---
kind: "section"
citation: "14 C.F.R. § 38.15"
title: "14"
number: "38.15"
heading: "Reference geometric factor."
url: "https://uscodex.org/cfr/14/38.15"
---

# §38.15. Reference geometric factor.


For each airplane subject to this part, determine the airplane's non-dimensional RGF for the fuselage size of each airplane model, calculated as follows:

- (a) For an airplane with a single deck, determine the area of a surface (expressed in m^2) bounded by the maximum width of the fuselage outer mold line projected to a flat plane parallel with the main deck floor and the forward and aft pressure bulkheads except for the crew flight deck zone.
- (b) **For an airplane with more than one deck, determine the sum of the areas (expressed in m^2) as follows—**
  - (1) The maximum width of the fuselage outer mold line, projected to a flat plane parallel with the main deck floor by the forward and aft pressure bulkheads except for any crew flight deck zone.
  - (2) The maximum width of the fuselage outer mold line at or above each other deck floor, projected to a flat plane parallel with the additional deck floor by the forward and aft pressure bulkheads except for any crew flight deck zone.
- (c) Determine the non-dimensional RGF by dividing the area defined in paragraph [(a)](#a) or [(b)](#b) of this section by 1 m^2.
- (d) All measurements and calculations used to determine the RGF of an airplane must be made in accordance with the procedures for determining RGF in section A38.3 of 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.