Due to failed negotiations on a collective bargaining agreement, trade union FNV called a strike in August 2016 involving the ground staff of KLM. KLM and Schiphol subsequently claimed a ban on this strike in interlocutory proceedings, which claim was allowed on 26 August 2016. In the past, the lawfulness of a strike for the purpose of an effective exercise of the right to collective bargaining was assessed on the basis of the so-called ‘rule of play’ test. This meant that a strike was unlawful when compelling procedural rules (the ‘rules of play’) were violated. These rules of play entailed, in brief, that an industrial action (i) should be used only as a last resort (ultimum remedium) and (ii) had to be announced in good time. Many proposed strikes were assessed as being unlawful on the basis of these rules of play. When this test did get passed, it was only possible to restrict the industrial action if a restriction of the right to strike was urgently required from a social point of view. All circumstances of the case had to be taken into account in such assessment. With the judgments of the Supreme Court in 2014 and 2015, this rule of play, however, ceased to apply as an independent test. The question as to whether a strike is allowed is now only assessed on the basis of the aforementioned test whether a restriction of the right to strike is imperative from a social point of view, having regard to all the circumstances of the case. The rules of play can then be taken into account as one of such circumstances of the case. This new way of testing by the Supreme Court seems to offer more room for a strike than before. Nevertheless, the Amsterdam Court of Appeal judged on Friday 26 August 2016, that the strike of the KLM ground staff was unlawful. The reason for this is that the effects of the strike would be so far-reaching, that a restriction of the right to hold an industrial action is justified. To this end, particular consideration was given to the fact that a strike during peak times, due to the holiday period, would seriously disrupt air traffic, resulting in major consequences for Schiphol and the passengers: hours of additional waiting time for passengers including those in aircrafts that had landed already. On 6 September 2016, the parties reached an agreement in respect of a collective bargaining agreement as yet.