It depends; your basic covers your position and in addition:
- if you feel it's appropriate for the company to cover out of pocket expenses down route then it's duty pay from the time you report to the time you return
- if you feel pay for your hard work is approprate then productivity pay in the form of sector pay is best
- or a combination of both
My company uses the basic + sector pay and I'm satisfied with that. There's also an extra payment for such things as nightstops.