People across Sheffield have reported numerous sightings of large military helicopters over the city in recent weeks.
The latest sightings of the Chinook - recognisable by the distinctive 'thud' of its huge twin rotor blades - came yesterday evening.
Between 6pm and 9pm last night the massive chopper was spotted over various parts of the city including Lowedges, Norton Lees, Parson Cross, Chapeltown and the city centre.
These were just the latest in a string of Chinook sightings over Sheffield since the beginning of July.
Photos posted on social media show the RAF helicopters - which are based at RAF Odiham in Hampshire - flying low over various parts of Sheffield.
Earlier this week Steve McCarthy posted on Twitter: "Sheffield peeps, anyone else noticed a Chinook flying over quite regularly in the last month or so? Think I've seen it three times this week."
The Boeing CH-47 Chinook is an American twin-engine helicopter which has been in service since 1962 and is operated by armed forces around the world.
The RAF uses the Chinook for trooping, resupply, and battlefield Casualty Evacuation (CASEVAC), and for carrying internal and/or underslung loads.
They can carry up to 55 troops (more, usually 24 to 40) and/or up to 10 tonnes of freight. A secondary role includes Search and Rescue.
An RAF spokesman told The Star this morning that the Chinooks spotted over Sheffield yesterday evening were taking part in a training exercise out of RAF Leuchars in Scotland.
The aircraft have since returned to their base at RAF Odiham.