The Employee Share Ownership Trust at Aer Lingus is seeking a meeting with the company's chairman over the decision to axe flights from Shannon to Heathrow.
ESOT says it is very concerned at recent events and is conscious of the need to protect the value of the Aer Lingus brand.
The trust, which controls 12.5% of Aer Lingus, says it is taking professional advice on its position and is contacting the airline's other shareholders.