Plane spotters might notice "slight" alterations in air traffic in and out of Pearson International Airport starting in February.

The changes are a result of a three-year study by civil air navigation authority Nav Canada. They represent the first major airspace redesign in the area in more than 30 years and reflect a doubling of air traffic levels since the 1980s. In 2010, the number of takeoffs and landings at Pearson totalled about 420,000.

The modifications, which aim to take advantage of advancements in satellite-based navigation, include new routes and adjustments in existing routes. They are part of a new flight scheme for the entire Toronto-Ottawa-Montreal corridor, which is the country's busiest and covers about 140 square kilometres.

The scheme aims to reduce delays and travel time, partly by reducing the time planes spend circling the airport waiting for a landing strip. This, in turn, is expected to cut fuel consumption and the resulting greenhouse gas emissions.

"The routes are just more efficient and more direct in terms of carting the planes in," said Nav Canada spokesman Ron Singer. "Every little bit helps."

Nav Canada's website insists the changes are in accordance with existing procedures that aim to "limit the impact of noise from aircraft landing and departing the airport on surrounding communities."

Details about the changes, including maps of affected runways, are available at navcanada.ca.