Protecting Aircraft From Wind And Volcanic Ash

Korean Airlines
Korean Airlines’ widebody fleet, sealed and parked at Seoul Gimpo Airport.
Credit: Korean Air

Part of the Asia-Pacific region straddles the so-called Pacific Ring of Fire, one of the most active tectonic and volcanic regions in the world. The area is also the birthplace of some of the strongest typhoons, causing billions of dollars in infrastructure damage in East Asia. So far, 2020 has seen five typhoons and 10 tropical storms. With mass groundings and travel restrictions related to COVID-19, provisions must be made to protect parked aircraft, which cannot be easily repositioned prior to an incoming natural disaster.

In recent months, the Korean peninsula experienced some 50 consecutive days of rain and was struck by three successive strong typhoons—Bavi, Maysak and Haishen—the last two arriving within four days of each other.

At its peak in May, South Korean flag-carrier Korean Air had around 40 aircraft comprising 10 aircraft types parked at Seoul Incheon, Seoul Gimpo and Gimhae airports. Usually, in preparation for a typhoon, aircraft are fueled to the maximum to increase their weight and will be drained following the storm. However, for KAL, fuel is loaded to the “normal” load as it usually takes too long to drain the fuel.

“For the stronger levels of wind, we moor the aircraft or load sandbags on the aircraft,” a KAL representative tells Inside MRO, going on to say that the most effective way to protect aircraft is to relocate them. This year, the carrier adjusted its flight schedule to reposition its aircraft to other domestic and international stations. The airline says there were no reports of any damage from the three recent typhoons.

KAL also added a desiccant with the engine coverings to prevent engine corrosion during the unusually long wet season. Cabin humidity is managed through checks and conducting air conditioning runs in cycles of 3-7 days. Sealing the aircraft also protects the airframe from dust storms that blow in from China’s Gobi Desert.

Taiwan’s China Airlines sometimes assigns engineers to sit in aircraft during a typhoon to make adjustments to prevent any airflow over the wings that might create undesired movements. 

Filipino low-cost carrier Cebu Pacific has to contend with both typhoons and the potential eruption of volcanoes across the archipelago. The Taal volcano erupted in January, forcing the closure of most airports around Manila.

Due to COVID-19, the carrier has already parked 14 aircraft, including Airbus A320s and A330s, at Alice Springs’ Asia-Pacific Aircraft Storage in Australia, to protect them against natural disasters and other environmental threats.

Although typhoons usually hit the Philippines’ north, Ian Wolfe, Cebu Pacific senior advisor for engineering and fleet management, says parking aircraft is dictated by commercial demands and is scattered across various hubs. Depending on the strength of the typhoon, aircraft may be evacuated to another airport in the country or simply moored to the ground. But volcanoes are harder to predict, and warnings usually provide less time to react than those for typhoons.

“Volcanoes may already be emitting smoke, but you will never know exactly when they will erupt. This can go on for days, or even weeks,” says Wolfe. In the aircraft preservation process, all openings are covered to prevent foreign objects from entering, including volcanic ash. Should there be an ash fall, there are specified procedures in aircraft maintenance manuals that must be completed.

For example, Boeing’s aircraft maintenance manual calls for a phased approach to aircraft inspection to allow the inspections to stop if no signs of damage or ash fall are found, so aircraft can return to service quickly. Superficial inspections include checks for unusual abrasion on pitot tubes, windows and lights, while a more detailed inspection of internal ash buildup on ozone converters, bleed systems and other sensitive components are done if the engines have a history of ash contamination.

Additional lightning protection for commercial airliners is unnecessary since it is designed into the aircraft. The metal frame forms a Farraday Cage in which the current passes through the airframe and is discharged safely. However, Wolfe adds that any ground activities would be halted during thunderstorms, depending on the airport’s lightning risk warning. In the Philippines, the Lightning Activity System categorizes the lightning risk as red or yellow, corresponding to the weather’s proximity and intensity.

Chen Chuanren

Chen Chuanren is the Southeast Asia and China Editor for the Aviation Week Network’s (AWN) Air Transport World (ATW) and the Asia-Pacific Defense Correspondent for AWN, joining the team in 2017.