What is a diversion?

A diversion or a diverted flight is a flight that has been diverted from its original destination to land somewhere else.

A diversion may be necessary for various reasons. To name a few examples:

  • Bad weather – the weather at the destination airport is below the minimum for landing (cloud base, RVR, wind, state of runway, etc.).
  • Closed airport – the runway may be blocked by another aircraft with a technical problem, etc.
  • Medical emergency – a sick passenger or crew member.
  • Aircraft technical problem – the aircraft is not able to continue safely to the destination or land safely at the destination (e.g. with failed equipment and downgraded performance the length of the runway is not sufficient, etc.).

Suitable alternate airports (usually called just “alternates”) used in the case of a diversion are nominated during the pre-flight planning.

There are alternates for different phases of the flight:

  • Take-off alternate airport – Used if the plane has to go back, but the departure original airport is no longer available or was only available for take-off, but not for landing.
  • En-route alternate airport – Used if the plane has to land en route to its destination.
  • Destination alternate airport – Used if the plane arrived at its destination, but the destination airport has become unavailable for landing.

What happens after a diversion depends on the nature of the reason for the diversion. In some cases, the plane can continue to its original destination (e.g. a sick passenger offloads, the technical problem on the plane is fixed, the closed airport re-opens, etc.). If the plane is unable to continue, the airline has to provide some other means of transport (e.g. bus, ship) or book a hotel for the passengers and crew.

Sometimes the delay may cause the crew to exceed the legal limit for a duty length (the crew is “out of hours”), so the crew has to be changed before the flight continues to its destination.