V2
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V2
Hello Guys n Gals,
I have just written a book about my 40 years on and off in the airline industry.
the book is finished and I had it proof read by a retired airline official who told
me that some of the explanations are not correct.
These are the explanations in question that I sourced from Google
and I would appreciate any comments to put me on the right track
(excuse the pun)
V1, is the speed beyond which the takeoff should no longer be aborted.
ROTATE, is the speed that the nose wheel of the aircraft leaves the ground.
V2 is the speed at which there is sufficient airflow over the control surfaces to actually control the aircraft.
He told me that the definition of V2 in particular troubled him.(He is not
a pilot)
I'm not interested in any sarcastic comments but just the good oil, the ridgy
didge stuff would be highly appreciated.
The book will be printed in the new year and will go on Trade Me,
Facebook, selected bookshops in NZ and BNE as well as E-Bay.
It goes back from recent times to the 1950's, in NZ with NZ, UT,
NM and ZQ, as well as Brisbane with AN.
Anyway thank you everyone so much for your help
Ozziekiwi
I have just written a book about my 40 years on and off in the airline industry.
the book is finished and I had it proof read by a retired airline official who told
me that some of the explanations are not correct.
These are the explanations in question that I sourced from Google
and I would appreciate any comments to put me on the right track
(excuse the pun)
V1, is the speed beyond which the takeoff should no longer be aborted.
ROTATE, is the speed that the nose wheel of the aircraft leaves the ground.
V2 is the speed at which there is sufficient airflow over the control surfaces to actually control the aircraft.
He told me that the definition of V2 in particular troubled him.(He is not
a pilot)
I'm not interested in any sarcastic comments but just the good oil, the ridgy
didge stuff would be highly appreciated.
The book will be printed in the new year and will go on Trade Me,
Facebook, selected bookshops in NZ and BNE as well as E-Bay.
It goes back from recent times to the 1950's, in NZ with NZ, UT,
NM and ZQ, as well as Brisbane with AN.
Anyway thank you everyone so much for your help
Ozziekiwi
https://www.legislation.gov.au/Details/F2005C00327
Speeds:
V1 means the take-off decision speed;
V1 (wet) means a reduced V1 established for use on a wet or contaminated runway;
V2 means the initial climb out speed which is not less than the take-off safety speed;
VR means the speed at which aeroplane rotation is initiated by the pilot during take-off;
VS means the minimum speed in a stall or the minimum steady flight speed.
Speeds:
V1 means the take-off decision speed;
V1 (wet) means a reduced V1 established for use on a wet or contaminated runway;
V2 means the initial climb out speed which is not less than the take-off safety speed;
VR means the speed at which aeroplane rotation is initiated by the pilot during take-off;
VS means the minimum speed in a stall or the minimum steady flight speed.
In English for the masses, I'd say
V1 is a speed before which if you have an engine failure or major failure you have to stop. If the problem happens after this, you have to keep going as there's usually not enough room to stop.
Vr is the predetermined speed that the pilot pulls pack on the stick or control column to lift the nose into the air
V2 is a speed the aircraft needs to fly faster than to climb out safely
V1 is a speed before which if you have an engine failure or major failure you have to stop. If the problem happens after this, you have to keep going as there's usually not enough room to stop.
Vr is the predetermined speed that the pilot pulls pack on the stick or control column to lift the nose into the air
V2 is a speed the aircraft needs to fly faster than to climb out safely
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V2 is the takeoff safety speed. It's the minimum speed at which the aircraft can fly, remain in control and comply with obstacle clearance requirements under 20.7.1b.
I remember in the turbo prop world some checkies would mark you down for not reducing to V2 in the second segment. This is idiotic and entirely incorrect. If you have an engine failure at a speed faster than V2, you'd maintain that to a limit. If you were slower than V2 you'd accelerate to that speed.
I remember in the turbo prop world some checkies would mark you down for not reducing to V2 in the second segment. This is idiotic and entirely incorrect. If you have an engine failure at a speed faster than V2, you'd maintain that to a limit. If you were slower than V2 you'd accelerate to that speed.
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V2 is the takeoff safety speed. It's the minimum speed at which the aircraft can fly, remain in control and comply with obstacle clearance requirements under 20.7.1b.
I remember in the turbo prop world some checkies would mark you down for not reducing to V2 in the second segment. This is idiotic and entirely incorrect. If you have an engine failure at a speed faster than V2, you'd maintain that to a limit. If you were slower than V2 you'd accelerate to that speed.
I remember in the turbo prop world some checkies would mark you down for not reducing to V2 in the second segment. This is idiotic and entirely incorrect. If you have an engine failure at a speed faster than V2, you'd maintain that to a limit. If you were slower than V2 you'd accelerate to that speed.
http://www.airbus.com/fileadmin/media_gallery/files/safety_library_items/AirbusSafetyLib_-FLT_OPS-TOFF_DEP_SEQ07.pdf
Folks,
Don't like your definitions of V1 much, mostly they reflect misinformation/misconception/misunderstanding that is all too common.
Boeing, derived from the certification standards of FAR 25 etc., and various FAA flight test guides in the last 30 or so years.
V1 --- the speed at which the takeoff must be continued, if the stopping has not already been commenced.
There is no decision at V1, it is go.
The decision to stop, and the initial actions to stop must be before V1.
Before you start ripping into me, I suggest you do your very basic homework, because too many company manuals fit the "misinformation/misconception/misunderstanding that is all too common."
So do the investigations of a number of not so successful rejected takeoffs.
Tootle pip!!
PS: Airbus words (not operator interpretation of) may seem a bit different, but the result is the same.
Don't like your definitions of V1 much, mostly they reflect misinformation/misconception/misunderstanding that is all too common.
Boeing, derived from the certification standards of FAR 25 etc., and various FAA flight test guides in the last 30 or so years.
V1 --- the speed at which the takeoff must be continued, if the stopping has not already been commenced.
There is no decision at V1, it is go.
The decision to stop, and the initial actions to stop must be before V1.
Before you start ripping into me, I suggest you do your very basic homework, because too many company manuals fit the "misinformation/misconception/misunderstanding that is all too common."
So do the investigations of a number of not so successful rejected takeoffs.
Tootle pip!!
PS: Airbus words (not operator interpretation of) may seem a bit different, but the result is the same.
Plus your v2 definition sounds more like the definition for Vmca and I think if memory serves me correctly V2 is usually 1.1 Vmca.
And your rotate definition is more rotation. When rotate is called we start the rotation proceedure but the nose wheel hasn't left the ground yet.
And your rotate definition is more rotation. When rotate is called we start the rotation proceedure but the nose wheel hasn't left the ground yet.
Last edited by aussie1234; 15th Dec 2016 at 23:18. Reason: Before the spelling gods get me
LeadSled has it. Misconceptions of V1 abound. It is not a decision speed, it is the speed at which the first action to stop takes place - applying brakes, reducing thrust, deploying speed brakes. The decision to stop therefore takes place prior to V1, see (a)(2) below. Interestingly, even Civil Aviation Order 20.7.1B gets the V1 definition completely wrong, so no wonder confusion exists.
The official definitions
§25.107 Takeoff speeds.
(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.
(b) V2MIN, in terms of calibrated airspeed, may not be less than—
(1) 1.13 VSR for—
(i) Two-engine and three-engine turbopropeller and reciprocating engine powered airplanes; and
(ii) Turbojet powered airplanes without provisions for obtaining a significant reduction in the one-engine-inoperative power-on stall speed;
(2) 1.08 VSR for—
(i) Turbopropeller and reciprocating engine powered airplanes with more than three engines; and
(ii) Turbojet powered airplanes with provisions for obtaining a significant reduction in the one-engine-inoperative power-on stall speed; and
(3) 1.10 times VMC established under §25.149.
(c) V2, in terms of calibrated airspeed, must be selected by the applicant to provide at least the gradient of climb required by §25.121(b) but may not be less than—
(1) V2MIN;
(2) VR plus the speed increment attained (in accordance with §25.111(c)(2)) before reaching a height of 35 feet above the takeoff surface; and
(3) A speed that provides the maneuvering capability specified in §25.143(h).
(d) VMU is the calibrated airspeed at and above which the airplane can safely lift off the ground, and con- tinue the takeoff. VMU speeds must be selected by the applicant throughout the range of thrust-to-weight ratios to be certificated. These speeds may be established from free air data if these data are verified by ground takeoff tests.
(e) VR, in terms of calibrated airspeed, must be selected in accordance with the conditions of paragraphs (e)(1) through (4) of this section:
(1) VR may not be less than—
(i) V1;
(ii) 105 percent of VMC;
(iii) The speed (determined in accordance with §25.111(c)(2)) that allows reaching V2 before reaching a height of 35 feet above the takeoff surface; or
(iv) A speed that, if the airplane is rotated at its maximum practicable rate, will result in a VLOF of not less than —
(A) 110 percent of VMU in the all-engines-operating condition, and 105 percent of VMU determined at the thrust-to-weight ratio corresponding to the one-engine-inoperative condition; or
(B) If the VMU attitude is limited by the geometry of the airplane (i.e., tail contact with the runway), 108 percent of VMU in the all-engines-operating condition, and 104 percent of VMU determined at the thrust-to-weight ratio corresponding to the one-engine-inoperative condition.
(2) For any given set of conditions (such as weight, configuration, and temperature), a single value of VR, obtained in accordance with this paragraph, must be used to show compliance with both the one-engine-inoperative and the all-engines-operating takeoff provisions.
(3) It must be shown that the one-engine-inoperative takeoff distance, using a rotation speed of 5 knots less than VR established in accordance with paragraphs (e)(1) and (2) of this section, does not exceed the corresponding one-engine-inoperative takeoff distance using the established VR. The takeoff distances must be determined in accordance with §25.113(a)(1).
(4) Reasonably expected variations in service from the established takeoff procedures for the operation of the airplane (such as over-rotation of the airplane and out-of-trim conditions) may not result in unsafe flight characteristics or in marked increases in the scheduled takeoff distances established in accordance with §25.113(a).
(f) VLOF is the calibrated airspeed at which the airplane first becomes airborne.
(g) VFTO, in terms of calibrated airspeed, must be selected by the applicant to provide at least the gradient of climb required by §25.121(c), but may not be less than—
(1) 1.18 VSR; and
(2) A speed that provides the maneuvering capability specified in §25.143(h).
(h) In determining the takeoff speeds V1, VR, and V2 for flight in icing conditions, the values of VMCG, VMC, and VMU determined for non-icing conditions may be used.
The official definitions
§25.107 Takeoff speeds.
(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.
(b) V2MIN, in terms of calibrated airspeed, may not be less than—
(1) 1.13 VSR for—
(i) Two-engine and three-engine turbopropeller and reciprocating engine powered airplanes; and
(ii) Turbojet powered airplanes without provisions for obtaining a significant reduction in the one-engine-inoperative power-on stall speed;
(2) 1.08 VSR for—
(i) Turbopropeller and reciprocating engine powered airplanes with more than three engines; and
(ii) Turbojet powered airplanes with provisions for obtaining a significant reduction in the one-engine-inoperative power-on stall speed; and
(3) 1.10 times VMC established under §25.149.
(c) V2, in terms of calibrated airspeed, must be selected by the applicant to provide at least the gradient of climb required by §25.121(b) but may not be less than—
(1) V2MIN;
(2) VR plus the speed increment attained (in accordance with §25.111(c)(2)) before reaching a height of 35 feet above the takeoff surface; and
(3) A speed that provides the maneuvering capability specified in §25.143(h).
(d) VMU is the calibrated airspeed at and above which the airplane can safely lift off the ground, and con- tinue the takeoff. VMU speeds must be selected by the applicant throughout the range of thrust-to-weight ratios to be certificated. These speeds may be established from free air data if these data are verified by ground takeoff tests.
(e) VR, in terms of calibrated airspeed, must be selected in accordance with the conditions of paragraphs (e)(1) through (4) of this section:
(1) VR may not be less than—
(i) V1;
(ii) 105 percent of VMC;
(iii) The speed (determined in accordance with §25.111(c)(2)) that allows reaching V2 before reaching a height of 35 feet above the takeoff surface; or
(iv) A speed that, if the airplane is rotated at its maximum practicable rate, will result in a VLOF of not less than —
(A) 110 percent of VMU in the all-engines-operating condition, and 105 percent of VMU determined at the thrust-to-weight ratio corresponding to the one-engine-inoperative condition; or
(B) If the VMU attitude is limited by the geometry of the airplane (i.e., tail contact with the runway), 108 percent of VMU in the all-engines-operating condition, and 104 percent of VMU determined at the thrust-to-weight ratio corresponding to the one-engine-inoperative condition.
(2) For any given set of conditions (such as weight, configuration, and temperature), a single value of VR, obtained in accordance with this paragraph, must be used to show compliance with both the one-engine-inoperative and the all-engines-operating takeoff provisions.
(3) It must be shown that the one-engine-inoperative takeoff distance, using a rotation speed of 5 knots less than VR established in accordance with paragraphs (e)(1) and (2) of this section, does not exceed the corresponding one-engine-inoperative takeoff distance using the established VR. The takeoff distances must be determined in accordance with §25.113(a)(1).
(4) Reasonably expected variations in service from the established takeoff procedures for the operation of the airplane (such as over-rotation of the airplane and out-of-trim conditions) may not result in unsafe flight characteristics or in marked increases in the scheduled takeoff distances established in accordance with §25.113(a).
(f) VLOF is the calibrated airspeed at which the airplane first becomes airborne.
(g) VFTO, in terms of calibrated airspeed, must be selected by the applicant to provide at least the gradient of climb required by §25.121(c), but may not be less than—
(1) 1.18 VSR; and
(2) A speed that provides the maneuvering capability specified in §25.143(h).
(h) In determining the takeoff speeds V1, VR, and V2 for flight in icing conditions, the values of VMCG, VMC, and VMU determined for non-icing conditions may be used.
Last edited by megan; 15th Dec 2016 at 23:40.
The decision to stop, and the initial actions to stop must be before V1.
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From my operators performance manual:
V1:
"The maximum speed in the takeoff at which the pilot must take the first action (i.e. apply brakes, reduce thrust, deploy speedbrakes, etc) to stop the aeroplane 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"
V2:
"Takeoff safety speed. The target speed to be attained at the screen height, assuming an engine failure during the takeoff. This speed must be at least 1.13 times VS in the takeoff configuration"
V1:
"The maximum speed in the takeoff at which the pilot must take the first action (i.e. apply brakes, reduce thrust, deploy speedbrakes, etc) to stop the aeroplane 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"
V2:
"Takeoff safety speed. The target speed to be attained at the screen height, assuming an engine failure during the takeoff. This speed must be at least 1.13 times VS in the takeoff configuration"
Traffic etc.,
That may well be your contention, but as I said, lots of misconception around.
I wouldn't be quoting your "contention" at an accident investigation, if I were you.
KZ Kiwi,
Same answer, despite years since the problem became known, and major training campaigns to get the message across were commenced, there is still plenty of what you quote in evidence.
I even had a CASA FOI tell me, quite recently, that because CASA has (demanded) approved (which CASA legally doesn't, they "accept") similar wording in a manual, therefor it was legal.
My question about whether CASA had a Legislative Instrument "legally" amending the laws of basic physics (as it applies to the dynamics of takeoff certification) of it, unsurprisingly, went straight through to the keeper.
Tootle pip!!
That may well be your contention, but as I said, lots of misconception around.
I wouldn't be quoting your "contention" at an accident investigation, if I were you.
KZ Kiwi,
Same answer, despite years since the problem became known, and major training campaigns to get the message across were commenced, there is still plenty of what you quote in evidence.
I even had a CASA FOI tell me, quite recently, that because CASA has (demanded) approved (which CASA legally doesn't, they "accept") similar wording in a manual, therefor it was legal.
My question about whether CASA had a Legislative Instrument "legally" amending the laws of basic physics (as it applies to the dynamics of takeoff certification) of it, unsurprisingly, went straight through to the keeper.
Tootle pip!!
Leadie, so who is correct? Boeing, or the FAA? You contend they are different. My contention agrees with the FAA def as supplied by Megan.
I think everyone in this thread, and the FAA and Boeing, are actually in heated agreement on what V1 should mean operationally: A decision to stop must have been initiated (past tense) at or before V1, otherwise you must continue. So if the toes hit the brakes at the same time as reaching V1, you can continue to stop even though you've reached V1 (and, on my reading of the FAA and Boeing words, even if you exceed V1 during the stopping action, provided the stopping action was initiated at or before V1).
The definition in CAO 20.7.1B seems the one that's out of step.
However, in fairness to the CAO and as I noted above, the FAA and Boeing words don't seem to rule out the possibility of exceeding V1 but continuing stopping, providing the stopping action was initiated at or before V1. So maybe there is the potential for (another) decision to be made at V1. What happens if your stopping action was initiated at or before V1, but fails? Your toes hit the brakes but they fail and have no effect. Wouldn't you have another decision to make? To 'un-make' your decision to stop?
The definition in CAO 20.7.1B seems the one that's out of step.
However, in fairness to the CAO and as I noted above, the FAA and Boeing words don't seem to rule out the possibility of exceeding V1 but continuing stopping, providing the stopping action was initiated at or before V1. So maybe there is the potential for (another) decision to be made at V1. What happens if your stopping action was initiated at or before V1, but fails? Your toes hit the brakes but they fail and have no effect. Wouldn't you have another decision to make? To 'un-make' your decision to stop?