British Airways unusual flight

Just happened to look up and see a 747 coming over. Checked my local activity and saw this. Unusual flight number and route. Any ideas?

https://flightaware.com/live/flight/BAW9174/history/20171211/2000Z/KPHX/TXKF

Repositioning flight for aircraft that lost an engine. BA 747 3 engine ferry PHX-LHR - Airliners.net

Thanks for the answer! She was able to still fly at 580 knots on 3 engines. Love the 747