Although I agree totally with 172driver's comments, unfortunately the current FAQ indicates otherwise. I've posted the current opinion below. Because I agree that the interpretation is not supported by 61.51 language, I've also included Doc's (of Doc's FAR Pages) opinion on this issue. (If you're not familiar with Doc's web site, it is THE place to get accurate information on reg interpretation.
http://www.propilot.com/doc/logging2.html.)
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From the FAA FAQ web site:
QUESTION 2: Am I correct in understanding that a CFII may log approaches that a student flies when those approaches are conducted in actual instrument conditions? Is there a reference to this anywhere in the rules?
ANSWER 2: Ref. §61.51(g)(2); Yes, a CFII may log approaches that a student flies when those approaches are conducted in actual instrument flight conditions. And this would also permit that instructor who is performing as an authorized instructor to “. . . log instrument time when conducting instrument flight instruction in actual instrument flight conditions” and this would count for instrument currency requirements under §61.57(c).
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From Doc's FAR Pages, in response to someone asking the same question:
I strongly disagree with the FAA's policy on allowing a CFI to log approaches flown by someone else. There is simply no legal basis for it in the FAR (See the link below). Yes, I know that the FAA has issued a policy through the AFS-640 site, and you can follow that until it is changed, if you wish.
But let me ask you a couple of questions. Why would you want to log the trainee's approaches as if you had flown them? Do you want to base your instrument proficiency on someone else's ability to fly?
I certainly cannot support and will never support basing instrument currency on someone else's instrument approaches. But, the FAA certification folks will (presently) allow it as stated on the FAA AFS-640 site and as quoted by Scott. However, that policy could change at any time. And we still do not know if the FAA Chief Counsel agrees with that position or whether you would be protected if there ever was a violation alleged based on the fact that you were maintaining currency on the back of someone else. Again, the current policy is not legally supported in the FAR. The FAR allows you to log instrument TIME, but is silent as to approaches (FAR 61.51(g)).
As for logging landings, the FAR (and the FAA AFS-640 BBS) are clear. In order to log landings for recency of experience, you must be the "sole manipulator of the flight controls" -- e.g. you cannot log student-flown landings (see FAR 61.57).