In aviation, V-speeds are standard terms used to define airspeeds important or useful to the operation of all aircraft.[1] These speeds are derived from data obtained by aircraft designers and manufacturers during flight testing for aircraft type-certification. Using them is considered a best practice to maximize aviation safety, aircraft performance, or both.[2]
The actual speeds represented by these designators are specific to a particular model of aircraft. They are expressed by the aircraft's indicated airspeed (and not by, for example, the ground speed), so that pilots may use them directly, without having to apply correction factors, as aircraft instruments also show indicated airspeed.
In general aviation aircraft, the most commonly used and most safety-critical airspeeds are displayed as color-coded arcs and lines located on the face of an aircraft's airspeed indicator. The lower ends of the white arc and the green arc are the stalling speed with wing flaps in landing configuration, and stalling speed with wing flaps retracted, respectively. These are the stalling speeds for the aircraft at its maximum weight.[3][4] The yellow band is the range in which the aircraft may be operated in smooth air, and then only with caution to avoid abrupt control movement. The red line is the VNE, the never-exceed speed.
Proper display of V-speeds is an airworthiness requirement for type-certificated aircraft in most countries.[5][6]
Regulations
The most common V-speeds are often defined by a particular government's aviation regulations. In the United States, these are defined in title 14 of the United States Code of Federal Regulations, known as the Federal Aviation Regulations (FARs).[7] In Canada, the regulatory body, Transport Canada, defines 26 commonly used V-speeds in their Aeronautical Information Manual.[8] V-speed definitions in FAR 23, 25 and equivalent are for designing and certification of airplanes, not for their operational use. The descriptions below are for use by pilots.
Regulatory V-speeds
These V-speeds are defined by regulations. They are typically defined with constraints such as weight, configuration, or phases of flight. Some of these constraints have been omitted to simplify the description.
Other V-speeds
Some of these V-speeds are specific to particular types of aircraft and are not defined by regulations.
Mach numbers
Whenever a limiting speed is expressed by a Mach number, it is expressed relative to the local speed of sound, e.g. VMO: Maximum operating speed, MMO: Maximum operating Mach number.[7][8]
V1 definitions
V1 is the critical engine failure recognition speed or takeoff decision speed. It is the speed above which the takeoff will continue even if an engine fails or another problem occurs, such as a blown tire.[9] The speed will vary among aircraft types and varies according to factors such as aircraft weight, runway length, wing flap setting, engine thrust used and runway surface contamination; thus, it must be determined by the pilot before takeoff. Aborting a takeoff after V1 is strongly discouraged because the aircraft may not be able to stop before the end of the runway, thus suffering a runway overrun.[50]
V1 is defined differently in different jurisdictions, and definitions change over time as aircraft regulations are amended.
The US Federal Aviation Administration and the European Union Aviation Safety Agency define it as: "the maximum speed in the takeoff at which the pilot must take the first action (e.g., apply brakes, reduce thrust, deploy speed brakes) to stop the airplane within the accelerate-stop distance. V1 also means the minimum speed in the takeoff, following a failure of the critical engine at VEF, at which the pilot can continue the takeoff and achieve the required height above the takeoff surface within the takeoff distance."[7] V1 thus includes reaction time.[26] In addition to this reaction time, a safety margin equivalent to 2 seconds at V1 is added to the accelerate-stop distance.[51][52]
Transport Canada defines it as: "Critical engine failure recognition speed" and adds: "This definition is not restrictive. An operator may adopt any other definition outlined in the aircraft flight manual (AFM) of TC type-approved aircraft as long as such definition does not compromise operational safety of the aircraft."[8]
^Most pilots often call out "rotate," instead of VR. The "rotate" callout has the same meaning of VR and Vrot.[27]
References
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^Craig, Paul A. (2004). "1". Multiengine Flying (3rd ed.). McGraw Hill. pp. 3–6. ISBN 0-07-142139-4. Retrieved 7 May 2008.
^FAA (July 2008). "Title 14: Aeronautics and Space PART 23—AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Subpart G—Operating Limitations and Information Markings And Placards, Part 23, §23.1545". Archived from the original on 29 September 2006. Retrieved 1 August 2008.
^"Pilot's Handbook of Aeronautical Knowledge – Chapter 7" (PDF). FAA. Archived from the original (PDF) on 3 September 2013. Retrieved 29 January 2010.
^"Pilot's Handbook of Aeronautical Knowledge – Chapter 8" (PDF). FAA. Archived from the original (PDF) on 3 September 2013. Retrieved 29 January 2010.
^FAA (July 2008). "Title 14: Aeronautics and Space PART 25—AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Subpart G—Operating Limitations and Information Airplane Flight Manual, Part 25, §25.1583". Archived from the original on 29 September 2006. Retrieved 1 August 2008.
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^ a b c d e f g h i j k l m n o p q r s t u v w x yTransport Canada (October 2012). "Aeronautical Information Manual GEN – 1.0 GENERAL INFORMATION" (PDF). Retrieved 1 January 2013.
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^CAP 698: Civil Aviation Authority JAR-FCL Examinations: Aeroplane Performance Manual (PDF). Civil Aviation Authority (United Kingdom). 2006. pp. Section 4–MRJT1 Page 3. ISBN 0-11-790653-0. Archived from the original (PDF) on 14 November 2009. Retrieved 9 December 2009.
^FAA Advisory Circular 23-19A Airframe Guide for Certification of Part 23 Airplanes, Section 48 (p.27) Archived 7 December 2016 at the Wayback Machine Retrieved 2012-01-06
^PANS-OPS, Volume I, Part I, Section 4, Chapter 1, 1.3.3
^Aircraft Noise Abatement: Hearings Before the Subcommittee on Aeronautics and Space Technology of the Committee on Science and Astronautics, U.S. House of Representatives, Ninety-third Congress, Second Session, July 24, 25, 1974, page 593.
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^"] 14 CFR 1.2 Abbreviations and symbols "VC"".
^"14 CFR 25.335(a) Design cruising speed VC".
^ a b cMIL-STD-3013A Department of Defense Standard Practice: Glossary of definitions, ground rules, and mission profiles to define air vehicle performance capability. 9 September 2008. Page 21.
^ a b cFederal Aviation Administration. (February 2009). "Title 14: Aeronautics and Space PART 25—AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Subpart B—Flight Controllability and Maneuverability § 25.149 Minimum control speed". Archived from the original on 4 October 2010. Retrieved 16 February 2009.
^Administration, Federal Aviation (2017). Airplane Flying Handbook: FAA-H-8083-3B. Skyhorse Publishing, Inc. pp. 15–9. ISBN 9781510712843. Retrieved 3 October 2017.
^ a b c dBell Helicopter Textron: Bell Model 212 Rotorcraft Flight Manual, page II. Bell Helicopters Textron Publishers, Fort Worth, Texas, Revision 3, 1 May 1998. BHT-212IFR-FM-1
^Pilot's Handbook of Aeronautical Knowledge: FAA-H-8083-25B. Federal Aviation Administration (FAA). 25 September 2016. Retrieved 6 June 2022.
^USA 14 CFR §23.1507 Archived 12 February 2017 at the Wayback Machine Retrieved 2012-01-06
^ a b"Code of Federal Regulations. Title 14 Chapter I Subchapter C Part 25 Subpart B Performance, Section 25.107 Takeoff speeds". ecfr.gov. Federal Register. Retrieved 12 October 2022.
^Cox, John (29 September 2013). "Ask the Captain: How do pilots decide when to take off?". USA Today. Retrieved 8 February 2023.
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^TPUB INTERMEDIATE FLIGHT PREPARATION WORKBOOK APPENDIX A
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^ a b cBristow, Gary (22 April 2002). Ace the Technical Pilot Interview. McGraw Hill Professional. ISBN 9780071396097. Retrieved 20 January 2009.
^Castaigns, Philippe; De-Baudus, Lorraine (July 2017). "Procedures" (PDF). skybrary.aero. Archived from the original (PDF) on 24 August 2021. Retrieved 4 March 2022.
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^ a b cFlight Sim Aviation (2009). "Aviation Rules of Thumb – V-Speeds Abbreviations List". Retrieved 19 January 2009.
^E.G. Tulapurkara, Chapter 10 Performance analysis VI – Take-off and landing, retrieved 18 November 2015
^"C-130 Takeoff and Landing Data Card" (PDF). Elite Electronic Engineering, Inc. Archived (PDF) from the original on 19 August 2018. Retrieved 18 August 2018.
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^Blue Ridge Air Works (n.d.). "Cessna 152 – 4843H General Info". Archived from the original on 5 July 2008. Retrieved 13 February 2009.{{cite web}}: CS1 maint: year (link)
^"Speeds: Various Aviation Authorities" (PDF). sdmiramar.edu. Retrieved 4 March 2022.
^"Takeoff Safety Training Aid" (PDF). Federal Aviation Administration. p. 3. Archived from the original (PDF) on 4 March 2016. Retrieved 18 June 2015. V1. [...](1) The maximum speed by which a rejected takeoff must be initiated to assure that a safe stop can be completed within the remaining runway, or runway and stopway;
^"Code of Federal Regulations. Title 14 Chapter I Subchapter C Part 25 Subpart B Performance, Section 25.109 Accelerate-stop distance". ecfr.gov. Federal Register. Retrieved 12 October 2022.
^Albright, James (November 2014). "Aircraft Performance: Certification versus the real world" (PDF). Business & Commercial Aviation: 46–52. Retrieved 12 October 2022.
Further reading
Getting to grips with aircraft performance (PDF). Airbus Customer Services. January 2002. {{cite book}}: |work= ignored (help)