My airline has been running a trial called CORSAIR (
COntaminated
Runway
State
Automatic
Identification and
Reporting) on the A320. From what I've read it works like this, it monitors objective braking action during landing electronically and then uploads its braking action report to a central unit. This objective information can be then sent back (automatically) to the tower at the relevant airport to generate an honest BA report. This essentially dispenses with the subjectivity that a 'Braking Action' PIREP might elicit.
I'd rather not post company material, but found this online:
https://ral.ucar.edu/sites/default/f...4-kicinger.pdf