lvj
Under the presumption you're talking a UK AOC working to CAP371, i can't see any reason why not. The sby should be a prompt for you to be aware you may be needed to fly. If you're paxing back anyway all the duty counts towards the duty limits and if you're on a lot of sby + fdp you might hit the limits quicker than the airline wants you to.
It might be seen as best practice by aircrew, you have a natural dislike of standbys generally....If the base is undermanned then this might not be ideal, however is this better than re-basing someone to that base who doesn't want to be there (you?) a la Ryanair unlucky off you go..
