Two major passenger satisfaction studies published three weeks apart in 2026 reached opposite conclusions. The American Customer Satisfaction Index released its Travel Study on April 21, putting Delta Air Lines first industry-wide at 79, while Southwest Airlines fell from 80 to 77 and out of the top spot it held in 2025. J.D. Power released its North America Airline Satisfaction Study on May 6, ranking Southwest first in economy and basic economy at 670 for a fifth consecutive year, with Delta second at 667.

Three points separate them in the J.D. Power economy segment, the narrowest margin of Southwest’s five-year run. Delta also won premium economy at 736 for a fourth straight year and placed second in first and business at 750, segments Southwest does not compete in with its single-class cabin. ACSI tied Southwest’s decline directly to reputational damage from the assigned seating announcement and the policy requiring larger passengers to buy a second seat.

Two Studies, Two Different Answers

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Two major passenger satisfaction studies published within three weeks of each other in 2026 reached opposite conclusions about which US carrier passengers rate highest. The American Customer Satisfaction Index released its Travel Study 2026 on April 21, placing Delta Air Lines at the top of the airline industry with a score of 79. J.D. Power released its 2026 North America Airline Satisfaction Study on May 6, ranking Southwest Airlines first in economy and basic economy for a fifth consecutive year with a score of 670.

The two studies are structured differently. ACSI scores airlines on a 100-point scale and publishes a single figure per carrier, which produced an industry-wide ranking with Delta on top and Southwest at 77. J.D. Power uses a 1,000-point scale and splits its results into three segments: first and business, premium economy, and economy and basic economy. Each segment has its own winner, and the study does not publish a combined overall ranking across all three. An airline can therefore lead one J.D. Power segment while placing second or third in another, which is exactly what happened in 2026.

That structural difference matters because Delta and Southwest do not compete across the same cabins. Southwest operates a single-class cabin and appears only in J.D. Power’s economy and basic economy segment. Delta appears in all three and won or placed second in each. Southwest’s win is in the one category it is eligible for, against a competitor that was also present in two segments Southwest does not sell. Reading either study as a clean answer to which airline satisfies passengers more requires ignoring what the other one found, and the two were published 15 days apart.

ACSI: Delta Takes The Lead As Southwest Falls

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Delta rose 3% to an ACSI score of 79 in 2026, up from 77 the year before, making it the highest-rated airline in the industry. Southwest moved the other way, falling 4% from 80 to 77 and dropping from 2025 industry leader to what ACSI described as the middle of the pack. The two carriers effectively traded positions in a single year, with Delta landing on the exact score Southwest vacated. The industry as a whole rose 3% to 76, mostly reversing the decline recorded in the previous study, with customer-facing technology including in-flight Wi-Fi and enhanced flight information systems showing notable gains.

ACSI identified where Southwest’s scores slipped. Ratings for flight crew courtesy, gate staff courtesy, and call centers all inched back in 2026. Those are service-delivery measures rather than product or pricing measures, which is notable for a carrier whose reputation has historically rested on staff interaction rather than hard product. The study attributed the decline in part to the reputational hits Southwest took from its announcements on moving to assigned seating and on requiring larger passengers to purchase a second seat, both of which generated substantial coverage before taking effect.

Delta was not the only carrier to improve. ACSI noted that American Airlines posted a substantial gain driven in part by customer appreciation for its loyalty program, particularly among business travelers. The ultra-low-cost segment diverged, with the two largest carriers in that category moving in opposite directions on satisfaction. The broader pattern in the 2026 study is of an industry recovering from a weak prior year, with Delta’s rise placing it ahead of a field that was improving around it rather than standing still. Southwest’s 77 is not a poor score in absolute terms. It matches Delta’s 2025 score and sits one point above the industry average. The significance is the direction of travel and the fact that a carrier that led the industry on satisfaction no longer does.

J.D. Power: Southwest Holds Economy By Three Points

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Southwest ranked first in J.D. Power’s economy and basic economy segment with a score of 670, its fifth consecutive year at the top of that category. Delta finished second at 667 and JetBlue third at 655. Business Travel Executive highlighted the margin, noting that only three points separate the highest-ranked and second-highest-ranked airlines in the segment, and paired that observation with the comment that Southwest has dramatically changed its operating processes at the behest of shareholders.

The study differs from ACSI. J.D. Power surveyed 10,914 passengers who had flown a major North American airline within the month before completing the survey, with fieldwork running from March 2025 through March 2026. Each airline is scored across seven dimensions on a six-point scale: airline staff, digital tools, ease of travel, level of trust, onboard experience, pre- and post-flight experience, and value for price paid. Those seven measures roll up into the 1,000-point segment score.

Overall satisfaction rose 8 points year over year across all three segments, following a 6-point gain in 2025. J.D. Power recorded that improvement despite a survey period that included heavy flight delays and cancellations, crowded airports, and rising ticket prices and baggage fees. The economy and basic economy segment averaged 627, against 682 for premium economy and 717 for first and business. Southwest’s 670 and Delta’s 667 both sit well above that segment average.

Delta Wins Both Premium Segments

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Delta ranked first in premium economy at 736, its fourth consecutive year leading that segment. In first and business, JetBlue took the top spot, with Delta second at 750 and Alaska Airlines third at 720. Delta’s score in that segment rose 26 points year over year, among the larger single-carrier improvements in the study. J.D. Power recorded satisfaction among first and business passengers jumping 17 points industry-wide, the sharpest gain of the three segments and roughly double the 8-point improvement across the study as a whole.

Southwest does not appear in either ranking. The airline operates a single-class cabin and is only eligible for the economy and basic economy segment, which is the one it won. That is not a criticism of Southwest so much as a limit on what the comparison can establish. A carrier with one cabin cannot be rated against a carrier with four in categories it does not sell, and no current methodology accounts for this structural discrepancy.

The segment averages show why the distinction matters when deciding which airline wins on satisfaction. First and business averaged 717 across the ranked carriers, premium economy averaged 682, and economy and basic economy averaged 627. A Delta premium economy passenger scored the airline 736, while a Southwest passenger scored it 670; they aren’t rating comparable products, and the 66-point difference largely reflects the cabin rather than the carrier. Delta’s advantage in the J.D. Power data is that it competes and wins in the segments where satisfaction runs highest, and where the industry posted its biggest gains this year. Southwest’s advantage is that it holds the only segment it plays, in a year when its closest competitor came within three points of taking it.

What Changed At Southwest

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ACSI was direct about what moved Southwest’s number. The study attributed the decline in part to the reputational hits the airline took from its announcements on moving to assigned seating and on requiring larger passengers to purchase a second seat. ACSI separately recorded slippage in Southwest’s ratings for flight crew courtesy, gate staff courtesy, and call centers, all of which inched back in 2026.

The J.D. Power survey window raises a timing question. The study fielded responses from March 2025 through March 2026, while Southwest’s assigned seating took effect for flights from January 27, 2026. Business Travel News flagged the overlap, noting that Southwest had added baggage fees and assigned seating since the prior survey. The fifth consecutive win therefore describes a period when the airline’s product changed substantially.

That makes the three-point margin more informative than the ranking. Southwest’s transformation under Bob Jordan has introduced checked bag fees, assigned and extra-legroom seating, and a segmented fare structure, replacing the open-seating and bags-fly-free model upon which the carrier built its reputation. ACSI, published in April, already shows the airline behind Delta. The 2027 studies will cover a full year of the new Southwest, and whether the carrier holds its J.D. Power segment for a sixth year will say more about how passengers have received the changes than this year’s result does.