I don't know the exact history of Position Task Books.  The National Wildfire Coordinating Group (National Wildfire Coordinating Group ) has been around since 1984, and in a document of that year they describe the qualifications for varous Incident Command System positions, but there isn't mention of a Taskbook:   https://www.nwcg.gov/sites/default/files/hist_310-1_Oct_1984.pdf'    However, this history of their Position Task Books indicates that they were writing them at least by the year 1999, well before the attack on the Twi Towers in 2001   https://www.nwcg.gov/sites/default/files/products/training-products/ptb-history.pdf

FEMA has had "taskbooks" for position qualification for some years.   Representative FEMA Task Books

With FEMA writing task books, somewhere in this the ARRL got into this mode of training, and several portions of their Field Organization have been in it .   I can find documentation at least as far back as 2015 (4 years ago) of some components adopting Task Books.   Here is a list of Position Tasks Books that I've compiled so far:


South Texas (from 2015)

North Texas

Sacramento Valley

Iowa (from 2016 / before)

West Riverside County ARES  (from 2018)

Eastern New York (2019)