What happened
On May 29, 2010, at 16:16 UTC, a Norwegian Airshuttle ASA Boeing 737-800, registration LN-DYA, was on final approach to Runway 28 at Faro Airport (LPFR). The aircraft was following an Embraer E-190 that was approximately 4NM ahead. To manage traffic flow, Faro Tower instructed the LN-DYA to reduce its speed to 160kt and eventually to its minimum approach speed.
During this sequence, the controller authorized a Brussels Airlines Boeing 737-400 to line up and depart on Runway 28, intending to intercalate this departure between the landing of the Embraer E-190 and the arrival of the LN-DYA. However, as the LN-DYA maintained its approach, the distance between it and the preceding Embraer decreased to approximately 3NM by the time the Embraer landed.
As the Brussels Airlines aircraft began its takeoff roll, the LN-DYA was passing near the runway threshold at an altitude of approximately 50ft. The Brussels Airlines aircraft became airborne at 16:16:22, at which point the LN-DYA was cleared to land. By the time the LN and DYA touched down at 16:16:44, the departing aircraft was approximately 1NM ahead and 100ft above it, resulting in a loss of required separation.
The investigation
The GPIAAF investigation examined the radar vectors, speed adjustments, and the separation standards applied by Faro Tower. The investigation found that while the controller attempted to optimize traffic flow, the separation between the aircraft fell significantly below the minimums required by ICAO Doc 4444.
Investigators noted that the airport's radar coverage limits prevented the controller from obtaining the precise relative positions of all aircraft involved. Furthermore, the investigation found that the AIP Portugal did not specify any special procedures or reduced separation minima for Faro Airport that would have legally allowed such a close interval. Consequently, the standard ICAO separation minima should have been strictly maintained.
Findings
- The incident was caused by an error in judgment by the Faro Tower controller, who permitted a departure between two successive arrivals without having accurate information regarding the relative positions of the aircraft.
- The separation between the arriving LN-DYA and the departing Brussels Airlines aircraft was well below the minimums established in ICAO Doc 4444.
- The radar coverage limitations at Faro prevented the controller from making a correct assessment of the separation.
- The airport was not operating under any authorized reduced separation minima, meaning standard ICAO separation procedures should have been applied.
- A potential conflict existed where, had the LN-DYA been forced to perform a go-around, its standard missed approach path would have intersected the departure path of the Brussels Airlines aircraft.