It depends. If the safety pilot is also acting as PIC (in charge of the flight), then the safety pilot may log PIC time while the flying pilot is under the hood. If not, the safety pilot is permitted to log second-in-command time. To understand the answer, make sure that you first understand the “golden key” to logging mentioned in the general logging PIC FAQ – the FAA treats “acting as pilot in command” and “logging pilot in command time” under FAR 61.51 as completely different concepts. Unless 61.51 specifically directs you to it, answering a logging question by including the word “acting” or pointing to any other FAR is always a mistake.
Logging PIC time as a safety pilot is one of those times that 61.51 tells you to look somewhere else. As usual, let’s start with 61.51. 61.51(e)(1)(iii) tells us that if you are a private or commercial pilot, you may log as PIC any time you are acting as PIC (in charge) of a flight on which more than one pilot is required by the regulations. More than one pilot may be required because the aircraft is not certified for single-pilot operations. But there are other situations as well. One is set up for us by 91.109(b):
No person may operate a civil aircraft in simulated instrument flight unless … The other control seat is occupied by a safety pilot who possesses at least a private pilot certificate with category and class ratings appropriate to the aircraft being flown.
So, a second “safety pilot” is required by the regulations while the “manipulator” is under the hood. If the two pilots agree that the safety pilot is acting as PIC, the safety pilot can log the time as PIC.
An important, but often misunderstood part of this rule is that in order to act as PIC in this context, the pilot must be qualified to do so. That means being current and having the appropriate endorsements in addition to ratings. Think it’s a little sneaky? Trying to get around the rules by looking for technicalities? Here’s what the FAA Chief Legal Counsel said about it decades ago in a 1993 interpretation letter sent to Steve Hicks:
In your second question you ask “how shall two Private Pilots log their flight time when one pilot is under the hood for simulated instrument time and the other pilot acts as safety pilot?” The answer is the pilot who is under the hood may log PIC time for that flight time in which he is the sole manipulator of the controls of the aircraft, provided he is rated for that aircraft. The appropriately rated safety pilot may concurrently log as second in command (SIC) that time during which he is acting as safety pilot.
The two pilots may, however, agree prior to initiating the flight 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). Enclosed please find a prior FAA interpretation concerning the logging of flight time under simulated instrument flight conditions. We hope that this interpretation will be of further assistance to you.
That was back in 1993. The specific FAR 61.51 subparagraph has changed but the substance has not. As with most logging questions, the FAA has been incredibly consistent since then, applying the same rules to a series of safety pilot scenarios almost 20 years later in an interpretive letter to William Trussell.