Dangers of Volcanic Ash

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"PERILOUS PATHS. Flight routes over the North Pacific to and from east Asia pass over or near about 100 Alaskan, Russian, and Japanese volcanoes (red triangles)." Travel Safety Threat

    Since its inception, commercial air travel has been noted for maintaining a very high standard of passenger safety. People around the world journey thousands of miles every day of the year by air for business or personal ventures to an expected, uneventful arrival at their intended destinations. Both these professional, highly trained air transport pilots and the high tech machines that they fly do their jobs and do them well time and time again. Yet, there are situations brought about by various environmental hazards that are elusive to onboard radar systems which could place commercial jet aircraft in harms way unexpectedly. The focus of this report is about one such dangerous environmental hazard to commercial jet travel known as volcanic ash. These ash cloud plumes, transported by atmospheric winds  are at the very least, responsible for major disruptions to air traffic and pose a potentially serious  threat to aircraft hundreds of  miles away from the origin of its eruption. They pose costly and potentially deadly dangers to aircraft unwittingly caught in them and then obligated to fly through them. Hence, this is a major concern when one considers the fact that there are 1,500 known volcanoes in the world and approximately 600 of them are considered to be active. In addition, it is estimated that between 55-60 volcanoes out of the identified active group will erupt each year and what is most significant, 8-10 of these eruptions will reach cruising altitudes of commercial jet aircraft. To put the magnitude of one such event in perspective, quoted are statistics from ofcm.gov dated February 25,2004. "When Mt. St. Helens erupted in 1980, the plume reached an altitude of  90,000 ft. in 30 minutes and was 50 miles wide. In 15 hours, the plume traveled 600 miles downwind. After 2 weeks, ash had circled the earth."
     Over the past twenty years, there have been approximately ninety such encounters between commercial jet aircraft and volcanic ash. Seven of these encounters have caused either in-flight loss of jet engine power or complete engine flame-out. Thankfully, none of them have resulted in crashes or fatalities. However, the effects of these far reaching volcanic ash plumes in terms of commercial air travel safety, costly aircraft damage received through all phases of flight and costly aircraft damage sustained while on the ground requires a total volcanic ash avoidance solution. Therefore, the necessary steps to accomplish such a goal will only be achieved through constant vigilance by the use of reliable remote sensing techniques, by the use of  dedicated monitoring agencies and by the delivery of timely warnings to air carrier operations center.

Damage in Flight

     As previously stated, aircraft through all phases of flight, which includes cruise altitude, taking-off and landing have been severely damaged from encounters with these drifting volcanic ash plumes. Ergo, the ramifications of flying through these ash clouds are serious and extensive; the list includes damage to critical aircraft components including lift surfaces, windshields and engines. This damage endangers passengers through the potential loss of aerodynamic lift, loss of engine power, visibility and degraded communications between flight crews and air traffic control centers.           According to  the International Airways Volcano Watch (IAVW), the effects upon jet engines, in particular, by ingesting this material containing mostly silicates is dangerous primarily because of the melting point of the ash is approximately 1100 deg C while the operating temperature of high bypass jet engines are around 1400 deg C. The ash, therefore, does not simply blow through the engines as dust/sand tends to, but Melts in the hot section (picture to the right-engine damage from ash ingestion) and FUSES randomly on fuel nozzle guide vanes and turbine blades."  Even limited exposure will cause degraded performance and the worst case scenario with continued exposure will incur a total engine failure condition known as "flameout".
     This ash is abrasive and has clogged pitot-static systems which are critical inputs to various aircraft user systems such as navigation equipment, flight controls and pressurization systems. Windshields and landing light lenses have been virtually "sandblasted" to a frosty finish thus rendering their visibility useless. Sulfur Dioxide gas (SO2), another byproduct of volcanic activity is extremely corrosive and extremely damaging to all aircraft metal components. Crews and passengers alike will inhale this noxious material as it is drawn into the flight deck and cabin compartments by the jet's air conditioning  and recirculation systems as evidenced by these ash-coated filters causing environmental control damage. Once the ash is ingested into the aircraft's air conditioning system, it will travel to all interior spaces both above and below deck  infiltrating such critical areas as avionics cooling systems which supplies necessary navigation instrument and computer ventilation to prevent overheating. It  also travels through circuit breaker and related electrical service panels located throughout the aircraft necessary for maintaining operation of essential systems.
     There are two issues here, obviously of paramount importance at all times is passenger safety. Secondly, for any business enterprise to remain a viable entity, one strives to control operating costs along the way. Yet, these very encounters with volcanic ash (electrical panel damage-right) as presented in these images can easily reach a staggering economic level in associated maintenance repair costs to the air carriers in terms of millions of dollars per aircraft per event. Estimates from the maintenance costs associated with the 1989 KLM 747 encounter with the Redoubt volcano in Alaska exceeded eighty million dollars.
    
Damage on the Ground

 Let's not forget about aircraft ground damage either. Timely warnings received by various air carrier operations can afford them the opportunity to move aircraft from one location to another, thus avoiding the situation all together. Improper wing and horizontal stabilizer loading caused by the added weight of volcanic ash accumulation on these surfaces can change the aircraft CG (center of gravity) and cause a situation for rear-engine mounted aircraft known as tail tip as evidenced in the photo of this DC-10. The end result is major structural damage to the airframe requiring hundreds of hours in related repair costs. According to a November 10, 2003 publication of Geological Society , airlines have taken a hit of over $250 million worldwide as a result of undetected volcanic ash in flight paths". Not included in this figure are the lost revenue dollars per flight per day caused by extensive aircraft downtime to accomplish these needed repairs.