Trade union Unite has said it's challenging a temporary lay-off of around 150 staff at Belfast City Airport by the support services firm Swissport.
The administration of regional airline Flybe, which the company said was precipitated by the impact of coronavirus on bookings, brought to a halt around 80% of Belfast City Airport's business.
The airline's collapse brought to a halt 14 air links with cities in Great Britain, although small airline Loganair confirmed it will pick up links to Aberdeen and Inverness.
Unite regional officer George Brash said stewards representing Swissport baggage handlers and check-in staff had been told on Friday that there was an "immediate threat" of temporary lay-offs.
Mr Brash said: "Swissport bosses briefed our shop stewards on Friday, on their proposals for a 24-day unpaid stand down period - in effect a temporary lay-off .
"This is a totally unacceptable response by Swissport. This is a hugely successful company which last year reported earnings before tax of more than €200m.
"This is not a company that needs to threaten the income of their employees in the aftermath of the Flybe collapse; indeed, with the prospect that many, if not all, former Flybe routes could be taken on by other airlines this is an unnecessary and unacceptable response rooted in a short-term desire simply to maximise profits.
"Unite is already engaging with our legal team to challenge the legality of a 14-day unpaid lay-off."
A spokeswoman for Swissport said: "Flybe's unfortunate news has come at a very challenging time for the industry. As a business, we have a responsibility to carefully consider the impact this has on our company and identify the best outcome for all our employees and partners across the business.
"Consultations with members of the Swissport team at Belfast City Airport are ongoing so we cannot comment further at this time."
Mr Brash said the collapse of Flybe demonstrated the importance of greater Stormont support for airports.
A spokesman for the City Airport said: "The airport is continuing its negotiations with a number of airlines in an effort to fill the routes vacated by Flybe. We understand this is a difficult time for all employees at the airport, but we hope to have positive news in the coming weeks."
Other support businesses in the City Airport confirmed they are assessing the impact of the loss of the flights. However, taxi firm Value Cab, which has a contract to provide taxi links from the airport, refused to comment.
Currency exchange firm Travelex said it was working with the airport about how the change affected it. A spokesman said: "Travelex has not made redundancies at Belfast City due to the collapse of Flybe, but we are working with the airport to assess how it impacts our future plans."
The spokesman added: "Travelex has business continuity plans in the face of major events such as natural disasters and pandemics, and has a Covid-19 taskforce in place who are monitoring government advice, implementing specific action plans and communicating to employees as appropriate."
And construction firms in Northern Ireland are bearing the brunt of the loss of Flybe's 14 routes to Great Britain, it's been claimed.
Manufacturing NI chief executive Stephen Kelly said NI construction firms who diversified away from the island of Ireland towards Great Britain after the economic crash were among those who were most affected by the loss of flights to locations like Manchester and Leeds.