It pulls data from an ADSB aircraft tracking site. Each aircraft is equipped with an ADSB transmitter which broadcasts the location and information, asdb recievers collect this data and upload it to the internet when JBv1 pulls it.
JBV1 doesn't detect aircraft. With Internet access (mobile Internet, tethered HotSpot, WiFi), JBV1 accesses databases that have the tracking information and then uses that data to display the proper information that could affect the driver based on your current GPS location and your setting.
Again JBV1 doesn't detect anything, it uses information from a V1 or an Internet connection.