Glass Panel Regs to Get Smaller? FAR 25 Design Standards Trending to Part 23?

ABSTRACT: Airworthiness standards currently applicable to transport airplanes under FAR Part 25 may soon be made applicable to lighter airplanes governed by FAR Part 23.

Ripples through the aerospace community suggest that recent revisions to FAR Part 25 regarding “glass panel” designs soon may be made applicable to FAR Part 23. Whereas Part 25 provides the airworthiness standards for transport airplanes (those with 10 or more seats or a maximum takeoff weight of greater than 12,500 pounds and propeller-driven airplanes with more than 19 seats or a maximum takeoff weight greater than 19,000 pounds), Part 23 sets forth the airworthiness standards for planes with a maximum takeoff weight of less than 12,500 pounds (e.g., most utility, aerobatic, and commuter airplanes).  

Effective as of July 2013, Section 25.1302 requires the following:

(a) Flight deck controls must be installed to allow accomplishment of all the tasks required to safely perform the equipment’s intended function, and information must be provided to the flightcrew that is necessary to accomplish the defined tasks.

(b) Flight deck controls and information intended for the flightcrew’s use must:

(1) Be provided in a clear and unambiguous manner at a resolution and precision appropriate to the task;

(2) Be accessible and usable by the flightcrew in a manner consistent with the urgency, frequency, and duration of their tasks; and

(3) Enable flightcrew awareness, if awareness is required for safe operation, of the effects on the airplane or systems resulting from flightcrew actions.

(c) Operationally-relevant behavior of the installed equipment must be:

(1) Predictable and unambiguous; and

(2) Designed to enable the flightcrew to intervene in a manner appropriate to the task.

(d) To the extent practicable, installed equipment must incorporate means to enable the flightcrew to manage errors resulting from the kinds of flightcrew interactions with the equipment that can be reasonably expected in service . . .

This provision reportedly is intended to enhance safety for operation of modern “glass panel” systems, including during the transition from traditional instruments. Importantly, it contemplates the design of systems to manage reasonably-expected flight crew error, to the extent practicable.   Questions of such reasonability and practicability may in turn raise issues of interpretation and debate as the cutting edge develops.

While the provisions of Part 25.1302 have yet to be incorporated within Part 23, the modern trend seems to point in this direction.