Twin Otter Flights

Many times, the breaks in my posts are because not much has been happening and there is not much to write about. Other times it is because of a flurry of activity that results in things not getting done along the way, including posts. This latter explanation is the reason for this latest delay. 

At the end of each work day, the Fixed Wing Office, which is in charge of the US Antarctic Program non-helo flights on the continent, posts a schedule for the Twin Otter and the Basler DC-3 planes. Currently, there are three Twin Otters in McMurdo, and a fourth when including the Twin Otter for the Antarctica New Zealand program. In addition to the primary mission for each plane, there are multiple backup missions that are also planned. Frequently, the primary mission is not able to happen because of bad weather at the destination. In fact, it is common for the backup missions to not be able to fly as well.

Two DHC-6 Twin Otter airplanes at the Alexander Tall Tower site.

Getting the West Antarctic Ice Sheet (WAIS) field camp put-in team to WAIS has been one of the primary Twin Otter missions for the last two weeks. They are roughly two weeks behind schedule for the camp open due to routinely bad weather at WAIS. This past Wednesday, we were on the Twin Otter flight schedule to Lorne as a backup to the WAIS flights. WAIS did not happen and neither did our our flight because of bad weather at the destinations. The same scenario happened on Thursday. For Friday, we were a backup mission to fly either to the Lorne or the Tall Tower sites. The primary mission was cancelled because of weather at the destination. That bumped us up to priority and we were put on a weather delay. The weather at Lorne and Tall Tower for the morning was messy and the forecast was for it to clear at Tall Tower later in the day. The flight schedule to Tall Tower included two planes to take us to the site. We knew that we'd be retro'ing about 3000 pounds of gear and equipment, including 1540 pounds in batteries. The second Twin Otter would allow us to retro all of the cargo in a single flight. As the day unfolded, it was determined that the weather at Tall Tower was good and that we'd take-off at 1:30 PM. There were some delays in getting us and all of our gear to work on the sites. By the time we loaded the plane and took off it was closer to 2:30 PM. Shortly before the flight the weather was determined to be good at Lorne site and the flight plans were modified one more time.

The Lorne Antarctic Precipitation System when we arrived on site. The power systems are entirely buried and there is about 40 inches of accumulation with the towers and instruments.

Snow accumulation, from blowing snow and precipitation, is something that is an accepted part of field work when having instruments installed in the field. Therefore, we knew that there would be a lot of digging of snow to remove all of the equipment. Going to Lorne was myself, my colleague on the project, Scott, two colleagues with UNAVCO that have worked with us a lot on the project, and two other people from another project who had a spare day to help us. One of the benefits of two Twin Otter planes is that we also had two flight crews with each plane having two pilots. I never expect, or plan, for the pilots to help us in the field. If they decide to help, at any level, it is a bonus. Last Friday we had a big bonus as the four pilots all helped and worked really hard in digging out the equipment. After we landed, I was asked for the expected ground time and I guessed four hours. I was thinking I was possibly being too optimistic. We ended up leaving almost exactly at four hours. In between was a lot of work by everybody at the site. The wind shield was lowered and disassembled. The instruments were removed from the instrument tower. The cases and 22 12V batteries (70 pounds each), similar to in your car except using a gel-cell, were dug out from several feet beneath the snow surface. All of the towers and snow anchors were also removed. Once we were done, we loaded the planes with the 3000 pounds of equipment and returned back to William Field Skiway and then onto McMurdo by a van.

The disassembly of the wind shield and the precipitation gauge.

Digging out two 3-watt battery systems, including 22 batteries, with the help of the Twin Otter flight crews.

We didn't get into McMurdo until around 8:30PM due to the late start to the day. We were all hungry and tired from all of the digging. We also learned that the town was having power outages, which I'll explain in another post. Dinner was no longer being served so we had to make sandwiches at the deli in the galley. Our thoughts started to shift to how we'd spend the next day unpacking and sorting through all of the equipment we had pulled. It was around then that we learned that we were on the flight schedule for next day with a 7:30 AM departure from the lab. This not only sounded exhausting, because we'd have to do the same work again in removing the Tall Tower site, but there were also two issues. The tools, and some of the gear, that we need to remove the site were in the cargo system and returning from the flight that we had just completed. We didn't have access to the tools and gear and we didn't know when we would. On top of that, the two people from the other group would not be able to help us with Tall Tower. I wasn't sure how the four of us would be able to do all of the digging to remove Tall Tower, because again, I never expect the pilots to help. I stayed up late that Friday night sifting through all that happened while we were in the field that day, and working through our options for the flight to Tall Tower the next morning. I ended the day by sending an email to Fixed Wing informing them of our issues in needing the cargo from Friday's flight, as well as a concern about having enough help to get the job done. Part of me wanted to remove ourselves from the flight schedule but my general rule is that you don't pass on flights when they are given to you.

The Lorne APS sites after the removal of all of the equipment leaving only the holes in the snow. The next storm that comes across the area with 20+ mph winds will quickly fill in those holes.

I got up at 6:15 Saturday morning to be available when Fixed Wing started to organize and make final decisions on the day. I hadn't heard from them by 7:20, and breakfast was about to end, so I quickly left to get breakfast. We were placed on a flight delay and I was guessing it was because of the issue with tools and gear in cargo. After returning from breakfast, I was asked by Fixed Wing for our status in being able to leave for Tall Tower. I clarified that we needed to find where our cargo was from the trip the night before. I walked across town to find our cargo. I also found a loader operator to deliver the Lorne APS cargo to the lab. The delivery was completed and we were able to sift through the cargo to quickly ready ourselves for that day's work. In the meantime, I also learned that they were able to get four boondogglers to help with the digging. This was another trip into the field where we had two Twin Otters. Things started to fall into place and we were ready to be picked up from the lab by 9:30 and we were in the air by 10:15. It was a whirlwind of an early morning but everything had fallen into place.

Working on the digging out and removal of the Antarctic Precipitation System site at Alexander Tall Tower with the assistance of the flights crews and the boondogglers.

The removal of the Tall Tower site was roughly the same as the removal of Lorne the day before. The boondogglers and pilots weren't as good as the digging as the crew we had the previous day, although at Tall Tower we had two more people. I think it also required less digging for Tall Tower than there was at Lorne. We again hit the four hour ground time, almost to the minute. 2500 pounds of cargo were loaded on the planes and we made it back to the Williams Field Ski-way by 3:30 and into McMurdo well before 5:00. We completed our first full week in McMurdo and the field visits to the two sites that required flights were completed. That puts us in a very good position to complete the season ahead of schedule. However, I am always cautious to think that way because you never know what might come up to set you behind by a week or longer.

Unloading the cargo from the Twin Otter plane into cargo boxes to be transported to the lab in McMurdo Station from the William Field Ski-way.