What should be checked before starting the after landing checklist?

Before starting the after landing checklist, it is essential to check normal taxi speed. This ensures that the aircraft is moving at a safe and controlled speed as it transitions from landing to taxiing. Adhering to a proper taxi speed is crucial for maintaining control of the aircraft, especially in busy airport environments where other aircraft, vehicles, and pedestrians may be present. It also helps prevent potential accidents or mishaps on the taxiway or while crossing runways.

The other options, while related to different aspects of flying, do not pertain specifically to the necessary conditions for starting the after landing checklist. Monitoring position on the active runway or time since takeoff might be relevant during different phases of flight, but ensuring the aircraft is taxiing at a normal speed is more pertinent directly after landing. Similarly, while ground speed on the GPS display can be useful information, it does not replace the importance of verifying that the aircraft's speed is appropriate for taxi operations.