"This is due to the response of European Union governments to the spread of the Covid-19 virus, which have since mid-March included widespread flight bans and travel restrictions, which have closed Europe's skies to all but a tiny number of rescue and medical flights", it said.
On a rolling annual basis, the group's passenger numbers edged up by 4% to 148.6 million.
The Ryanair group saw traffic in March fall by 48% from 10.9 million passengers in 2019 to 5.7 million passengers last month.
Navy Capt. Crozier's coronavirus decision was the right thing to do
Modly said the leak of Captain Crozier's letter had panicked the crew and family members, and embarrassed the Navy's leadership. Captain Crozier would be reassigned while investigators considered whether he should face disciplinary action, Mr Modly said.
But it still expects to report pre-tax profits of between €950m (£831m) and €1bn for the year ending March 31 - even though traffic fell by almost 50pc last month compared to the previous year. At the start of March, Ryanair had been on track to achieve a full-year total of 154m. Of the schedule of 2500 flights, less than twenty are operated daily.
It is now flying less than 20 daily flights, compared to its usual 2,500.
Since mid-March there has been widespread flight bans and travel restrictions which have closed Europe's skies to all but a tiny number of rescue and medical flights.
COVID-19 patients discharged from hospitals on Chinese mainland
A day of remembrance was declared in China on Saturday to honour the greater than 3,300 individuals who died of Covid-19. Trump mentioned his trade deal and Chinese spending on American agriculture and tempered his criticism.
For now, the carrier expects its fleet to be grounded at least through the end of May.
Ryanair also estimated it will take an exceptional charge of about €300 million ($324 million) due to the ineffectiveness of its fuel hedging practices for this year, given that oil prices have cratered to as low as $20 per barrel (The net profit estimate includes this charge). "We now estimate this will amount to an exceptional charge of approximately €300m".
On Thursday, the International Air Transport Association said February passenger numbers had declined 14.9%, the steepest fall since the 2001 terrorist attacks in NY. It has also suspended share buybacks and frozen recruitment.
China Holds Day of Mourning for Coronavirus Victims
However, new infections and in particular asymptomatic infections, means there is presently no end in sight. Among those who died was Li Wenliang, a young doctor who tried to raise the alarm about the disease.
Ryanair said it has one of the strongest balance sheets in the industry, with year-end cash equivalents of 3.8 billion euros and 327 aircraft, 77% of the group's owned fleet, debt free.