(Note: The FAA has temporarily un-cancelled Advisory Circular 91-57. See Update, below.)

The FAA’s withdrawal of Advisory Circular 91-57 is causing a round of concern that the agency is taking steps to make hobby drones illegal. This article from Vice is an example.

The Federal Aviation Administration took the first initial steps today toward severely restricting or banning all hobby and commercial drone flights in the country, putting in a request to formally cancel the document under which model aircraft have legally operated since 1981.

While we have expressed our own concerns about FAA overreach, we think that panic in this case is unwarranted. The more likely explanation is that the FAA is cleaning out its attic in preparation for instituting a final regulatory framework under the FAA Modernization and Reform Act of 2012.

First, it is important to understand the applicable language of the FMRA pertaining to model aircraft:

SEC. 336. SPECIAL RULE FOR MODEL AIRCRAFT.
(a) IN GENERAL.—Notwithstanding any other provision of law relating to the incorporation of unmanned aircraft systems into Federal Aviation Administration plans and policies, including this subtitle, the Administrator of the Federal Aviation Administration may not promulgate any rule or regulation regarding a model aircraft, or an aircraft being developed as a model aircraft, if—
(1) the aircraft is flown strictly for hobby or recreational use;
(2) the aircraft is operated in accordance with a community-based set of safety guidelines and within the programming of a nationwide community-based organization;
(3) the aircraft is limited to not more than 55 pounds unless otherwise certified through a design, construction, inspection, flight test, and operational safety program administered by a community-based organization;
(4) the aircraft is operated in a manner that does not interfere with and gives way to any manned aircraft; and
(5) when flown within 5 miles of an airport, the operator of the aircraft provides the airport operator and the airport air traffic control tower (when an air traffic facility is located at the airport) with prior notice of the operation (model aircraft operators flying from a permanent location within 5 miles of an airport should establish a mutually-agreed upon operating procedure with the airport operator and the airport air traffic control tower (when an air traffic facility is located at the airport)).

(b) STATUTORY CONSTRUCTION.—Nothing in this section shall be construed to limit the authority of the Administrator to pursue enforcement action against persons operating model aircraft who endanger the safety of the national airspace system.

(c) MODEL AIRCRAFT DEFINED.—In this section, the term ‘‘model aircraft’’ means an unmanned aircraft that is—
(1) capable of sustained flight in the atmosphere;
(2) flown within visual line of sight of the person operating the aircraft; and
(3) flown for hobby or recreational purposes.

In other words, Congress has told the FAA that it can’t impose any regulations on model aircraft. That is the law. However, the FAA – for better or worse – is charged with promulgating regulations interpreting the laws that Congress passes, and the courts grant agencies like the FAA a fair amount of deference in how they construe statutory language.

The current fight is over how broadly, or how narrowly, Congress’ definitions for model aircraft should be construed. For example, what did Congress mean by “flown strictly for hobby or recreational use”? What did Congress mean by “flown within visual line of sight of the person operating the aircraft”?

The language of Section 336 of the FMRA, by itself, conflicts with Advisory Circular 91-57 in some respects. For example, AC 91-57 provided for voluntary notice to a control tower when operating within 3 miles of an airport. The FMRA requires notice if operating within 5 miles. Thus, even if the FAA ends up construing (or is forced to construe) the definitions for “model aircraft” broadly, the final language is almost certainly going to be inconsistent with the language of Advisory Circular 91-57.

We therefore see the cancellation of AC 91-57 not as part of a plot to criminalize modeling, but as an example of agency housekeeping.

UPDATE: Well, never mind, then:

FAA does plan to cancel AC 91-57 in order to reconcile the outdated AC with current sUAS policy and the “Special Rule for Model Aircraft” provided by Congress as part of the FAA Modernization and Reform Act of 2012. However, this will occur at a later date and will be accompanied by additional information and an explanation as to the reason for the cancellation.