https://en.wikipedia.org/wiki/Heathrow_arrival_stacks https://en.wikipedia.org/wiki/Heathrow_arrival_stacks > On 1 December 2003 at 6am, a major disaster in th

https://en.wikipedia.org/wiki/Heathrow_arrival_stacks https://en.wikipedia.org/wiki/Heathrow_arrival_stacks > On 1 December 2003 at 6am, a major disaster in the stack was narrowly avoided. An air traffic controller was blamed by a later inquiry for misdirecting traffic when he ordered a United Airlines Boeing 777 into a level of the Bovingdon Hold (or stack) already occupied by a similar British Airways plane. The two planes, carrying 500 passengers, flew within 600 vertical feet (180 m) of each other.[4]