Jetting into Jiddah -- but not out

European and Middle Eastern magazines often run handsome color advertisements for the latest architectural or industrial marvel that Saudi oil money has financed. Jiddah airport is one such space-age wonder.

But no less an authority than the United States State Department is now warning that in some cases appearances can be deceiving. In a recent diplomatic ''travel advisory,'' the State Department said even in transiting through Jiddah airport a hard-won Saudi visa ''is an absolute necessity.''

Frequently, the advisory adds, American diplomats have been detained or dispatched from the country on the first available flight for failing to have proper documentation.

''The modern appearance of Jiddah airport is deceptive,'' the advisory warns. ''There are no full-service restaurants or other facilities usually available for travelers. A missed flight could lead to an uncomfortable period of confinement in the airport. As a general rule, Jiddah is not an ideal airline connecting point, especially if the connection is between Saudia, the national carrier, and other airlines. The two terminals are 16 kilometers (10 miles) apart, and as a practical matter three hours minimum are required to connect.''

The report concludes: ''Although empirical evidence is lacking it may be true that 'it is easier for a camel to pass through the eye of a needle' than for a traveler without a valid visa to enter the Kingdom of Saudi Arabia [with apologies to Matthew].''