Old Aug 21, 15, 3:06 pm
Join Date: Sep 1999
Location: SF Bay Area
Programs: UA 1K MM, Accor Plat, Htz PC, Natl ExEm, other random status
Posts: 2,848
Originally Posted by choefman View Post
V1 and Vto are the same thing...
I'd defer to one of United's finest, but I don't think that's necessarily true.

Admittedly, my piloting experience is limited to aircraft of the small single-engined Cessna variety, but my understanding is that "Vto" is at most a shorthand catch-all term to refer to all varieties of takeoff speeds.

By contrast, V1 (like other takeoff speeds) is defined in the FAA Regulations (as may be adapted by manufacturers and airlines in consultation with the FAA).

Section 25.107 of the FAR's defines V1 as follows:

(a) V1 must be established in relation to VEF as follows:
(1) VEF is the calibrated airspeed at which the critical engine is assumed to fail. VEF must be selected by the applicant, but may not be less than VMCG determined under 25.149(e).
(2) V1, in terms of calibrated airspeed, is selected by the applicant; however, V1 may not be less than VEF plus the speed gained with 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 initiation of the first action (e.g., applying brakes, reducing thrust, deploying speed brakes) to stop the airplane during accelerate-stop tests.

Other regulators define it differently.

Perhaps you were thinking of V LOF, which is really a statement of fact, rather than a calculated number?

The FAR's (same link, Sec. 25.107) define V LOF as:

the calibrated airspeed at which the airplane first becomes airborne
Of course, I could be wrong, and I'd love to hear a real pilot explain it.

greg99 is offline