Airline customer satisfaction is down 2.7 percent overall in 2018, according to the latest travel report from the American Customer Satisfaction Index (ACSI).

At least four U.S. carriers saw passenger satisfaction increase. However, the industry as a whole posted a score of 73 on a scale of zero to 100.

Southwest Airlines ranks highest in satisfaction, earning an ACSI score of 80 for the third straight year. However, it remains to be seen if the recent high-profile incident involving one of the airline's Boeing 737 engines will derail its future standing.

Trailing Southwest are JetBlue and Alaska Airlines with identical scores of 79. The former dropped 4 percent while the latter jumped up 1 percent following its acquisition of Virgin America. The biggest riser of 2018, Allegiant Air climbed 4 percent to 74, tying legacy carriers American Airlines and Delta Air Lines, both of which dropped 3 percent.

Similar to Southwest, it's unclear how Allegiant's score will be impacted moving forward on the heels of a damning “60 Minutes” segment profiling the airline's recent mechanical incidents.

Meanwhile, only ultra-low-cost carriers Frontier Airlines and Spirit Airlines — which each dropped 2 percent to score 62 — trail United Airlines after the carrier saw a 4 percent decline in customer satisfaction, posting an ACSI score of just 67. 2017 was a tumultuous year for United following the infamous dragging incident last April.

Although satisfaction with the overall airline check-in process remained solid at 82, passengers are less content with making reservations (81), flight crew courtesy (80) and baggage handling (79) compared to a year ago. Unsurprisingly, seat comfort continues to be a pain point for air travelers, dropping 3 percent to 69 in 2018, according to ACSI.

"The 18-point gap between first place and last place among airlines is fairly typical," said David VanAmburg, managing director at ACSI, in a statement. "Customer satisfaction is going to be lower for the ultra-low-cost carriers, which are focused more on price than quality, and the scores reflect that. The same holds true among hotels. As costs rise and seats shrink, a focus on customer service and loyalty will set some airlines apart."

ACSI's 2018 Travel Report, which is based on more than 12,000 customer surveys collected between April 18, 2017, and March 18, 2018, found that guest satisfaction with hotels remains unchanged from last year (76) while fulfillment with internet travel services is down 1.3 percent to 78.

Hilton (82) ranks highest in customer satisfaction among hotels, edging out Marriott International (81) and its recently acquired Starwood brands (79). Hyatt Hotels (79), Best Western (77), InterContinental Hotels Group (IHG) (77) and La Quinta (76) each matched or exceeded the industry average.

Choice Hotels and Wyndham each fell 1 percent to 73 and 70, respectively, but still managed to beat out last-place Motel 6 (65). The G6 Hospitality brand has grown even more unpopular of late in wake of troubling reports of staff sharing guest information with immigration authorities.

While customer satisfaction with Expedia declined 3 percent to 78, Expedia Group's subsidiaries Orbitz and Travelocity each saw a 4 percent jump to 81 and 80, respectively. Following a sizable dropoff a year ago, Priceline bounced back with a 1 percent climb to 78.

———

(TravelPulse is a leading travel authority on the web, providing consumer travel news and insider tips and advice for an ever-changing travel world. Read more stories at travelpulse.com