helidromen.

1951 Daily Tel. 5 June 4/6 Helidrome, rotorport, helistop and helihalt are among recent verbal coinage[s] to signify a helicopter station.

1952 Times 10 Oct. 7/4 What..is a ‘helidrome’? So far as I can see it is either a place where marsh-meadows run..or a place where [s]nails run..But in either case the word ought to be ‘helodrome’.

1953 Listener 25 June 1040/2 One can almost hear the sound of rockets being fired from the space ships moored at the South Bank helidrome to herald in the twenty-first century.

1966 Punch 6 July 8/2 The Director..with a personal helidrome at Great Yarmouth.