The US Federal Aviation Authority is expected to make a decision early today on when transatlantic flights will be allowed to resume. However it is thought likely that any resumption of services will be on a restricted basis.
All three airlines operating out of Ireland - Aer Lingus, Continental and Delta - have cancelled today's schedule and Aer Lingus has also cancelled inbound flights due from north America to Ireland on Friday morning.
Aer Rianta spokesman Mr Flan Clune described the situation as "unprecedented".
"In my 40 years in the business I have never seen anything like it".
A spokesman for Aer Lingus said all transatlantic flights were cancelled today because of the security situation.
Customers could receive updates on flight schedules by visting the website at www.aerlingus.com or by telephoning 1800 22 22 21.
In the US, the number is 1866 IRISH-FLT.
The cancelled inbound flights on Friday are: EI 104 from New York to Dublin; EI 136 from Boston to Dublin; EI 134 from Boston to Shannon; EI 128 from Chicago to Dublin and Shannon; EI 112 from New York to Shannon and Belfast; EI 106 from Newark to Shannon and Dublin; EI 144 from Los Angeles to Dublin and Shannon and EI 118 from Washington to Shannon and Dublin.
A spokeswoman for Continental Airlines said today's flights from Dublin and Shannon to Newark, New Jersey, had been cancelled.
"For those passengers whose itineraries have been affected, Continental is waiving change fees for tickets issued for travel between September 11th and September 17th.
" Customers may extend their outbound and inbound travel period by up to one year from the date of ticket issuance, without penalty or change fees.
"In addition, customers holding non-refundable tickets who were scheduled to travel September 11th and September 12th may also request a refund in the original form of payment." She advised "ticketed passengers" to telephone Continental on 1890 92 52 52, or consult the website at www.continental.com
A spokeswoman for Delta said flights from Dublin and Shannon to Atlanta were cancelled today. It was reviewing the situation of ticket-holders.
Passengers could check the status of their flight on www.delta.com