Heathrow: The Hexagram Runways, the 3 p.m. Swap and the Third Runway Fight

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London Heathrow opened as a small airfield in 1930, became London Airport in 1946 and took the Heathrow name in 1966. In the 1950s it had six short runways in three intersecting pairs, a hexagram that let tail-dragger propeller planes always land close to into the wind and avoid ground loops. Jets with tricycle landing gear handled crosswinds better but needed far longer runways, so two east-west runways were extended and the rest of the star was folded into the taxiways, where its outline is still visible from the air. Today those two runways run at more than 98 percent capacity for about 83.9 million passengers a year. Arrivals queue in four holding stacks over London, stacked 1,000 feet apart, and land as close as 2.5 nautical miles apart, roughly one every 45 to 60 seconds.

Noise rules shape everything: continuous descent approaches keep engines near idle, the noisiest jets are banned between 11 p.m. and 4 a.m., and on west-wind days the landing and takeoff runways swap at 3 p.m. to give residents a break. Terminal 5 took 19 years and £4.3 billion to build and opened in March 2008 with a baggage system meltdown that cancelled more than 500 flights in two weeks; by 2014 it was voted the world's best airport terminal. The Airports Commission backed a third runway to the northwest in 2015. In early 2020 the Court of Appeal blocked it for failing to account for the Paris Agreement, and in December 2020 the UK Supreme Court overturned that ruling.

• In 2008 the 40 percent scale Concorde model at the entrance tunnel was replaced by a model of an Emirates Airbus A380.
• The Fly Quiet and Green league table, launched in 2017, ranks airlines on relative rather than absolute improvement and does not publish how its scores are calculated.
• Theft by baggage handlers in the 1970s earned the airport the nickname Thief Row, and Scotland Yard took over policing; the Brink's-Mat gold bullion robbery followed in the 1980s.
• Nine centimeters of snow in December 2010 filled all 198 aircraft stands, cancelling 4,000 flights and leaving 9,500 people sleeping in terminals.
• In November 2024 Heathrow began testing an AI system that combines radar and ground video to predict touchdown times and keep taxiways clear.