People have taken to social media after seeing helicopters flying over the district.
Express readers said they had spotted military aircraft over Newton Hill, Stanley, Outwood, Eastmoor, Carlton, Castleford and East Ardsley.
Lisa Mason wrote: "I saw two circling Pinderfields Hospital, both landed then took off again quickly. Very random!"
Victoria Hilton said: "They flew over my house and towards the hospital. I thought it was strange how there were two, they didn't look like the usual air ambulance or police helicopters either."
And Grace Cooper said: "Both landed at Pinderfields Hospital in turn while other was circling round. Only on ground about 30 seconds then took off again."
Commenting on a video of one helicopter landing at Pinderfields Hospital, taken by Karl Grubb and posted on the Wakefield Express Facebook page, an RAF spokesman said: "It shows an RAF Puma HC2 from 33 Squadron based at RAF Benson.
"Helicopter landing sites are available across the UK and are widely publicised for use. The Royal Air Force utilises these for training on a regular basis.”
Did you see the aircraft?
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