Think of the Payload in this case as a sensor systems, some of which are interchangeable. There are zoom cameras, or thermal imagers, or both as interchangeable payloads, etc.
The Payload Functionality variant of each test introduces some small amount of operational workload to perform in addition to maneuvering. That is, as you’re paused in front of a bucket (or two) and aligned correctly, then work your system interface to zoom in as far as possible to measure your maximum effective visual acuity including the stability of the aircraft, vibrations, twitchy pointing, digital zoom interface, contrast, focus, etc. The score for visual acuity is separate from the score for maneuvering. The trial time probably increases as well. We advocate 5 minute time limits for Maneuvering trials and 10 minute time limits for Payload Functionality trials. But even that might not be enough if your system is slow or unstable to zoom fully – that’s what you’ll learn by performing the test over and over again and comparing scores with other aircraft or with other pilots who perform better on your same aircraft.
If your aircraft has no zoom capability, or limited zoom, the Payload Functionality variant of each test is not applicable.
The Payload Functionality variant of the tests are also helpful when evaluating other sensors such as thermal imagers. If your system is ready for Payload Functionality tests, then the Point and Zoom Cameras test should be performed first to measure the baseline capability of the system. See the Usage Guide or Forms Book for more information.