15 weekly flights between Ireland West Airport Knock and the UK cities of Edinburgh, Manchester and Birmingham have been cancelled with immediate effect, after Flybe collapsed into administration overnight.
It includes two inbound and outbound flights today from Knock to Manchester and Birmingham.
Over 2,000 jobs, including 150 jobs in Belfast, are at risk, with Flybe blaming its decision on a fall in bookings due to coronavirus.
All passengers with Flybe bookings are advised not to turn up at airports.
Passengers are unlikely to get their money back from the airline directly, but those who bought their ticket using a credit or debit card may be able to do so - they're advised to contact their card provider, while those with travel insurance are also advised to contact the insurance company to see if they're covered for the failure of an airline.
The Flybe administrator can be contacted at a UK phone number - 0044 207 951 7801