Schiphol improves monitoring of infrastructure based on TNO recommendations

Problems at Schiphol after voltage drop

A voltage drop in Tennet’s high-voltage grid on 29 April 2018 led to a power outage in one section of Schiphol, resulting in disruption to a number of important operational processes.

‘In the direct aftermath of the power outage, we inspected other, comparable systems just to be certain,’ says Schiphol Board member André van den Berg. ‘We also took immediate steps to resolve the issues identified as causes of the power outage. For the longer term, we asked TNO to apply their expertise to investigating the technical aspects of this failure. This yielded valuable insights that, together with our own evaluation and analysis, have enabled us to learn a few lessons. We will be following TNO's recommendations in order to minimise the likelihood of a recurrence, in the interest of all stakeholders. None of this changes the fact that we deeply regret the events of 29 April.’

The findings of the TNO investigation support the conclusion that this event was the result of a combination of circumstances. At the time of the incident, work to improve the power network was being carried out in Terminal 3, which involved the use of a temporary emergency generator. Its settings and connections were not the same as those of Schiphol’s other emergency power generators. Three groups were adjusted to improper settings; as a result, they failed to be activated together with the emergency power supply. After the power supply had been restored, Schiphol encountered problems with the data networks at the airport. A certain connecting element (a switch) had been improperly installed and failed to start up fully. Another switch was affected by software problems. The problems in the data networks led to disruptions to the check-in and baggage system.

TNO's recommendations

TNO's analysis of the direct causes of the outages has revealed a number of flaws in the (temporary) emergency power facilities and the telecommunications infrastructure. TNO has ascertained that Schiphol has since implemented measures to rectify the flaws that were identified. The investigation next explored the question of which measures or barriers should have been in place to prevent these events. According to TNO, the decision to implement additional or more robust barriers is one Schiphol must take based on an assessment of risks and economic considerations. At Schiphol's request, TNO has issued recommendations to prevent or mitigate the risk of similar incidents in future. TNO also recommends that Schiphol use the same specifications for temporary systems (which Schiphol uses during renovation work, for instance) as it does for permanent systems, to minimise the chances of a malfunction occurring. In a similar vein, TNO recommends that Schiphol test both temporary and permanent systems under peak typical operating conditions, and – in light of the large number of modifications and settings applied at the airport – ensure that the system dependencies and settings of all critical systems are analysed and inspected regularly. TNO also recommends that Schiphol – in conjunction with all parties involved (internal or external) – look into whether and how improvements can be made to the notification, alert and escalation process regarding faults in the data infrastructure. A multidisciplinary technical response team will be established to assist in these efforts.

Schiphol is adopting the recommendations made by TNO and will closely monitor the follow-up and implementation.