By Aeruxo — Licensed Flight Dispatcher | 15+ Years in Airline Operations
June 2025. Mount Lewotobi Laki-Laki, a volcano on the island of Flores in eastern Indonesia, erupted with an ash column that shot 11 kilometers into the sky. The mushroom-shaped cloud was visible from 150 km away. Dozens of volcanic ash flights to and from Bali—800 km to the west—were immediately cancelled. Jetstar, Virgin Australia, Singapore Airlines, AirAsia, and Korean carriers all scrapped services. Over a thousand tourists were stranded.
Three weeks later, the same volcano erupted again. This time the ash reached 18 km—well into the stratosphere, higher than any commercial aircraft flies. More cancellations. More stranded passengers. More social media outrage from travelers who could not understand why their Bali flight was cancelled when the volcano was not even on the same island.
I understand their confusion. But as a flight dispatcher who has managed volcanic ash disruptions on our Indonesia routes for over 15 years, I also know exactly why those flights were cancelled—and why they had to be. Volcanic ash is not like other weather hazards. It is invisible to radar, it can destroy jet engines in minutes, and it drifts silently for thousands of kilometers from the eruption site. It is, quite literally, aviation’s most dangerous invisible enemy.
This article explains everything: what volcanic ash does to aircraft, how dispatchers and pilots detect and avoid it, why eruptions hundreds of kilometers away can cancel your flight, and what you can do to protect your travel plans in one of the most volcanically active regions on Earth.
Key Takeaways
- Volcanic ash can destroy jet engines. The microscite particles melt inside the engine’s combustion chamber, then resolidify on turbine blades—potentially causing complete engine failure.
- Ash is invisible to aircraft weather radar. Unlike thunderstorms, volcanic ash does not show up on the radar that pilots use to detect weather. Avoidance depends on satellite data, ground observation, and advisory systems.
- An eruption 800 km away can cancel your flight because ash clouds drift with upper-level winds, crossing entire flight corridors. The volcano does not need to be at your destination—it just needs to be in the airspace between you and your destination.
- Indonesia has 120 active volcanoes along the Ring of Fire, making it the most volcanically active country in the world. Any flight to Bali, Jakarta, or surrounding destinations carries inherent volcanic risk.
- There is zero tolerance for flying through volcanic ash. After near-catastrophic incidents in the 1980s and 1990s, the global aviation industry adopted a policy of complete avoidance. If ash is in the airspace, flights do not operate.
1. What Volcanic Ash Does to Aircraft: The Science of Destruction
To understand why volcanic ash forces flight cancellations, you need to understand what happens when ash meets a jet engine. It is not a minor inconvenience—it is a potential catastrophe.
Volcanic ash is not like regular dust or sand. It is composed of tiny fragments of pulverized rock, glass, and minerals—sharp, abrasive particles that are incredibly destructive to aircraft systems.
Engine destruction. When ash particles enter a jet engine, they pass through the combustion chamber where temperatures exceed 1,400°C. At these temperatures, the glite and silicate components of volcanic ash melt. The molten material then flows onto the turbine blades and vanes downstream, where the temperature is lower, and resolidifies as a glass-like coating. This coating blocks the cooling holes in the turbine blades, disrupts airflow, and can ultimately cause the engine to surge, lose power, or shut down completely.
Windscreen sandblasting. Volcanic ash particles are abrasive enough to sandblast the cockpit windscreen, reducing visibility to near-zero. Pilots who have inadvertently flown through ash clouds report the windscreen becoming completely opaque within minutes.
Pitot tube and sensor blockage. The fine ash can block the aircraft’s pitot tubes (which measure airspeed) and static ports (which measure altitude), giving the crew erroneous instrument readings—a dangerous situation at any phase of flight.
Airframe erosion. The leading edges of the wings, tail, and engine nacelles are eroded by the abrasive particles, similar to industrial sandblasting. While this does not cause immediate structural failure, it degrades the aircraft’s aerodynamic performance and requires expensive repair.
The most famous volcanic ash encounter in aviation history is British Airways Flight 9 in 1982. A Boeing 747 flew into the ash cloud from Mount Galunggung in Indonesia (the same volcanic region we fly through today). All four engines flamed out. The aircraft glided powerlessly for 16 terrifying minutes before the crew managed to restart the engines after descending below the ash cloud. All 263 passengers survived, but the incident—and several similar ones in the following years—fundamentally changed how aviation treats volcanic ash.
The lesson was clear: volcanic ash and jet engines are incompatible. There is no safe concentration. There is no acceptable exposure time. The only safe response is complete avoidance.
2. Why a Volcano 800 km Away Cancels Your Flight
This is the question I get from passengers more than any other during volcanic disruptions: “The volcano is on Flores. I am flying to Bali. Bali is 800 km away. Why is my flight cancelled?”
The answer is wind.
Volcanic ash does not stay above the volcano. Once ejected into the atmosphere, the ash cloud is carried by upper-level winds—and at the altitudes where commercial aircraft fly (30,000-40,000 feet), winds can exceed 100 km/h. An ash cloud from Flores can reach Bali’s airspace in 6-8 hours. It can reach Jakarta in 12-16 hours. It can affect flight corridors across the entire Indonesian archipelago within a day.
The critical point is this: the ash does not need to be at your destination airport. It needs to be in the airspace that your flight would pass through. If the ash cloud has drifted into the corridor between Incheon and Bali—even if Bali itself is clear—the flight cannot operate through that contaminated airspace. The only option is to route around the ash (which may be impossible if the cloud is too wide) or cancel the flight and wait for the ash to disperse.
During the June 2025 Lewotobi eruptions, this is exactly what happened. The volcano was on Flores. Bali’s airport was technically open—the ash had not reached Bali’s immediate airspace. But the ash cloud was positioned directly in the flight corridors used by airlines flying from Australia, Singapore, and Korea to Bali. The flights could not reach Bali without passing through the ash zone. So they were cancelled—not because Bali was dangerous, but because the route to Bali was impassable.
As a dispatcher, this distinction is critical to my decision-making. I do not just check the weather at the destination. I check the entire route—every kilometer of airspace from departure to arrival—for volcanic ash contamination. If any segment is contaminated, the flight cannot operate through that segment.
3. How the Aviation System Detects and Tracks Volcanic Ash
Unlike thunderstorms, which show up clearly on aircraft weather radar, volcanic ash is invisible to radar. This makes detection and tracking a specialized, multi-layered operation.
Volcanic Ash Advisory Centers (VAACs). ICAO has designated nine VAACs worldwide, each responsible for monitoring volcanic activity in their region. For our Southeast Asia routes, the relevant center is the Darwin VAAC, operated by the Australian Bureau of Meteorology. The Darwin VAAC issues Volcanic Ash Advisories (VAAs) that include the observed and forecast position of ash clouds, their altitude, and their projected movement over the next 6, 12, and 18 hours.
Satellite imagery. VAACs use geostationary and polar-orbiting satellites equipped with infrared sensors that can detect volcanic ash in the atmosphere by its spectral signature—ash absorbs and emits infrared radiation differently than water vapor or ice crystals. This allows forecasters to map the ash cloud’s position and track its movement in near-real-time.
Pilot reports (PIREPs). Pilots who observe volcanic activity or encounter unusual haze, sulfur smell, or reduced visibility report these observations to ATC, who relays them to the VAAC. These reports are invaluable because they provide ground-truth confirmation of ash at specific altitudes and locations.
SIGMETs. When volcanic ash is detected or forecast in an aviation corridor, the responsible meteorological authority issues a SIGMET (Significant Meteorological Information)—a formal advisory that alerts all dispatchers and pilots to the hazard. As a dispatcher, SIGMETs are among the most critical documents I monitor. A volcanic ash SIGMET for Indonesian airspace triggers an immediate assessment of all affected flights on my desk.
4. Inside the OCC: Managing a Volcanic Ash Event
When a volcanic ash event affects our routes, the OCC response follows a structured but intense sequence. Let me walk you through a realistic scenario based on my experience with Indonesian eruptions.
Hour 0: The Eruption
The first notification comes from the Darwin VAAC—a Volcanic Ash Advisory reporting an eruption at Mount Lewotobi with an ash column reaching FL350 (35,000 feet). The advisory includes the observed ash position and a forecast showing the cloud drifting westward toward Bali at approximately 50 km/h.
I immediately identify all flights on my desk that route through or near the affected area. We have three flights relevant: an Incheon-Bali service departing in 4 hours, a Bali-Incheon return service scheduled 8 hours from now, and an Incheon-Denpasar via a southern routing that might avoid the ash.
Hour 1-2: Assessment
I pull up the latest satellite imagery and overlay it with our planned flight routes. The ash cloud is currently concentrated east of Bali, but the forecast shows it spreading west across the standard arrival corridor. I run routing scenarios: can the Incheon-Bali flight route south around the ash? I calculate the fuel required for the detour. The southern routing adds 45 minutes of flight time and 2,800 kg of fuel. At the planned payload, we do not have enough fuel capacity for the detour. Can we reduce payload? That means offloading 20 passengers. That creates a rebooking problem.
Meanwhile, the VAAC issues an updated advisory extending the ash cloud further west than the initial forecast. The southern routing is now also contaminated. There is no clear path to Bali.
Hour 2-3: Decision
I recommend cancellation of the Incheon-Bali flight. The duty manager concurs. We also preemptively cancel the Bali-Incheon return service, since even if Bali’s airspace is clear, the aircraft that was supposed to operate the return will not be there. Two flights down. 378 passengers affected.
I set a review timer: reassess in 6 hours when the next VAAC advisory is issued. If the ash dissipates faster than forecast, tomorrow’s flights might be salvageable.
Hour 6-24: Monitoring and Recovery
The situation is now a waiting game. I monitor VAAC advisories every 6 hours, checking whether the ash is dissipating, spreading, or being reinforced by new eruptions. Mount Lewotobi has a history of sequential eruptions—a pattern I have seen before where one eruption is followed by another within days. I cannot assume the event is over after a single eruption.
If the ash clears within 24 hours, we can resume normal operations the next day—though the domino effect of today’s cancellations means tomorrow’s schedule will still be disrupted. If the ash persists or new eruptions occur, we may be looking at multi-day cancellations, similar to what happened during the Lewotobi sequence in June-July 2025.
5. Indonesia: Flying in the World’s Most Volcanic Country
Indonesia has 120 active volcanoes—the highest concentration of any country on Earth. The entire archipelago sits along the Ring of Fire, where tectonic plates converge and create the conditions for frequent volcanic activity. For anyone flying to Bali, Jakarta, Yogyakarta, Labuan Bajo, or any other Indonesian destination, volcanic risk is a permanent background factor.
The volcanoes that most frequently affect Bali-bound flights include:
Mount Lewotobi Laki-Laki (Flores) — Erupted in November 2024, March 2025, June 2025, and July 2025. Located 800 km east of Bali, its ash clouds have repeatedly drifted into Bali’s flight corridors. This is currently the most active threat to Bali aviation.
Mount Agung (Bali) — The volcano that sits on Bali itself. Its 2017-2019 eruption series caused massive disruption to Bali flights, including complete airport closures. Currently calm, but monitored continuously.
Mount Rinjani (Lombok) — Just east of Bali, eruptions from Rinjani have shut down Bali’s airport in the past, most notably in 2016.
Mount Raung and Mount Semeru (East Java) — Located west of Bali, eruptions from these volcanoes can affect flights approaching Bali from the west—including flights from Incheon that route over Java.
As a Korean LCC dispatcher with Bali on our network, I maintain awareness of the status of all of these volcanoes. Before releasing any flight to Denpasar, I check the latest volcanic activity reports, VAAC advisories, and satellite imagery for the entire Indonesian volcanic belt. This is not optional—it is a fundamental part of flight planning for Indonesian destinations.
6. The 1982 Lesson That Changed Everything
The modern approach to volcanic ash in aviation—zero tolerance, complete avoidance—exists because of a single terrifying flight.
On June 24, 1982, British Airways Flight 9, a Boeing 747 carrying 263 people from Kuala Lumpur to Perth, flew into the ash cloud of Mount Galunggung over Java. The crew had no warning—volcanic ash was not well understood by the aviation community at that time, and there were no VAAC advisories or satellite-based detection systems.
All four engines flamed out. The aircraft, a 400-tonne jumbo jet carrying 263 souls, became a 400-tonne glider over the Indian Ocean at night. The crew attempted to restart the engines repeatedly as the aircraft descended from 37,000 feet. After 16 minutes of powerless descent—one of the longest in aviation history—the engines restarted below the ash cloud at around 12,000 feet. The aircraft diverted to Jakarta and landed safely with heavily damaged engines, sandblasted windscreens, and a cabin full of shaken passengers.
A similar incident occurred just three weeks later when a Singapore Airlines 747 encountered the same volcano’s ash cloud. And in 1989, KLM Flight 867, a 747 approaching Anchorage, flew through ash from Alaska’s Mount Redoubt and lost all four engines temporarily.
These incidents—none of which resulted in fatalities, but all of which came terrifyingly close—drove the creation of the global VAAC network, mandatory volcanic ash SIGMETs, and the aviation industry’s current policy of absolute avoidance. As I discussed in my article on aviation safety, the system learns from every incident and builds protections to prevent recurrence. Volcanic ash avoidance is one of the strongest examples of this principle.
7. Practical Guide: Protecting Your Trip from Volcanic Disruption
If you are traveling to Indonesia or anywhere in volcanic Southeast Asia, here is my practical advice—drawn from 15 years of managing these exact disruptions.
Buy travel insurance. This is non-negotiable for Indonesia. Volcanic eruptions are classified as natural disasters, and most standard airline policies provide limited compensation. A comprehensive travel insurance policy that covers volcanic disruption—including accommodation, alternative flights, and trip cancellation—is essential. I give this same advice for typhoon season travel, and it applies equally here.
Monitor volcano status before and during your trip. Indonesia’s Center for Volcanology and Geological Hazard Mitigation (PVMBG) publishes alert levels for all active volcanoes. The Darwin VAAC provides aviation-specific advisories. If a volcano on or near your flight path is at elevated alert levels before your departure, start preparing backup plans.
Build flexibility into your itinerary. If you are flying to Bali for a 5-day holiday, consider booking 6 or 7 days to allow for potential disruption on either end. The extra night’s accommodation is trivial compared to the cost and stress of being stranded without options.
Know that eruptions are unpredictable in timing but predictable in pattern. Indonesia’s volcanoes erupt regularly—this is not a question of “if” but “when.” Mount Lewotobi erupted in November 2024, March 2025, June 2025, and July 2025. If you are planning a trip during a period of elevated volcanic activity, the probability of disruption is higher. But volcanic eruptions are inherently unpredictable at the specific-day level, so flexibility is your best defense.
If your flight is cancelled, rebook immediately through the app. The same advice I give for all cancellations applies here: do not wait in the phone queue. Rebook via the airline’s app as soon as possible. During volcanic events, available seats on alternative flights fill within minutes. The passengers who act fastest get the best options.
Do not assume the disruption will be short. Some volcanic ash events clear within 12-24 hours. Others—particularly when a volcano enters a phase of repeated eruptions—can disrupt flights for days or even weeks. The 2010 Eyjafjallajökull eruption in Iceland closed European airspace for six days, stranding 10 million passengers. Indonesian eruptions are typically shorter-lived, but multi-day disruptions are entirely possible and have occurred in 2024 and 2025.
8. A Dispatcher’s Perspective: Living with Volcanic Risk
In my 15 years on Southeast Asian routes, volcanic ash has been a recurring operational reality—not a rare surprise. I have managed disruptions from Indonesian volcanoes more times than I can count. Each event reinforces the same principles:
The system works. Since the BA Flight 9 incident in 1982, there has not been a single catastrophic accident caused by volcanic ash encounter on a commercial airline that was following VAAC advisories. The detection, communication, and avoidance systems built over the past four decades are remarkably effective.
But the system requires patience. Volcanic ash does not operate on airline schedules. It disperses when atmospheric conditions allow, not when passengers need to catch their connecting flight. The most professionally managed volcanic disruption still inconveniences thousands of travelers. That inconvenience is the price of safety—and after learning what volcanic ash does to jet engines, I believe every informed traveler would agree it is a price worth paying.
Indonesia is worth the risk. I do not say this as a travel endorsement—I say it as someone who has spent 15 years dispatching flights to Indonesian destinations. Bali, Labuan Bajo, Yogyakarta—these are extraordinary places. The volcanic risk is real but manageable with proper preparation: travel insurance, flexible scheduling, and the understanding that in one of the most geologically active places on Earth, nature occasionally reminds us who is in charge.
Learn more about our mission and operational background on the About Aeruxo page.
Frequently Asked Questions
Can planes fly through volcanic ash?
No. The global aviation industry maintains a zero-tolerance policy for flying through volcanic ash. Ash particles melt inside jet engines at combustion temperatures and can cause complete engine failure. They also sandblast windscreens, block pitot tubes, and erode airframe surfaces. After near-catastrophic incidents in the 1980s and 1990s, regulatory authorities and airlines agreed that no concentration of volcanic ash is acceptable for flight operations. If ash is detected or forecast in an airspace sector, flights are rerouted around it or cancelled.
Why was my Bali flight cancelled when the volcano is 800 km away?
Volcanic ash drifts with upper-level winds, which can carry it hundreds or thousands of kilometers from the eruption site. An eruption on Flores can spread ash into Bali’s flight corridors within 6-8 hours. Even if Bali’s airport is technically clear, the airspace between your departure city and Bali may be contaminated, making the route impassable. Airlines cancel flights when the ash prevents safe transit through any segment of the route—not just conditions at the destination airport.
How long do volcanic ash flight disruptions typically last?
It varies enormously. A single, short eruption with favorable winds may disrupt flights for 12-24 hours. A sustained eruption or a series of sequential eruptions (as Mount Lewotobi demonstrated in 2025 with multiple eruptions across several months) can cause disruptions lasting 2-5 days per event. The worst-case scenario was the 2010 Eyjafjallajökull eruption in Iceland, which disrupted European aviation for six consecutive days. Indonesian eruptions are typically shorter but can recur repeatedly over weeks or months.
Is Bali safe to visit given the volcanic activity?
Yes. The volcanic risk to Bali travelers is primarily a disruption risk (flight cancellations and delays), not a personal safety risk—unless a volcano on Bali itself (Mount Agung) erupts, which is currently not occurring. Eruptions on neighboring islands affect flights but do not pose a direct threat to people on Bali. The key is preparation: travel insurance, flexible itineraries, and awareness of current volcanic activity levels before and during your trip.
How do pilots know if there is volcanic ash in their path?
Pilots cannot detect volcanic ash with their onboard weather radar—ash is invisible to radar. They rely on pre-flight briefings that include VAAC advisories and SIGMETs, real-time updates from ATC based on the latest VAAC data, pilot reports from other aircraft, and visual observation (though ash clouds are often difficult to distinguish from regular clouds). The dispatcher also provides ongoing updates via ACARS during the flight if the situation changes. The entire detection system is ground-based and satellite-based, not onboard.
What should I do if I am already in Bali when a volcano erupts?
Stay calm. Check your airline’s app and website for flight status updates. Contact your airline proactively to understand rebooking options. Document all additional expenses (hotel extensions, meals) for insurance claims. Monitor the Darwin VAAC website for the latest ash advisories and projected clearance times. If your return flight is cancelled, the airline will typically rebook you on the next available service—but this may be 1-3 days later during a major event. Having travel insurance and a flexible mindset are your most valuable assets in this situation.
Planning a trip to Indonesia? Have questions about volcanic ash and flying? Leave a comment—I will answer from a dispatcher’s perspective.
Disclaimer: The views expressed in this article are my own professional opinions based on 15+ years of operational experience. They do not represent the official position of any airline, aviation authority, or regulatory body.