A new round of fare increases appeared in the makings yesterday as Delta Airlines, followed soon after by Eastern Air Lines, announced plans to raise ticket prices by 4.2 percent.

If adopted industry-wide, the Oct. 1 price hike would be the second major fare boost since Iraq's Aug. 2 invasion of Kuwait sent jet fuel prices soaring, and it would bring the total fare increase since then to nearly 10 percent.

Earlier this month, Pan Am and Alaska Air said they would increase their ticket prices beyond the 5.3 percent fare increase that took effect at the end of August. But now with a major and more prosperous carrier like Delta joining in, airline officials and industry analysts speculate that others may soon follow.

The airlines have been playing an edgy waiting game over fare increases in recent weeks, watching to see who would blink first and adopt the price hikes the industry says are needed to offset the rising cost of jet fuel. Although the airlines desperately wanted the increase, they were hesitant to be the first to raise fares for fear of winding up the lone carrier with higher prices in the midst of a weak market.

"If we blinked, it was because of the pain and the agony of the increased fuel costs," said Delta spokesman Neil Monroe. Delta's fuel costs have increased by a systemwide average of 33.5 cents a gallon since the end of July, he said. On an annualized basis, that translates into $670 million in additional costs for the Atlanta-based airline.

When fuel costs first headed up, American Airlines and USAir proposed a 10 percent fare increase, but it didn't catch on with competitors. Later, Delta proposed a 5.3 percent increase.

"At that time, fuel was up between 10 and 12 cents a gallon," Monroe said. The rest of the industry followed Delta's lead on that fare boost, but the increase was postponed once and was implemented in such a way that travelers who could plan ahead could lock in discounts before prices went up.

Edward Starkman, an airline industry analyst with PaineWebber Inc., said the airlines need even more than the price increase that Delta is now proposing in order to keep up with rising fuel costs. The outlook for the airlines, which was rather bleak even before the Mideast crisis, has deteriorated rapidly. Starkman said the industry as a whole may lose more than $500 million this year.

Although the industry is anxious to offset those losses, "the other side {of the question} is how much do you raise fares before you shoot yourself in the foot and chase passengers away," Starkman said. "That's an empirical experiment: You go out and notch it up and see what happens."

Given the weak market, the airlines are likely to continue promoting discounts in order to capture the dollar of price-conscious business and leisure travelers. But if the new fare increase holds, any new discounts will apply against the higher fares.