Flight operations on display: An airline as a “glass factory”

More and more often, we hear or read about diversions or emergency signals such as “Pan-Pan” and “Mayday.” Flightradar24 shows a flight changing course, a “7700” code appears somewhere, and shortly afterward the first news reports or social media posts begin to circulate. But are these events really becoming more frequent, or are they simply more visible today? Together with SWISS Head of Long-Haul Fleet and Boeing 777 captain Frank Zuber, we take a look behind the scenes and explain what happens when a flight does not go as planned.

In the age of Flightradar24, Live ATC (Air Traffic Control), social media, and citizen journalists, operational irregularities are visible in real time. As a result, they quickly become a topic of discussion and can be shared worldwide within minutes. This transparency has changed the public perception of airline operations, but greater visibility does not automatically mean more incidents. Flying has not suddenly become less safe, flying has become more visible. And behind every event are clearly defined processes, both in the air and on the ground.

Why diversions happen
A diversion is the landing of a flight at an airport other than its originally planned destination. This includes both landings at an alternate airport and returns to the departure airport. Diversions are established operational options, and they can occur for a variety of reasons.

At SWISS, there were 150 diversions in 2025 out of approximately 143,000 flights. That represents 0.1 percent of all flights, or roughly one out of every thousand flights. On average, this means a diversion occurred every two and a half days. The most common causes include weather conditions and technical events. Major weather disruptions can significantly affect annual statistics without indicating a broader trend. Compared with the previous year, SWISS recorded an increase in diversions due to drone sightings near airports, air traffic control outages, and poor visibility conditions. Drone sightings, for example, can lead to temporary restrictions or even a complete suspension of airport operations. In such situations, arriving aircraft must determine whether there is sufficient time to hold or whether they need to proceed to an alternate airport. During medical emergencies, airports with strong medical infrastructure, or simply the nearest suitable airport depending on the urgency of the situation, become the priority. In every case, safety remains the overriding consideration.

“A diversion is a conscious decision in favor of safety.”

Frank Zuber
SWISS Head of Long-Haul Fleet

What happens in the cockpit?
Pilots continuously assess weather conditions, monitor the aircraft’s technical status and fuel state, and review available alternate airports throughout the flight. These alternates are predefined along every route. “We are always thinking in terms of scenarios and alternatives during a flight,” says Frank Zuber, SWISS Head of Long-Haul Fleet. “The key is to identify and implement the safest option as early as possible.” Throughout the process, the flight crew remains in regular contact with the operations control center. Safety always takes precedence over punctuality, cost, or operational complexity. The final decision is always made by the captain in command.

“A diversion is a conscious decision in favor of safety,” Frank Zuber emphasizes. “Depending on the situation, we may opt for a precautionary landing in order to mitigate a potential risk.”

"Pan-Pan" and "Mayday" do not describe causes
In radio communication, different signals are used to draw attention to unusual situations. While flight crews evaluate various options, elements of these processes can now also be observed from the outside. This may occur when the emergency transponder code 7700 is activated or when a “Pan-Pan” or “Mayday” call is heard over publicly accessible radio channels. However, a code alone does not reveal the specific cause or severity of an event. The underlying reason can vary greatly and may even be medical in nature. “When observers see the 7700 code, they often immediately assume a serious emergency,” explains Frank Zuber. “In reality, the reasons can vary considerably and generally cannot be assessed from the outside.”

Aviation safety systems are also designed with redundancy in mind. The failure of a single system therefore does not automatically mean an aircraft can no longer be operated safely. For example, if one hydraulic system fails, two additional systems can take over its functions. In a medical emergency, the immediate care of the affected passenger is the highest priority. The crew will generally attempt to stabilize the patient using the comprehensive range of emergency medications available on board. These are administered in close consultation with MedAire, our medical support provider, which can be contacted via satellite phone when necessary. In exceptional cases involving acute, life-threatening medical conditions, a diversion may also be considered.

"Pan-Pan", "Mayday", and 7700 at a glance
“Pan-Pan” and “Mayday” indicate the urgency level of a situation:

  • “Pan-Pan” indicates an urgent situation. This may involve technical or operational issues, such as a passenger’s medical problem or the failure of a single system.
  • “Mayday” indicates an emergency. By using this call, the flight crew notifies air traffic control of an emergency or distress situation.
  • 7700 is the aircraft transponder’s general emergency code. Air traffic control may also instruct a crew to squawk 7700 to increase visibility for controllers.

A diversion involves an entire operational chain
For SWISS flights bound for Zurich, the most important alternate airports are Basel, Geneva, and Stuttgart. A diversion may end the flight, but the operational effort is only just beginning. Passengers, crews, and aircraft suddenly find themselves in the wrong place. They are not where they intended to be, nor where they are needed. A technical inspection may be required, along with specific spare parts or support from maintenance personnel. If maximum crew duty limits are exceeded, a replacement crew must also be arranged. If replacement crews or aircraft are unavailable, knock-on delays or flight cancellations may occur. Affected passengers are informed as quickly as possible, and alternative travel arrangements are organized without delay.

A diversion may end the flight, but the operational effort is only just beginning.

What happens on the ground?
On Flightradar24, the aircraft is visible on the map. What cannot be seen are the cause of the diversion or the actual situation on board. On the ground, our teams face a wide range of challenges. Passengers need to be rebooked, while hotels, meals, and transportation must be arranged until their onward journey can continue. Dozens of decisions have to be made, all with the goal of helping passengers reach their destination as quickly and safely as possible. The Passenger Care Center (PCC) supports passengers around the clock. And behind every decision lies a simple question: "What is the best overall solution for the greatest number of passengers?"

Passengers also play a role
Since January 2026, SWISS has implemented new regulations regarding power banks. Passengers may carry no more than two power banks. They may not be charged or used on board. Passengers therefore share responsibility for maintaining overall safety. At the same time, our crews undergo regular training to ensure they can respond to all situations in accordance with clearly defined procedures.

A diversion is therefore much more than a changed flight path on Flightradar24. Behind every single event lies a complex series of decisions in the air and on the ground. The objective is always to restore safe and stable operations as quickly as possible while minimizing the impact on passengers.