Four people, including the presidents of an Arizona aviation firm and a West German company, face charges of exporting sophisticated radar navigational systems to Iran in violation of a U.S. embargo.

Three indictments arising out of a complex sting operation were released after the president of Marsh Aviation Co. was arrested at the company's headquarters in Mesa, Ariz.Floyd Stilwell, 61, of Phoenix, Ariz., was arraigned in Phoenix on charges of exportation of defense articles, conspiracy to export items to Iran and making false statements to authorities, U.S. Attorney Peter K. Nunez said.

Also facing charges in the case is the president and two employees of Beechcraft West Germany, formerly called Beechcraft Vertrieb Und Service.

The equipment was manufactured by San Diego-based Teledyne-Ryan Electronics, whose officials tipped federal investigators to the suspicious purchasers and prompted the operation by U.S. Customs Service.

The charges against both companies and their owners stem from the alleged diversion of U.S.-made equipment from West Germany to Iran, which shops around the world for military equipment for its war with Iraq.

An export embargo on U.S.-made equipment was first placed on Iran by President Carter during the height of the U.S. hostage crisis.

This navigational system supplies aircraft with an accurate, independent method for quickly responding to military orders, said Assistant U.S. Attorney Phillip B. Halpern, who is in charge of the case.

Beechcraft West Germany owner Hans Schneider, who was indicted on Sept. 25, 1987, along with his company, is a fugitive and authorities were not optimistic that he would be extradited for trial in San Diego, Mr. Nunez said.

Mr. Schneider's company sells, services and distributes parts for Beechcraft Aircraft Corp. of Wichita, Kan., in West Germany. There is no evidence that the U.S. firm participated in the scheme, Mr. Nunez said.

Two other employees with Beechcraft West Germany helped authorities in the investigation after pleading guilty to related charges, Mr. Nunez said.

The firm's managing director, Bernd Pleuger, 51, of Stuttgart, West Germany, and salesman A. Juergen Zimmermann, 37, of Augsburg, West Germany, were charged originally with conspiracy and illegal exportation in a 1986 indictment.

They pleaded guilty in a secret proceeding and cooperated with the sting operation, apparently continuing in their positions with Beechcraft as the investigation developed.

Two shipments of the equipment worth about $200,000 were believed to have reached Iran before the undercover operation was implemented, Mr. Nunez said.

Teledyne-Ryan President Robert Steenberge said the first two shipments were sent to West Germany at the direction of the CIA, whose officials told him they wanted to monitor the deal before taking further action.

Mr. Stilwell allegedly submitted false export information to Teledyne Ryan, the U.S. State Department and Customs in an attempt to conceal the fact that the equipment's final destination was Iran.

Mr. Stilwell is scheduled to be extradited to San Diego to appear in court Monday.