There have been three such landings to date this year, all by Boeing 707 aircraft. The first took place on 23 April, the other two on 5 May. The first flight left on 24 April and the others on 7 May. The landings were for refuelling and crew rest. The grant of permission in these cases was made subject to the normal conditions that apply to landings at Irish airports by foreign military aircraft; namely that the aircraft would be unarmed, would carry no arms, ammunition or explosives, would not engage in intelligence gathering, and that the flights in question would not form any part of military exercises or operations. The practice of permitting landings by foreign military aircraft at Irish airports, subject to such conditions, has been in place for more than fifty years.