Original Message

you can be on duty for 16 hours, 18 hours, 24 hours..... just can't operate a aircraft under Part 135 unless you can show 10 hours of rest looking back from the planned completion of a flight assignment (ie, the landing). it's been that way since before you were in diapers holding a toy helicopter. you operate under 135.267 (b) & (d), which you can verify looking at your company's GOM.