At 8:37 last Sunday morning in Seattle, 120 miles from Mount St. Helens in the Cascade Range, a federal bureaucrat was jolted by a sudden ominous sound. As he reported to his headquarters in Washington:

"In case you're interested in what an exploding mountain top sounds like from about 120 miles away, its exactly like a strong sonic boom. From that distance, no prior warning nor following rumbles -- just a good solid boom. No lava flows have appeared yet. The damage in the immediate vicinity of the mountain was due to heavy mud flows and high temperature gases in the explosive shock wave which leveled every tree, or anything else standing, north of the mountain for a radius of 10 to 15miles. For the benefit of the Washington office people, the effects would be the same if everything from the Washington headquarters building 15 miles west to Fairfax or Vienna had been literally leveled to the ground."

Not long after that, an Air West Dc-9, en route from San Francisco to Calgary, Canada, and flying at 31,000 feet, unwittingly moved directly into the cloud of volcanic ash rising into the heavens. The plane was in the cloud only four minutes before the pilot made an abrupt 180-degree turn and headed for an emergency landing in Phoenix, Ariz. But those few minutes were traumatic.

Once on the ground, the pilot reported the plane's extensive damage. His windshield was heavily pitted, the leading edges of the wings were sandblasted, the engine oil was contaminated, the engine compressor blades received significant abrasive action, and all the air conditioning system filters had been impaired enough to require replacement.

That was the first known incident of what happened when an airplane encountered the effects of the Mount St. Helen's eruption, a volcano that had been dormant since 1857. Soon that information was being dispatched by the government throughout the country with a warning that all planes avoid the cloud of ash. "The significant damage to that flight was an important part of the data we had to pass on to airlines," a Federal Aviation Administration official recalled in Washingtn. "There are many channels of communications. We wanted to hit them all. We hit them all. Our concerns were that we capture every aircraft in the system interested in flying, in addition to pilots coming to flight services to get their normal briefings. We wanted to make sure they were aware of the damage to that flight and other information we were able to pass on to alert them."

In recent years, and particularly in recent days, many Americans have come to believe that nothing works, especially the government. Foulups and failures are almost expected. Yet what we've seen this last week -- or have failed to see -- in the extraordinary aftermath of the natural disaster in the West, is an example of the government performing splendidly, quietly, competently, and efficiently. The way the Federal Aviation Administration handled the threat to aircraft provides a case study of government at its uncelebrated best. For this crisis at least, the government was well prepared and reacted promptly.

As soon as the volcano began stirring in March an emergency crisis team was put together. Contingency plans were adopted in the event of a volcanic eruption. Experience gained from similar disasters were studied -- what happened to aircraft when volcanoes erupted in Alaska, Japan and Italy. Prevailing wind patterns were examined, and predictions made of where the ash would go if the mountain blew. These proved to be correct.

What the government couldn't forsee was the magnitude of the explosion or the damage wrought. As one official said, "We never had anything like this before."

Once the volcano erupted, the emergency plans were put into effect. Flights around the volcano already had been banned, and now the extensive monitoring of all information began. From the FAA's command center on Independence Avenue, telephone conference calls were conducted with stations around the country and overseas. Meterologists studied satellite photographs of the ash cloud. Reports from pilots around the country were passed on.("I'm getting a smell of sulfuric acid," a pilot said over Pittsburgh. "But then again I get that over Pittsburgh most of the time.") A federal radioactivity task force, used to monitor such things as atomic tests in the past and the nuclear accident at Three Mile Island, was reinstituted. Special aircraft, including U2s, flew into the cloud to collect samples.

Government scientists found the ash contained both abrasive and corrosive materials such as sulfuric acid and fluoride and chloride salts and acids. Depending on the location of the volcanic ash fallout, the particle sizes ranged from as small as 5 microns to as large as 100 microns. Most aircraft filters screen out material as small as 15 microns. But tinier particles pass through the filters and cause damage.

With the report of damage to the Air West flight and other potential hazards, the FAA wrestled with whether to ground all flights. Some bureaucrats worried lest reports of aircraft damage from ash be played up sensationally in the press. "I could just see the headline, 'Killer Cloud Girdles Globe,' setting off a panic," one of them said.

Grounding all planes was not necessary. Aircraft could avoid the cloud by flying above, below or around it. But maintenance problems remain. Now the FAA has issued special instructions to all aircraft owners, and all airlines, on procedures to take for any plane exposed to the ash. The cost of maintenance is going to be extremely high -- and essential. Monitoring of the situation continues throughout the country.

This story is not over. The long-term impact to both equipment and people remains unknown. And another explosion of similar magnitude could still occur at Mt St. Helens. But for citizens there are lessons, and for once some comfort. "I don't think we've done anything unusual," an FAA official said. "You have to have systems that will deal with things like this. And this shows us the system works very well."

Which is not what many of us had thought.