Hello everybody, 

I have noticed that the 777 calculates pretty high V1 speeds especially when I am really heavy, is this normal? For example, below is a picture of me taking off from KSFO RW 28R inbound OMDB (lot of fuel) and fully loaded in passengers and cargo. As you can see I am taking off with 95% thust and I had flaps 15. I would expect for my VR and V2 to be so high but what about V1? Can someone explain? Here are my V-speeds calculated by the FMC.
V1: 171
VR: 171
V2: 173
I am 100% sure I wouldn't be able to stop with that little RW left ahead of me if I aborted takeoff at let's say V1-1 knot.
Thanks in advance.

The FMC does not know about runway length. It will not calculate a V1 that makes sure you will be able to stop.

 

The FMC computes a "balanced field" V1, which is, after V1, it will take exactly the same legth to stop as to take off.

It is then your responsibility as a captain to ensure balanced field length for your conditions is less than actual field length.

So the only solution is to calculate the takeoff speeds on my own?

Weights?

I don't exactly remember, my ZFW was 290.1 and my FOB was around 127 Tons, so my weight was around 417 tons.

Max Takeoff Weight of the 777-200LR is 347,45t - so any questions of why your V-Speeds are that high left.....?

 

http://www.boeing.com/boeing/commercial/777family/pf/pf_lrproduct.page

Something must be wrong. Note that I am not complaining about my V-speeds, only about my V1
Anyway, the thing is that in my flightplan, (created using simbrief) my ramp fuel was around 127 tons if I remember correctly (in FMC it was shown around 85%) and I had selected full payload and I did not get any errors. I suppose if it couldn't take off wouldn't it have said "V-speeds not available?" or something? Also I didn't get a warning that I had passed my MTOW.

 

 

I am 100% sure I wouldn't be able to stop with that little RW left ahead of me if I aborted takeoff at let's say V1-1 knot.

 

As mentioned, it calculates "balanced field" v-speeds.  This is not a runway-specific measurement.  As such, your picture isn't at all surprising to me.

Further reading: http://en.wikipedia.org/wiki/Balanced_field_takeoff

 

To calculate runway-specific V₁, you will need to use a program like TOPCAT.

As mentioned, it calculates "balanced field" v-speeds.  This is not a runway-specific measurement.  As such, your picture isn't at all surprising to me.

Further reading: http://en.wikipedia.org/wiki/Balanced_field_takeoff

 

To calculate runway-specific V₁, you will need to use a program like TOPCAT.

Any freeware tools would be appreciated (if available). I am low on cash, saving for the -300ER expansion Thanks.

 

 

Any freeware tools would be appreciated (if available).

 

I'm not aware of any, though I'm sure there are a few out there.  I'll leave it up to others to post with recommendations.

So, why the FMC doesn't give any V speed until you fill in the departure runway? Only for fun or to take the runway lenght into the calculation?

 

Diego Mayán

Needs to be pointed out that TOPCAT doesn't support the 777 as of yet though. I wouldn't buy it expecting that.

Needs to be pointed out that TOPCAT doesn't support the 777 as of yet though. I wouldn't buy it expecting that.

 

haha - yeah, good point!  I was just addressing the topic of calculating runway specific speeds in general and blanked on the particular plane we were talking about.  It's definitely Friday...

are you doing derated takeoff?  and if so 1 2 or temp based drate?  might have to recalc your drates.

 

 

Thanks Andrei.

I noticed that the QRH reference speed for V1 I get with the 737NG is usually lower than the speed TOPCAT computes. I thought this was quite odd.

 

Not sure if TOPCAT is working on a performance file for the 777, but http://www.aurasim.com/ apparently is; as heads-up to whom it may concern.