Try:
SELECT Max(YourTableName.SeatimeID) AS MaxOfSeatimeID, YourTableName.CrewID, Last(YourTableName.JoinDate) AS LastOfJoinDate, Last(YourTableName.LeaveDate) AS LastOfLeaveDate
FROM YourTableName
GROUP BY YourTableName.CrewID
ORDER BY Max(YourTableName.SeatimeID);