The action picks up as an incoming jet enters Yk airspace. The switch from Edmonton's air traffic control to the Yellowknife tower normally occur when aircraft are 25 air kilometres (five minutes) out. Sometimes it can be as far 50 to 65 kilometres.

The runway-tower chatter is clam and deliberate: "Hotel runway ... altimeter ... umpire two ... Roger alpha ... X-ray ... golf ... zero..."

Tonge enters the tower and dons a headset. He controls the override button for his three-month tower trainee, Natalia Varevac.

In four-and-a-half years with various trainees, he's only had to use the override button twice. Tonge describes the air traffic controller oral exam.

"Whatever you say, your first answer is your final answer." There's second-guessing. Questions are simply logic and math. For example, an aircraft is flying at 500 km/h and another at 700 km/h -- when are they due?

The examiner then fixes the trainee in a stare, thrusts forward a forearm bearing a wrist watch and begins a 30-second count. No writing materials are available. The mental calculations must be swift and accurate.

You can teach the basics, but you can't teach timing and air space conceptualization, says Tonge.

Now the trainees have to show they can make a decision based on knowledge and skill -- they have to have that or they don't make it.

Training someone can be as stressful as managing a flight yourself. "You try to let them go as far as they can without creating a hazardous situation, it wears you down," he says.

Russell says once the trainer steps back, then the real learning can begin, when the trainees have to think on their feet and do precise mental calculations.

Accidents or mishaps are rare, but when they do occur, there's peer de-briefing available. Normally, the controller would be relieved and sent home with pay.

As a stress reliever, six of the 10 tower crew belong to Harley's Hardrock softball team, although it's sometimes difficult to get together as a group.

Air traffic controllers who train in the tower are dubbed "spinners" after their training in Cornwall is completed.

Tonge, a self-described perfectionist, has been in the aviation business for 15 years. "I like to make decisions," he jokes. "My wife won't let me made them at home."

Natalia was an air traffic controller in Bosnia.

"Back home, my decision was made 12 years ago. After high school, I took law at home. I didn't like it. I had a bachelor of law. I have basic English. When the war started, I left. I lost everything. I was sponsored and came here."

It took 22 months before she knew she could stay.

Based on her previous experience working overseas, she was exempted from the simulation training and controller's oral exams.

Natalia came by herself, then her husband joined her later. Family members are still in Bosnia.

Phyllis Haines, a spokeswoman for NAV Canada at Yellowknife's airport, says it's interesting to watch the air traffic controllers train.

"When they start using original thinking, it's so neat to see."