As already pointed out, instructors and DMs who work with classes are also pretty much diving solo, because in those cases, the students cannot even be considered full-fledged divers, capable of assisting in a rescue. Of course, I don't take my students to 130 feet or into overhead environments, either
Mark Powell discusses instructors diving with students in his talk 'Solo Diving: Coming Out of the Closet'. He says instructors are not just solo diving - they are solo diving with an impediment. The full talk was recorded and is well worth watching whatever type of diving you do, and whether or not you intend on diving solo:
[video=vimeo;49259855]http://vimeo.com/49259855?[/video]
This video was posted on a couple of UK dive forums, one of which was the BSAC forum. It stimulated quite a bit of debate, which developed into an out and out ruck between some. Mark refers to 'volunteer instructors' in his lecture, which applies mainly to BSAC instructors. In the UK, commercial diving instructors are bound by the Diving at Work Regulations which require commercial diving instructors to have a safety diver in the water with them. Agencies like BSAC teach in a club environment so they are not bound by these regulations.
I got into a somewhat heated debate with a BSAC instructor, who disagreed with this stance, saying all students are taught rescue skills, including the controlled buoyant lift.
It does depend on who you are diving with. If I am diving with a buddy then the checks are done, they are clear, we have a clear plan, and separation is not an option nor is it acceptable. Otherwise I am diving solo. But that it planned as such.
With students on checkout dives I am not diving solo. The student buddy pair, or the student in the case of a private class, is my buddy. If I did not think my students, including OW students, could not assist me if I had a problem I could not, by my agency and my own standards, take them into open water.
If an instructor feels like he/she is diving solo with their students as regards the student's ability to render assistance how can they issue a cert card? Knowing that the card means those people are now certified to dive without supervision and the assistance of a so-called "dive professional" in the water with them.
The last comment is very valid, and I wish there were more instructors who thought this way. I do not agree that a student can be relied on to rescue an instructor. I have seen students who are amazing in the pool, yet when they get in open water, they go to pieces. I would be worried that even if they seemed calm at first, could you predict how they'll react if they see their instructor in trouble?
The Sky News rebreather incident is a good example. An underwater camera team were filming police demonstrating an ROV in a quarry operated as an organised dive site. The camera crew were all diving AP Inspiration units, which they had trained on together. Due to a spectacular f**k-up, caused by incorrect training, the most experienced of the group got into trouble. A lot of the video is probably of little interest to non-rebreather divers, and I am bearing in mind this is the basic scuba forum, so I won't go into detail on the cause of the incident or the poor techniques used, but the response of his team is interesting. There is something clearly wrong, but the less experienced members of the team seem to panic and don't have a clue how to react. These are not inexperienced divers either. In order to train on the units, they would have to be experienced open circuit divers, but they seem to freeze because the diver they look to as a leader is having difficulties. If experienced divers respond in this manner, I would never rely on a student as a competent buddy irrespective of my perception of their abilities.
[video=youtube;2RBzqy_s5Tw]https://www.youtube.com/watch?v=2RBzqy_s5Tw[/video]