The slightest leak on an Air System Bhj will be known by the driver by a warning in his / her cab, that truck had "brake fade" ( With respect to that young driver) continuous use of the brakes on a sever down hill decent loaded, that HGV has what they call an Exhaust brake, this device is a flap within the Manifold that chokes the engine by not allowing the exhaust gases to escape, with that the correct gears should have been used to assist braking, I'd seen on the news the route that the truck had taken, looking at the situation & knowing the driver was losing the ability to stop, to an experienced driver would have gone for the first available wall, I stress, an experiened driver, this lad had only just started the job, this is where the HGV Test is a load of BULL ***, they are taken out on an empty HGV with 32 tonns in the tipper, the load pushes the truck as this driver found out, this is something that will affect his life & I doubt if he will ever drive a HGV again.