That looks very much like a mission strip I flew into a few times at the top end of the Markham and quite close to Dumpu ( I can't remember the name of the strip). If I'm right, it had a windsock at each end which almost invariably pointed exactly 180 degrees in opposite directions in strong winds. Real easy to get caught with a long tailwind float and have to do some frantic braking if you didn't touch down close to the landing threshold before the wind switched direction....
