Which Airline Is the Most Reliable?

Delta and Alaska by a significant margin, ranking at the top in every metric we tracked.
Meghan Coyle
JT Genter
By JT Genter and  Meghan Coyle 
Updated
Edited by Meg Lee

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One of the biggest sources of customer complaints about airlines is unreliability, from canceled flights to lost baggage.

To see which airlines kept flight disruptions to a minimum, NerdWallet dug into data from the U.S. Bureau of Transportation Statistics to analyze the on-time percentage, cancellation rate, flight diversions, mishandled baggage, tarmac delays and involuntary denied boardings from July 2022 to May 2023. This helped us determine the most reliable airlines in the U.S.

For an airline to be eligible for our analysis, it had to be based in the U.S. and have a publicly available rewards search calendar with availability from 15 days to eight months from the time of search.

We used percentages and rates to avoid penalizing airlines with more extensive operations. For example, Delta Air Lines may have had more cancellations than the smaller Frontier, but as a percentage of all operated flights, Frontier had a higher cancellation rate.

Here's a breakdown of the winners and losers in each category.

On-time percentage

An airline's on-time percentage is perhaps the most important statistic for showing how well an airline performs. After all, this is a factor that affects every passenger on the plane.

The Bureau of Transportation Statistics tracked the percentage of flights that arrive at the destination gate within 15 minutes of the scheduled arrival time, which it considers “on-time.”

Based on BTS data from July 2022 to May 2023, only one airline topped an 80% on-time percentage: Delta Air Lines, at 83%. Alaska Airlines landed just behind Delta with a 79% on-time percentage.

The worst performers were Frontier Airlines — with 67% of flights arriving within 15 minutes of the scheduled arrival time — and Hawaiian Airlines, with a 68% on-time percentage.

Flight cancellations

So, what airlines have the least cancellations? BTS data from July 2022 to May 2023 shows Hawaiian canceled the least flights of U.S. airlines analyzed, with just a 1.10% cancellation rate. Delta took second place with a cancellation rate of 1.38%.

Southwest canceled the highest percentage of all flights (2.75%), but it's worth noting the period analyzed includes the airline’s 2022 holiday travel meltdown. Since then, Southwest has made some improvements and performed better from January to August 2023.

Note that the flight cancellation data includes flights canceled seven days or less before departure only. That means this metric doesn't penalize airlines that reschedule or cancel flights more than a week ahead of departure.

Mishandled luggage

Nothing may be worse than getting off the airplane to find out your baggage never made it.

Hawaiian had the most consistent luggage handling of the airlines in this analysis with only 0.41% of checked bags mishandled from July 2022 to March 2023 per BTS data. Frontier also did relatively well in this category, with just 0.48% of bags mishandled.

American Airlines (0.87%) was the worst-performing airline for mishandled luggage during the period analyzed.

Flight diversions

Flight diversions are when a flight is sent to an airport other than the intended destination airport.

BTS data for July 2022 to May 2023 shows that JetBlue Airways diverted 866 flights, for the worst diversion rate of 0.33%. Alaska Airlines was the second worst performer with 715 diverted flights during this period for a diversion rate of 0.32%. To better avoid flight diversions, fly Hawaiian (0.11%), Spirit (0.15%), Frontier (0.16%) or Delta (0.17%).

Other performance metrics

To round out our analysis, we also looked at the number of tarmac delays and involuntary denied boardings.

Airlines must report when a flight has a "tarmac delay" of over three hours for a domestic flight and over four hours on an international flight. From July 2022 to March 2023, United had the highest percentage of tarmac delays — 1.29 delays for every 1,000 flights. The longest United tarmac delay was almost 6-and-a-half hours.

An involuntary denied boarding happens when an airline oversells a flight and doesn't get enough volunteers to take a later flight. Delta didn't record a single involuntary denied boarding for the period analyzed. Frontier, on the other hand, had the highest rate of involuntary denied boardings, with 2.36 for every 10,000 passengers.

The rankings of reliable airlines

Based on our analysis, Delta is the most reliable airline.

Delta Air Lines performed the best in on-time percentage and involuntary denied boardings during the time period we analyzed. Alaska Airlines came in second, followed by United Airlines and American Airlines.

The worst performer was Frontier Airlines, which lagged on on-time arrivals.

Methodology

For this analysis, we looked at several types of operations data from the U.S. Bureau of Transportation Statistics that captured performance of U.S. airlines from July 2022 to May 2023.

Here is our full dataset:

Airline

On-Time

Cancellations

Diversions

Mishandled bags

Tarmac delays per 10,000 flights

Denied boardings rate per 10,000 flights

Alaska Airlines

79.38%.

1.52%.

0.32.

0.70%.

0.23.

0.10.

American Airlines

78.03%.

1.68%.

0.25.

0.87%.

0.11.

0.40.

Delta Air Lines

82.97%.

1.38%.

0.17.

0.51%.

0.46.

0.00.

Frontier Airlines

66.70%.

2.21%.

0.16.

0.45%.

0.33.

2.36.

Hawaiian Airlines

67.77%.

1.10%.

0.11.

0.41%.

0.14.

0.01.

JetBlue Airways

68.44%.

1.88%.

0.33.

0.66%.

0.54.

0.04.

Southwest Airlines

74.70%.

2.75%.

0.20.

0.56%.

0.06.

0.42.

United Airlines

78.89%.

1.73%.

0.25.

0.68%.

1.29.

0.01.

Spirit Airlines

72.53%.

2.15%.

0.15.

0.52%.

0.09.

0.34.


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