Directions on how to land on Pack ice


26 April 2007

Directions on how to land on Pack ice

New record: we have crossed this Wednesday the 88°degree latitude north. We are getting closer to the Pole (less than 300 km away) and it is quite possible that Tara may make Nansen’s dream come true: to drift on pack ice on the earths’ highest geographic point. For the moment however, one has to accomplish the planned observation missions for April and to do so, it was necessary to bring men and equipment with the DC3. To land a plane on pack ice is never an easy deed, especially when visibility is restricted. Today, everything was white on Tara. Off course, one could see a little. But all the perspectives, the landscapes were merged: sky, horizon, ground, everything was white!

For Brian Crocker and Louis-Eric Bellanger, the DC3 pilots, the job was not simple. It is hard to measure at eyesight the ground distance (if one can see the ground), it is hard to estimate the lateral wind speed during the landing, it is even hard to spot the boat sunk deeply into the snow or even to distinguish the runway, barely marked out with little red flags and empty kerosene barrels. It is in fact the Twin Otter crew that took in charge the DC3 landing, playing the role of a control tower.

Jim Hattew and Mathew Colistro are the pilots of this little plane that usually accomplishes the scientific missions pour the Damocles team. For instance, they have just finished the air-dropping of 16 weather buoys for Michael Offermann of the Hamburg University, that will transmit for a year the atmospheric pressure and temperature over a square of 500 km per side. In the past three days, the Twin Otter and his crew camp on the Tara base.

To help their colleagues land, the Twin pilots have had to first size up the vertical visibility ie the ceiling “At least 1000 feet” has estimated Jim Hattew, the head pilot at the beginning of the afternoon. This was confirmed by the weather balloon that Timo Palo has let go in the polar atmosphere for the Geography institute of the Tartu University (Estonia). The modern Zeppelin, that measures 4,5 meters long and 2 meters wide is bright orange and perfectly visible. One can spot it clearly up to 400 meters high which indicates the ceiling. From the runway that is located 800 meters from there, on can still see it. This gives us a good estimate of the ground visibility: 900 meters. The DC3 can land.

This information is communicated to Brian Crocker who is still 25 minutes away from Tara. From the cockpit of the Twin Otter, Jim informs his colleague that the balloon will be lowered to 30 meters at his approach and that a distress rocket will be lit at the beginning of the runway where the Twin Otter will position itself.

Matching his actions to his words, Jim is moving the throttle and makes the plane spin on its skis. The Twin Otter as well as the DC3 are not equipped with directional landing gear; To move these planes on the ground, the engines need to be activated to anticipate exactly the resulting sideslip. Precise manoeuvring, delicate but accomplished with mastery by the head pilot who drives his throttles to the tip of his fingers makes the plane slide to its spot. It is most probably visible from the sky because of its colour orange. On the ground, one does not have the impression that visibility exceeds 100 meters. Everything is still so white.

In front of us, the runway is marked out with barrels and some flags.
The strip is in fact just made of snow that has been packed down, slightly more flat than the surrounding pack ice. From the sky anyway, the lack of relief prevents one from distinguishing it from the rest of the landscape. Some meters behind the plane, Guillaume, Taras’ mechanic is about to light the distress rocket that is used as a signal buoy. The DC3 is now tree minutes away from his first approach: he must fist pretend to land, by flying as close to the ground as possible to identify the runway before turning around and land at his second passage. The landing without being dangerous is nevertheless perilous.

It is at this particular moment that Brian Hattew and Mathew Colistro his co-pilot in the Twin notice two fluorescent figures, right in front of them on the runway. Two members of the Tara expedition (we will not disclose their names) were heading right where the DC3 is supposed to touch down the ice. It is likely that they were convinced that the plane would land in the other direction and that they found themselves at the end of the runway…
Mathew then opens the door of the Twin, sets foot on the snow and runs to warn the two reckless persons not to remain there. The figures scatter off to the sides.

With engines roaring, the oblong shape of the DC3 passes over the Twin, flies over the runway a few meters above the ground in a cotton cloud. The plane turns on his left wing, rises up again to turn around and aligns itself with the Twin. Brian Crocker informs his colleague Jim that the runway is well visible and that he is ready to land. In a renewed white roar, the DC3 flies closely over the Twin, maybe 10 meters over, goes down slowly… stable on his landing strip and touches down. In his seat, the Twin co-pilot, Mathew approves the performance by applauding: “great landing”.