From BBC: https://www.bbc.com/news/live/cly24zvvwxlt
Heathrow Airport is closing all day Friday because of a large fire at a nearby electrical substation that supplies it
The airport closure is expected to last until 23:59
Heathrow, the UK's busiest airport, has warned of "significant disruption" over the coming days and told passengers not to travel "under any circumstances" until it reopens
At least 1,351 flights to and from Heathrow will be affected by Friday's closure, according to flight tracking website Flightradar24