Accounting for 60% of the total score, on-time performance was a key factor in determining the winner.

This criterion was based on figures from individual airports' on-time departures and arrivals. As AirHelp reports, flights departing within 15 minutes of their scheduled departure times and arriving within 15 minutes of their published arrival time were considered on time.

The total of flights falling within this category in the space of a year was then calculated and expressed as a percentage; the higher the figure, the higher the number of on-time flights on a typical day.

The highest scoring airport was Brussels South Charleroi Airport, which received a score of 8.6, meaning 86% of in-bound and out-bound flights were on time in 2018.

Following on from Brussels’ score were Moscow’s Sheremetyevo International Airport and Tokyo International Airport. Overall winner Hamad Airport came sixth in this category, with an on-time performance of 83%.

According to AirHelp chief executive Henrik Zillmer, calculating results for Athens was more puzzling, as the team had to take into consideration that sunny weather leads to fewer delays and potentially better reviews from passengers.

At the bottom of the ranking in this category are Kuwait International Airport, which saw only 43% of its in-bound and out-bound flights on-time, Lisbon Portela Airport with 47% and Eindhoven with 49%.

Two British airports, Gatwick and Manchester, also ranked among the ten worst-performing airports based on this criterion. This is likely due to the 33-hour drone chaos that grounded tens of flights in Gatwick in December 2018.

AirHelp spoke to thousands of passengers globally to collect data on airports’ service quality, a category that was worth 20% of the total score.

This was made possible by a collaboration with intelligence platform Attest, which ran hundreds of surveys with airport and airline users across the world for a total of 40,000 people surveyed in over 40 countries.

Within this framework, passengers were asked to rate an airport based on three factors, namely customer service, security wait times and cleanliness. Each category had to be rated on a scale from very good to very bad – and give them an equivalent numeric value of 1 to 5.

The three ratings were then summed up, and the higher the score, the better the airport performed.

Unsurprisingly, Singapore’s Changi Airport topped the ranking with an impressive score of 92%. Key to its success was the recent opening of Jewel, its stunning lifestyle hub featuring an IMAX cinema, an immersive indoor garden and a range of activities for travellers of all ages.

Delhi Indira Gandhi International Airport bagged the second place for service quality, followed by Athens, which scored 90%. Despite their high scores of 84% and 83% respectively, neither Hamad nor Tokyo made it to the top ten.

On the other side of the ranking, Bucharest’s Henri Coandă International Airport received the lowest score with a mere 61% of appreciation.

The service quality category was also rather damning for US airports, four of which were listed among the ten worst-performing hubs. These include Los Angeles International Airport, which received the second lowest score, as well as Newark Liberty International Airport, Miami International Airport and New York’s JFK.

AirHelp’s last criterion was once again based on feedback from extensive surveys, which were carried out in a partnership with Attest.

In this case, passengers were asked to grade their experience at airports considering two types of amenities, shopping options and food options.

Once again, feedback ranged from very good to very bad, with the total mark accounting for 20% of the final score.

Hamad received an impressive 8.5/10 thanks to its Qatar Duty Free shopping emporium, which is home to over 90 shops, 30 cafes and restaurants spreading across 40,000ft2 of combined retail, food and beverage facilities. Tokyo got 8.4, while Athens scored a remarkable 8.7.

However, Indian airports were the overall best-performing hubs in this category, with the likes of Delhi Indira Gandhi, Mumbai Chhatrapati Shivaji and Hyderabad Rajiv Gandhi earning the top three spots for food and shops.

Bucharest’s Henri Coandă was again at the bottom of the ranking, which also saw Kelowna International Airport in Canda and Berlin’s Schönefeld Airport as second and third worst-performing hubs.