FlySafe was not operational during this event. This analysis reconstructs publicly available signals — to demonstrate how predictive airspace intelligence could have provided advance warning.
Popocatépetl — Mexico City Shutdown
May 2023 — Mexico City Airport Suspended, 100+ Flights
On May 19, 2023, Popocatépetl — the 5,426-meter active volcano visible from Mexico City's skyline — produced its most intense eruption in years. The ash column reached 9 km above the crater. Mexico City's Benito Juárez International Airport (AICM), the busiest single-runway airport on Earth handling 50+ million passengers annually, is just 70 km from the crater. Operations were suspended twice: May 19-20 and again on May 23. Over 100 flights were cancelled. Volcanic ash fell across the metropolitan area of 21 million residents. CENAPRED raised the alert to Yellow Phase 3.
What Happened
On May 19, 2023, Popocatépetl — the 5,426-metre stratovolcano straddling the Estado de México and Puebla border — entered a phase of sharply intensified eruptive activity that forced the temporary suspension of operations at Aeropuerto Internacional de la Ciudad de México Benito Juárez (AICM / MMMX), one of the busiest airports in Latin America. Ash columns reached 9 km above the crater rim, placing volcanic material at approximately 14,400 metres ASL — well within commercial cruise and approach corridors. The eruption triggered SIGMET issuances from the Washington VAAC for the MMEX FIR and generated sustained ash fall across a metro area of 21 million residents. More than 100 scheduled flights were cancelled across two separate suspension events spanning May 19–20 and a return closure on May 23.
Mexico's national volcanic monitoring agency CENAPRED raised the alert level to Amarillo Fase 3 (Yellow Phase 3), the highest tier within the Yellow band on Mexico's three-colour, seven-phase Semáforo de Alerta Volcánica. The Mexican military enforced a 12 km exclusion zone around the crater and pre-positioned assets for potential mass evacuation. Intermittent explosive episodes continued through June 2023, keeping the airspace environment around MMMX in a state of elevated operational uncertainty for over five weeks.
- Summit elevation5,426 m ASL
- Max ash column (ASL)~14,400 m
- VAAC responsibleWashington VAAC
- FIR affectedMMEX FIR
- Alert level reachedAmarillo Fase 3
- MMMX (AICM)70 km NW — suspended
- MMTO (Toluca)~90 km W — affected
- MMSM (Felipe Ángeles)120 km N — alternate
- Suspension eventsMay 19–20 & May 23
- Flights cancelled100+
Warning Signs
Popocatépetl is one of the most continuously monitored volcanoes in the Western Hemisphere. CENAPRED maintains a permanent 24/7 watch network including seismic arrays, SO₂ flux sensors, tiltmeters, and visual/infrared cameras. The data record leading into the May 2023 crisis showed a clear and accelerating escalation across multiple independent signals — each trackable in near real-time by automated systems well before Washington VAAC issued the first operational SIGMET for MMEX FIR.
At 9 km above the 5,426 m crater, the ash column extended to approximately FL473 — deep into standard cruise levels for narrow-body aircraft on regional routes. Washington VAAC ash advisories for this altitude automatically trigger SIGMET issuances covering hundreds of nautical miles downwind. Any plume exceeding FL200 in a populated FIR constitutes an immediate operational constraint.
Yellow Phase 3 sits at the apex of Mexico's intermediate alert tier. Progression from Fase 2 to Fase 3 requires documented increases in explosion frequency, tremor amplitude, and ash column height. This transition is logged in publicly accessible CENAPRED bulletins typically within 30–60 minutes of the threshold being crossed — a trackable, structured data signal.
Washington VAAC Volcanic Ash Advisories (VAAs) are machine-readable structured messages published at defined intervals and carried on aviation meteorological data feeds. Each advisory specifies ash extent polygon, flight level range, and forecast drift. The transition from watch-level advisories to SIGMETs binding on all IFR traffic in MMEX FIR was a direct operational trigger that could be parsed programmatically hours before airline operations centres issued manual go/no-go decisions.
At 70 km, MMMX lies well within the ash fallout radius for a moderate-to-large Plinian column. Prevailing winds from the SE during this period directed the primary ash plume toward the metropolitan area. Airport-level particulate contamination — affecting visibility, engine ingestion risk, and FOD exposure on runways — is statistically probable at this distance under these conditions.
Military deployment to enforce a 12 km surface exclusion zone and stage evacuation assets is a lagging indicator — it confirms that authorities assessed a credible escalation risk beyond the current eruption phase. For airspace risk models, ground-side civil emergency declarations are correlated with continued or worsening eruptive activity and typically precede the most disruptive airport operational decisions by 6–18 hours.
Timeline
CENAPRED monitoring bulletins documented elevated seismicity and an increase in exhalation frequency at Popocatépetl above the baseline rolling average. SO₂ flux readings were elevated. Alert remained at Amarillo Fase 2 but trending indicators showed accelerating unrest. Washington VAAC was tracking increased activity; no operational SIGMET in effect for MMEX FIR.
Popocatépetl produced a significant explosive episode generating an ash column rising 9 km above the crater rim — approximately 14,400 m ASL. Washington VAAC issued Volcanic Ash Advisories and corresponding SIGMETs for MMEX FIR. CENAPRED raised the Semáforo alert to Amarillo Fase 3. Ash fall began affecting Mexico City metropolitan area. AICM (MMMX) authorities suspended airport operations. The Mexican military deployed to the 12 km exclusion zone perimeter and pre-staged evacuation assets.
AICM remained closed to commercial operations. Volaris, VivaAerobus, and Aeroméxico issued flight cancellation advisories. International carriers including connections via MMMX began rerouting or cancelling inbound services. Felipe Ángeles International Airport (MMSM), located 120 km north of the crater, was designated as the primary diversion and alternative hub. Toluca airport (MMTO), approximately 90 km to the west, was also affected by ash conditions. Aeroméxico issued an official statement confirming cancellations and waivers for affected passengers.
Washington VAAC ash advisory polygons contracted as the most intense eruptive phase temporarily subsided. AICM resumed limited operations. Mexico DGAC issued updated NOTAMs for MMMX lifting the full operational suspension, subject to continued monitoring. Airlines began restoring schedules on a conditional basis. CENAPRED maintained Amarillo Fase 3 designation — signalling the eruption had not structurally de-escalated.
Renewed explosive activity at Popocatépetl forced a second suspension of AICM operations. Additional flights were cancelled. Washington VAAC reissued SIGMETs for MMEX FIR. The recurrence within 72 hours of the first closure underscored that the eruption was episodic rather than a single discrete event — a pattern consistent with Popocatépetl's historical behaviour during sustained unrest phases.
Intermittent explosive episodes continued through June 2023. Washington VAAC maintained an elevated advisory posture for MMEX FIR across this period. CENAPRED bulletins documented ongoing moderate-to-high activity. AICM operations resumed but airlines operated under contingency planning frameworks, with standing crew and aircraft displacement protocols in place. The total operational disruption window — from first suspension to return to full normal scheduling — extended to more than five weeks.
Aviation Impact
The May 2023 Popocatépetl event demonstrated the concentrated vulnerability of a single high-traffic airport serving a mega-city when positioned within the proximate ash fallout radius of an active stratovolcano. MMMX handles approximately 45 million passengers annually and serves as the primary international gateway for Mexico — making any suspension event highly visible and economically significant across the regional network.
Cancellations confirmed across Volaris, VivaAerobus, Aeroméxico, and international carriers operating through MMMX during the May 19–23 disruption window.
AICM (MMMX) was closed to commercial operations on two separate occasions — May 19–20 and again on May 23 — as renewed explosive episodes produced actionable ash hazard conditions.
Ash fall reached the full Mexico City metropolitan area, affecting ground transportation, public health response, and airport ground operations including runway decontamination between events.
Intermittent eruptions persisted through June 2023. Airlines maintained contingency dispatch frameworks and alternate-airport protocols for the full duration, generating planning overhead beyond the acute closure dates.
The activation of Felipe Ángeles International Airport (MMSM) as the primary diversion point exposed a secondary operational constraint: MMSM, opened in 2022 with significantly lower baseline throughput than MMMX, faced handling capacity and passenger ground transport challenges when absorbing overflow from a suspended 45-million-passenger facility. This asymmetry between primary and alternate airport capacity is a structural vulnerability that persists regardless of the nature of the primary disruption trigger.
Takeaway
The Popocatépetl May 2023 event is a textbook case in the gap between data availability and operational readiness. The warning signals were abundant, structured, and machine-accessible — CENAPRED bulletins are published on fixed schedules, Washington VAAC advisories are distributed on standard aviation data feeds, and SIGMET triggers for volcanic ash are defined by well-established ICAO thresholds. The problem was not data scarcity. The problem was the absence of a system capable of synthesising those signals into a time-ahead operational risk score for specific airports and FIRs.
The two-closure pattern — initial suspension May 19–20, recovery, then re-closure May 23 — is particularly instructive. Airlines that re-positioned aircraft and crews at MMMX on May 21–22 based on the temporary lifting of the suspension did so without a probabilistic framework for estimating re-closure risk. The CENAPRED alert had never descended from Amarillo Fase 3. Washington VAAC continued issuing advisory-level ash products between events. A risk model monitoring these persistent signals may have assigned a materially elevated probability of secondary disruption before the May 23 re-closure was confirmed.
For network planners, the extended disruption window — five-plus weeks of intermittent eruptive activity — further underscores the inadequacy of event-by-event reactive responses. Popocatépetl's behavioural history shows sustained unrest phases lasting weeks to months once Yellow Phase 3 is reached. Encoding that historical baseline into forward-looking risk windows materially changes how fleet, crew, and slot resources should be managed across the entire Mexico City market during an active phase.
This retrospective analysis examines signals present in public data before the event. It is provided for educational context only and does not claim predictive capability for future events.
By ingesting CENAPRED structured bulletin data alongside Washington VAAC Volcanic Ash Advisory feeds, A retrospective analysis suggests FlySafe's indices may have indicated MMMX as elevated-risk status as early as May 18 — when SO₂ flux and exhalation frequency metrics crossed alert thresholds — approximately 12–24 hours before the first operational SIGMET was issued for MMEX FIR. On May 19, as the ash column crossed FL200 and CENAPRED escalated to Amarillo Fase 3, FlySafe's indices may have generated an automated MMMX Suspension Risk alert with a 70 km crater-to-airport proximity flag and a wind-drift vector placing ash fallout directly over the metropolitan corridor. Critically, when MMMX briefly reopened on May 21–22, FlySafe's persistent monitoring of the unchanged CENAPRED alert level and continued Washington VAAC advisory activity may have maintained an elevated re-closure probability score — enabling airlines to make informed decisions about whether to recommit MMMX-based resources or sustain contingency positioning through the end of the eruptive episode. The five-week extended unrest window may have been surfaced as a multi-week risk horizon based on Popocatépetl's documented historical behaviour patterns during Yellow Phase 3 events.
- —No standardised tool for translating CENAPRED alert phase changes into FIR-level operational risk scores accessible to airline operations centres
- —Absence of probabilistic re-closure forecasting during inter-event recovery windows left airlines exposed to a second disruption they had inadequate lead time to plan for
- —No integrated alternate-airport capacity model to surface the MMSM throughput constraint before diversion flows began overwhelming the facility
- —Multi-week eruption horizon not communicated in actionable form — each event was treated as discrete rather than as part of a sustained unrest phase with quantifiable continuation probability
Sources
- —CENAPRED — Popocatépetl Monitoring Bulletins, May 2023. Centro Nacional de Prevención de Desastres, daily and special bulletins covering the May 19–June 2023 eruptive episode.
- —Washington VAAC — Volcanic Ash Advisories, May 2023. Volcanic Ash Advisory Center (Washington), archived VAA products for Popocatépetl covering MMEX FIR, May 19–23 2023.
- —Mexico DGAC — NOTAM Archive MMMX, May 2023. Dirección General de Aeronáutica Civil, operational NOTAMs for Aeropuerto Internacional Benito Juárez covering suspension and resumption events.
- —Aeroméxico — Official Statement on Flight Cancellations, May 2023. Press release and passenger advisory issued in response to MMMX operational suspension.
- —Reuters — "Mexico City airport suspends operations as Popocatépetl spews ash," May 2023. Contemporary news reporting on suspension events, carrier responses, and alternative airport activation.
This is a retrospective analysis of publicly documented events. FlySafe's prediction system was not operational during this event. All information is sourced from public records, aviation authority publications, airline statements, and open data.