share of Synergies at 19% Pro Forma Ownership Creates ~$1.2bn of Additional Value for Spirit Stakeholders, which Alone Results in Recovery of ~55% to Secured Noteholders and Convertible Noteholders Note: Based on 13.0% discount rate and 3% perpetuity growth rate. Assumes illustrative transaction close as of June 30, 2025. Illustrative blended tax rate of 23%. Confidential and proprietary 16 16

• Minimal confirmatory due diligence required • Transaction can proceed towards an expedited announcement Next Steps

• Given extensive diligence conducted to date, Frontier envisions an expedited due diligence process that may be completed in approximately 5-10 days • Key diligence items include: – Sales performance relative to plan – Confirmation of latest Pratt & Whitney agreement – Updated 2-year cash flow forecast, inclusive of Chapter 11 costs – Disclosure of any material contract or business changes – Tax considerations, including any Chapter 11 impact to NOLs Confidential and proprietary 18 18

Exhibit 99.8

CONFIDENTIAL

Frontier Group Holdings, Inc.

4545 Airport Way

Denver, Colorado 80239

Attn: Mr. W. Franke, Mr. B. Biffle

January 28, 2025

Gentlemen:

Thank you again for your proposal letter dated January 7, 2025 (the “Proposal”), and for engaging with us and with our stakeholders.

As we have previously told you, we are always, and remain, open to executable ideas and proposals that maximize value for our Company and its stakeholders. We also share your view that a combination of our two companies could create a potent competitor in the marketplace.

Unfortunately, despite the clear guidance we and others have provided for three weeks as to the Proposal’s many deficiencies, you have addressed virtually none of them, leaving it (1) impossible for Spirit to effectuate, including because of the demand for $350 million in new funding from our creditors, (2) risky and costly, with no certainty as to either timing or outcome and (3) woefully insufficient financially – particularly when compared to the economic agreement we reached last Summer and Fall from which Frontier unilaterally walked away. Nor does it cover our funded debt or suffice to provide a recovery for equity.

As you know, our bondholders at our urging agreed to come under NDA and be restricted from trading, and we have delayed our confirmation hearing and thus our emergence from bankruptcy, among other reasons, to give the Proposal due consideration. Our Board has been fully apprised and carefully considered the Proposal throughout this period, including your latest communication that arrived tonight — less than two hours before the previously-scheduled Board meeting we had discussed with you.

Our Board has concluded that continuing to delay our confirmation and emergence process carries too many risks for the Company and its stakeholders and would be irresponsible. Moreover, both our bondholder groups tonight advised that they will not be extending tomorrow morning’s termination of the NDAs.

A few explanatory points from our exchanges since January 7:

As noted above, we were and have been willing to work with you constructively to see if there is a deal that can be reached that is acceptable to all necessary stakeholders — despite the Proposal arriving only three weeks before our scheduled confirmation hearing, and in the middle of our solicitation of plan votes and after the launch of our ERO.

While we appreciate your continued interest and share your view of the logic of a potential transaction, your January 7 terms (which have not been improved on in the last three weeks) are both inadequate and unactionable.

In light of the above, our Board has directed management and advisors to proceed with confirmation of our extremely efficient standalone reorganization that will position us well for the future.

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Should you wish to make a revised proposal that is in fact capable of closing, and addresses the material deficiencies catalogued here and in our many communications, we would be happy to consider it and again work to activate our stakeholders to do so as well.

Sincerely,
Ted Christie				Mac Gardner

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