The 2021 Airline Index

The best domestic and international airlines in the US

With more countries finally opening up to tourism and the ability to see our friends and family in far-flung cities increasing, it's tempting to hop on the first plane out of here.

However, we all know how frustrating it can be to find yourself trapped in a cramped cabin without Wi-Fi or waiting in the departure lounge for hours with no plane in sight.

That’s why we’ve analyzed the experiences of passengers as well as airline punctuality and maximum luggage allowance for both domestic and international airlines to see which airline leaves customers smiling.

Best Domestic Airlines

1. Delta Airlines


Airline Index Score

Taking the top spot is Delta, scoring highly as it has the second-highest percentage of arrivals on time (86.7%) and a relatively low number of complaints, 494 from January to June of 2021. This is owed to CEO Ed Bastain’s dedication to improving customer satisfaction, which is no easy feat as Delta Airlines serves more than 300 destinations in 50 countries.

2. Hawaiian Airlines


Airline Index Score

Coming second is Hawaiian Airlines. Based in Honolulu, it is the tenth-largest commercial airline in the US. Despite coming second overall, it is the most punctual airline with 87.7% of flights leaving on time. However, it is let down by the lack of inflight entertainment, only scoring two out of five.

3. Horizon Air


Airline Index Score

This regional airline serving the West Coast of the US and Canada ranks third, despite having the lowest number of complaints at just 17. Added to this, the airline also tops the list for service, scoring four out of five. Although, it is let down by its poorly rated inflight entertainment, coming last in our rankings.

Worst Domestic Airlines

1. Spirit Airlines


Airline Index Score

Despite having one of the most fuel-efficient and youngest fleets of domestic carriers, Spirit comes in as the worst-ranked airline. Spirit ranks very low in both quality of food and drink, as well as inflight entertainment, scoring one out of five. It also ranks third for the total number of complaints at 665 from January to June 2021.

2. Allegiant Air


Airline Index Score

Ranking lowest overall in punctuality with only 56.6% of flights arriving on time, this low-cost domestic airline headquartered in Las Vegas serves leisure travelers from colder to warmer climates. The airline keeps ticket prices low by not offering in-flight entertainment, which explains its low airline index score of one out of five for this category.

3. American Airlines


Airline Index Score

Based in Fort Worth, American Airlines is the world’s largest airline when measured by fleet size and carries an estimated 200 million passengers a year. It ranks as the third-worst domestic airline, receiving the highest number of complaints, and comes out tenth in our overall rankings.



Arrivals on Time (July 2021)

Complaints Jan-June 2021

Staff Service


Seat Comfort

Inflight Entertainment

Maximum Free Baggage Allowance (kg)

Airline Index Score /10

Best International Airlines

1. All Nippon Airways


Airline Index Score

Based in Tokyo, this carrier is the largest airline in Japan by both revenue and passenger numbers. It ranks the highest in customer-rated staff service, the only airline in our list to score full marks in our airline index for this factor. It also has a relatively low number of complaints at 34.

2. Singapore Airlines


Airline Index Score

Operating since 1972 and based in Singapore Airport, Singapore Airlines ranks number two due to its high baggage allowance of 30 kilos, a low number of complaints (23), and high seat comfort, having won awards for their aircraft seating. Singapore Airlines scores four out of five for every category in our index, so it’s no surprise this carrier comes second in our ranking as the best international carrier.

3. Korean Air


Airline Index Score

Serving 120 cities in 43 countries, Korean Air carried 3,576,000 passengers in 2020. The airline scored four out of five for each customer satisfaction category in our index and ranked lower in the number of complaints than Singapore Airlines (21). However, it missed out on second place due to its lower baggage allowance of 23 kilos.

Worst International Airlines

1. Viva Air Colombia


Airline Index Score

This low-cost airline has carried 22.55 million passengers in the last seven years and operates around 40,000 flights a year. This carrier scores one out of five in our index for meals, seat comfort, and inflight entertainment due to the fact that few amenities are offered to customers free of charge. Although it did receive the lowest number of complaints overall.

2. Viva Aerobus


Airline Index Score

Based at Monterrey International Airport in Mexico, this budget airline carries passengers internally as well as operates international flights to cities in the US. It scores one out of five in our index for both inflight entertainment and meals and two out of five for staff service. This could be due to its buy-on-board program where food and drink have to be purchased.

3. Volaris Airlines


Airline Index Score

This low-cost airline based in Mexico City is one of the few airlines that is expected to make a profit for 2021 despite the impact of COVID, due to its focus on leisure and visiting friends and relatives markets. However, due to the airline discontinuing inflight entertainment in 2019, it has one of the lowest scores in our index, and with a low maximum baggage weight allowance of 10 kilos, this carrier ranks as the third-worst airline.



Complains Jan-June 2021

Staff Service


Seat Comfort

Inflight Entertainment

Maximum baggage Allowance (kg)

Airline Index Score / 10


We gathered a list of the most popular domestic and international airlines operating in the US.

These airlines were then ranked by the following factors:

Maximum free baggage allowance: taken from each airline website.

Staff service, meals, inflight entertainment, and seat comfort:

Number of complaints received by each airline from January to June 2021:

We then gave each airline a normalized score out of ten according to these seven factors, before taking an average across these scores to find an overall score out of ten.