Airplane Controllability

FAR 23.2135 — Airplane Controllability

FAR 23.2135 sets controllability standards for Part 23 airplanes: maneuverability across the envelope, landing control, Vmc, and aerobatic demonstration.

In Plain English

FAR 23.2135 establishes the controllability and maneuverability standards a Part 23 airplane must meet to earn certification. The airplane has to be flyable without demanding exceptional skill, alertness, or strength from the pilot.

Specifically, the airplane must remain controllable:

At all loading conditions for which certification is requested
Through all phases of flight
With a likely reversible failure of a flight control or propulsion system
During configuration changes (flaps, gear, power)

The airplane must also be able to complete a landing without substantial damage or serious injury when flown at the steepest approved approach gradient, with a reasonable margin below the approach angle of attack.

For multiengine airplanes, the applicant must determine Vmc — the calibrated airspeed at which control can be maintained following the sudden critical loss of thrust — for the most critical takeoff and landing configurations.

If aerobatic certification is requested, the applicant must demonstrate each aerobatic maneuver and establish entry speeds.

Why it matters: this rule is why your POH limitations, Vmc, and approved maneuvers exist — they were proven during certification.

Regulation Text

14 CFR § 23.2135

§ 23.2135 Controllability. (a) The airplane must be controllable and maneuverable, without requiring exceptional piloting skill, alertness, or strength, within the operating envelope— (1) At all loading conditions for which certification is requested; (2) During all phases of flight; (3) With likely reversible flight control or propulsion system failure; and (4) During configuration changes. (b) The airplane must be able to complete a landing without causing substantial damage or serious injury using the steepest approved approach gradient procedures and providing a reasonable margin below Vor above approach angle of attack. (c) Vis the calibrated airspeed at which, following the sudden critical loss of thrust, it is possible to maintain control of the airplane. For multiengine airplanes, the applicant must determine Vif applicable, for the most critical configurations used in takeoff and landing operations. (d) If the applicant requests certification of an airplane for aerobatics, the applicant must demonstrate those aerobatic maneuvers for which certification is requested and determine entry speeds.

Oral Exam Questions a DPE Might Ask

Q1What does FAR 23.2135 require regarding controllability across the operating envelope?

Per FAR 23.2135, the airplane must be controllable and maneuverable without requiring exceptional piloting skill, alertness, or strength at all approved loading conditions, during all phases of flight, with a likely reversible flight control or propulsion failure, and during configuration changes.

Q2How is Vmc defined under FAR 23.2135 and when must it be determined?

FAR 23.2135(c) defines Vmc as the calibrated airspeed at which, following the sudden critical loss of thrust, control of the airplane can be maintained. For multiengine airplanes, the applicant must determine it for the most critical takeoff and landing configurations.

Q3If a manufacturer wants the airplane certified for aerobatics, what does FAR 23.2135 require?

Under FAR 23.2135(d), the applicant must demonstrate each aerobatic maneuver for which certification is requested and determine the appropriate entry speeds for those maneuvers.

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Related Sections in Part 23

§ 23.1457

Cockpit Voice Recorders

§ 23.1459

Flight Data Recorders