REAL-TIME ETA ON A DRIVE: while a bus or van drive is on, the day schedule shows a note under that drive: Real-time ETA 8:58 AM · 15 min later · as of 2 min ago. It uses where your phone is right now and today's traffic to work out when you'll arrive. If you're on the bus, your phone is where the bus is, so a co-driver waking up in the bunk can open ATOM and see it.
THE SCHEDULE NEVER CHANGES: the drive line keeps its saved times (1:00 AM to 8:43 AM stays as planned). The real-time ETA is only a note under it. Day sheets, PDFs and shared pictures keep printing the saved times.
COLORS: teal when you're on plan or early ("12 min early"), amber when you're running later ("15 min later"). It refreshes on its own every 5 minutes; tap the note to refresh it now. After 15 minutes without an update it fades and says how old it is.
WHEN IT SHOWS: from half an hour before the drive leaves until a few hours after it should arrive, and only on a phone away from both ends of the drive (someone already at the venue doesn't get an "ETA from here"). The first time, tap Show real-time ETA and allow location for ATOM; after that it shows on its own while the drive is on. ATOM looks at your location only while the app is open, never stores it, and only the arrival time is shown, never where the bus is.
ON THE IPHONE APP: location needs the next App Store version of ATOM. Until it's installed, the note doesn't appear in the iPhone app (it works in Safari and on a computer).
WHO SEES IT: anyone who can see the drive on the schedule.