L2019-02 Incident on Helsinki-Vantaa Airport Runway 22L on January 18, 2019
At approximately 1715 h on Friday, January 18, 2019, a Turkish Airlines Boeing 737-900 operating a service from Istanbul landed on runway 22L at Helsinki-Vantaa airport, followed one-and-a half minutes later by a Norwegian Air International Boeing 737 Max on a service from Krakow. Traffic situation was normal for the time of the day, and visibility was good.
Observing the Turkish airplane in the process of vacating the runway, the controller cleared the Norwegian flight to land since there was reasonable assurance that prescribed separation would exist when the flight arrived at the runway threshold. The controller also cleared two Scandinavian Airlines (SAS) flights - which were at that time on taxiway Y and link ZD - to cross active runway 22L behind the Turkish airplane and prior to the landing of the Norwegian flight.
The Turkish airplane had slowed down markedly during rollout, and by the time it entered exit taxiway ZJ it was traveling at 9 kt. Speed reduced further to approximately 4 to 5 kt on the exit taxiway, and by the time the Norwegian flight was coming overhead the threshold, the aircraft was entirely on the exit taxiway. The Norwegian pilots considered the runway clear and concentrated on landing the airplane safely. Cockpit resource management was good.
Since the controller’s focus was on the two SAS jets crossing the runway, the controller was unable to monitor continuously the movement of the Turkish airplane. It should also be noted that it is inherently difficult to discern a slow movement and assess its speed, both visually and on the surface movement radar display; this led to the belated update of the status of the Turkish airplane that was vacating the runway and of the Norwegian flight approaching from an entirely different direction. Since the controllers were unable to positively determine whether the former was stationary or in motion, they told the Norwegian flight to go around. The call consisted of a single brief message: “go around, I say again, go around."
This instruction was transmitted at a very late stage of the landing. The pilots did not hear the message since the automated callout system was outputting voice alerts of remaining altitude (50 to 30 ft) in ten-foot increments, and the message, delivered in a normal tone and volume of speech, was masked by the loud callouts. Instead of executing a go-around, the airplane landed normally and vacated the runway along the same exit taxiway as the Turkish Airlines flight.
The investigation determined that a go-around instruction will ensure runway safety only if two conditions are met; i.e., if the controller monitors the situation actively and calls a go-around sufficiently early, and if the pilot complies with the instruction.
Investigation also disclosed that the regulations pertaining to vacating of the runway after landing are interpreted inconsistently within the Finnish controller community. An underlying safety management principle is that actions shall not contradict rules and regulations.
The Safety Investigation Authority Finland recommends that
- The Finnish Transport and Communications Agency Traficom and air traffic service providers (ANS Finland) embark on a joint long-term risk analysis of potential hazards associated with landing clearances that are based on reasonable assurance. The analysis would look at challenges to the controllers, potential consequences of non-executed go-around instructions, and other contingencies. The results would be used to revamp the existing procedures by eliminating the possibilities of inconsistent interpretation resulting from the way the conditions are presented in current documents.
- ANS Finland pays attention to controllers’ voice modulation (tone and pitch) in transmitting immediate-action instructions.
- Traficom and ANS Finland jointly see that the controllers’ actions are in compliance with the existing instructions and clarify the definition of a vacated runway in national documents if necessary.