Aerobatic flight is not defined in the AIM, although acrobatic flight is defined in two respects. In the AIM's Pilot/Controller Glossary, acrobatic flight is first defined with reference to Part 91 as "an intentional maneuver involving an abrupt change in an aircraft's attitude, an abnormal attitude, or abnormal acceleration not necessary for normal flight." In the second instance, it is defined by the International Civil Aviation Organization as "maneuvers intentionally performed by an aircraft involving an abrupt change in its attitude, an abnormal attitude, or abnormal variation in speed." The two definitions seem essentially the same, and as best I can tell, the terms aerobatic and acrobatic are used interchangeably in the context of the regulatory obligation that we will be reviewing.
The definition is rather general. It does not identify specific degrees of pitch or banking; it does not reference stress limits or operating limitations; and it does not list particular maneuvers. However, by its plain language, we can get a good sense of what the definition includes. To start, the language of the regulation requires that an aerobatic maneuver must be an "intentional" maneuver. So, for example, if extreme weather or wake turbulence causes your aircraft to become inverted unintentionally, that would not be considered aerobatic flight. Second, the maneuver must involve an "abrupt" change in the aircraft's attitude, an abnormal attitude, and/or abnormal acceleration. Finally, the maneuver must not have been necessary for normal flight - so, if the aircraft's movement is smooth and normal flight requires the maneuver, it would not be considered aerobatic.
Over the years, this general definition has been explained through FAA interpretation. The FAA maintains that smoothly executed steep turns, approaches to stalls, stalls, and unusual attitudes for the purpose of demonstrating recovery procedures are not considered aerobatic because they do not involve an abrupt change in an aircraft's attitude. In addition, the FAA believes that the attitudes and accelerations involved in these maneuvers are incidental to and necessary for training flights. In this regard, then, the FAA considers such training flights to be normal flights.
On the other hand, spins, loops, rolls, and other types of abnormal attitude maneuvers performed outside the scope of "normal training flights" would fall within the definition of aerobatic flight. A steep climbout after takeoff and a left turn at a very low altitude has been viewed as aerobatic because it was abnormal and not necessary for normal flight. And, a steep dive and pullout has been determined to constitute aerobatic flight because it involved an abrupt change in attitude that was not necessary for normal flight. Similarly, an accelerated pass down a runway may be viewed as aerobatic flight.
But remember, if these maneuvers are not performed intentionally, and if they are performed smoothly as part of normal flight, then they won't be viewed as aerobatic under the FAA's definition. To the extent that such maneuvers are performed within the flight training curriculum to obtain a certificate or rating, they would be viewed as part of normal flight. Although we have not seen a specific interpretation on this, aerobatic training flights would probably not be subject to this "normal flight" exception, since they would be performed intentionally and would generally involve abrupt changes and abnormal attitudes and acceleration. Therefore, those training flights would otherwise have to comply with the regulations applicable to aerobatic flight.
Next month, we'll look at some of the regulatory restrictions put on aerobatic flight.
Kathy Yodice is an attorney with Yodice Associates in Washington, D.C., which provides legal counsel to AOPA and administers AOPA's Legal Services Plan. She is an instrument-rated private pilot.