An RCMP spy plane that last drew attention when it was detected circling over Kingston, Ont., during an anti-terrorism investigation has been spotted again, this time over rural Ottawa.

On Wednesday, an amateur plane spotter using specialized software picked up C-GMPB flying over an area centred somewhere near Flewellyn Road and Black's Side Road, just outside Stittsville.

"I've been tracking planes my whole life, so I keep an eye on what's going on around me," said John Clarke, who measured the single-engine turboprop aircraft's altitude at about 7,800 feet.

Clarke regularly monitors a website called ADS-B Exchange, a kind of clearing house for crowdsourced flight data. All plane spotters need to pick up an aircraft's unique six-digit serial number is a receiver that can be purchased on Amazon for about $200.

The centre of the plane's orbit is near this farmer's field outside Stittsville. (Stu Mills/CBC)

Planes used for surveillance

Unlike flight information available from popular sites like Flightaware and Flightradar24, ADS-B Exchange shares serial numbers transmitted by military or VIP planes that their operators would rather not be made public.

"You can still know when interesting aircraft are passing by," said Clarke, who checks the site at least twice a day "just to know what's around."

A promotional photo for the Pilatus PC-12 Spectre shows the aircraft's belly-mounted sensing equipment. (Pilatus Aircraft)

A screen grab showing the RCMP plane's flight path over the course of about one hour of a six-hour flight Wednesday reveals some interesting information. The aircraft's serial number, C065E0, is well-known among plane spotters.

The RCMP love the $6-million Pilatus PC-12, which costs about $2,400 per hour to fly. The Mounties have 12 of the Swiss-made planes in hangars across the country, using them to ferry prisoners, witnesses and evidence, and to transport officers to remote detachments.

They're also used for surveillance work.

C-GMPB is a "Spectre" model, which Pilatus describes as a "special mission" aircraft equipped with an electro-optical turret capable of capturing high-resolution video and photos, as well as intercepting radio and cellular communication.

The manufacturer says the plane is capable of providing hours of surveillance "at distances undetectable by subjects on the ground."

An operator on board the PC-12 can train its sensing equipment on activity far below. (Pilatus Aircraft)

But earlier this year, when C-GMPB circled at several thousand feet above the Kingston home of a suspected terrorist, plenty of people detected it.

Social media soon filled with the complaints from residents annoyed by the spy plane's incessant droning

Now, people in Ottawa are taking notice of C-GMPB. On a Facebook group for Barrhaven residents Wednesday, Dana Courdin asked: "Anyone else keep hearing that plane circling Barrhaven?"

The RCMP claims to have no information about the flight.

"We have enquired and unfortunately do not have any information about an RCMP aircraft in the Stittsville area. It is quite possibly not an RCMP aircraft," the Mounties told CBC in an email Wednesday.