The programme is available online, see here:
https://www.bbc.co.uk/programmes/m000v8w8
Originally Posted by
India Four Two
I've just read the accident report. It mentions that the investigators were able to tell how much work had been done by each of the brake units. How was that determined?
I suspect that they looked at the wear on the brake discs and linings. From the original certification testing they will have known how much wear is produced by having a brake unit absorb energy to its maximum capacity. When other units have less wear, you can then compare the levels of wear. It's not precise, but the difference must have been significant enough.
I realise that it's a long time ago that you asked this question, but better late than never.