It has disappeared, hasn't it, and no-ones heard of it for a decade or more!
You forgot to renew your subscription, here's a convenient link for you:
https://secure.nature.com/subscribe/nature
For anyone stupid enough to discharge a powder extinguisher in a cockpit, one first hand account:
http://www.casa.gov.au/fsa/2006/jun/20-22.pdf
Chubb's summary of the implementation of the Montreal Protocol:
Chubb Fire Halon Decommissioning
What the rest of the non-exempt world uses:
DuPont? FM-200® waterless fire suppression systems