We’re preparing for our third set of round-the-world flights measuring the global distribution of particulate matter on the NASA Atmospheric Tomography Mission. We spent last week at NASA Armstrong, where the plane we use, a DC-8, is based. We tested instruments, installed some last-minute upgrades and then flew a test flight to make sure everything was working correctly.
Even with so many flights under our belts now, and with the test flight just a short 5h, heading out to the plane for pre-flight still felt slightly epic. It partly the scale of things, the big hangar doors are open and you feel tiny walking through them. Outside it is hot, the California sunshine almost blinding without shade, it’s noisy with power units running for the plane, and the air smells strongly of diesel. Perhaps it’s also the respect we have for the plane and the crew and all the work that goes into maintaining the plane, training the pilots and crew, and all the work we scientists put into the payload of instruments.
The flight protocols, which when I first started doing research flights, felt strange and foreign to me, now feel like comforting routines. Communications checks on the headsets, engine start ups and transferring power from ground units to aircraft power, another check that all instrument teams a ready for take-off, and then we’re off.
In many ways test flights are more stressful than research flights. On research flights, the aim is to just keep everything running fine and undisturbed, which, if things are going to plan, happens without much tinkering. On test flights the goal is to test all systems of the instruments in as many different conditions as possible, to push them to their limits, and to optimize their performance. Consequently, this flight was 5 hours of leaping up and down to change valves, run calibrations, adjust the software controlling the instruments … oh and keep yourself from falling over or throwing up during maneuvers or turbulence.
Each flight we do a set of pitch, yaw, roll and box maneuvers to test the pressure and velocity sensors on board. This feels slightly like a rollercoaster, and is generally more intense if we do it at lower altitudes and more gentle at higher altitudes. On this flight we did it at the lowest possible altitude, just 1000ft over the ocean. Thew crew even handed out sick-bags at the beginning of the flight, so we knew to expect it to be bad. The pilots were quite gentle though, and it was soon over.
We came back over land and did a long stretch of time flying in the boundary later (the first kilometer or so of air above the land, where it is well mixed, there’s lots of local influence from mountains and sources of pollution), where there’s generally a lot of turbulence, and there really was a lot of turbulence! With the amount of flying we do, I’m generally un-phased now by turbulence, but this had me sitting down in my seat and even wondering if that sick bag might come in necessary. Others on the plane were less fortunate, and didn’t need to wonder.
Turbulence aside though, it was an excellent flight. The upgrades we made to our instruments performed splendidly and I was able to fine-tune the code that controls them in flight. We, and the other instrument teams were happy with overall performance, and are looking forward to the beginning of the science flights. For now, we have a week back home for final preparations before we head off around the world again.