---
kind: "section"
citation: "40 C.F.R. § 1030.25"
title: "40"
number: "1030.25"
heading: "Reference geometric factor (RGF)."
url: "https://uscodex.org/cfr/40/1030.25"
---

# §1030.25. Reference geometric factor (RGF).


For each airplane subject to this part, determine the airplane's nondimensional reference geometric factor (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 cockpit 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 cockpit 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 cockpit 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 according to the procedures for determining RGF in Appendix 2 of ICAO Annex 16, Volume III (incorporated by reference in [§ 1030.110](/cfr/40/1030.110.md)).

## Notes

### Authority

Authority: 42 U.S.C. 7401-7671q.

### Source

Source: 86 FR 2171, Jan. 11, 2021, unless otherwise noted.