AER LINGUS has written to its employees expressing its 'regret' at the decision of SIPTU to serve strike notice on the company, as well as on the Dublin Airport Authority over a €700 million hole in the airline and airport workers' pension scheme.In a letter to employees seen by the Fingal Independent, Michael Grealy, the 'chief people and change officer' at Aer Lingus tells staff: 'As you are aware, SIPTU served notice of industrial action on Aer Lingus yesterday afternoon. We regret that SIPTU has seen fit to take this action. 'Aer Lingus management have engaged fully with the Labour Relations Commission process and we have been actively working to find a resolution to the IASS funding shortfall. 'We believe that there is no justification for this course of action and we refute strongly SIPTUs claim that a breach of collective agreements has occurred.' Mr Grealy goes on to say: 'I want to assure you that Aer Lingus remains fully committed to finding an appropriate resolution to this issue and we have called on the LRC to use its good offices to ensure that all parties remain fully engaged in the on-going discussions. 'We will be assessing the situation over the coming days and we will communicate proactively with our customers regarding alternative travel arrangements to apply in the event of disruption to scheduled services on October 1. We will also continue to communicate with our employees as appropriate.'