Somalia's decision to allow West German commandos to storm a hijacked Lufthansa jet at Mogadishu airport, and the earlier refusal of any Arab country to take in the hijackers, has provided dramatic new evidence that most Arab countries - whatever their politics - are no longer willing to encourage air piracy.

Not a word of criticism has been heard of Somalia's decision or of South Yemen's attempt to prevent the airliner from landing by blocking the runway at Aden airport. The United Arab Emirates, which permitted the plane to land at Dubai but also cooperated with the West Germans, says it will not allow any more such landings. Kuwait, which has permitted hijacked jets to land in the past, says it will never do so again.

Even Libya, which has a reputation as the terrorism capital of the Middle East, has been proclaiming a change of policy. As for the Palestine Liberation Organization, its hijacking days are long in the past and PLO officials here noted with satisfaction that they were not automatically suspected in the Lufthansa case.

"The entire Arab world has passed from an era of ideology to an era of pragmatism." a respected Arab political analyst said today. "The time is past when Arab countries supported revolutionary acts just for their own sake.

Hijackings are the tactics of the past.

Analysts here pointed out that the Arab's reaction in the Lufthansa case might have been different if the hijackers had associated themselves with the Palestinian cause rather than with the cause of the Baader-Meinhof terrorist band in West Germany. But the trend even in the most radical countries, such as Libya, Iraq and South Yemen, is generally away from support for hijacking as an acceptable or useful tactic.

Palestinian leaders, attempted to present themselves to the world as responsible people with whom it is possible to negotiate, have often said that they found their spectacular hijackings of past years to be counterproductive and they no longer condone even hijackings that purport to us to go back to the hijacking days," be on their behalf.

"The Israelis would just love for a PLO official said. "It would give truth to their claim that we are just a bunch of terrorists. But those days are gone."

Evidence is less clear some Arab governments have abandoned other forms of terrorism. The past two years have seen the bombing of Baghdad airport, the kidnapping of oil ministers from their meeting in Vienna, attacks by armed men on a hotel in Damascus and bombings in Egyptian trains and publci buildings.

The hotel attack reportedly was carried out by Palestinians enraged by Syria's intervention in the Lebanese war, itself the scene of atrocities and terrorism for nearly two years. Egypt and Saudi Arabia have blamed the Libyan regime of Col. Muammar Qaddafi for the other. Libya disclaims any responsibility for terrorist acts, but any casual visitor to tripoli can encounter members of the Japanese Red Army drinking coffee in the lobby of their hotel. The United States repeatedly informed Libya that any improvement in relation with depend on evidence that Libya has disvowed terrorism.

The undersecretary of the Kuwaiti Foreign Ministry, Rashid Rashid, summed up the prevailing view of the Arab governments on the hijacking. "Our position is clear. It is to deplore air piracy and not to allow any hijacked aircraft to land on our territory," he said.

South Yemen and Somalia, as Marxist and radical as Kuwait is monarchical and conservative, now take the same position. Both have been under pressure from Saudi Arabia to moderate their politics.

Like saudi Arabia, Egypt is exerting strong anti-hijacking influence. Last year the Egyptians staged a small commando action of their own when a domestic airliner was hijacked from Cairo to Luxor.

The result of this trend is that hijackers can no longer expect refuge in Arab countries.

A possible exception may be Algeria. The Algerian government permitted a hijacked Japan Air Lines jet to land there on Oct. 3, and the hijackers apparently have not been arrested. The Algerians said they allowed the plane to land at the request of the Japanese government, and are reported to have been angered by Japan's subsequent request for extradition, which has not been honored.