Seventeen months ago, in September, 1975, Secretary of State Henry A. Kissinger flew home from the last of his Middle East shuttles after successfully negotiating an Israeli-Egyptian disengagement in the Sinai, a pact he hailed as a step on the road to eventual peace.

On MOnday night his successor, Cyrus R. Vance, boards a U.S. military jet at Andrews Air Force Base to continue the quest, but with a very different strategy and mode of operation.

For all his tactical brilliance, Kissinger only nibbled around the edges of the long-running and deeply ingrained Arab-Israel; dispute, employing "step by step" procedures to separate opposing arhies and obtain modest Israeli withdrawals from Egyptian and Syrian land.

In contrast, Vance is starting right away to discuss the fundamental issues for a comprehensive settlement - recognition, relationships, and security guarantees for Israel in a peaceful Contest; extensive Israeli withdrawal from occupied Arab lands: a future mini-state for the Palestinian people.

In keeping with the gravity of the problems and his cautions, lawyer-like tendencies, Vance is beginning with a present schedule of high-level diplomatic soundings designed to produce a major U. S. initiative in about six months. Even then, quick success is not foreseen. In almost every utterance on the subject, Vance has spoken of the beginning of a negotiating "process" and some signs of "progress" - but never of a full solution - sometime in 1977.

In the coming week Vance will fly to Israel, Egypt, Lebannon, Jordan, Saudi Arabia and Syria in a whirlwind of working sessions to hear the positions and ideas of Israeli and Arab leaders. Though Vance has said he has some ideas about ways to negotiate a settlement, aides say he plans this week mostly to listen rather than try out his own conceptions.

From March to June the Israeli and Arab leaders are expected to visit Washington one by one for conferences on the subject with President Carter. In the summer and fall the United States will face, in the words of one official, " the moment of truth" when it must act, forging a new drive for an overall diplomatic settlement out of the hopes, fears and conflicting requirements of the parties concerned. Vance has said it is "critically important" to undertake comprehensive negotiations this year.

The present U.S. plan of action is unlike that the Nixon administration's first Secretary of State. William P. Rogers, who worked closely with Soviet leaders but kept the Middle East parties at arms length in conceiving and announcing a settlement plan.

It is even less like the dazzling highwire performance of Kissinger which was necessary to achieve limited accords without a final settlement in view. This time there will be no shuttling back and forth - at least at this stage - but a systematic exploration of varied views. And this time the Secretary of State will be the advance man and agent rather than the principal actor, with the President taking a far larger role.

Although the man and his methods will be mising, Kissinger's influence on his successor's mission will be great. It was Kissinger, before Inauguration Day, who convinced Vance that face-to-face diplomacy with top leaders is essential to Middle East solutions. Until then, Vance and Carter had expected to handle the early stages like most other overseas problems, through special emissaries and ambassadors.

Once Vance reaches the Middle East, Kissinger's legacy will confront him at every turn. The limited agreements of 1974-5 deliberately created new U.S. political, military and economic commitments to Israel, forged new political and foreign aid relationships with Egypt and Syria and led to a sharp reduction of Soviet power in the region.

The unexpected consequences were also great: the bitter divisions in the Arab world that contributed to Lebanon's murderous civil war, the battering and bloodletting of the Palestiniian revolutionaries, the growing domination of Lebanon by Syria, the rise of Saudi power and authority which finally brought about a Lebanese settlement and steps toward reunifcation of the Arab world.

Kissinger's style, design and operations established the United States as the foremost diplomatic broker between Israel and the Arabs. In so doing, he generated large hopes and expectations which, if frustrated, are likely to contribute to new chaos in the Arab world, and a new war.

The Carter-Vance diplomacy begins at an extraordinary moment, when established relationships are in flux and many leaders under stress. This will be amply demonstrated on Vance's itinerary:

ISRAEL - The ruling Labor Party will choose Feb. 22 between Prime Minister Yitzhak Rabin and his challenger, Defense Minister Shimon Peres, who probably would be bolder and less predictable. The winner faces national elections May 17 to determine the party or coaltion that will rule. Powerful in U.S. politics but heavily dependent since 1973 on U.S. aid, Israel faces a dangerous long-range challenge to its future because of the rising wealth, power and sophistication flowing from Arab oil.

EGYPT - The leader by common agreement in the current Arab peace offensive, President Anwar Sadat is in trouble at home. The widespread rioting that broke out Jan. 18 against government austerity measures was the worst in many years, dramatizing the deep difficulties of the economy. Egypt's needs have outstripped U.S. aid of about $750 million yearly and even larger Saudi and other Arab aid. Without early progress toward peace to change the patterns, Sadat's future appears bleak and Egypt's course highly uncertain.

LEBANON - Just beginning to breathe again after the devastating conflict that claimed 60,000 lives and left Beirut in shambles, the country is faced with a massive rebuilding task and a still-shaky peace. Syrian influence grew with the restrained yet steady use of its military forces to stop the killing; all internal forces lost. Syrian troops in Southern Lebanon near the Israeli border, seen as a threat in Jerusalem, are evidently to be withdrawn in a U.S.-assisted arrangement.

JORDEN - The survival of King Hussein and his mini-state is something of a miracle, given the turbulence all around them. Hussein, recovering from the death of his third wife in a helicopter crash last week, has been forging ever-stronger ties to Syria while preserving subsurface ties to friendly Palestinians in the Israeli-occupied West Bank just across the Jordan River. A move is afoot to patch up Hussein's relations with the palestine Liberation Organization., outsted from the country in a bloody 1970 struggle.

SYRIA - The most solidly entrenched of the Arab leaders around Israel, President Hafez Assad is a supposed hardliner who has shown himself resourcemul, cool and pragmatic under fire. In the Lebanese civil war, he stared down the Russians and hammered down his expected allies, the Lebanese left and palestinians. For the long-term growth of his country, Assad needs a settlement with the Israeli neighbor he bitterly condemns.

SAUDI ARABIA - Increasingly the crucial factor in Middle East economic and diplomatic dealings, Saudi wealth and authority underlie the current drive to re-establish Arab unity in pursuit of a settlement with Israel.Kissenger's shuttle diplomacy was in response to the 1973 Saudi oil embargo, and Vance's efforts respond in part to the demonstration of Saudi power in last Secember's oil price decisions. U.S. dependence on Saudi oil imports is still growing, making this desert kingdom among the nations most important to U.S. prosperity and growth.

THE PALESTINIANS - Although Vance refuses recognition, in keeping with a secret written promise by Kissinger to Israel on his last shuttle, the Palestine Liberation Organization and the movement it represents are at the heart of the Arab-Israeli problem. Batered in Lebanon and pressured by Saudi Arabia, by other Arab najtions and reportedly the Soviet Union as well, the PLO is moving toward de facto recognition of Israel and acceptance of a mini-state on the West Bank. The nature of that state, its affiliations and restrictions are key questions in any comprehensive settlement.