Americans overwhelmingly approve of the way President Reagan handled the crisis involving Trans World Airlines Flight 847, but only about one-third believe that the U.S. response will deter similar acts, according to initial findings of a Washington Post-ABC News poll.

About four in 10 say the hijacking ended more as a victory for the terrorists than for the United States. But more than half of those surveyed say they oppose military retaliation.

In interviews with 654 people Sunday afternoon and evening, a time when the 39 Americans were moving from Beirut to Damascus and eventually to Frankfurt, the poll also showed a sharp, favorable turn of sentiment toward Israel after a period during the crisis when a growing minority favored distancing the United States from Israel as a means of stemming terrorism against Americans. There were these other findings as well:

Two of every three interviewed said they were afraid to travel on some international flights because of the threat of terrorism.

Two of every three felt that the incident had made no change in the way the world views the United States; the remaining third was about equally split over whether this nation now appears stronger or weaker.

On the question of military retaliation, about one-third approved of the idea, but half of these backed away from any action that might bring about a wide war.

These were the first results in what is to be a two-day nationwide survey. Although the sample of 654 people was relatively small, it was large enough to yield a broad depiction of national sentiment.

Three-quarters of the people surveyed said they approved of Reagan's overall handling of the crisis. That high rating is clearly an expression of satisfaction about the president's accomplishing what earlier polls had shown to be the public's No. 1 goal, the safe return of the hostages held by Lebanese Shiite Moslems.

But signs of worry about future terrorism were equally clear. Only about one-third of the people interviewed agreed with the proposition that the United States' handling of the situation would "help reduce the chances of such things happening to Americans in the future," while 51 percent disagreed.

In addition, roughly four people in 10 (42 percent) thought the outcome was a victory more for the terrorists than for the United States; 28 percent thought it was more a U.S. victory.

And, despite their overall approval of Reagan's actions, a significant minority, 36 percent, said the president was not tough enough.

The change toward Israel showed up on a number of fronts. The terrorists' chief demand was that Israel release more than 700 Lebanese, mostly Shiites, taken to Israel during Israel's withdrawal from southern Lebanon.

Three earlier Post-ABC News surveys during the crisis saw a steady increase in the number of respondents saying Israel should release those Shiites with or without a request from the United States. By about 2 to 1 in the three surveys, 53 to 26 percent, a majority took the view that Israel had not "done what it should to help resolve the hostage situation."

Sunday, however, 46 percent agreed that "Israel helped the United States deal with the hostage situation as much as it could," with 37 percent disagreeing and 17 percent expressing no opinion.

In addition, the last of those earlier polls -- released last Wednesday -- showed Americans almost evenly split on whether "the U.S. should reduce its ties to Israel in order to lessen the acts of terrorism against us in the Middle East," with 42 percent agreeing and 41 percent disagreeing.

But Sunday, only 33 percent agreed and 51 percent disagreed.

Between Wednesday and the release of the Americans Sunday, American and Israeli leaders repeatedly stated that the two nations were in agreement on a response to the terrorists' demands and had been working together closely.

On another controversial aspect of the crisis, network television coverage, 55 percent said they approved of the networks' airing interviews with the hostages even though the Shiite captors set the ground rules. Forty-one percent said they disapproved.

A total of 654 people in the continental United States, randomly selected, were interviewed Sunday in the first part of a Washington Post-ABC News survey of attitudes after Lebanese Shiite Moslems released 39 Americans.

Theoretically, in 19 cases out of 20, a poll that size is subject to a margin of sampling error of about 4 percentage points. Practical polling difficulties may also introduce sources of error.