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. 

Spirit Airlines operates to destinations in the USA, South America, the Caribbean and Mexico, and saw 1% of its 16,093 scheduled flights cancelled in July 2018 alone.

Next up is Allegiant Air who offer flights to 117 destinations in the USA. They saw a 1.6% cancellation rate, out of 10,325 operated scheduled flights in July.

While Southwest Airlines is just 0.2% up from Allegiant Air with a cancellation rate of 1.8% it also has the largest number of scheduled flights in the ranking (120,114), which also means the largest number of overall cancelled flights (2,107).

Mesa Airlines, known as American Eagle from Dallas and Phoenix airports and as United Express from Washington Dulles and Houston, saw a 1.9% cancellation rate out of 19,702 scheduled flights in July putting it in ninth place.

The first to edge past the 2% mark is American Airlines, with 2.3% of flights cancelled out of a total of 80,736 scheduled flights.

JetBlue Airways might be the nation's sixth-biggest carrier, but a 2.4% cancellation rate puts it in seventh places as the worst for departures that never happened.

Customers of PSA Airlines saw 2.6% of services cancelled. The brand, a subsidiary of American Airlines group and flying under the American Eagle brand, runs around 800 flights per day going to nearly 100 destinations.

In fifth place is ExpressJet Airlines. They operate a codeshare with United Express and American Eagle and have a cancellation rate of 2.8%.

Pushing past the 3% mark is Endeavor Air – known as Delta Connection – with 3.1% of flights cancelled out of a total of 21,462 scheduled flights.

Serving USA, Canada and Caribbean destinations including Jamaica, Frontier Airlines is the third worst with 3.8% of flights not getting off the ground.

Another regional carrier for American Airlines, flying under the American Eagle name, Envoy Air narrowly misses the top spot by just 0.1% thanks to 1,070 operations cancelled at rate of 4.1%.

But the worst offender in the ranking is Republic Airline, another brand who is a partner of American Eagle, Delta Connection and United Express. Republic Airline's passengers saw 4.2% of its 27,536 scheduled flights cancelled in July 2018.

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. 

Next is JetBlue Airways with 5,779 baggage reports in the month and a report rate of 1.96 per thousand passengers. Again this is an increase from the previous year when the rate was 1.81.

A total of 5,177 baggage reports and a report rate of 2.11 per thousand passengers puts Spirit Airlines in 10th place.

There's good news for Hawaiian Airlines whose report rate has dropped from 2.58 per thousand passengers in 2017 to 2.43 in 2018, with a total of 2,360 baggage reports. This is also the lowest total number of baggage reports in the list.

United Airlines has also seen a fall year-on-year. In 2017 the baggage report rate stood at 2.86 per thousand passengers while the figure for 2018 is 2.77. The total number of baggage reports came in at 23,985.

While there has been a one point increase in the baggage report rate per thousand passengers between 2017 and 2018 (1.79 vs 2.79) for Alaska Airlines, this reflects airline's takeover of Virgin America, reflected in the report from April 2018. The total number of baggage reports came in at 9,288.

Taking sixth place in the ranking is Frontier Airlines with a report rate of 3.10 per thousand passengers and a total of 5,452 baggage reports.

With a total of 49,484 baggage reports, Southwest Airlines has the highest total number of baggage reports in the ranking. This could also reflect the fact it has the highest number of passengers (14,613,767) in the list. Its report rate however is 3.39 per thousand passengers making it the fifth worst airline in this category.

SkyWest, who operate under the Delta Air Lines, United Airlines, American Airlines and Alaska Airlines names comes in fourth place with a report rate of 4.32 per thousand passengers and 11,569 baggage reports.

Edging higher up the list is American Airlines with a report rate of 4.39 per thousand passengers and a total of 44,079 baggage reports.

Despite the fact that it has the lowest total passenger numbers in the list (663,679) ExpressJet Airlines has the second highest report rate at 5.46 per thousand passengers. The total number of baggage reports came in at 3,623.

In first place for all the wrong reasons is Envoy Air with 6,719 total baggage reports and a rate of complaints at 6.37 per thousand passengers.

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.

With 22 involuntary denied boardings, Delta Air Lines achieves a near perfect involuntary rate of 0.00 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. 

Also coming in with a rate of 0.01 per 10,000 passengers, but a slightly higher number of involuntary denied boardings (five) is Endeavor Air.

With a total of 16 involuntary denied boardings JetBlue Airways also has a rate of 0.01 per 10,000 passengers.

The final airline with a 0.01 rate per 10,000 passengers, the total number of involuntary denied boardings at United Airlines came in at 44.

In 12th place is ExpressJet Airlines with 15 involuntary denied boardings and a rate of 0.03 per 10,000 passengers.

Following on is Republic Airline with 62 involuntary denied boardings and a 0.07 rate per 10,000 passengers.

PSA Airlines has a slightly lower number of involuntary denied boardings (54) but a higher rate of 0.08 per 10,000 passengers putting it in 10th place.

Matching PSA Airline’s rate of 0.08 per 10,000 passengers, a total of 58 passengers were involuntarily denied boarding on Allegiant Air.

A rate of 0.09 per 10,000 passengers puts Mesa Airlines in eighth place, with a total of 57 passengers involuntarily booted off their flights.

The data doesn’t look much better for American Airlines, with 678 travellers involuntarily bumped from their seats on the airline and a rate of 0.10 per 10,000 passengers. However they do handle the most passengers of any airline in this section, with 66.2 million of us flying American from January to June 2018.

Southwest Airlines is the first airline in the ranking to push past the thousand mark, with a total of 1,045 involuntary denied boardings and a rate of 0.13 per 10,000 passengers.

294 presumably disgruntled customers waved goodbye to their plane seats without their say, giving SkyWest Airlines an involuntary denied boarding rate of 0.17 per 10,000 passengers.

In fourth place is Envoy Air, with 120 involuntary denied boardings and a rate of 0.19 per 10,000 passengers.

Once again the 2018 figures reflect the merger of Alaska Airlines and Virgin America, with a total of 446 passengers denied boarding involuntarily. This equates to a rate of 0.30 per 10,000 passengers.

There has been no improvement for Frontier Airlines this year: from 2017 to 2018 it retained a rate of 0.47 per 10,000 passengers bumped from flights. The total number of people denied boarding involuntarily in 2018 was 443.

Despite not having the highest number of passengers flying with the brand (13,242,426) Spirit Airlines still manages to clock up 1,322 involuntary denied boardings and a rate of 1.0 per 10,000 passengers. On a brighter note this rate is down from the figure of 1.06 for the same period in 2017.

The next part of the Air Travel Consumer Report focused on consumer complaints, taking into account any grievances addressed in writing, on the phone, via email or in person during July 2018. It covers just the largest US domestic airlines. In total, US homegrown carriers received 964 complaints, compared to 636 levied against foreign airlines.

With just three complaints, ExpressJet Airlines has come up trumps with the lowest number of formally logged issues at just 0.36 per 100,000 passengers.

In total, SkyWest Airlines received 15 complaints. Ten concerned flight problems and four were about baggage, but just one regarding poor customer service. Their total was just 0.41 people with issues in every 100,000 who flew with the carrier.

Next on the list is Hawaiian Airlines, with five complaints (0.46 per 100,000) spread across a few topics, from flight problems to fares.

Endeavor Air had to deal with six complaints, four of which were about flight problems.

PSA Airlines is next in line with six complaints from consumers, again mainly about flight problems, with no concerns about fares or customer service.

Southwest Airlines was on the receiving end of 0.51 complaints per 100,000 of its passengers, putting it 12th on our list. In total there were 76 formal concerns raise, although the fact the airline had the highest passenger numbers, with 14,961,822 travellers boarding, must be taken into account. While most of the issues raised were flight problems, baggage and customer service remain clear concerns for customers.

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.

Last year in the same list, Delta Air Lines came fourth with a catalogue of gripes. This year the airline has stepped up, seeing 89 complaints down from 132 in the same period last year. However the range of issues causing passengers' grief was wide: everything from flight concerns and tickets to baggage and customer service.

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.

JetBlue dealt with 44 complaints in July. Of these, 19 were about flight problems with five about boarding and tickets, seven about baggage and nine about customer service.

With 136 complaints in just a month, passengers travelling with United Airlines got vocal about a range of issues: 43 spoke up about flight problems, 13 about ticket issues, 23 about customer service and two people even highlighted concerns about United's advertising, the only airline on the list to face such a grievance. However, United have shifted the right way up the table moving from second place in 2017 to sixth this year.

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. 

Seeing 234 complaints means American dealt with grumbles from 1.69 passengers in every 100,000. Flight problems, baggage, refunds, fares, customer service and civil rights complaints by air travellers with disabilities were the hot topics.

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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