If I was in crisis, yes, I would not hesitate. I would first make sure I exhausted all my tools, though, before calling. If my tools did not help, I'd call, especially if I was given explicit permission to do so.

Last time T was away and a huge crisis ensued, I had my other support team member helping me, and was leaving T messages every day with the update. I knew she was checking messages but would not be returning calls until she got back in the office, but this way, she was kept up to date on the situation, which helped not only me, but it also was helpful for her to know what was going on.