Security fears: Confidential correspondence from the head of the defence secretariat at the Ministry of Defence in Whitehall, London, draws attention to growing fears of an impending airborne attack from the Provisional IRA.
A letter in January 1974 from Tony Stephens at the MoD refers to the urgent desire on the part of the general officer commanding in Northern Ireland to prohibit overflying at low altitudes by civil aircraft "because of the threat of attacks from the air by the IRA".
Worries about an air attack started after the Provisional leader, Séamus Twomey, had successfully escaped from Mountjoy prison by helicopter on October 31st, 1973.
Shortly after the escape, Twomey declared to the Hamburg-based news magazine, Der Spiegel, that "very soon we shall also fight from the air". Reference to an IRA plan to resort to such tactics "including", in the words of an MoD memorandum, "the possibility of training pilots", was duly carried by other newspapers.
Given Twomey's record, "we must expect the Provisionals to mount attacks of maximum ferocity", wrote the MoD.