As the seizure of a Kuwaiti jetliner this week shows, skyjacking has become much less a mode of transportation than a means to terrorist ends. Fewer people are commandeering planes to fly to Cuba. Most of those who have stolen airliners at gunpoint this year were representatives of disaffected political factions from the hot spots of the world, such as Iran and India.
(At midday Thursday, five Arabic-speaking hijackers in Tehran still held the Pakistan-bound jet with 161 passengers aboard. Conflicting reports from Iranian news media indicated that the hijackers had killed at least one hostage and perhaps several others.)
The number of skyjackings remains moderate. So far this year there have been 20 successful seizures of scheduled airline flights, according to the International Civil Aviation Organization. In 1983 there were 21 successful skyjackings; in 1982, 18. (A ''successful'' hijacking is one in which the hijacker manages to gain control of the aircraft.)
The last big year for hijackings, say experts, was 1980, when there were 32. ''We had lots of Cuban stuff that year,'' says an official of the Federal Aviation Administration (FAA), as Cuban nationals who had entered the United States on the boat brigade from Mariel, Cuba, grew frustrated and tried extreme means to return home.
But none of this compares with the late '60s and early '70s, years when skyjacking was almost a fad and there was little airport security or international cooperation in defeating such acts. In 1969 there were 40 skyjackings in the United States alone, according to FAA figures.
The most highly publicized hijackings this year have involved either Mideastern or Indian terrorists, with the exception of a jet hijacked by Somali troops to Ethiopia last month.
In August, for instance, members of an outlawed Sikh extremist movement, the All-India Sikh Students Federation, commandeered an Air India plane and shuttled around the Mideast, finally surrendering in the United Arab Emirates. That same month, three men claiming to represent the Islamic Organization for the Liberation of Qods (Jerusalem) stole an Air France flight and took it Tehran, demanding that France release five pro-Khomeini Iranians from jail. They blew up the plane's cockpit after releasing the passengers.
The last successful hijacking of an airliner in the US took place March 28, when a Delta flight from New Orleans was commandeered to Cuba. In general, however, the pattern of skyjacking today follows the world pattern of political strife, says Eugene Sochor, an official with the International Civil Aviation Organization.
''At one point (the popular destination) was Cuba. Lately, (Cuban President Fidel) Castro has been very harsh with hijackers,'' Mr. Sochor says. ''It's the Middle East today.''
Sochor points out that skyjackers today must be highly motivated, since they have little hope of getting off free when they land. ''No country in the world today welcomes skyjackers with open arms,'' he claims. (A number of experts, however, suspect that Iran, among other countries, does provide a haven for certain skyjackers.)
Terrorists have strong motivation. But is skyjacking a good tool for terrorists, since their explicit demands - often freedom for jailed colleagues - are usually not met? ''Absolutely,'' says Yonah Alexander, a terrorism expert with Georgetown University's Center for Strategic and International Studies, even though ''nation-states today are much more reluctant to submit to the demands of perpetrators.''
''Hijacking works'' for terrorists, Mr. Alexander says, because ''even if they failed in their mission, they're still able to highlight their grievances. The wider audience is their ultimate target.''
Alexander says he is not surprised by the Tehran hijacking, reportedly by an Islamic group trying to free colleagues jailed in Kuwait. The Kuwaitis have a number of people in jail in connection with the attack earlier this year on the US Embassy in that country, and he says it was likely the prisoners' colleagues would strike.
''This is a tough bunch,'' he says of the Hezballah, the fundamentalist Islamic organization that may be responsible for the crime. ''They're very capable because they get state support - from the Iranians, and Syrians.''
(The Associated Press reported that the hijackers' demand for the release of the prisoners was rejected by the Kuwaiti minister of state for foreign affairs, Abdul Aziz Hussein. Early Thursday, the hijackers demanded the plane be refueled and that authorities remove the barriers set up around the plane to prevent its departure, Iran's Islamic Republic News Agency said.
(US officials declined to say whether there was any reason to fault the Iranian government's handling of the hijacking. The State Department has issued several statements calling on Iran to live up to its commitment under international law to seek to ensure the safety of the passengers and to prosecute the hijackers.)
Getting back airport security these days is no easy thing, but it is far from impossible. The Air France jet hijacked earlier this year, for instance, left from Frankfurt, West Germany, where airport security is close to the best in the world, experts say. US airline industry sources say they suspect the hijackers had confederates who held airport maintenance jobs.