L2018-02 Two serious incidents occurred on two consecutive days in January 2018 at Helsinki-Vantaa aerodrome

In the first incident, on 23 January 2018 at 09:32, the Air Traffic Control (ATC) cleared an airliner to take off from a runway on and around which three runway maintenance vehicles were working. They were clearing snow off of runway and taxiway lights. Visibility was good at the time of the incident and the snow clearance was being done following the previous day’s snowfall. Two vehicle operators noticed the take-off and stopped ahead of the runway on the link taxiways. The third vehicle was working so far ahead close to the other end of the runway that the turboprop aircraft in question managed to get airborne before that point.

The time-consuming snow clearance operation had not been agreed on in advance, as prescribed by the Memorandum of Understanding signed between the ATC and aerodrome maintenance. Rather, each vehicle operator had individually asked the ATC for permission to work on the runway strip. The runway was not closed for the duration of the maintenance, which would have been indicated by the colour red on the ground control radar screen and, thus, warned the air traffic controller. The controller issued the take-off clearance after having both looked outside and checked the ground control radar. Each vehicle happened to be off of the runway strip at that point in time, therefore, the runway appeared to be free. Nor did the vehicles’ ‘strips’ on the ATC system’s touch screen monitor, i.e. the ‘e-Strip’ display, sufficiently capture the controller’s attention because they were the same colour as all of the other ‘strips’ on the display.

In the second incident, on 24 January 2018 at 10:47, a business jet inadvertently taxied onto an active runway for which an airliner on approach was on short final. During this incident the weather was snowy and windy and only one runway was in use. The ATC noticed the runway incursion from the ground control radar display and ordered the aircraft to stop immediately. The aircraft turned around and vacated the runway approximately one minute after the incursion occurred. The ATC ordered the approaching airliner to go around. As it passed above the occurrence site the business jet that had made the runway incursion had already vacated the runway strip.

The business jet had been standing outside in the snow for approximately two hours because the take-off time had been delayed for reasons independent of the operator. The cockpit windows were covered with snow and were frozen over; they were not cleaned before taxiing. Even though cockpit heating kept the windshield thawed, the side windows had become covered with snow and ice. The flight crew started going through the before take-off checklist as soon as they started taxiing. Owing to the limited visibility and focusing their attention on the instruments the pilots passed the taxiway junction without noticing it. In the blowing snow they passed the stop bar and, instead of turning onto a taxiway, entered the active runway.

The Safety Investigation Authority issues the following safety recommendations:

- The Safety Investigation Authority recommends that Finavia and ANS Finland handle future violations of the Memorandum of Understanding signed between aerodrome maintenance and the ATC as defects. By doing so they will be properly analysed.

- The Safety Investigation Authority recommends that ANS Finland and Finavia improve the ATC system’s touch screen displays in such a manner that aircraft and vehicles are clearly distinguishable from each other.

- The Safety Investigation Authority recommends that the Finnish Transport Safety Agency, when conducting inspections of operators, ensure that the operators’ taxiing procedures take into account that flight crews continuously maintain sufficient situational awareness.

L2018-02 Investigation report (in Finnish (, )

Published 17.10.2018