Few things are worse than an unexpected event derailing your travel plans – particularly when it's your airline at fault. But now thanks to the Air Travel Consumer Report by the US Department of Transportation travellers can get a picture of the performance of domestic airlines in the USA before they book. The data reveals which carriers fare the worst when it comes to four key areas: cancellations, mishandled baggage, overbooked flights and complaints. Here we've ranked the airlines in each category from those underperforming to the worst offenders. 

Unsurprisingly many passengers struggle to keep their cool when they glance up at airport departure boards and see the word 'cancelled' next to their flight number. The first part of the study looks at the number of flight cancellations per carrier from US airports in July 2018, with flights considered to be 'on time' if they leave within 15 minutes of their scheduled departure time. It's good news for Hawaiian, Delta and United customers, who saw less than 1% of services cancelled, but listed next are those with worse performance. 

Arriving at your destination to find your luggage didn't make it or was damaged in transit can put a real dampener on your travel plans. The second part of the study looks at the number of baggage reports – including baggage that has been lost, damaged, delayed or stolen – per carrier from US airports in July 2018. The baggage report rate is calculated per thousand passengers.

At the bottom of the ranking with the fewest baggage reports is Delta Air Lines. They saw a total of 20,760 baggage reports and a report rate of 1.83 per thousand passengers – this is up from 1.77 in 2017. 

We may all think that our seats on a plane are guaranteed but many airlines overbook flights, hedging their bets that a number of passengers will be no shows on the day. The third part of the study looks at the total number of passengers involuntarily denied boarding – i.e. bumped from flights – for domestic US flights and international flights that originate in the US between January 2018 and June 2018. The rate of involuntary denied boardings is calculated per 10,000 passengers.

A total of four involuntary denied boardings – the lowest in the ranking – gives Hawaiian Airlines a rate of 0.01 per 10,000 passengers for the island based carrier. 

Ten concerns were sent Republic Airline's way, with eight passengers venting about flight problems, one about customer service and one complaint from a customer with a disability too. Republic Airline's rate of complaints per 100,000 is 0.6.

With nine complaints – 0.66 in every 100,000 – Mesa Airlines is inside the top ten worst offenders. Its customers' main moans were about flight problems with only one person concerned with customer service. 

With 24 complaints, spread across flight problems, baggage, customer service and issues relating to disability and discrimination, Alaska Airlines – including Virgin America services – is next on the list.

Envoy Air might have only had 20 complaints but that means that 1.61 customers in every 100,000 had concerns strong enough they felt compelled to raise an official grumble, putting it at five on the list. 

Allegiant Air’s customers were not impressed with its flights during the first half of the year with 17 of 26 complaints relating to flight problems.

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In second place, and ranked one spot worse than last year, Spirit Airlines handled 98 complaints. Aside from flight problems, baggage issues, reservations, ticketing, boarding and customer service were also on passengers' minds.

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Claiming the dubious accolade of number one for customer complaints is Frontier Airlines. Their 106 complaints means that per 100,000 passengers 5.82 had serious concerns. Aside from the 63 issues over the flights themselves, reservations and ticketing, baggage and customer service were all worries for those flying with the carrier. 

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