In a negative sign for airline industry performance, Continental (CAL) says bookings for the next six weeks are strong, but unit revenue has deteriorated due to declining business travel.

With fewer premium tickets being sold, deterioration in revenue per available seat mile "has accelerated sequentially since January 2009 and has become significant," Continental said, in a filing with the Securities and Exchange Commission.

The carrier said consolidated domestic bookings for the next six weeks are running four to five points higher, as compared with the same period a year earlier. Mainline Latin bookings are flat to one point higher. Transatlantic bookings are five to six points higher, and Pacific bookings are flat.

In the first quarter, consolidated domestic capacity is down 10.7% while total consolidated capacity is down 7.3%.

Avondale Partners analyst Bob McAdoo said he expects Continental to report a first quarter loss of 80 cents; he had previously estimated 82 cents. In a report, McAdoo said he reduced revenue estimates as well as estimates for fuel and non-fuel unit costs.

"We have left our estimates for the remainder of the year unchanged, as there continues to be almost no visibility into demand," McAdoo wrote. "CAL, along with other airlines, will likely see improved results as the peak travel season begins in earnest."

On Monday, US Airways ( LCC) said it too has seen weaker business demand and declining ticket prices, but the carrier said its unit revenue stabilized in March after declines in January and February.

Shares in Continental traded Wednesday morning at $8.28, down 46 cents. Most other airline shares were also trading down. Delta ( DAL) was down 36 cents to $5.79. US Airways was down 10 cents to $2.93.

More from Stocks

Why The FANG Stocks' Dominance May Not Be So Bad For The Market

Why The FANG Stocks' Dominance May Not Be So Bad For The Market

Danica Patrick's Final Race at 2018 Indianapolis 500: What She Thinks About Cars

Danica Patrick's Final Race at 2018 Indianapolis 500: What She Thinks About Cars

At End of May, Investors Signalling They May Stay Away

At End of May, Investors Signalling They May Stay Away

Inside Carnival's Mind Blowing New Horizon Cruise Ship (Video)

Inside Carnival's Mind Blowing New Horizon Cruise Ship (Video)

Neel Kashkari: The Heart of Our Financial System Is More Radioactive Than Ever

Neel Kashkari: The Heart of Our Financial System Is More Radioactive Than Ever