Pilot Counsel:

Defining 'necessary'

July 1, 2012


The flight rules of FAR Part 91, which specify the minimum safe altitudes for flight, provide that “except when necessary for takeoff or landing, no person may operate an aircraft below the following altitudes.” The rule then goes on to prescribe the specific minimum altitudes. John Yodice

Here are the minimum altitudes of FAR 91.119: There is an “anywhere” rule that requires a pilot to fly high enough so that “if a power unit fails,” the pilot would be able to make a landing without creating an “undue hazard” to persons or property on the surface. Then the rule goes on to prescribe minimums depending on the nature of the geographical area over which the aircraft is operated. For a “congested area,” the minimum is 1,000 feet above the highest obstacle within a horizontal radius of 2,000 feet of the aircraft (the term congested area is not defined in the rule). Over a populated area that is not congested, the pilot must fly at least at “an altitude of 500 feet above the surface.” Over a sparsely populated area, or over open water, an aircraft may be operated down to the surface so long as it is not operated any “closer than 500 feet to any person, vessel, vehicle, or structure.”

There is an important nuance to the takeoff and landing exception to the rule. A moment’s reflection will remind many of us that there are airports where a departure or an approach to landing will be over geographical areas where a normal and usual operation would violate the rule but for that exception. What has caused the most questions for pilots in interpreting the exception is the word necessary in the phrase “except when necessary for takeoff or landing.” The FAA has not established a specific definition in the rule. So, must a pilot make an unusually steep departure to stay within the requirements of the rule? Must a pilot stay at a higher altitude and make an unusually steep approach to landing to stay within the requirements of the rule? Whether a maneuver is “necessary” for takeoff or landing is a factual determination to be made by the pilot. Indeed, an early FAA interpretation letter emphasizes that the responsibility is squarely on the pilot. It states that a pilot “must determine whether that portion of the flight is necessary to permit the pilot to transition between the surface and the en route or pattern altitude in connection with a takeoff or landing.” The closest we come to a definition is a longstanding FAA policy on the need for a pilot to “take full advantage of the performance capabilities of his aircraft so as to spend as little time as possible at altitudes below the minimums established for cruising flight.”

But I must be clear—and the FAA would agree—that there is nothing in the rule requiring a pilot to execute a maneuver outside the performance capabilities of the aircraft.

The FAA chief counsel recently issued an interesting interpretation that arguably could provide some insight regarding IFR procedures. The interpretation involved a similar “except when necessary for takeoff or landing” exception to an FAR Part 135 rule prohibiting descent to an altitude below the power-off glide distance from shore. The interpretation said that the pilot of a single-engine turboprop aircraft must refuse a routine ATC instruction issued for traffic separation that would cause a descent to a lower altitude. The interpretation distinguished an ATC direction to a particular altitude to intercept the localizer for an instrument approach. Whether or not these two situations can be reconciled, the interpretation suggests that an ATC clearance or instruction does not automatically provide compliance with the rule.

To provide meaningful guidance, we must rely on what is happening in practice. In my experience with the AOPA Legal Services Plan, where we get a good view of what the FAA is doing in practice, we have not seen any FAA enforcement action against pilots for normal and usual departures or approaches to landings where they overfly the geographical areas we have mentioned below the minimum altitudes specified. That is true even if it could be argued that maximum performance (as opposed to normal) maneuvers within the capability of the aircraft could have been utilized. FAA inspectors typically use reason and discretion in the enforcement of this rule. However, a word to the wise. I would not be surprised to see enforcement actions against pilots who intentionally or carelessly fly below normal and usual patterns, especially in response to reasonable complaints from persons on the ground.

Legal counselor John S. Yodice is a commercial pilot and flight instructor who owns and flies a Cessna 310.

John S. Yodice