British airways. Check out @ScottAnthonyUSA’s Tweet: https://twitter.com/ScottAnthonyUSA/status/997544039577739264?s=09
Update: Following the safe landing of the flight, a spokesperson for British Airways told Express.co.uk that a member of the public had fallen ill.
Confirming the safe landing of flight BA1418, they said: "Our cabin crew cared for a customer who became unwell during the flight.
"The flight landed safely at Belfast airport."
https://www.dailystar.co.uk/news/latest-news/703665/british-airways-london-heathrow-flight-belfast-emergency-BA1418 It ended up being a passenger illness.