Brake Assist System (BAS) requirements have been established by the Economic Commission for Europe (ECE) in R13H. Electronic Stability Control (ESC) systems typically have the value added function of Panic Brake Assist (PBA) which is defined as a Category C (sensitive to multiple criteria) Brake Assist System. PBA is designed to force the vehicle into Antilock Brake System (ABS) and to maintain ABS control when the driver spikes the brake pedal and then temporarily reduces brake pedal force before reasserting more brake pedal force.ECE test protocol requires the use of brake ramp applications to define the mean acceleration force (maF) curve which is used to define the brake pedal force where ABS activates (FABS). After completing the brake ramp application test maneuvers and completing the data processing to define the maF curve, FABS, upper, and FABS, lower, the test driver then proceeds to run the panic brake assist portion of the test. A high level of skill is required for a test driver to spike the brake pedal and then reduce the brake pedal force to a level between FABS, upper and FABS, lower.Numerous panic brake assist test runs can cause the test driver fatigue and the amount of force within specified range is difficult to vary from the high end to the low end of acceptable range. Hardware-in-the-loop simulation that includes the physical brake system and the ability to control brake pedal force serves as another test method which can be used to eliminate need for the test driver and to more precisely control the amount of brake pedal force varying from the high end to the low end of the specified range.The methodology of using hardware-in-the-loop (HIL) simulation to validate Category C Brake Assist System vehicle performance will be presented. HIL simulation provides additional ability to validate different versions of ESC software and calibrations. The combination of physical tests and simulations is an effective methodology to demonstrate Category C Brake Assist System compliance for all variants of a vehicle program.