NORAD dispatched two CF-18 fighter jets to the skies over Ottawa after a drone was spotted flying near the airport of the nation's capital last month.

The CF-18s were scrambled from Canadian Forces Base Bagotville in Quebec at about 5:45 p.m. ET on May 25, after commercial airline operators raised concerns about a "suspicious" unmanned aerial vehicle seen near the Ottawa airport, according to a Department of National Defence spokesperson.

The drone was spotted by the pilots of WestJet Flight 366, from Toronto to Ottawa, as well as Air Canada Flight 458, also from Toronto to Ottawa.

The WestJet pilots flew past the drone as the Boeing 737 plane was descending into the Ottawa airport at about 4:45 p.m. ET.

The pilot's call to the airport's air traffic controllers was recorded by the website liveATC.net, which monitors air traffic control communications across the globe.

Listen to the air traffic control audio here.

'We just flew pretty close to a drone'

"Just to let you know we just flew pretty close to a drone at 6,700 feet," a pilot can be heard telling air traffic controllers.

After confirming the altitude, the pilot was advised to continue the plane's heading and descent.

The pilots of the Air Canada flight spotted the drone on their descent in an Airbus A320 just a few minutes after the WestJet flight spotted it.

"I can see the drone," a pilot can be heard telling air traffic controllers in another recording.

The scrambled fighter jets were not able to locate the drone when they arrived and the jets returned to CFB Bagotville, according to DND. The RCMP is investigating.

Transport Canada files report

On June 6, nearly two weeks after the incident, Transport Canada filed a report about the sightings of a "large drone" near the flight paths of the two planes.

The report says the WestJet pilots spotted the drone on the plane's left side at the same altitude of the plane, about 6,700 feet. The Air Canada flight was flying at 8,000 feet when its pilots spotted the drone about 1.8 kilometres to its left, flying about 2,000 feet below the plane's altitude.

The drone headed to the southeast at 37 to 55 km/h on radar and was lost at about 4:55 p.m. ET, the report states.

Residents in Ottawa who heard the CF-18 fighters wondered about their presence on social media.

F18s continuing to orbit skies over Ottawa. Sound as if they're moving further out from city centre. Practice? <a href="https://twitter.com/hashtag/fightersoverottawa?src=hash">#fightersoverottawa</a> <a href="https://twitter.com/hashtag/ottnews?src=hash">#ottnews</a> —@WordBanks