The scientific objective for this flight was to make observations of gas-phase diurnal cycles in clean, clear air over the Coral Sea. A stack of circles was planned for this purpose, intended to be out of the plume of Australia as well as any nearby islands. The mission objective was complicated by the fact that a storm system was passing through most of the ferry path as well as the intended study area. In order to find clear air for the stacks, we attempted to locate them near the eye of the storm, although intermittent clouds were a problem.

Take-off from Hobart (21:01 GMT) ascended through several cloud layers. When we reached our ferry altitude of ca. 19,000' we were in clear air but appeared to be between 2 cloud layers (21:45). At 21:57 we skimmed near the top of a cumulus cloud and broke out into clear air, with clear air ahead. At 22:21 there was a hazy layer above and around us, and 8 minutes later we entered a cloud. At 22:39 we appeared to cross an air traffic track (with a high NO signature). (This could be the Brisbane-Melbourne route.)

At 23:01 we were back in clean air, but we entered another cloud at 23:17. At 23:45 we had left the major cumulus clouds but the air at 19,000' was once again very hazy with occasional clear patches ahead. Below was scattered low-level cumulus and some stratus.

At 23:47 we began our descent to 100' for the first circle. The starting point was the point designated in the flight plan to be well south and east of Lord Howe Island, so as to minimize continental pollution sources. We came about and started this circle from a heading of 320 (counterclockwise) in order to attempt to keep the sampling in the clear air region. Several clouds dotted the surroundings and we may have encountered some during the circles.

At 00:16:25 the first 30-min circle at 100' began (counterclockwise). The circles were calculated to drift with the wind by changing the heading by a fixed amount every minute. At 00:46:25 the circle was completed and we climbed to 1500'. The first 100' circle started at 00:49:16 from a heading of 137 in a clockwise fashion. It was completed at 01:19:16 and we climbed to 3800'. At 01:22:26 we reached this altitude and began a counterclockwise circle from a heading of 319. The 3800' circle was completed at 01:52:26. The next circle at 5500' began at 01:56:08 in the wrong direction and was restarted at 01:58:14 from a heading of 140 in a clockwise direction. The 5500' circle was completed at 02:28:14.

At 02:28 at a request from the scientists (Hudson?) we maintained our altitude and turned into the wind for a 5 min calibration. At 02:37 we began profiles across the boundary layer as specified in the flight plan. The inversion level seemed consistent with our earlier (pre-circle) profile indicating a temperature inversion at about 4400'. At 03:05:40 we returned to 100' to begin a counterclockwise circle from a heading of 271. This final 30-min circle was intended to provide an estimate of diurnal changes since the ca. 3 hours since our earlier circle at this level.

At the completion of this circle we climbed slowly up to ferry altitude. We stopped at 04:00 at ca. 17,000' to collect data in what we thought might have been a "layer" similar to those observed in the Hobart flights. At 04:40 we continued at 18,000', and continued to observe patchy cumulus below. At 05:24 we reached the Australian coastline.