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mikealpha

V-Speeds - Invalid entry

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I need a heads up what might lead to "Invalid entry" when trying to enter V-Speeds (also not getting any automatic V-Speeds).

 

I try to enter a flight from LFPO (Paris Orly) to TFFR (Guadeloupe), flight planning made with PFPX. Not matter which weight I use (close to MTW or 30t underload), the above mentioned V-Speed problem happens.

 

I assume something must be out of range, but what ?

 

Mike

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The invalid entry will occur if you try to enter speeds more than 5kt lower than the ones calculated by the FMC.

 

If you use an external software to calculate the takeoff speeds and you have more than 5kt discrepancy it can come from different cause:

 

_ external software calculates wrong takeoff speeds or updated with wrong parameters (wind, QNH, OAT, runway length, TOW)

_ page 2 of takeoff page in the FMC not correctly filled (wind, slope, OAT)

_ N1 TO rating not properly selected in the FMC

 

If you have no speed calculated by the FMC, it means you have not chosen a departure runway in the departure page of the FMC.

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If you have no speed calculated by the FMC, it means you have not chosen a departure runway in the departure page of the FMC.

Or the assumed temperature, derates, flap settings will not produce V speeds for a balanced field. On more than several occasions I have had TOPCAT calculate settings for the above items. Put those settings in the FMC and there are no V speeds in the FMC.

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Yes you're right, I forgot that as it never happened to me...

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Oh OK, thanks Romain and Michael for the answers. It was TOPCAT stuff indeed. Apparently the advice given in a different thread to use the 777F Profile in PFPX/Topcat for the 777-300ER (with some weights adjusted) does not work as it should.

 

Thanks again !

Mike

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While we`re at it, are you using the 300ER as well ?

Which sources are you using to get reasonable assumed temperatures or derates.

Toper (available at Simmarket) seems even more off than Topcat, when using the 777F for the 300ER. Huge differences between the two. 44C and 67C for the same flight, just to mention an example.

 

Mike

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While we`re at it, are you using the 300ER as well ?
No. I only have the base package. No 300ER.

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Toper (available at Simmarket) seems even more off than Topcat, when using the 777F for the 300ER. Huge differences between the two. 44C and 67C for the same flight, just to mention an example.

 

I'm not sure I have understood what you compare here.

 

I have TOPER and it works fine.And it comes with 4 profiles:  -200ER, -200LR, -300, -300ER.

So if you get TOPER you won't use the 777F for the 300ER but the 300ER profile.

 

If you compare the results from Topcat 200LRF profile to the TOPER 300ER profile, then yes you may have significant discrepancies but in that case I wouldn't trust Topcat as it is not the proper profile!

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I'm not sure I have understood what you compare here.

I have TOPER and it works fine.And it comes with 4 profiles: -200ER, -200LR, -300, -300ER.

 

Romain,

 

I saw a recommendation to use the 777F profile in TOPCAT for the 777-300ER (with weights adjusted). Still different engines, so it is already questionable.

And was wondering about the sometimes huge difference in assumed temperature when comparing it with TOPER 777-300ER results.

If I have understood correctly, both tools are using a different calculation approach.

 

Hard to judge for me which results to trust. So it's good to read you are confident with the TOPER results.

 

Mike

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Ok, so I had understood correctly.

So once again, I wouldn't trust  takeoff speeds calculated by Topcat with a profile for the -200LRF. As you have said, the two aircrafts don't have the same engines nor the same specifications.

Even with modified weights, Topcat remains irrelevant for the -300ER.

 

While Toper gets a profile specifically for the -300ER, I would trust much more these results.

 

However, I'm not a real pilot nor I get anyway to verify the takeoff speeds calculated by TOPER. The only thing I can say is that the discrepancies between the speeds calculated by the FMC (fully filled) and TOPER are very low in all the range I have tested, from very low weights to full takeoff weights.

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