BONN, MAY 31 -- West Germans toasted the skill and daring of their newest flying ace, Mathias Rust, this weekend and chuckled over the Kremlin's embarrassment at allowing the 19-year-old amateur pilot to penetrate the vaunted Soviet air defenses and land in Moscow's Red Square.

"I laughed my head off," Foreign Minister Hans-Dietrich Genscher told the magazine Der Spiegel.

Several newspapers noted that Rust, by reaching Moscow after a 420-mile hedgehopping flight from Helsinki, had done better than the German Army during World War II.

Although Germany traditionally has been known as a country with great respect for following rules, a poll by the Wickert Institute showed that 88 percent of West Germans "had respect" for Rust's solo accomplishment, even though it violated Soviet borders and airspace.

News commentators compared Rust to famous German fliers ranging from World War I ace Baron Manfred von Richthofen, the "Red Baron," to Adolf Hitler's deputy Rudolf Hess, who made a mysterious solo flight to Scotland during World War II and was immediately arrested.

"The young man goes into the Guinness Book of World Records and into history. He has brought about the fall of a defense minister and an air marshal of the Soviet Union," the Moscow correspondent of West Germany's ARD television network reported.

Rust's family and acquaintances expressed surprise in interviews on television and radio that the shy, quiet computer operator would pull such a dramatic stunt. But they agreed that Rust, who devoted almost all of his spare time and money to flying, was too good a pilot to have flown to Moscow by mistake.

"A five-hour flight, such as from Helsinki to Moscow, is a completely normal thing for Mathias," Rust's father, Karl-Heinz, said in the family's hometown of Wedel near the North Sea port of Hamburg. Karl-Heinz Rust said his son looked "simply great" in a film, taken just after his landing in Moscow, that was shown on West German television this evening.

Rust flew his rented, single-propeller Cessna to Moscow on Thursday. He had removed three of the plane's four seats before leaving Hamburg May 13 and used the extra space for additional fuel tanks and camping equipment, including a small tent and sleeping bag, family members said.

Soviet leader Mikhail Gorbachev responded yesterday to the breach in air defenses by forcing Defense Minister Sergei Sokolov into retirement and firing air defense commander Alexander Koldunov.

Rust's achievement, though generally viewed with amusement, prompted some serious commentary. Newspapers assured readers, for instance, that the incident probably would not hurt West German-Soviet relations.

The leftist-oriented weekly Der Spiegel, which produced a cover story on Rust on two days' notice, said the trip showed that it was an "illusion" that "it is possible to buy security with ever more expensive technology."

Another somber note was injected by Rust's flying club, Aero-Club Hamburg, which announced that the stunt would cost Rust his flying license and said it could prevent him from realizing his dream of becoming a professional pilot. The club also said Rust would be liable for costs of up to $14,000 for bringing back the plane from Moscow.

The light-hearted vein dominated most coverage, however, as the weekly Bild am Sonntag newspaper interviewed several young women who had refused to date Rust. They said he preferred classical music to disco, wore old-fashioned clothes and "behaved like an old man."

But Andrea Kuhn, 19, suggested a motive for Rust's flight. "He once said that he wanted to do something great," she recalled. "He said, 'I want to master the world.' "