Landing at wrong aerodrome. On 29 March 2006, an Eirjet Airbus 320 was operating a scheduled passenger flight from Liverpool to Londonderry Airport in Northern Ireland for Ryanair in daylight. At eight nm from LDY, the operating crew reported that they were having problems with the ILS glideslope on approach to Runway 26. They judged that they were too high to carry out a safe landing from the ILS approach and requested permission from ATC to carry out a visual approach. The aircraft, with the commander as PF, then flew a right hand descending orbit followed by a visual circuit from which it landed. Upon landing, the crew were advised by Londonderry ATC, who had had the aircraft in sight when it called Finals and had then cleared it to land that they had, in fact, landed at Ballykelly airfield, a military helicopter base 5 nm to the east-north-east of Londonderry