If you look at the OSHA references, it is clear that OSHA does not consider a scissor lift an aerial lift. 29 CFR 1926.453 - Aerial Lifts considers scissor lifts to be one of the following:
- Extensible boom platforms
- Aerial ladder
- Articulating boom platform
- Vertical towers
- A combination of the above.
Scissor lifts do not fit under this classification, so they are not aerial lifts. In 2000, OSHA released a letter of interpretation helpfully titled "Scissor lifts are not aerial lifts - are considered scaffolds."
However, OSHA references an ANSI standard from 1969 for definitions of Aerial Lifts. That standard was updated in 2018 - and it clearly includes scissor lifts as a Group A mobile elevated work platform.
OSHA has not updated their references to match the new ANSI definitions of Mobile Elevated Work Platforms. It seems clear this will eventually happen, as the ANSI regulations are incorporated by reference in the OSHA regulations.