An index that is used at Canadian military aerodromes to report the runway coefficient of friction. It is determined via a vehicle-mounted decelerometer with a scale that is graduated in increments from 0 to 1. Small numbers represent low braking coefficients of friction while numbers on the order of 0.8 and above indicate the braking coefficients to be expected on bare and dry runways. JBI charts may be found in the Military Flight Data and Procedures section of the Canada Flight Supplement (CFS).