The airlines will have a tough time maintaining load factor - a measure of how full planes are - over 85 percent, analysts led by Helane Becker wrote in a client note.

Business and leisure consumers are likely to curb travel in the face of Europe's economic woes and possible slowing growth in China and India.

Dahlman Rose analysts said they expect industry passenger unit revenue (PRASM) growth to slow in July, August and September.

The analysts also cut their ratings on the stocks of several airliners including Delta Air Lines Inc (DAL.N), JetBlue Airways Corp (JBLU.O), Republic Airways Holdings Inc (RJET.O) and United Continental Holdings Inc (UAL.N).

Shares of Delta closed at $9.65 on Tuesday on the New York Stock Exchange. United Continental stock closed at $18.89. (Reporting by Sagarika Jaisinghani and A. Ananthalakshmi in Bangalore)

• A Permanent Economic Emergency