Referring to a recent MAA turnaround (not planned as a variation flight) included the usual CONOTAM to indicate that it was a burnout flight. Given cruise time less than six hours etc, there is no extension of duty time beyond the "normal" two-crew duty times right? So if it's not a variation flight and can be done within two-crew duty limits then the augmenting pilot has exactly the same duty time as the other two poor blokes, so whether it's a burnout flight or not is irrelevant i.e. everyone will "burnout" at the same moment. (A rare and spectacular sight for sure!)
Then, I read in this weeks Flight Safety digest that the Flight Safety Department believes these flights are operating as "variation flights" and are safe for two crew. Huh?!?!