What happened
On June 7, 2008, at 14:05 UTC, an Airbus A320-214, operated by TAP Portugal with registration TAP873C, was on an ILS approach to runway 03 at Lisbon International Airport. Simultaneously, a HeliPortugal Eurocopter AS 350 B2, registration CS-HFP, was operating in the vicinity of the airport to provide television coverage for the Euro 2008 football tournament.
The helicopter had previously informed Lisbon Tower that it would remain near the runway 35 threshold for several minutes. However, as the Airbus was descending through 2300 feet and established on the ILS, the helicopter began a left turn at approximately 1300 feet. This maneuver was likely an attempt by the helicopter crew to position themselves head-on with the approaching Airbus to establish visual contact.
This sudden change in flight path resulted in a vertical separation of only approximately 100 feet between the two aircraft, triggering a TCAS (climb) Resolution Advisory (RA) on the Airbus. The flight crew of TAP873C immediately responded to the RA by initiating a go-around, notifying the tower that they were overshooting due to the TCAS alert.
The investigation
The GPIAAF investigation examined the movements of both aircraft and the communications between the flight crews and Lisbon Tower. The investigation reviewed the helicopter's flight pattern, noting that the aircraft had been performing a series of back-and-forth maneuvers near the airport, moving away from the approach path whenever informed of approaching traffic.
The investigators also analyzed the radiotelephony communications. While the Airbus crew correctly identified the reason for the maneuver, the investigation noted that the pilot used the non-standard phrase "overshooting" instead of the ICAO-standard "going around." Additionally, the investigation found that the controller's response and the pilot's subsequent instructions regarding altitude maintenance did not strictly adhere to standard ICAO phraseology for TCAS RA events.
Findings
- The primary cause of the incident was the unpredictable left turn performed by the helicopter CS-HFP, which was intended to achieve visual separation but instead caused a loss of vertical separation.
- A contributing factor was the expectant attitude of the Lisbon Tower controller, who assumed the helicopter would move east of the ILS approach path, as it had done during previous encounters.