If they are on a 4 hour cross country Ifr clearance do you only log the 2 minutes it took to climb through a layer?
Yes. Often shown in the logbook under the column name "Instrument" or even broken down as "Actual/Simulated".
Total time is always higher unless you're flying something that departed 0/0 and has Cat III capabilities (and even then you might be 0.1 off. Heh...). Part of any instrument flight is VMC. Maybe a lot, maybe just a little.
There's even rules about what can be logged for approaches for Instrument currency and that the pilot must be flying "by reference to instruments" but can "break out" to VMC on the approach and still count that approach for currency if specific conditions are met. With a view limiting device and a safety pilot, one can log "Instrument" time also. ("Actual", no. But you rarely see that column in logbooks unless you added it and want to track that. Many people do. There often a "Simulated" column right next to it... Both totaled together would be "Instrument" time.)
See document below, published last year, probably in response to some "confusion" about it and the regs.
http://www.faa.gov/other_visit/avia...afety/info/all_infos/media/2015/info15012.pdf
You're probably wondering where all this "logging PIC as sole-manipulator vs logging PIC as acting PIC and yadda yadda comes from. It's both the FAR itself and often backed by legal interpretation letters from the FAA legal staff.
In fact, an awful lot of stuff comes from legal interpretation letters from the FAA legal staff these days. For better or worse, these are part of what the FAA will refer to as "law" once published. You won't find ALL the answers in the FAR/AIM.
Some of them make sense and match what the aviation world at large "thought" the regulations meant. Some fly in the face of that and change long held "beliefs".
An example of one that follows the common thoughts about SIC logging, as an example, is this one. The pilot asked if he could "double log" any time spent "manipulating the controls" in an aircraft that required two crewmembers in which he was legally SIC, but also as PIC at the same time for the "manipulation". FAA said no.
http://www.faa.gov/about/office_org...2015/murphy - (2015) legal interpretation.pdf
In that letter they also reiterate that no two-person logging of PIC as "acting" and "manipulating" may happen unless both pilots are required crewmembers.
It can get messy. These letters aren't in the FAR, but they're generally treated as law before an Administrative Law Judge if you find yourself ever standing before one due to doing stuff blatantly wrong.
They're more difficult to find and stay on top of than the FARs, obviously. But they're perhaps a necessary evil. People will try to find loopholes and exploit them, and without a rewording of a particular FAR, they're the fastest way for FAA to communicate their intent.
Or more accurately, their lawyers intent, as to how they'd proceed in a court case, based on the current regulations.
Time logging questions are pretty common in these letters. They're worth a read. Unfortunately no "table of contents" exists for them and they're not always easy to find particular topics in. Like I said above, kinda messy.
The nice summaries like the AOPA article are based in these messy direct-from-FAA letters and publications that someone took the time to summarize for easier readability. But lesser known or obscure topics tend not to get press summaries ... you just have to dig in the real stuff.
Chief Counsel letters, InFOs publications, Advisory Circulars, all sorts of "official" information outlets beyond and behind the FARs.
Google can sometimes be your friend by adding "FAA", "FAA interpretation" or "FAA chief counsel" to a particular aviation topic.
Or just hang around here and someone will dig them up. Haha.
