In the words of the Second Doctor, a helicopter was a "primitive form of flying machine". They were also known as choppers and "whirly bird". Helicopters were used as late as 2018, though not early enough that Jamie McCrimmon — from the 18th century — would recognise it. (TV: The Enemy of the World) They were frequently used on Earth by the military, as they didn't need runways to land or take off.
Victoria Waterfield was kidnapped by the seaweed-possessed John Robson in one of Euro Sea Gas's helicopters, and the Second Doctor and Jamie McCrimmon were flown out to Rig D in another in order to rescue her. After appropriating Robson's helicopter to enable him and his companions to escape from the rig, the Doctor mentioned once they were in the air that he had learnt how to fly a helicopter by watching Astrid Ferrier, but also pointed out that he wasn't sure how to land it. (TV: Fury from the Deep)
Helicopters frequently patrolled the area surrounding Gwen Cooper's house in Wales. This aroused her suspicions as she was in hiding, but Rhys Williams passed it off as army practice. Following "Miracle Day", an armed helicopter was sent to kill her. Gwen destroyed it with a bazooka after a short chase. (TV: The New World)