The idea that a partner will prevent an accident isn't logical.
A partner will speed up someone helping you after you have fallen, but not prevent the fall.
A team of hood cleaners here in Nashville, guy walks off a roof, falls 2 stories, lands on cement stair case, falls down the stair case, ripping his leg off and lands in a big bloody heap at the bottom.
Facilitec bid the job, sub'd work out to another company, who sub'd the actual work out to a crew of hood cleaners. Fan sits right near the edge of the building with no side rails, or raised edge.
Safety has to be taught through and through when doing hood cleaning. You have to have the voice of your trainer stuck in your head constantly reminding you to work safely.
You ask anybody that has been trained by us what is going through their mind when cleaning and you'll get a consistent response. Roger's voice is constantly in your head reminding you of "his commandments." Break one of his commandments and you will get hurt.
Working alone every night cleaning hoods can be dangerous, but not because I'm alone, but because of mental distraction and improper lighting.
Also, rarely am I truly alone, almost always there is an employee, or manager on site.
As far as your idea, the police have a similar device that if they wind up in a horizontal position, it automatically calls the dispatcher. It could probably be modified to use a cell phone, sort of like the "I've fallen and can't get up" type from years ago.
We don't get paid the big bucks to clean hoods because this is easy and safe work. If it was easy and safe, everybody would be doing it. We get paid for our ability to perform safely and give the customer satisfaction knowing that a good job was done for them.
I wish for everyone to always keep safety at the top of their noodle when doing this work. Just driving to our jobs sometimes can be more dangerous than actually performing the work.