V2 callout

[Speedbird744]

Can someone clarify why the PNF doesn't bother calling out V2 during the takeoff+climbout?

There are, I'm sure airlines around the globe that have this as part of their SOPs, but many that don't.
And I would have thought this is a pretty important speed in the event of climbing away safely on one engine.

Thank you,
S744

[Carnage Matey!]

Perhaps its because V2 is speed thats usually bugged on the airspeed indicator so theres no need to call it, you can tell just by looking. Also you tend to achieve V2 during the rotation manouvre, which by definition is transient, so calling it would add an extra complication when you should be concentrating on achieving the correct pitch attitude and not scraping the tail. Just my thoughts.

[BOAC]

Also worth remembering is that the handling pilot is normally looking out of the window at V1 but by V2 is on instruments.

[Dockjock]

We call (PNF)"Venr"/ (PF)"Flaps Up" but its for a medium turboprop.
And realistically the call is usually late after the "Positive Rate"/"Gear Up" call has been completed we're usually through Venr +10 anyway.

[GlueBall]

It's altogether more important for the PNF to call out if V2 and V2+10/20 is not achieved. :{

[fireflybob]

Remember too that speed callouts are advisory. We are all capable of error and it would not be the first time if the PNF misread the ASI and/or made the wrong call at the wrong time, etc.

For this reason the PF flying should be aware of the relevant speeds and act accordingly.

[411A]

Yes, all too often.
As part of training, have asked the PNF to 'call' V1 and Vr ten knots early.
The rather inexperienced guys nearly always start the rotation maneuver, irrespective of the correctly set bug on their ASI.

Lets face facts here.
IF the PF cannot actually look at his ASI, and determine for himself the correct speeds, they really don't belong on the flight deck.

Period.

[Old Smokey]

For jet operations -

No significant 'event' occurs at V2, and calling V2 would be totally pointless.

V1 and Vr ARE significant 'event' speeds, and should be called.

At V1 the aircraft transitions from the 'NO GO' to the 'GO' state, and the call establishes this altered status in flight crew's awareness. The V1 call is so important that modern aircraft incorporate an automated V1 call from the FMC to cockpit speakers.

Vr is a significant 'event' speed, at Vr the PNF calls "Rotate" (or something similar), and the PF executes the rotation of the aircraft to become airborne.

V2 is a very important speed, but no event takes place. It is the speed which is achieved by 35 feet following engine failure, the minimum speed for initial climb-out etc. A PNF call of "V2" would have no meaning. A PNF call if speed was below V2, or too much above would be appropriate.

In times of old when I flew DC3's, we did call V2, because V1, Vr, and V2 were all incorporated into the one speed. Simpler aeroplanes, simpler times.

[Speedbird744]

Thats well put indeed.

Thanks Old smokey.

[510orbust]

When calling out a speed, ie. V1 something usually happens ( pf hands come off the thrust in case of engine out you are commited to the take off) Vr ( you rotate) in the operation I was part of only time V2 was mentioned was if there was an engine failure and the PF calls were engine failure, speed, bug V2 (again something happening) if I was to fly v2 on take off it would give me a deck angle of about 28 degrees depending and a rate of climb ( well I am not going to make you all drool ) but you get the idea.. So yes in some instances a totally useless call in abnormal situations a very important one

510

[FO4FlyI]

Remember your human factors training as it relates to communication...The more you talk the less is heard.

[126.9]

Shouldn't the question be: "Who can p!ss the furthest?" :}

[Old Smokey]

7p3i7lot,

[QUOTE] I guess that is part of the Boeing philosophy of "quiet and dark" unless something needs your ATTENTION! [UNQUOTE]

Thanks for reinforceing my earlier remark. It was the "quiet and dark" BOEING 777 - 200 / 300 that I was referring to.

[mutt]

Hate to go in a tangent, but I'm going to.... We initially had the V1 automotically called out by a female voice on the B772, as i live in one of the more conservative Middle Eastern countries, this was quickly changed to a male voice... :):) Guess that the locals didnt like taking orders from a female!

At V1 the aircraft transitions from the 'NO GO' to the 'GO' state

Old Smokey, we are striving to teach that the aircraft has TRANSITED.... All has to do with VEF on newer aircraft.

Mutt.

[Old Smokey]

Mutt,

Point well taken, I'll check my grammar more carefully in future.

[Devils Advocate]

Not sure if this helps.....

Aircraft performance should be such that, with an engine failure at V1, the aircraft will obtain a minimum of V2 by the screen height ( 35ft dry / 15 ft wet ). Nb. With all engines running, this is more likely to be V2 + 15 to 20 Kt.

In the configuration used for takeoff, V2 is never less than 1.1 x Vmca, OR 1.2 x stall speed. Thus, when at V2, the aircraft is (10%) above Vmca, and (20%) above the power-off stall.

Nb. Most piston engined aircraft have a V2 which is 15% above the power off stall speed, but with jet aircraft the benefit of prop wash over the wing is lost and so, to make up for this, the margin was increased to 20%.

You might recall ( from Perf’A )

The 1st segment begins at ‘reference zero’ and ends when gear retraction is complete wherein it assumes you have attained and maintained V2.

W.r.t. 1st segment climb gradients - BCARs/JARs require a minimum gross climb gradient in this segment of:
2 power units = 1.0%
3 power units = 0.7%
4 power units = 0.5%

Nb. If landing gear is fully retracted by 35ft, there will be no 1st Segment and the Take-off Flight Path will commence with the 2nd Segment….. starting at 35ft ( dry ).
Failing that, the 2nd segment climb begins at the end of the 1st segment and ends at a minimum height of 400' above the runway and a maximum height of 1500ft ( which also happens to be where the net take-off flight path normally ends ).

Aside - many company Airport Analysis / Performance table specify an acceleration altitude of 1000ft AGL ( the B737 FMC usually defaults to 1500ft )

V2 ( with gear 'Up' ) must be maintained throughout the 2nd segment to a minimum of 400 ft AGL, such that the 2nd segment climb performance criteria is met.

W.r.t. 2nd segment climb gradients - BCARs/JARs require a minimum gross climb gradient in this segment of:
2 power units = 2.4%
3 power units = 2.7%
4 power units = 3.0%

This is always the most restrictive climb segment for all two engine jets currently certificated. Nb. It may not be the most limiting for some older airplanes whose engines have a substantial difference between Take-Off, and Maximum Continuous power.

V2 is not ‘performance’ related but to do with the handling characteristics of the aircraft. Achieving and flying at V2 will assure that the aircraft performs as stated in the Aircraft Flight Manual (AFM). If an engine is lost at a speed greater than V2, you will be above the minimum required takeoff flight path ( .... think about it :hmm: ).

V2 is not Vxse ( minimum ground distance to altitude / best angle single engine ) and neither is it Vyse ( minimum time to altitude / best rate single engine ) where these speeds are typically 20 to 70 knots higher respectively. Accordingly V2 is set as somewhat of a compromise between what would be optimum for takeoff ( suffering an engine failure at V1 ), and what would result in the most optimum initial climb performance.

V2 varies with weight and flap setting. Less flaps means better climb performance, but usually requires a longer runway ( .... again, think about it ! ;) )