The only problem I can see with this survey is that some people are unlikely to admit their 'actual' hours and teabreak lengths against their 'scheduled'times. I realize that night shifts may be genuinely tiring in ramp areas but in base maintenance,well it's an eye opener to see how quiet it is after 3am.
The one vital question missing from the survey is....How many early traps or Job- and-away's do you get? That would tell the surveyor all he needs to know!