14 CFR § 38.13 - Specific air range.

---
identifier: "/us/cfr/t14/s38.13"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "14 CFR § 38.13 - Specific air range."
title_number: 14
title_name: "Aeronautics and Space"
section_number: "38.13"
section_name: "Specific air range."
chapter_name: "FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION"
subchapter_number: "C"
subchapter_name: "AIRCRAFT"
part_number: "38"
part_name: "AIRPLANE FUEL EFFICIENCY CERTIFICATION"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "42 U.S.C. 4321  7572; 49 U.S.C. 106(g), 40113, 44701-44702, 44704; 49 CFR 1.83(c)"
regulatory_source: "Docket No. FAA-2022-0241, Amdt. No. 21-107, 89 FR 12654, Feb. 16, 2024, unless otherwise noted."
cfr_part: "38"
---


# 38.13 Specific air range.

(a) For each airplane subject to this part, the SAR of an airplane must be determined by either:

(1) Direct flight test measurements; or

(2) Using a performance model that is:

(i) Validated by actual SAR flight test data; and

(ii) Approved by the FAA before any SAR calculations are submitted.

(b) For the airplane model, establish a 1/SAR value at each of the following reference airplane masses:

(1) High gross mass: 92 percent MTOM.

(2) Low gross mass: (0.45 * MTOM) + (0.63 * (MTOM^0.924)).

(3) Mid gross mass: simple arithmetic average of high gross mass and low gross mass.

(c) To obtain (1/SAR)<sub>avg</sub> as required to determine the fuel efficiency metric value described in § 38.11, calculate the average of the three 1/SAR values described in paragraph (b) of this section. Do not include auxiliary power units in any 1/SAR calculation.

(d) All determinations made under this section must be made in accordance with the procedures applicable to SAR as described in appendix A to this part.