There are really two questions here:
- Can ATC clear you for a low approach? Yes.
- Does ATC have the authority to waive a CFR? No.
A better question might be:
- If ATC cleared me for a low approach and I held 200’ for the length of the runway before climbing to pattern altitude, would that be a violation of CFR 91.119?
I believe the answer is no, as I explain further below.
The Anderson Interpretation was used in another answer to support a position that a 200’ low approach would be (arguably) illegal, but I disagree. We don’t know exactly what Mr. Anderson was asking about, but can glean important information from the response and other examples cited.
In clearing you for a low approach ATC would not be waiving 91.119 because it isn't applicable to traffic pattern operations. Quoting from an earlier interpretation by another FAA Assistant Chief Counsel, the responding FAA Assistant Chief Counsel for Regulations states:
The FAA has determined that"§ 91.119 does generally not apply to aircraft operations within airport traffic patterns," and that "aircraft operating within a traffic pattern are excepted from the regulation for a considerable portion of each pattern, i.e., during climb to pattern altitude following each takeoff, and during descent from pattern altitude prior to each landing."
…the takeoff and landing exception to § 91.119 "applies equally to all practice approaches, including repeated 'touch and go,' 'stop and go,' and 'low approach' operations”.... "
It goes on to quote the NTSB:
These practice maneuvers come within the takeoff or landing exemption to the [section 91 .119] restrictions because their purpose is to improve a pilot's capabilities in those operations."). Therefore, if the operation is not within the traffic pattern, or involves the approaches noted above, the pilot must operate in accordance with §91.119
The corollary to the statement in bold is if the aircraft IS within the traffic pattern, the pilot is NOT required to operate in accordance with 91.119.
The examples given in the Anderson interpretation that do NOT fall within the exception are pretty egregious compared to a low approach directly over the active runway. In one example an aircraft was circling low over a residential subdivision taking photographs, and another was circling just 100’ over some houses while troubleshooting a problem. Both instances were apparently well outside the normal traffic pattern, therefore not meeting the definition of normal runway operations, (T&G, Low approach, etc.) and were close enough to housing to be certain to generate complaints.
However, the space directly over the airport runway is clear from the surface to pattern altitude for all pattern operations. If tower clears you for a low approach you may fly at any altitude in between. Any buildings and other obstructions in the immediate vicinity have already been factored into the airport and instrument approach procedure design. Airport structures are not the intent of 91.119.
If tower has cleared you for the option they don’t care if your wheels touch or not, whether you initiate a go-around at 20’ and climb to TPA at Vx, or execute an early missed approach at instrument minimums and stay level while you retract the landing gear and accelerate to flap retraction airspeed. The manner in which you fly the low approach is at pilot’s discretion.
The crux of the question seems to then hinge on intent, specifically offering the examples of “non-flight training purposes, e.g., an aircraft sales demonstration, videotaping, etc.” But what exactly does this mean?
Let’s consider an example that combines a couple elements…
Jim is demonstrating an airplane he has for sale to Bob. Jim’s hangar is located in close enough proximity to departure end of the runway in use that if it were NOT located right there at the airport it would be a violation of 91.119 to fly as close to it as every single plane that uses the runway does. But that’s OK, because this is an airport…
Bob’s wife Alice remains behind at the hangar with a video recorder to document the test flight, transition training, or whatever we decide to call this flight. Both the demonstration and recording of it are perfectly legal per part 91.
During a practice ILS Jim suggests that they hold their altitude at mins while they clean up off the practice missed approach until the upwind numbers to demonstrate level acceleration and pitch changes during flap retraction, and also give Alice a good shot of the airplane. Bob agrees, gets clearance for the option, and that’s what they do.
During this pass they are actually even a bit further away from the hangar than they were on the initial take off, as well as an earlier stop and go!
So, the question really becomes this: Does the lack of a positive rate of climb, or secondary intent to allow Alice a slightly better view to record video create a violation?
The CFRs aren’t nearly that specific, but as long as they are in the tower controlled pattern and over the runway I think even a pretty conservative interpretation would answer no. Intent generally only becomes relevant if a reportable incident occurs as a result of the pilot’s actions. (For example a mishap, or noise complaint leading to an investigation.)
If Jim or Bob were really “showing off” and screwed up the low approach the investigation might question why they remained at 200’ along the runway before climbing further, otherwise it is doubtful ATC would care.