Santa Claus has delivered billions of presents to children around the world and is already delivering gifts in some Canadian communities, according to the team at the North American Aerospace Defence Command (Norad) tracking his reindeer and sleigh.

By 9 p.m. ET, Santa had delivered presents to Alert in Canada's far north, Norad said on its website. He later made stops in Canada's east coast.

Volunteers at Peterson Air Force Base, headquarters of Norad's annual Santa-tracking operation, are in Colorado monitoring Santa's progress. Monday evening they were on pace to break last year's record of 107,000 calls from children wanting to know everything from old Saint Nick's age, to how reindeer fly, to when they can expect their presents.

Each year, the job of watching out for Santa on Dec. 24 falls to Norad personnel — the same people who monitor North American skies year round.

Norad's Santa-tracking work all started with a typo more than a half-century ago.

In 1955, a department store advertisement in a Colorado Springs newspaper gave the wrong phone number for children to talk to Santa at the Sears Toyland.

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Instead, the children were ringing through to the operations hotline for the then Continental Air Defence Command, a predecessor of the bi-national Norad command that was created in 1958.

The American director of operations at the time, Col. Harry Shoup, heard his calling to pitch in as an elf and made the best of the mistake: he told his staff to check the radar for indications of Santa making his way south from the North Pole.

Children who called the number from then on were given updates on his location.

Tracking Santa in 2012 has become a major undertaking for Norad, with 1,250 volunteers on duty to provide updates to the public and media.

The tradition of a telephone hotline remains (1-877-HINORAD), but a countdown clock, videos and other information are also available on Norad's website: www.noradsanta.org.

Military planners briefed Santa

Over 1,200 volunteers across North America track and report Santa's exact location to the media and the public throughout the day and night on Dec. 24. (YouTube/Norad Tracks Santa)

In footage of an earlier video teleconference between Norad commanders and Santa Claus posted on its website, Gen. Chuck Jacoby, Commander of Norad and U.S. Northern Command (U.S. Northcom) and his deputy, Lt.-Gen. Alain Parent from the Royal Canadian Air Force, walk Santa through the 2012 preparations.

"We're going to make sure you get to everybody's house Santa," Jacoby assures him. "Don't worry about the journey. We've got the watch."

"Thank you," Santa tells Jacoby and Parent. "Ho ho ho."

Three high-tech systems track the flight of that one sleigh from the North Pole: radar, satellites and specially installed Santa cams that were installed at strategic locations around the world in 1998 for this one special day of use.

Norad is the first to know when the reindeer take off from the North Pole, thanks to its "North Warning System" of 47 installations that Norad’s team compares to a string of Christmas lights strung across the top of North America.

The Canadian Air Defence Sector at 22 Wing in North Bay, Ont., closely monitors this radar system to make sure Santa and his reindeer are not delayed.

Rudolph’s introduction to the reindeer team some years back also makes it possible for Norad to use its space satellites to track the sleigh’s journey: his nose gives off an infrared signature, the heat from which is picked up by the satellites’ sensors.

Finally, animation from the Santa cams is posted throughout the day on Dec. 24, giving keen observers a glimpse of the big man in motion.

Advice for Canadian kids

Over the years, Norad has been able to compile data of practical use to Canadian children plotting their own Christmas Eve agendas.

Santa usually starts at the International Date Line in the Pacific Ocean and travels west. Historically, he visits the South Pacific first, then New Zealand and Australia. After that, he covers off Japan, Asia, Africa and then onto Western Europe, Canada, the United States, Mexico and Central and South America.

But Norad cautions that Santa’s exact route year to year can be affected by weather and remains unpredictable.

Santa Claus met with senior Norad commanders earlier this fall to begin preparations for this year's Christmas flight. (YouTube/Norad Tracks Santa)

"Norad co-ordinates with Santa’s Elf Launch staff to confirm his launch time, but from that point on, Santa calls the shots," says Wright Eruebi, a spokesman for the Royal Canadian Air Forces 1 Canadian Air Division in Winnipeg. "We just track him."

In most countries, on average, Norad finds Santa arrives between 9 p.m. and midnight local time. But if children are still awake when Santa arrives, he has to move on to other houses and return later after they’re asleep.

Norad advises that one of the best ways children can help him out logistically (and, perhaps, stay on his “nice” list in the process) is to help him stick to his intended flight path by going to bed on time.

Magical flight

Faced with the eternal question of how St. Nicholas can pull it all off in one night, Norad researchers suggest Santa "functions within his own time-space continuum."

That poses a real challenge for the two teams of Canadian CF-18 pilots assigned to escort him through Canadian airspace Monday night.

"Santa travels at the speed of one T [in layman’s terms, a twinkling of an eye]," explains Eruebi. "Santa usually slows down the sleigh when Norad pilots are approaching, and he likes to wave and acknowledge the pilots when they tip their wing to show their respect.

"The main reason we [give Santa a fighter jet escort] is to treat him like the VIP that he is and, of course, to capture a few images of him in action," Eruebi explains. "He slows down to allow our fighters to catch up and he humours us. He appears to like posing for the camera."

On behalf of a five-year old reader in Ottawa, CBC News asked the air force what Santa’s fighter jet escort does while he's on the roof of each house.

The CF-18s, Eruebi says, "simply wait."

"Santa does a strange manoeuvre just before he disappears into a home through the chimney," Eruebi says. "He switches back to the speed of one T and he's gone."

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With files from The Associated Press