Average firework displays cause few problems... there are large numbers on the approaches to Heathrow every year and some raise comments from crews. Hence a true story about a flight approaching Heathrow along the Thames one 5th November:
Lufthansa: "We see lots of fireworks; what is the reason please"
Heathrow: "It's a traditional thing in the UK when we celebrate attempts by Guy Fawkes to blow up the Houses of Parliament"
Lufthansa: "Hmmmm.. we see he was not too successful"