Friday, 22 July 2011

Instrument Problems but Another Good Flight

Thursday 21st July, flight B624, and again we were chasing the smoke. This was Axel's last flight as flight manager and so he was aiming for the perfect score for flight quality in the debrief meeting. So far he has been given a 6.5, 7.5 and an 8 out of 10, a bit harsh considering they had a brilliant flight on Wednesday, but maybe it's because they had a power cut at Quebec. So we were aiming for the perfect 10, that elusive perfect flight.

That morning we had a visit from a journalist and a photographer from The Chronicle Herald who chatted to Paul for a while about what we were doing and took some pictures around the aircraft. This was then published on Friday morning on the online site at

Photograph from the piece on The Chronicle Herald website. Mike working hard on the CIMS instrument.

We took off just before 2pm local time a little early to give us more time for science. Pretty soon after take off, about 20 minutes or so it started to become apparent that this wouldn't be a perfect flight for me! The apparent NO2 concentration shot up but without a corresponding rise in the other channels, a clear indicator that something was wrong. I found a work around and carried on measuring but then about an hour and a half in, another channel, measuring the peroxyacyl nitrates (PANs), also went crazy. On inspection of the tubing connecting our heated inlet to the detection cells I discovered that the one to the PAN cell was full of condensation. Not good news! In the end the decision had to be made to disconnect the inlet and try to dry out the cells by flowing cabin air through. So the measurements made by our LIF instrument score about a 2/10 for this flight.

Thankfully other instruments were behaving better with some interesting shapes being seen in the carbon monoxide (CO) and ozone traces. It looked like we were seeing a really clear boundary between in plume measurements and those around the outside with ozone and CO often anti correlated and the high ozone correlated with nitrogen oxides. The step changes up and down as we flew into and out of the plume were quite striking so hopefully some good science there, just a shame we don't have the reactive nitrogen measurements from the LIF to back it up.

We had some problems with the ground power unit on landing at St John's for a refuel but on the fifth try we managed to get a unit that worked. Then after a short break and some refreshments we headed off again for a short flight back to Halifax. We encountered a plume as we flew out of St John's and another just before landing at Halifax. Debrief was done inflight and after some deliberation the flight was awarded a score of 9.5/10, much to the delight of Axel. Only the lack of LIF measurements lowered the score from the 10 we were hoping for, it was decided that since this was out of my control this must be the pilot's or mission scientist's fault for flying through such damp air. As we landed the rain was hammering down and there was a watefall pouring off the roof of the building. A bit of a damp ending but all in all, a good flight and hopefully sone good data.

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