---
kind: "section"
citation: "14 C.F.R. § 38.13"
title: "14"
number: "38.13"
heading: "Specific air range."
url: "https://uscodex.org/cfr/14/38.13"
---

# §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)avg as required to determine the fuel efficiency metric value described in [§ 38.11](/cfr/14/38.11.md), calculate the average of the three 1/SAR values described in [paragraph (b)](#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.

## Notes

### Authority

Authority: 42 U.S.C. 4321 et seq., 7572; 49 U.S.C. 106(g), 40113, 44701-44702, 44704; 49 CFR 1.83(c)

### Source

Source: Docket No. FAA-2022-0241, Amdt. No. 21-107, 89 FR 12654, Feb. 16, 2024, unless otherwise noted.