Ryanair said that falling fuel costs had boosted profits but added that cut-price fares would result in losses for the rest of the year.
The firm said pre-tax profits were €419.4m (£376.6m) in the six months to 30 September, from €105.2m (£94.4m) last year, but said the results were "heavily distorted" by a 42 per cent drop in fuel costs.
Ryanair said this masked a 17 per cent decline in average fares and warned that prices would fall 20 per cent over the rest of the year, resulting in losses for the last two quarters.
Ryanair chief executive Michael O'Leary said the group would be "substantially profitable at a time when many of our competitors are losing money, consolidating or going bust".
He said traffic growth is strong "but at the expense of declining average fares", while the weakness of sterling and tourist taxes in the UK and Ireland had also hit takings.
"Ryanair remains ideally positioned to return to substantial profit growth as Europe emerges from this economic downturn and we remain confident that our 'growth during a recession' policy will continue to deliver substantial returns for our passengers, our people and our shareholders," he said.
Revenues were down 2 per cent at €1.8bn (£1.6bn).
Market conditions continued to be tough, particularly in Ireland and the UK, where overall air traffic is forecast to decline 15 per cent and 10 per cent respectively.
Ryanair said it would consider binning growth plans if it cannot agree a deal with Boeing over an order for 200 aircraft due for delivery between 2013 and 2016.
"We see no point in continuing to grow rapidly in a declining yield environment, where our main aircraft partner is unwilling to play its part in our cost reduction programme by passing on some of the enormous savings which Boeing have enjoyed both from suppliers and more efficient manufacturing in recent years," Mr O'Leary said.
Source: The Belfast Telegraph