AFLT (Advanced Forward Link Trilateration)

A type of handset-based position location technology. Unlike A-GPS, AFLT does not use GPS satellites to determine location. To determine location, the phone takes measurements of signals from nearby cellular base stations (towers) and reports the time/distance readings back to the network, which are then used to triangulate an approximate location of the handset. In general, at least three surrounding base stations are required to get an optimal position fix.

Ref: NENA STA-015, NENA Standard Data Formats for 9-1-1 Data Exchange & GIS Mapping