From a previous discussion On Martin’s RPI where the use of iBeacons was discussed, the RPI is potentially on a small isolated network with no Internet access… on a plane (as noted at the top of this thread).
iBeacon had some potential, but also a number of challenges. It would also be rather slow to cycle for multiple packets of work.
Without Internet access, the RPI would need to host a mail service for the iPad to access and download mail from.