Air traffic controllers will escalate industrial action over the controversial remote towers project.
Members of the Prospect Union say they may work to rosters or implement an overtime ban unless plans to centralise air traffic control services are stopped.
Other steps which may be taken include a refusal to commence training of new controllers who started with the airport authority after a ballot taken last November.
However, members say they will carry out necessary work for search and rescues as well as emergency and medical flights.
The union says almost 50 staff will be made redundant – with Hial needing to recruit a similar number in Inverness “at very significant expense to the taxpayer”.
The action is in addition to the continuous action short of a strike notified on the 21st of December 2020, which started on 4th January.
Staff have already refused to engage with the proposals to close air traffic service workplaces.