In the summer months, severe thunderstorms repeatedly sweep over Switzerland. As soon as lightning is registered in the immediate vicinity of an airport, a so-called handling and refueling stop comes into effect on the apron. This means that aircraft may not be loaded or unloaded, refueled, docked, or pushed back. Passengers may also neither board nor disembark at remote stands. The reason is simple and serious: the open apron, with its many metallic devices, vehicles, and aircraft, is a dangerous place when lightning strikes. A single strike can have life-threatening consequences. These measures serve to protect ground staff and passengers.

When is a handling stop necessary?
These weather-related stops can unfortunately lead to delays; in individual cases, flights must also be canceled. The decision for a handling stop on the apron of an airport depends on clearly defined weather criteria. For example, Zurich Airport works closely with MeteoSwiss. Using ground measurements, radar, satellite, and lightning data, it is continuously monitored whether thunderstorms are nearby.

If, for example, lightning is expected within an eight-kilometer radius at Zurich Airport within the next 30 minutes, a pre-warning is issued. As soon as a cloud-to-ground lightning strike is registered within a five-kilometer radius, the complete handling stop is ordered by the responsible airport authority. The responsibility for the decision lies with the on-duty Airport Manager.

Procedure during a stop
After the alarm is triggered, everyone stops work: the fuel truck driver, the staff who load the suitcases onto the aircraft, those who bring food to the aircraft, or the tractor driver who would have to push back the plane. For all of them, it means: “hands off and take cover.” Aircraft may continue to land and take off, as long as the current situation allows it. Passengers in already docked planes can board and disembark via the passenger bridge.

At the same time, employees from the Airport Authority, construction safety, and Apron Service check the apron to ensure that no one is left unprotected in the open. During this phase, it may happen that passengers at remote positions must wait in buses or aircraft until the thunderstorm has passed. Only when no lightning strikes are reported within the relevant radius is the operation gradually resumed.

Communication and safety systems
Communication in the event of an approaching thunderstorm takes place quickly and in a coordinated manner. MeteoSwiss is in direct contact with the tower and airport management around the clock. As soon as there are signs of possible thunderstorm development, early warning is given by phone. This information is immediately passed on to all airport partners, such as SWISS or the handling agent Swissport.

The “alarm star” system ensures the alerting of all parties involved. This includes mobile devices, handhelds, and displays at gates, fuel stations, or information boards. On the apron, lightning warning lamps with yellow or red light signal the respective danger level.

Lightning strikes aircraft – is it dangerous?
A lightning strike during flight is harmless. Aircraft act like a Faraday cage—the electrical energy is dissipated through the outer skin. Passengers and crew remain protected. Electronic systems in the cockpit are redundantly secured. Nevertheless, each affected aircraft is technically inspected after landing to rule out damage. The details are also explained in the video segment from the series “Ask the expert”.

Safety comes first
Thunderstorms are a serious danger in flight operations—especially for ground personnel. A clearly regulated process, precise weather monitoring, and a reliable communication system ensure that even in lightning and thunder, the safety of employees and passengers always comes first.