Everybody knows tonight's the night Santa departs the North Pole on his round-the-world trip delivering presents. What you might not know is that because the weather at the North Pole can be challenging this time of year, Santa has an instrument approach procedure available for his arrival back home.

Pilots use an instrument approach procedure to guide them to an airport in lousy conditions like, say, an Arctic storm. When flying in clouds, known asinstrument meteorological conditions or IMC, there are no ground references available to navigate by. Pilots must rely on instruments. Radio signals have been used for decades, but these days, GPS is the most common navigation aid.

Following signals alone isn’t enough to land safely. Coming into an airport, an approach procedure is used to assure the pilot there won't be any conflicts with terrain (such as failure to maintain clearance), and assure both pilot and air traffic controller that the aircraft will be in a predictable place. An example of an approach procedure for SFO in San Francisco is shown below.

Santa's instrument-approach procedure allows him to get himself and the reindeer back home safe and sound after a long night of flying.

Santa has the option of using a newer GPS approach, as well as an old-school non-directional beacon (NDB) radio approach as a backup. He can’t risk a satellite constellation failure, and thankfully the FAA hasn't decomissioned his NDB approach.

Across the top of the "approach plate" you see the various radio frequencies Santa has available to receive weather information and talk to air traffic control. Who knows why there is a North Pole Unicom. This is typically the frequency to talk with other aircraft in the area. I always just assumed there would be a temporary flight restriction at the North Pole during Christmas.

Anyhow, Santa can make his approach down to 400 feet. At that altitude, known as the minimum descent altitude (MDA), he must be able to see part of the runway or the lights illuminating it. However, having Rudolph up front with his nose so bright probably gives Santa a bit of an advantage and he might even be tempted to bust minimums every now and then.

If Santa can't see the runway or markers at 400 feet, he must execute a missed approach procedure that includes a climbing right turn to 1,500 feet, then a holding pattern before making another attempt.

One convenience Santa enjoys is the simple heading to remember to get home. As the approach plate shows, as long as he follows a true heading of 360 degrees, he should find his way whether he's coming from Sydney, New Delhi or London.

With a 5,739-foot runway, Santa has plenty of room to get his sleigh down in even the worst conditions. And at only 17 feet above sea level, thin air won't be an issue affecting the performance of his nine reindeer.

Hopefully in the coming years, Santa will get a required navigation performance (RNP) approach, allowing him to land with lower minimums (cloud levels). The regulating authority at the North Pole is a bit slow – the precision approach technology is just now catching up with the red-nosed illumination landings Santa's been making for a long time. At least, he doesn’t have to rely on the NDB approach, which can frustrate even the most experienced pilots.

Meanwhile, you can track Santa and watch for the time when he pulls out his instrument approach plate and lands safely back at home.

North Pole Image: J. Budge / SFO Image: NACO