The 404 error that was coming up suggests significant tomfoolery.
Don't know the cause but over here in the U.S. the ba.com site comes up OK but the flight status page yields this enlightening message:
Error 404--Not Found
From RFC 2068 Hypertext Transfer Protocol -- HTTP/1.1:
10.4.5 404 Not Found
The server has not found anything matching the Request-URI. No indication is given of whether the condition is temporary or permanent.
If the server does not wish to make this information available to the client, the status code 403 (Forbidden) can be used instead. The 410 (Gone) status code SHOULD be used if the server knows, through some internally configurable mechanism, that an old resource is permanently unavailable and has no forwarding address.
This message is like the man in a balloon joke, technically correct but of little value to the end user.
Looking at FR24, several BA international inbounds are parked with the power on, apparently still waiting to offload pax and several more (including BOM, DME, LCA and BKK) are airborne inbound.
A few narrowbodies appear to still be inbound to LGW including FNC, FAO and VCE.
A wave of BA arrivals will soon land in the U.S., in time for local reporters to cover the scene at baggage claim and customs if the onward connections were hit by the computer outage. If the luggage tags were printed while the computers were working would everything still be routed OK on arrival?