Safety Pilot may log time as SIC or PIC
There are two legal interpretations that allow you to log SIC or PIC time when acting as a safety pilot. The first, Beaty (2013), addressed logging cross-country time for the safety pilot, but explicitly says that the safety pilot can log the time as PIC if they are acting as PIC.
In your first scenario, Pilot A and Pilot B, who hold private pilot certificates and ratings appropriate to the aircraft, take a flight. Pilot A acts as the pilot-in-command (PIC). During a portion of the flight, Pilot B acts as the safety pilot and second-in-command (SIC) while Pilot A operates in simulated instrument flight. You ask whether Pilot B may log SIC and/or cross-country time for the portion of the flight during which Pilot B acts as safety pilot.
Section 61.51 (f) governs the logging of SIC time and states, in relevant part, that a person may log SIC time only for that flight time during which that person holds the appropriate ratings for aircraft being flown and “more than one pilot is required under the type certification of the aircraft or the regulations under which the flight is being conducted.” When a pilot is operating an aircraft in simulated instrument flight, 14 C.F.R. § 91.109(b), in relevant part, requires that a safety pilot, who possesses at least a private pilot certificate with category and class ratings appropriate to the aircraft, occupy the other control seat. Accordingly, Pilot B may log SIC time for the portion of the flight during which Pilot B acts as safety pilot because Pilot B was a required flight crewmember for that portion of the flight under § 91.1 09(b). The FAA previously has interpreted that a person acting as safety pilot for a portion of a flight may not log cross-country time because that person is not a required flight crewmember for the entire flight. See Legal Interpretation to Jeff Gebhart (June 22,2009) (copy enclosed). Accordingly, Pilot B may not log cross-country time for any portion of the flight.
Gebhart (2009) also says you may log the time as safety pilot as PIC.
Section 61.51(e) governs the logging of PIC time and states, in relevant part, that a sport, recreational, private, or commercial pilot may log PIC time for the time during which that pilot is “the sole manipulator of the controls of an aircraft for which the pilot is rated or has privileges” or “acting as pilot in command of an aircraft on which more than one pilot is required under … the regulations under which the flight is conducted.”
Hicks (1993) is even more explicit about logging time as SIC, so this is not a new interpretation.
Section 61.51(e) governs the logging of PIC time and states, in relevant part, that a sport, recreational, private, or commercial pilot may log PIC time for the time during which that pilot is “the sole manipulator of the controls of an aircraft for which the pilot is rated or has privileges” or “acting as pilot in command of an aircraft on which more than one pilot is required under … the regulations under which the flight is conducted.”
Responding specifically to your inquiry, the pilot that is under the hood may log PIC time for that time in which he is the sole manipulator of the controls of the aircraft, provided that he or she is rated for that aircraft. The appropriately rated safety pilot may concurrently log as second-in-command (SIC) that time during which he or she is acting as safety pilot.
However, the two pilots may, prior to initiating the flight, agree that the safety pilot will be the PIC responsible for the operation and safety of the aircraft during the flight. If this is done, then the safety pilot may log all the flight time as PIC time in accordance with FAR 1.1 and the pilot under the hood may log, concurrently, all of the flight time during which he is the sole manipulator of the controls as PIC time in accordance with FAR 61.51(c)(2)(i). In order to assist you further in this regard, enclosed please find a prior FAA interpretation concerning the logging of flight time under simulated instrument flight conditions.