The US Department of Transportation (DOT) gives airlines a lot of leeway when declaring flights to be “on time” – a flight can touch down up to 15 minutes late and still be considered to have arrived on schedule.

Southwest Airlines, however, is the leader in actually getting travellers from point A to point B in the shortest amount of time, according to a report by Forbes.

Rather than looking at DOT “on-time” data, Forbes and consultant Aerospace Engineering and Research Associates graded airlines on how close they came to matching ideal “block times” for flights – the time elapsed between airliners releasing their brakes upon takeoff and applying them when landing.

The study found that Southwest flew routes an average of just 12.5 minutes of the minimum achievable block time on flights in 2018, an industry best, even thought Southwest only placed fifth among US airlines in DOT’s on-time rankings for that year.

Southwest’s operation efficiency and willingness to allow pilots to increase airspeed in order to keep flights on time were credited for allowing the airline to stick close to block times on flights.

Other carrier, like Alaska Airlines, performed more poorly because of inefficient airports that frequently forced flights into holding patterns due to congestion at their gates.