Visibility Hub's ETA calculation is dependent on various factors. Having a time reference (such as a time slot / appointment time) defined for a stop is an highly important parameter in order to be able to provide an accurate ETA as well as an ETA status (on time / delayed).

In case one or multiple stops of a transport are missing such a time reference, this warning is shown, no matter in which state the transport is. The effected stops are also mentioned as part of the warning so that it's easy to identify which stops suffer from an inaccurate ETA and missing on time / delayed status indication. Only "Visited" can be seen in this case.

Visibility Hub strongly recommends to have a time reference defined for each stop in the transport, as tracking success is heavily dependent on that.

Note that in case Visibility Hub wasn't able to confirm arrival/departure of a given stop based on the tracking data provided and the most likely reason is the missing time reference, the transport tracking is cancelled with the respective cancellation reason "Timeslot missing". For more information on cancellation reasons, have a look here.

Transports where all stops are missing a time reference are considered as invalid and therefore not accepted by Visibility Hub at all.