Italian investigators have pointed out that NOTAM information warned of normal runway operations being restored at Cagliari Airport before a Ryanair Boeing 737-800 mistakenly landed on a taxiway on 12 April.
The country's Agenzia Nazionale per la Sicurezza del Volo (ANSV) says it is obtaining the air traffic control transmissions as well as the on-board recordings from the aircraft, identified as EI-DCE, in order to "correctly understand the dynamics" of the incident.
Italy's aeronautical information publication included a supplement, effective 20 December 2007, detailing changes at Cagliari to allow maintenance on the main runway 14/32.
This runway was closed and renamed taxiway J, while the parallel taxiway E was redesignated as a temporary operational runway, 14L/32R. The two strips are separated by about 180m (590ft).
Aircraft conducting an instrument landing system approach to Cagliari followed largely the same flight path but, shortly before touchdown, performed a side-step manoeuvre to line up with 14L/32R.
ANSV says that NOTAMs referred to the supplement remaining in effect until 8 April. The main runway 14/32 re-opened on 9 April.