Sunday, November 7, 1999

Keeping the planes apart

Published in the Antarctic Sun

It’s a blue-sky day out on McMurdo Station’s ice runway, but the world’s turned upside down in the tower.

An LC-130 is leaving for the South Pole and the tower crew is thinking “north.”

“Planes fly north to the South Pole,” air traffic controller Heidi McCaffray said, watching the aircraft head between Black Island and White Island.

Here, that statement makes sense. Close to the magnetic poles of the earth, navigation by compass is unreliable at best and dangerous at worst. Navigation is by “grid,” based on calculations involving the longitude of a current position in relation to the 180-degree longitude line, explained air traffic controller Robert Virgil.

Since McMurdo is so close to 180 degrees of longitude, “grid north” is very close to true south.

Oddly, though, helicopters use true north and south for their navigation. It means the tower has
to keep straight not only the type of aircraft on the radio, but also its direction— in real space and on its map.

They manage to do this with ease, fulfilling their basic mission. According to tower manager Mike
MacLean, “We keep the airplanes apart.”

That’s may not seem too tough at an airport which deals with only about a dozen different planes all season. But it’s not all that easy.

Runways are busy places, even when there are no planes around. Surveyors are out on the runway checking the sea ice movement, snow plows are keeping the path clear, maintenance workers are checking lights and navigational equipment, and the decelerometer crews are measuring the braking qualities of the ice.

Any time a plane comes near, to take off or land, the tower clears the runway of all people and equipment and calls out the fire department’s crash vehicle in the event of a mishap.

It’s all done by radio, and largely without the aid of tower radar, except in bad weather. Then the machine in the downstairs closet goes to work. It’s the pilot’s eyes, connected to the airplane only by the voice of the tower controller, every five seconds during final approach in bad conditions.

Of the 15 controllers on staff, two are on duty at any given time. Sometimes there are more, if they’re training or checking equipment. There’s a bed in the tower, too, in case the controllers get stuck at the runway. They don’t go home until all the planes are in.

There’s also a weather person in the tower, taking readings on the instruments outside and observing conditions on the sea ice.

Sandra Lorenzana, one of the tower’s rotating weather crew, said she does hourly observations as well as special reports and more frequent full reports if the weather is changing rapidly. These are called into Mac Weather and Mac Center, she said, to assist them in determining severe weather conditions and informing the pilots of what to expect during approach and landing.

A bit later in the season, MacLean said, there will be two towers operating around McMurdo; one will be at the ice runway until it shuts down, and the other will be at Williams Field. Last year they just had one tower and were unable to move it and set it up again in time for flights to
arrive on schedule. Now, with an extra tower (which is presently at the ice runway, just next to the operating tower), Williams Field will be up and running with fewer delays.