Delta Air Lines, the third-largest American carrier, is seeking to ease terms of loan agreements and said it may have to file for bankruptcy protection if those efforts fail.The company’s shares fell 10%.

The airline said in a regulatory filing yesterday that it’s asking to amend terms that require earnings to exceed a certain level before some costs. Delta got the $630 million in loans from a General Electric unit and American Express last year.

Delta said that if it can’t comply with or rework the terms, the loans may become due immediately, which could force the company into bankruptcy. The Atlanta-based airline lost $1.1 billion in the first quarter as fuel prices rose and competition held down fares. Delta, which forecasts a “substantial” loss for 2005, had said in a March annual filing that it expected to be in compliance with the terms this year.

Yesterday’s filing “just underscores the fact that it’s unlikely that the company can restructure without a Chapter 11 filing,” said Helane Becker, an analyst at Benchmark in New York with a “sell” rating on Delta. “This is the strongest language they’ve used to indicate how bad things are.”

Delta shares fell 33 cents to $2.97 yesterday in New York Stock Exchange composite trading, for the biggest one day percentage drop since March 10. They have declined 61% this year.

A Delta spokesman, Anthony Black, wouldn’t discuss talks the airline may be having with the lenders on changing loan terms. The lenders probably will make changes because they would have more difficulty getting repaid with Delta in bankruptcy, Mr. Becker said. The carrier in 2004 avoided a bankruptcy filing by getting $1 billion in annual concessions from pilots for five years.

The airline got the loans from GE’s Commercial Finance unit, with American Express providing $100 million of the financing.They were secured by almost all Delta’s assets not already pledged to other lenders and require the airline to maintain certain amounts of cash and earnings before interest, taxes, depreciation, amortization, and aircraft rent.

Delta in the Securities and Exchange Commission filing yesterday said it has more than $2.4 billion in debt and other payments coming due before the end of this year, as well as $450 million in employee pension-fund contributions.

At the end of the first quarter, Delta reported $1.8 billion in cash, cash equivalents, and short-term investments. The carrier yesterday said that unless it can increase revenue, cut costs, sell assets, or raise more capital, it expects that amount to be “substantially lower” by December 31.

Delta said that higher fuel prices as well as changes in a Visa/MasterCard credit-card processing contract after it expires in August and incorrect assumptions in the company’s business plan may cause it to fall short of loan terms.

The chief executive,Gerald Grinstein, said last month that rising prices for jet fuel were throwing off Delta’s plan.

The carrier, which has had net losses of $9.5 billion since the start of 2001, is trying to cut $5 billion a year in costs by the end of 2006 and increase revenue through a new system of lower fares intended to attract more customers. The fare cut earlier this year was an attempt to compete with growing East Coast discounters such as AirTran Holdings.

“They screwed themselves up by doing this whole new airfare program right at the worst time,”Mr.Becker said.

Jet-fuel spot prices for delivery in New York harbor have risen 24% from a year earlier to $1.52 a gallon. Delta’s first-quarter fuel costs increased 54%, pushing up total costs 18% to $4.6 billion.

Delta hasn’t been able to afford to hedge against the rising fuel prices. Airlines hedge by buying financial securities that increase in value as fuel prices climb.

Higher fuel prices contributed to $1.87 billion in first-quarter losses by four of the five largest American airlines. The last of the top five, United Airlines parent UAL Corp., hasn’t yet reported results for the quarter. Southwest Airlines, almost tripled its profit, mainly because of fuel hedging and growth into new markets.