Regulation Text
For airplanes covered by this subpart and operated under part 125 of this chapter, the following regulations apply as specified:
(a) For each airplane operation to which requirements prescribed under this subpart applied before November 29, 1980, those requirements of this subpart continue to apply.
(b) For each subsonic airplane operation to which requirements prescribed under this subpart did not apply before November 29, 1980, because the airplane was not operated in the United States under this part or part 121, 129, or 135 of this chapter, the requirements prescribed under § 91.805 of this subpart apply.
(c) For each supersonic airplane operation to which requirements prescribed under this subpart did not apply before November 29, 1980, because the airplane was not operated in the United States under this part or part 121, 129, or 135 of this chapter, the requirements of §§ 91.819 and 91.821 of this subpart apply.
(d) For each airplane required to operate under part 125 for which a deviation under that part is approved to operate, in whole or in part, under this part or part 121, 129, or 135 of this chapter, notwithstanding the approval, the requirements prescribed under paragraphs (a), (b), and (c) of this section continue to apply.
[Docket 18334, 54 FR 34321, Aug. 18, 1989, as amended by Amdt. 91-276, 67 FR 46571, July 15, 2002]
The short answer
(14 CFR § 91.803) For airplanes covered by this noise subpart operated under part 125, this section designates which noise requirements apply. Operations regulated before November 29, 1980 keep those requirements; later subsonic operations follow § 91.805, and later supersonic operations follow §§ 91.819 and 91.821.
Research Notes
Common Questions
Which noise rules apply to a part 125 airplane operation?
It depends on whether the subpart applied before November 29, 1980 and whether the airplane is subsonic or supersonic. Pre-1980 operations keep their existing requirements; otherwise § 91.805 (subsonic) or §§ 91.819 and 91.821 (supersonic) apply.
“For each airplane operation to which requirements prescribed under this subpart applied before November 29, 1980, those requirements of this subpart continue to apply.” — 14 CFR § 91.803(a)
What if a part 125 airplane gets a deviation to operate under part 121, 129, or 135?
Under paragraph (d), even with that deviation approval, the requirements in paragraphs (a), (b), and (c) continue to apply.
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