V1, V2 & Vr

[bindook]

Hi Roberto,
Who works out the V1 V2 & Vr speeds for t/o & approach? Is it the mcdu after u have put all the info in? I think i have seen the approach speeds worked out (is this right?) in the mcdu.


Thanks

Michael

[Westozy]

FMC does it in the Boeing

[Bob Reed]

I am sure this is the case with the AB too.... Done with the MCDU... Pilot may double check...

[Trevor Hale]

I would agree with these fine Gents. As the V1, VR, V2 are all based on a formula taking into account OAT, ZFW, GW and Fuel Temp etc.

Definitely calculated by the MCDU, however the pilots do have a Matrix Graph they can use to check.

[Michael Carter]

And all this time I've been using paper! :p

[Bob Reed]

And all this time I've been using paper! :p

Ummmm Skunky!!???.... I think they have put a FMC in some of the 727's that are still in service... So you could stop using paper! :D

[Michael Carter]

Private and corporate 727's have been retro-fitted in many cases. Virtually the entire avionics suite is replaced during this. $$$$:

I'll stick with the paper though. :D

[mr rowntree]

V1 V2 and Vr are calculated by a LPC (Less Paper Cockpit laptop on board) which has all the weather and loading data entered into it. It then calculates the speeds against the runway and intersection selected for takeoff, then you are presented with 2 sets of speeds, a Flex Set of Speeds and a TOGA set of speeds, it also gives you the flap setting to use if you select an option which states Optimum Flap Config,

Some companies say that if the LPC comes out with Flap 3 you have to then tell it you want Flap 2 and then let it calculate the speeds for this specific flap setting but normally Flap 1 or 2 are used.

make sense?

[bindook]

ok, i entered in all the flight details & on the page where i put the v1 etc next to that column was V1= 146 v2 = 155 no flaps = 226 is this the info i put in ?


Thanks
Michael

[dodiano]

Hey Mike,

Actually V1, VR and V2 are calculated at least in my company by th e engineering Department and are placed in the planes in large books called Runway analyisis... These books are organized in alphabetical order for Example you have El Salvador our home base, we have a single Runway 07/25 so we have our runway analysis charts for Runway 07 and Runway 25 for Config 1,2 and Config 3 and we have a table on the left side we have the weight in Kilos and then we have several boxes where it ways the wind component from -15knots to I think 15 plus knots for certain Runways so we take the weight... and in the Boxes we check the wind normally we take into account 0 Wind and then the V1,VR,V2 AND flex are shown there for that weight we check the TREF to see if we canuse flex or Toga... Now these charts are made in Base of the Info on the FCOM Volume 2 that deals with Performance for the Bus... it is a bit complicated but actually we don´t look it up anymore in our weight and balance paper is already calculated for us, we can double check it if we want or if by any chance the weight and balance is made for runway 25 and we are taking off from 07 we just check the charts and correct the speeds... We can also get V1,VR,V2 corrections for contaminated runway and other factors that might affect T/O Performance... I think also Boeing in real life is entered via charts not sure though...

Is a bit complicated sorry but I cannot post these charts online!!

Take care,

Roberto.

By teh way Mike that was an excellent question...

[mr rowntree]

In my previous company we used these performance books and now since I came on to the Bus with this company we use a computer on board as I previously stated, I just presumed that all companies flying the 320 family used this method also, but as Roberto has stated his company use the printed book method.

I was told that the reason my company and a lot of other UK companies use the Laptop on board is because the computer can calculate the performance needed more accuratley than looking on graphs etc and therefore it can usually give us a de-rated thrust setting (FLEX) of around 1 degree hotter and therefore improve engine life, now 1 degree didn't sound much to me either but take this across a company operating the aircraft up to 12 sectors per day and this can make a huge saving!

Thanks to Roberto for filling me in on his companies methods, there are pictures on Airliners showing the laptops some companies use!

Regards

Rowntree

[bindook]

What i'm doing at the moment is ok as i make vr about 160kts.......& i haven't crashed yet....so i will just keep guesssing :-)



Michael

[dodiano]

Well we don´t use the laptop cause the speeds are printed in pur weight and balance Sheet which is calculated by the dispatch system, the books we use it in case or a Runway change... Ok I will have to say if you are Full Load on an A-320 Something like V1-138,VR-145,V2-150 should do the trick I´m guessing here.

Take care,

Roberto

[NigelD]

Hi Guys...
There is a small free tool I use to calculate these speeds for Airbus. However since it is not working right now (registry issues on my computer) and I want to broaden my knowledge - how the devil can these speeds be calculated by a dummy?! I fly the (increasingly unsatisfying) Wilco Airbusses. Usually 321 and 330-200. Some charts are included with the aircraft in a PDF, but they don't seem to add up. The figure I believe is supposed to be Flex jumps in tens....that seems like too much to me?

Also...what does the Flex figure mean? I understand it's a derated t/o, but what is the difference in real terms between Flex 35 and Flex 40?

Nigel.

[Michael Carter]

I don't know what that Flex figure refers to, but performance charts in the POH will help you calculate your V-speeds.

The problem is finding a POH for newer aircraft. :roll: