The failure of a commercial aircraft to touch down during a storm is not an "accident avoided" but the execution of a high-stakes kinetic calculation. When Storm Therese intersected with the Canary Islands’ unique orographic features, it created a localized atmospheric environment where the margin for error in low-altitude maneuvers effectively reached zero. A go-around, or aborted landing, is the mechanical response to a destabilized approach where the aircraft’s energy state—its speed, altitude, and vector—no longer aligns with the required parameters for a safe transition from flight to ground roll.
The Mechanics of Unstable Approach in Transonic and Subsonic Flight
The primary driver of the aborted landings observed in the Canary Islands was not the wind speed itself, but the turbulence and wind shear generated by the archipelago's volcanic topography. In aviation, wind shear represents a sudden change in wind velocity or direction over a short distance. During Storm Therese, the interaction between high-velocity synoptic winds and the mountainous terrain of islands like Tenerife and La Palma created "mountain waves" and "rotors."
The aircraft's performance during these events is governed by the lift equation:
$$L = \frac{1}{2} \rho v^2 S C_L$$
Where $\rho$ is air density, $v$ is velocity, $S$ is wing surface area, and $C_L$ is the lift coefficient. In a wind shear event, the velocity ($v$) can drop or spike instantaneously. If the headwind suddenly becomes a tailwind (a "microburst" effect), the indicated airspeed drops. If this drop occurs at low altitude while the aircraft is in a high-drag landing configuration (flaps and gear down), the wing may reach a critical angle of attack and stall before the engines can spool up to provide compensating thrust.
Pilots operate within "stabilized approach criteria." If any of the following variables are compromised below 1,000 feet, a go-around is mandatory:
- Flight Path: The aircraft must be on the correct glide slope.
- Speed: Airspeed must be within a narrow margin of the target ($V_{ref}$).
- Configuration: Flaps and landing gear must be locked in position.
- Power Setting: Engines must be at a thrust level that allows for immediate acceleration.
Orographic Lift and the Flooding of Volcanic Geographies
The flooding associated with Storm Therese serves as a case study in the limitations of drainage infrastructure on volcanic terrain. The Canary Islands are characterized by steep gradients and "barrancos"—deep ravines carved by historical water flow. While these natural channels are designed for drainage, they become catastrophic failure points when the rate of precipitation exceeds the soil's infiltration capacity.
The "Orographic Effect" amplified the rainfall totals. As moist air from the storm was forced upward by the islands' peaks (some exceeding 3,700 meters), it cooled and condensed rapidly. This resulted in "stalled" rain bands that dumped months’ worth of precipitation in hours.
The resulting flash floods are governed by fluid dynamics where the velocity of the water increases exponentially with the slope. In urbanized areas of the Canaries, the "impervious surface ratio"—the amount of land covered by concrete and asphalt—prevented natural absorption. The hydraulic pressure in the barrancos eventually exceeded the structural integrity of bridge abutments and coastal roads, leading to the "cascading failure" of the regional transport network.
The Economic Cost Function of Extreme Weather Diversions
An aborted landing and subsequent diversion to a "relief airport" (often hundreds of miles away in mainland Spain or North Africa) triggers a massive operational cost surge for an airline. This is not a linear expense; it is a complex function of several variables:
- Fuel Burn: A go-around followed by a climb to a holding pattern, and then a cruise to a diversion airport, can consume several thousand kilograms of additional Jet A-1 fuel.
- Crew Duty Limits: Aviation regulations strictly limit the number of hours a pilot can be on duty. A diversion often pushes a crew past their "Flight Duty Period" (FDP), requiring the airline to ground the aircraft and fly in a replacement crew or put the passengers in hotels.
- Downstream Logistical Collapse: The aircraft diverted to Fuerteventura or Morocco was scheduled to fly a return leg. When that aircraft is out of position, the "tail swap" logic of the airline's hub-and-spoke system fails, causing cancellations across the entire network.
The decision to attempt a landing in a gale-blasted environment involves a "Risk vs. Utility" matrix. Modern Flight Management Systems (FMS) provide pilots with real-time data, but the ultimate authority rests with the Captain. The pressure to land is immense due to the costs mentioned above, yet the physical limit is reached when the "crosswind component" exceeds the aircraft's certified maximum—typically between 25 and 35 knots for most narrow-body jets like the Boeing 737 or Airbus A320.
Infrastructure Fragility and the Tourism Bottleneck
The Canary Islands represent a "bottleneck economy." They are almost entirely dependent on aviation and maritime transport for both supply chain stability and the tourism revenue that drives their GDP. When a storm like Therese shuts down airports and floods the arteries leading to the resorts, the economic "time-to-recovery" becomes the critical metric.
The failure points in the Canary Islands' infrastructure are categorized by:
- Power Grid Decentralization: High winds frequently down lines in remote mountainous areas, leading to "rolling blackouts" that affect water desalination plants—the islands' primary source of fresh water.
- Telecommunications Attenuation: Microwave links used for communication between islands can be degraded by extreme precipitation (rain fade), hindering emergency response coordination.
- Runway Occupancy Time: During storms, the interval between landings must be increased to allow for wake turbulence dissipation and to ensure the runway is clear of standing water, which causes "aquaplaning" or "hydroplaning."
Hydroplaning occurs when a layer of water builds up between the aircraft tires and the runway surface, leading to a loss of friction. The critical speed at which this occurs ($V_p$) is calculated based on tire pressure:
$$V_p = 9 \sqrt{P}$$
(where $P$ is tire pressure in psi). For a commercial jet, this speed is often lower than the landing speed, making the "aborted landing" a necessary safety protocol rather than an optional maneuver.
Strategic Decision Matrix for Future Volcanic Island Aviation
The convergence of increased atmospheric energy and aging infrastructure requires a shift from reactive to predictive modeling. Airlines and regional governments must prioritize the following tactical adjustments:
- Synthetic Vision Systems (SVS): Implementation of heads-up displays that allow pilots to see a digitized version of the runway through clouds and rain, reducing the cognitive load during go-arounds.
- Permeable Pavement Integration: Retrofitting coastal roads and urban centers with porous materials to reduce the "peak flow" of floodwaters during orographic rain events.
- Microgrid Implementation: Developing localized solar and wind grids with battery storage to ensure that critical services like hospitals and air traffic control remain functional when the main grid fails.
The events in the Canary Islands during Storm Therese demonstrate that our current margin of safety is being squeezed by the increasing frequency of "unstable" atmospheric states. The transition from a "terrifying moment" to a controlled, data-driven recovery is the difference between an operational hiccup and a systemic disaster.
Airlines should immediately re-evaluate their fuel reserve policies for the Macaronesia region, increasing the "contingency fuel" percentage to account for the higher probability of orographic-induced diversions. Simultaneously, the regional government must audit the "discharge capacity" of the barranco systems against the updated 100-year flood projections, as the historical data used for their construction no longer reflects the kinetic reality of modern storm systems.
Would you like me to analyze the specific flight path data and fuel-burn telemetry for the aircraft involved in the Storm Therese diversions?
