Pilots flying into Dublin Airport have been warned about the risk of mistaking rooftop lights for an approach to a runway.

The warning came after an incident last month in which a flight from Lisbon on approach to the airport's alternative runway just before midnight began to deviate course and continued to descend without proper visual identification.

On instruction from Air Traffic Control, the plane ascended and later landed without further incident.

The Air Accident Investigation Unit found that flight FLT344E had mistaken the roof lighting of a 16-storey building at Santry Cross for the red and white lights of a runway approach system.

The warning to pilots was part of interim safety recommendations from the AAIU (read the report here) to the Irish Aviation Authority on the incident, which is still being investigated.

The investigators also asked the IAA to review the suitability of what it called 'obstacle lighting' on the 52-metre high building.

Speaking on RTÉ Radio's Morning Ireland, aviation journalist Gerry Byrne said the tone of the AAIU's report demonstrated the potential danger of what was called a 'serious incident'.

'They normally use very measured language in these reports and the use of the word serious implies that a disaster could have happened if this had not been corrected,' Mr Byrne said.