PADI's outdated ascent rates

PADI loves to self promote, they are the masters of self-promotion and never miss an opportunity to do so. Likewise, should good practices get in the way of self-promotion, they will always err on self-promotion. PADI originally published a set of dive tables based on the US navy tables with shortened no-decompression limits. The US navy settled on an 18 metres per minute (mpm) ascent rate on their tables for all dives based on a compromise as combat divers wanted a 30 mpm ascent rate as they naturally don't want to hang around whilst the hardhat divers requested a 6 mpm ascent rate since they are winched to the surface.

The 18 mpm compromise rate was decided for the 1955 USN dive tables based on dual use and stayed that way until 1992 when a revision was undertaken by Workman et al. with the new 9 mpm ascent rate and revised no-decompression limits. Without the technology of dive computers and ascent rate indicators available at the time; an ascent rate of 1 foot per second (60 fpm/18 mpm) was reasonably easy to execute. This was broadly in line with dive computer research and development, PADI developed their revised dive tables in the early 1980s with time pretty much standing still down at PADI headquarters. Regardless, PADI maintained their stance on the 18 mpm ascent rate even though the majority of computer manufacturers and US navy had long undergone revisions based on extensive research and testing.

Not only did PADI maintain the 18 mpm ascent rate on their recreational dive planner, the successor to the PADI dive tables, they defended their position based on the premise that it was proven in the field. PADI will refute this claim as their own testing was conducted with the 18 mpm ascent rate in the chamber and later actual test dives.

PADI are in the business of selling dive courses and certification of divers, that is instructional design technology and supporting dive training materials - a standardised system of dive training. Consequently PADI sell their recreational dive planner to support dive training, they profit from every certification, every training material sold and instructor membership fees. 

PADI makes no money from dive equipment sales; hence, the requirement to purchase outdated dive tables complete with ascent rates that are twice the rate of current recommendations.