PRM pre-notifications ride on PAL, CAL and PSM messages — and when one silently fails, the first anyone knows is a passenger arriving with no assist booked. There is no end-to-end monitoring of message health, so gaps are found on the floor, not in the feed.
"How would we even know a PAL message dropped — before the passenger turns up unbooked?"
Silent message failures
Live messaging health view
To first outcomes