Volcanic Ash: A Naturally-Occurring Aviation Hazard
Question: What did the flights of two Air Force F-4E Phantom jets on a training exercise from Galena to King Salmon on January 22, 1976, the flight of a Japan Airlines DC-8 cargo jet bound for Tokyo from Anchorage on January 25, 1976, the flights of two Japan Airlines passenger jets (a DC-8 and a Boeing 747) on the same route and at the same date, and the flight of a British Airways 747 en route from Java to Perth, Australia, on June 23, 1982, all have in common?
Answer: They were all flying near the lane of the famed "Pacific Ring Of Fire," they all encountered a volcanic ash cloud, and all were in some danger, either from reduced visibility or engine failure. All of them made it safely to their destination, and this is probably the most amazing fact of all. The following are excerpts from eye-witness accounts of the incidents.
Pilots of the F-4E fighters recounted that "The two jets were flying at 31,000 feet, when suddenly the clouds darkened slightly and then there was instant total darkness. The planes were flying in close formation about 10 meters apart, and had the lead pilot not immediately turned on his lights, the following pilot would have lost contact. Upon landing in King Salmon, the canopies of the aircraft were found scoured and the paint at the wing tips was sandblasted off. Very fine rouge colored material was found in every nook and cranny of the airplanes." The cause? Mt. Augustine in Cook Inlet had erupted.
The incidents involving the three Japan Airlines aircrafts three days later were also related to the Mt. Augustine eruption. As recounted by Mr. K. Noguchi of Japan Airlines: "After flight JAL672 took off from Anchorage, it was reaching cruising altitude of 33,000 feet when it suddenly encountered an ash cloud near Whitefish Lake. Upon landing in Tokyo, the scoured center windshield had to be replaced, and abrasion damage was found on external radio parts, landing gear and the air conditioning system." The other two passenger planes also sustained minor damage.
A more dramatic event, reported in the November, 1983 issue of Natural History, involved the nighttime South-Pacific flight of the British Airways 747. In this incident, "St. Elmo's Fire," an electrical discharge phenomenon, was observed extending from the engines and sparking across the instrument panel, while smoke was smelled inside the passenger cabin. In minutes, the number four engine shut down, followed in rapid succession by the remaining three. The aircraft glided from 37,000 feet to 12,000 feet before the crew was able to restart the engines and steer for an emergency landing at Jakarta. Even then, the danger was not over, because the windshield was so scarred that forward vision was impossible. Skillful teamwork by the crew finally resulted in a happy landing.
As it developed, Mt. Galunggung in western Java had erupted just before the aircraft passed over. Sucked into the air conditioning system, ash appeared as smoke, and the static electricity created by the ash hitting the windscreen and wings created the "St. Elmo's Fire." The engines had been extinguished as effectively as if someone had thrown a bucket of sand into them. Only in the clear area below the ash cloud had restarting the engines been possible.
After landing, a Boeing representative told the crew that it was the most severely damaged 747 that had ever flown. Clearly, closer links should be established between international air traffic controllers and volcano-monitoring agencies. Looking at a map, it is astonishing to find that so many airline routes closely parallel active volcanic belts, particularly those of the Aleutians, the Southwest Pacific, Japan, South and Central America, and the Cascades.
