Requirements for Logging practice Instrument approaches, (and holdings, and course interceptions) while in VMC

Question

Does anyone know the FAA rational for requiring the second pilot on board to have access to a complete Fully functioning set of flight controls in order to act as safety observer for the purpose of logging instrument activities with a view limiting device in VMC?

I have a Long EZ, which has a flight control side stick in the rear cockpit, but no rudders or throttle. I have been told I cannot log practice approaches in VMC with a rated pilot in the back seat because it does not have a complete set of flight controls. This is (as far as I can see from FARs), documented in 14 CFR § 91.109, (c), which reads:

To address comments below, please see FAA interpretation of "fully functioning dual controls" and Final FAA Interpretaton.

The first FAA Letter above basically states that brakes are not required, but that pitch, roll, and yaw controls are required. It does not discuss or mention power.
The second reference is the final FAA order, (Bulletin HBGA 00-08) it does specifically discuss the throttles, and then states:

Office of General Counsel clarified its position that
the term “dual controls” as used under 14 CFR section 91.109(a)
refers solely to the flight controls of an aircraft (e.g., pitch,
yaw, and roll controls)

As it would seem that the purpose of the safety observer is observe the sky for other traffic and, in the event of an impending or threatening conflict, either

1. Inform the pilot to take off his/her view limiting device and deal with it, or ...
2. Take the controls and maneuver the aircraft to avoid the conflict.

I do not understand how rudders or throttle in any way impede the capability of the safety observer to perform that function. It's also curiously inconsistent with the exception made for aircraft with throwover control wheels, (like in Bonanzas). Also, because I fly in Arizona where the flight conditions are (thankfully), IMC only 25-30 days a year, and because of the wide diversity of avionics in so many GA aircraft nowadays, because of this constraint, my only alternative is to perform practice approaches in another aircraft with different avionics and autopilot switchology from what is in my primary aircraft. With modern avionics, basic instrument procedures and instrumentation now represent an ever-increasingly smaller percentage of the knowledge and skills necessary for IFR flight, so satisfying my IFR currency requirements in an aircraft with very different avionics becomes more and more counter-productive instead of actually increasing my proficiency.

Does anyone know the actual FAA rational for this constraint?

Answer 1

You won’t get an authoritative answer on this unless the FAA publishes their rationale, and someone would have cited such by now if it existed.

However, we can deduce a few things from what is and is not required to act as a safety pilot. In particular, they do not need to have any special endorsements (such as complex or tail wheel) nor landing currency, nor do they need to have brakes available, but they do need flight controls and a clear view.

From this, I think it is fairly obvious the intent is that the safety pilot can quickly take over the flight controls in an emergency, such as to prevent a mid-air collision or a crash if the primary pilot gets disoriented, but then give them back to the original pilot as soon as the emergency is over, i.e. they’re not expected to land the plane.

To deal with such emergencies, which may necessitate a rapid climb or recovery from a stall or spin, they will need access to the rudders and throttle.

The case of a throwover yoke is clearly not ideal here, but apparently someone decided it can be done quick enough for the safety pilot to do this duty.

Answer 2

Because, for all intents and purposes, there must be a appropriately certificated and rated PIC with the ability to fully control the aircraft at all times during operation. If you’re flying under the hood but don’t yet hold an instrument rating, you don’t yet qualify for that. I’ve never had anyone explain a full set of rationale for that regulation. But that being said it’s the offer full control of that aircraft at all times in case something happens with the guy under the hood. Spatial disorientation at low altitudes and/or high alpha regimes for flight would demand a recovery that requires immediate access to all flight controls and throttle; there may not be enough time available to tell the guy upfront to take the hood off and recover.