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AIR FORCE HISTORY: The Evacuation of Clark Air Force Base

Ash plumes from the volcano, Mount Pinatubo, that forced Philippine evacuations including Clark Air Force Base. (Courtesy photo)

Ash plumes from the volcano, Mount Pinatubo, that forced Philippine evacuations including Clark Air Force Base. (Courtesy photo)


On June 10, 1991, Col. Jeffrey R. Grime, commander of the 3rd Tactical Fighter Wing at Clark Air Force Base, began carrying out the order to evacuate Clark Air Base, Philippines. U.S. Naval Base Subic Bay eventually followed suit. It was worried that a harmless looking nearby volcano, Mount Pinatubo, would erupt. Indeed, the mountain had been releasing steam since the previous April.


Worried they were being overcautious and that more people would be hurt in an evacuation than anything, he nevertheless followed his orders to the letter to evacuate more than 20,000 American personnel.


It had already been a trying year for everyone at Clark Air Base, the largest Air Force base outside the continental United States. In May 1990, two airmen were assassinated near the base by members of the New People’s Army, a communist-based guerrilla group. As a result of this and other activity of the NPA, there were frequent restrictions to base.


In July 1990, an earthquake measuring 7.8 on the Richter scale shook central Luzon. Little damage happened on base, but Airmen quickly rushed to help in off-base relief operations, including pulling bodies from a poorly constructed school that had collapsed on 250 children. During the following fall, nearly 3,000 Filipino workers on the U.S. government payroll went on strike, causing bitterness that led to further base lockdowns. This was followed by several typhoons, though not as bad as a super typhoon that had smashed through the base in 1989.


So it was a few days after the steam plume appeared on April 2, 1991, during a regular staff meeting the 3rd Support Group commander, Col. John Murphy, mentioned the threat of a volcano eruption. The vice commander’s famous response – in hindsight – was, “Volcano? What volcano?”


This was the uniform view of everyone serving at Clark. The idea that one of the little Zambales Mountains that was just barely bigger than the other mountains could be dangerous seemed ludicrous. It had not erupted in 500 years or more. Meanwhile, 60 miles away in Manila, Dr. Raymundo Punongbayan, director of the Philippine Institute of Volcanology and Seismology, was well aware that Mount Pinatubo was a volcano. His team had reported a half mile long fissure had opened on Pinatubo’s northwest side, killing vegetation and continuously emitting steam and sulfur fumes. Dr. Punongbayan called a friend at the U.S. Geological survey, Dr. Chris Newhall, who found a way to cut through layers of red tape to rush a team to the Philippines.


The USGS team quickly came to the conclusion that Pinatubo was turning out to be a Plinian, or explosive volcano. This was no prediction that it would erupt; only that it could erupt. The data pointed to Pinatubo being a volcano prone to episodes of voluminous explosive eruptions separated by centuries to millennia of repose. Wing leadership was told what might happen if the volcano were to erupt: Pyroclastic flow would dump hot fragments and a huge amount of ash in rolls down the volcano’s flanks in enormous clouds. These flows typically are approximately 1,000 degrees centigrade, move at 50 to 100 mph and, because they are so dense, wipe out everything in their path. On June 7, 1991, the first magmatic eruptions took place and Operation Fiery Vigil, the emergency evacuation of Department of Defense personnel and dependents from Clark Air Force Base began days later. It happened barely in time.


When the evacuation began on June 10, it was a land evacuation bringing 15,000 personnel and several thousand vehicles onto U.S. Naval Base Subic Bay. Preparations for the arrival of so many was quickly found to be inadequate, but senior officer and NCO leadership quickly started sorting out the situation. Then on June 12-14, several waves of Pinatubo eruptions generated columns up to 80,000 feet in altitude and pyroclastic flows, avalanches of superheated gas and ash, along with volcanic bombs, masses of molten rock. This was just the beginning. On June 15, 1991, the major eruption of Mount Pinatubo occurred, sending ash and tephra, airborne fragments that fall to the ground, over 100,000 feet into the air. Both Clark Air Base and Subic Bay Naval Station were heavily damaged by ash from this eruption, the second largest terrestrial eruption of the twentieth century.


One foot of ash accumulated on both bases, causing many buildings to collapse from the weight. A cloud of volcanic ash hundreds of miles across was created and 20 million tons of sulfur dioxide and 11 cubic kilometers of tephra were ejected, causing the mountain to become 1,000 feet shorter after the eruptions ended.


Very few of the 20,000 ever returned to either base after the evacuation. Most were processed back to the U.S. at Anderson Air Base, Guam. The United States Secretary of the Air Force announced on July 12, 1991, that the Air Force would leave the Philippines for good. When SECAF visited Clark Air Base on Nov. 5, he paid tribute to the “Ash Warriors.” The American flag was lowered for the last time by those same warriors on Nov. 26, 1991, and Clark Air Base was turned over to the government of the Philippines, ending more than 90 years of U.S. service there. What started out as Fort Stotsenburg in 1903 was but a memory. Much had happened over the years at Clark Air Base.


Allied prisoners of the Bataan Death March passed by the main gate. The base was recaptured by the Americans in January 1945. The base supported conflict operations in both Korea and Vietnam.

Much can be learned by the tragedy of the eruption. The men and women of the 3rd Tactical Fighter Wing hoped for the best but prepared well for the worst. The trials they faced before the eruptions, the assassinations, the typhoons, local political unrest and more, trained them to work together. This proved vital during the epic unexpected event.


History is a poor predictor. Famous author Kurt Vonnegut famously said, “history is merely a list of surprises.” One can imagine a volcano going off on the Pacific Rim, but no one thought sleepy, dormant Pinatubo would be the one. Manmade history is rife with such surprises; the sack of Rome by the Visigoths in 410, the Battle of Trenton in 1776, Pearl Harbor in 1941, the Six Day War in 1967 and the attacks on Sept. 11, 2001. No one knows the where, the when, or the what might happen. This is what the Ash Warriors can teach us: prepare, work together, and do whatever it takes. How we work together every day matters. How we take care of each other after hours can matter even more. How seriously we take our training and exercises may very well decide how many thousands of lives are saved if the unexpected happens to us.


Notes and sources: The vice commander (“Volcano? What volcano?”) mentioned above was Col. Clarence R. “Lucky” Anderegg. He wrote a very good book entitled, “The Ash Warriors” from which much of the above was taken.