Apple’s AirTags and third-party Find My items proved a boon as people returned to travel in earnest over the last two summers to the extent that some airlines even recommended dropping a tracker into your luggage as an extra finding aid. However, what if you check in and then check Find My, and it looks like your bag was left behind?
This is the special nature of Find My items, Apple’s and licensed third-party ones: they rely on nearby iPhones, iPads, and Macs with internet connections to relay up-to-date location information. Nearby means within Bluetooth range, which can be hundreds of feet with obstructions and a clear line of site. However, with trackers inside luggage, with a mass of bags piled up or in bins, and with no baggage handler with an iPhone close enough for the signal to penetrate, no update will occur.
The sheer density of iPhones is high enough that it’s usually only a temporary matter before an AirTag’s weak ping over Bluetooth is picked up and passed on (encrypted, securely, without personal information attached) by someone’s device.
Read more at Macworld.com