[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: 14CFR23.51]

[Page 188-189]
 
                     TITLE 14--AERONAUTICS AND SPACE
 
CHAPTER I--FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION
 
PART 23_AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND 
COMMUTER CATEGORY AIRPLANES--Table of Contents
 
                            Subpart B_Flight
 
Sec.  23.51  Takeoff speeds.

    (a) For normal, utility, and acrobatic category airplanes, rotation 
speed, VR, is the speed at which the pilot makes a control 
input, with the intention of lifting the airplane out of contact with 
the runway or water surface.
    (1) For multiengine landplanes, VR, must not be less than 
the greater of 1.05 VMC; or 1.10 VS1;
    (2) For single-engine landplanes, VR, must not be less 
than VS1; and
    (3) For seaplanes and amphibians taking off from water, 
VR, may be any speed that is shown to be safe under all 
reasonably expected conditions, including turbulence and complete 
failure of the critical engine.
    (b) For normal, utility, and acrobatic category airplanes, the speed 
at 50 feet above the takeoff surface level must not be less than:
    (1) or multiengine airplanes, the highest of--
    (i) A speed that is shown to be safe for continued flight (or 
emergency landing, if applicable) under all reasonably expected 
conditions, including turbulence and complete failure of the critical 
engine;
    (ii) 1.10 VMC; or
    (iii) 1.20 VS1.
    (2) For single-engine airplanes, the higher of--
    (i) A speed that is shown to be safe under all reasonably expected 
conditions, including turbulence and complete engine failure; or
    (ii) 1.20 VS1.
    (c) For commuter category airplanes, the following apply:
    (l) V1 must be established in relation to VEF 
as follows:
    (i) VEF is the calibrated airspeed at which the critical 
engine is assumed to fail. VEF must be selected by the 
applicant but must not be less than 1.05 VMC determined under 
Sec.  23.149(b) or, at the option of the applicant, not less than 
VMCG determined under Sec.  23.149(f).
    (ii) The takeoff decision speed, V1, is the calibrated 
airspeed on the ground at which, as a result of engine failure or other 
reasons, the pilot is assumed to have made a decision to continue or 
discontinue the takeoff. The takeoff decision speed, V1, must 
be selected by the applicant but must not be less than VEF 
plus the speed gained with the critical engine inoperative during the 
time interval between the instant at which the critical engine is failed 
and the instant at which the pilot recognizes and reacts to the engine 
failure, as indicated by the pilot's application of the first retarding 
means during the accelerate-stop determination of Sec.  23.55.
    (2) The rotation speed, VR, in terms of calibrated 
airspeed, must be selected by the applicant and must not be less than 
the greatest of the following:
    (i) V1;
    (ii) 1.05 VMC determined under Sec.  23.149(b);
    (iii) 1.10 VS1; or
    (iv) The speed that allows attaining the initial climb-out speed, 
V2, before reaching a height of 35 feet above the takeoff 
surface in accordance with Sec.  23.57(c)(2).
    (3) For any given set of conditions, such as weight, altitude, 
temperature, and configuration, a single value of VR must be 
used to show compliance with both the one-engine-inoperative takeoff and 
all-engines-operating takeoff requirements.
    (4) The takeoff safety speed, V2, in terms of calibrated 
airspeed, must be selected by the applicant so as to allow the gradient 
of climb required in Sec.  23.67 (c)(1) and (c)(2) but mut not be less 
than 1.10 VMC or less than 1.20 VS1.

[[Page 189]]

    (5) The one-engine-inoperative takeoff distance, using a normal 
rotation rate at a speed 5 knots less than VR, established in 
accordance with paragraph (c)(2) of this section, must be shown not to 
exceed the corresponding one-engine-inoperative takeoff distance, 
determined in accordance with Sec.  23.57 and Sec.  23.59(a)(1), using 
the established VR. The takeoff, otherwise performed in 
accordance with Sec.  23.57, must be continued safely from the point at 
which the airplane is 35 feet above the takeoff surface and at a speed 
not less than the established V2 minus 5 knots.
    (6) The applicant must show, with all engines operating, that marked 
increases in the scheduled takeoff distances, determined in accordance 
with Sec.  23.59(a)(2), do not result from over-rotation of the airplane 
or out-of-trim conditions.

[Doc. No. 27807, 61 FR 5184, Feb. 9, 1996]