Without written SOPs what happens when the attorneys come around? One of the most expensive lawsuits in business aviation history centered around lack of SOPs. Unwritten non-verbal communication is not 100 perfect. Of course, neither is verbal, "takeoff power" "the weather is diminishing", etc. Most of the accidents out there centered around a miscommunication or a failed shared mental model.
Seriously, I would encourage at least some semblence of a manual - I addressed this topic in one of the aviation safety publications last year. If two guys are "already doing it" come to an agreement and document it. The concept of "unwritten familiarity with each others styles and habits" is contrary to current 6th generation CRM best practices. Compliance is another issue entirely. Behavior that's not measured will decay. Almost impossible in smaller departments but the premier part 91 departments check compliance.
One of the last cases I was involved with was an overrun in which the pilots told the NTSB, "we don't have any SOPs or written procedures." Case closed. Very convincing to a civil court jury - when you're getting personally sued for damages - that the science, NTSB, ISBAO,EASA, best practices require written SOPs.
Well-written, properly documented, constantly evolving, objective and measured SOPs, will benefit any operation. Even two pilots who feel they "know each other very well."
Last edited by Std Deviation; 04-21-2012 at 05:15 AM.