View Full Version : A320 performance

27th Oct 2009, 15:21

At the bottom of A320 RTOW chart, there are MIN V1/Vr/V2.
If after corrections I get V1 or V2r less than indicated there what to do?
Should I set TOGA and take MIN speeds, or maybe itís not possible to take-off at all?:sad:
Thank you.

27th Oct 2009, 16:41
:rolleyes:I think you're stuck, add weight.:ugh:

28th Oct 2009, 04:13
If you read the fine print it will tell you to use the corrected speeds or min speeds whichever is LARGER.

28th Oct 2009, 08:13
When reading too much - you're right it's easy to get too deep in the fog:ugh:

28th Oct 2009, 12:37
We just go up the speeds with the max flex until we reach the highest weight/speeds with maximum flex, which has always taken the V speeds above the minimum required in my experience. Also we get the benefit of increased climb performance.

28th Oct 2009, 17:51
Hi Tom ,

You are talking about how to use a RTOW chart in normal conditions. Minimum V1/Vr/V2 speeds are not just there for decoration.

There are some rare cases like: a very light aircraft in wet conditions use of engine anti ice , where speeds have to be reduced and the resulting speeds would be below minimum speeds. In that case speeds have to be compared to minimum V1/Vr/V2 speeds.
V1 can not be lower than Vmcg therefore a minimum V1 has been defined
V2 can not be lower than VMU that s the purpose of a Minimum V2 !

if V2 is below Vmu , Flex take off is not allowed .

28th Oct 2009, 18:16
Citation 2

You mean VR when you say V2, in the last part of your post, don't you?
I mean, V2 has nothing to do with VMU, but VR does.

29th Oct 2009, 00:13
I meant V2 when I said V2 in my previous post . V2 has to be above Vr , and VR and VMU are related, so indirectly V2 is related to VMU.-----> V2 must be above VMU

FCOM 2.02.14 P3 : " Check V2 against VMU limitation. If V2 is lower than V2 limited by VMU ,flex take off is not possible . Set TOGA thrust and retain the speeds associated with maximum permissible take off weight or the speeds read in the chart of the actual weight if they are all lower . "

I also recommend you to have a look at the diagram summary on FCOM 2.02.14 P8 :
V2> Minimum V2 ( VMU) ? If no---->flex take off not possible.

I also recommend to have a look at the table "V2 limited by VMU " FCOM 2.02.25 Page 2

VMU is the minimum speed at which the aircraft can safely lif off the ground. There are situations where V2 is limited by VMU . In that case V2 would have to be increased to minimum V2.

Example : FCOM 02.02.25 P4 : weight 60 t , pressure altitude 0 ---> minimun v2 limited by VMU is 124.

Again at low weights and altitudes , wet runways ..., Corrections applied on speeds make them lower than they should be . V1 might be less than VMCg, in this case V1 would have to be increased to VMCg .

If V1 is lower than VMCg in case of an engine failure , you will not keep the runway centerline.

29th Oct 2009, 01:23
To answer your question. You cant just "up" your V1 to the minimum. This can as said happen on short runways in certain conditions(wet, etc as stated earlier) You can end up in a situation where you cant go, ( with those conditions)
Solution, find/wait for some headwind, or wait for runway to "dry" so that speeds now meet the "min speeds" requirements.Have a look at Jersey (wet).
(In passing, i think V2 can be, equal to,or greater than Vmu.)

29th Oct 2009, 01:28
in a small benelux country i worked in many moons ago the company there used vfr figs should the rtow figs not tally up....it was a new one on me.....:}