Delta, Eastern Hike Fares; Other Carriers May Follow : Airlines: The latest price increases, due Oct. 1, are blamed on high fuel costs. Business travelers are expected to be hit hardest.

Delta Air Lines said Thursday that it plans to raise fares Oct. 1--its second fare hike in a month--to cover higher jet fuel costs. The move was quickly matched by Eastern Airlines and was expected to trigger increases at other airlines.

Delta said the 4.2% increase in domestic fares would boost the one-way cost of a regular coach-class ticket for a Los Angeles-New York flight by $28 to $684. The cost of a regular coach class fare between Los Angeles and San Francisco would rise $8 to $204.

Airline industry analysts said the fare hikes were warranted. “I think the industry needs a lot more than 4%,” said Edward J. Starkman, an analyst with the Paine Webber investment firm in New York. “I think all the big boys will go along.”

Starkman said it is possible that the fare jump will chase away some travelers. “It’s a fine line to tread,” he said. “But you don’t know what effect it will have until you try it.”

It appeared likely that other airlines besides Eastern would go along. On Wednesday, American Airlines Chairman Robert Crandall told securities analysts in New York that another fare increase was needed to cover fuel costs.

On Thursday, American, USAir, Continental Airlines, Northwest Airlines and Trans World Airlines said they were studying Delta’s move. A United spokeswoman would not comment.

Pan American World Airways and Alaska Airlines had previously announced fare increases, but neither airline is considered a pricing leader. Pan Am has announced a 4.4% hike effective Sept. 21 and Alaska Airlines will raise fares 4.7% effective Oct. 1. Representatives of both airlines said Thursday that they may adjust their proposed fares to match those of competitors.

“We are going to wait to see what United or Continental and the others do and decide who to follow,” Greg Winter, an Alaska spokesman, said.

The industry raised fares 5.3% on Aug. 30 to help cover a rise in jet fuel prices that followed Iraq’s Aug. 2 invasion of Kuwait. Jet fuel prices rose from around 60 cents a gallon before the invasion to a high of $1.06 on Aug. 23. Prices have since fallen back to around 90 cents a gallon.

If the industry follows Delta’s actions, fares will have risen around 10% since the end of August. That gives the industry the 10% boost it sought after the Iraqi invasion. At that time, Transportation Secretary Samuel K. Skinner pressured the airlines to reduce the size of the increase.

Joe Brancatelli, editor of Frequent Flyer magazine in New York, said the new fare hikes seemed excessive given the recent leveling off in jet fuel prices and that business travelers would be hit hardest.

Brancatelli said he expects the airlines to discount away the fare hike for leisure travelers during the fall and winter months when traffic slows.