[Code of Federal Regulations]
[Title 14, Volume 1]
[Revised as of January 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 14CFR25.123]

[Page 358]
 
                     TITLE 14--AERONAUTICS AND SPACE
 
CHAPTER I--FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION
 
PART 25_AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES--
Table of Contents
 
                            Subpart B_Flight
 
Sec.  25.123  En route flight paths.

    (a) For the en route configuration, the flight paths prescribed in 
paragraphs (b) and (c) of this section must be determined at each 
weight, altitude, and ambient temperature, within the operating limits 
established for the airplane. The variation of weight along the flight 
path, accounting for the progressive consumption of fuel and oil by the 
operating engines, may be included in the computation. The flight paths 
must be determined at any selected speed, with--
    (1) The most unfavorable center of gravity;
    (2) The critical engines inoperative;
    (3) The remaining engines at the available maximum continuous power 
or thrust; and
    (4) The means for controlling the engine-cooling air supply in the 
position that provides adequate cooling in the hot-day condition.
    (b) The one-engine-inoperative net flight path data must represent 
the actual climb performance diminished by a gradient of climb of 1.1 
percent for two-engine airplanes, 1.4 percent for three-engine 
airplanes, and 1.6 percent for four-engine airplanes.
    (c) For three- or four-engine airplanes, the two-engine-inoperative 
net flight path data must represent the actual climb performance 
diminished by a gradient of climb of 0.3 percent for three-engine 
airplanes and 0.5 percent for four-engine airplanes.