When you enter a turnaround view in AGOA, you are automatically subscribed to its notifications. You will receive a notification if:
A task that should have started has not yet started.
The ADO or ADC is expected to be completed but has not been completed (see What do STA, ETA, STD, etc. stand for on AGOA? for these acronyms).
At the moment, it is not possible to unsubscribe from turnaround notifications. Once you've entered a turnaround, you'll keep receiving its notifications until the turnaround is completed. You can, however, turn off all AGOA notifications from your device settings.