Originally Posted by corporate-wage-slave

Potentially yes, so long as the engine trouble wasn't extraordinary - it almost certainly will not be. Also she needs to be 3 hours late minimum - 2 hours 58 minutes isn't enough. Now luckily you raised this case here soon after the event, so I can still see some of the log files. She was due into LHR from MIA at 06:50 originally, but she ended up arriving into LHR at 11:34 hrs, which I reckon to be over 4 hours late, and thus gets the full payment of £520, rather than the half rate for a 3 hour delay. Doors open at 11:37. This is assuming an arrival into Heathrow on 7 November.

The baggage issue won't normally give rise to compensation, but she can claim for anything essential that was in her baggage that she needs, with a few exceptions.