The Munich air disaster occurred on 6 February 1958 when British European Airways Flight 609 crashed on its third attempt to take off from a slush-covered runway at Munich-Riem Airport, West Germany. The aircraft was carrying the Manchester United football team, nicknamed the "Busby Babes", along with supporters and journalists. There were 44 people on board, 20 of whom died at the scene. The injured, some unconscious, were taken to the Rechts der Isar Hospital in Munich where three more died, resulting in 23 fatalities with 21 survivors.

The team was returning from a European Cup match in Belgrade, Yugoslavia, having eliminated Red Star Belgrade to advance to the semi-finals of the competition. The flight stopped to refuel in Munich because a non-stop flight from Belgrade to Manchester was beyond the range of the "Elizabethan"-class Airspeed Ambassador. After refuelling, pilots James Thain and Kenneth Rayment twice abandoned take-off because of boost surging in the left engine. Fearing they would fall too far behind schedule, Captain Thain rejected an overnight stay in Munich in favour of a third take-off attempt. By that time, snow was falling, causing a layer of slush to form at the end of the runway. After hitting the slush, the aircraft ploughed through a fence beyond the end of the runway and the left wing was torn off when it struck a house. The tail section broke off and hit a barn with a parked fuel truck in it, that caught fire and exploded. Fearing the aircraft too might explode, Thain began evacuating passengers while Manchester United goalkeeper Harry Gregg helped pull survivors from the wreckage.

An investigation by West German airport authorities originally blamed Thain, saying he did not de-ice the aircraft's wings, despite eyewitness statements indicating that de-icing was unnecessary. It was later established that the crash was caused by the slush on the runway, which slowed the plane too much to enable take-off. Thain was cleared in 1968, ten years after the incident.

Manchester United were aiming to become the third club to win three successive Football League titles; they were six points behind league leaders Wolverhampton Wanderers with 14 games still to play. They also held the FA Charity Shield and had just advanced into their second successive European Cup semi-finals. The team had not been beaten for 11 matches. The crash not only derailed the team's title ambitions that year but also destroyed the nucleus of what promised to be one of the greatest generations of players in English football history. It took ten years for the club to recover after the tragedy. Busby rebuilt the team and won the European Cup in 1968 with a new generation of "Babes".

Manchester United Football Club is a professional football club based in Old Trafford, Greater Manchester, England, that competes in the Premier League, the top flight of English football. Nicknamed the Red Devils, the club was founded as Newton Heath LYR Football Club in 1878, but changed its name to Manchester United in 1902. The club moved from Newton Heath to its current stadium, Old Trafford, in 1910.

Manchester United have won the joint-record number of trophies in English club football, including a record 20 League titles, 12 FA Cups, five League Cups and a record 21 FA Community Shields. They have won the European Cup/UEFA Champions League three times, and the UEFA Europa League, the UEFA Cup Winners' Cup, the UEFA Super Cup, the Intercontinental Cup and the FIFA Club World Cup once each. In 1968, under the management of Matt Busby, 10 years after eight of the club's players were killed in the Munich air disaster, they became the first English club to win the European Cup. Alex Ferguson is the club's longest-serving and most successful manager, winning 38 trophies, including 13 league titles, 5 FA Cups and 2 UEFA Champions League titles, between 1986 and 2013. In the 1998–99 season, under Ferguson, the club became the first in the history of English football to achieve the European treble of the Premier League, FA Cup and UEFA Champions League. In winning the UEFA Europa League under José Mourinho in 2016–17, the most recent trophy won by the club, they also became one of five clubs to have won the original three main UEFA club competitions (the Champions League, Europa League and Cup Winners' Cup).

Manchester United is one of the most widely supported football clubs in the world, and has rivalries with Liverpool, Manchester City, Arsenal and Leeds United. Manchester United was the highest-earning football club in the world for 2016–17, with an annual revenue of €676.3 million, and the world's third most valuable football club in 2019, valued at £3.15 billion ($3.81 billion). After being floated on the London Stock Exchange in 1991, the club was taken private in 2005 after a purchase by Malcolm Glazer valued at almost £800 million, of which over £500 million of borrowed money became the club's debt. From 2012, some shares of the club were listed on the New York Stock Exchange, although the Glazer family retains overall ownership and control of the club.