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NickFlightX

V Speeds

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When i go to put in my V Speeds for a flight, it sometimes wont show up automaticlly, but after i change the weight and the ZFW, the V Speeds appear. Whats wrong?

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Likely (more-so on a de-rated takeoff) the speeds needed would be outside the parameters for the combination of runway length, weight, and temp.

 

Since there is no Topcat profile for the T7 yet I play with the settings for de-rated takeoff/climbs and if I de-rate and I get no V-Speeds its because there wouldn't be enough runway for the takeoff at reduced thrust.  And if not de-rated then simple the runway could be to short.

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Likely (more-so on a de-rated takeoff) the speeds needed would be outside the parameters for the combination of runway length, weight, and temp.

 

Since there is no Topcat profile for the T7 yet I play with the settings for de-rated takeoff/climbs and if I de-rate and I get no V-Speeds its because there wouldn't be enough runway for the takeoff at reduced thrust. And if not de-rated then simple the runway could be to short.

Not true. Calculated Vspeeds does not take runway length into account. Make sure the initial pages are re-executed.

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You need your performance data entered and the departure runway selected. Furthermore, T/O speeds don't show until the ADIRS is fully aligned.

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Not true. Calculated Vspeeds does not take runway length into account. Make sure the initial pages are re-executed.

 

Eh? How are balanced field calculations done without it? And the PERF INIT page doesn't require execution.

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How are balanced field calculations done without it?

 

Balanced field calculations are always done without it... by definition.

 

Balanced field is such a field, that in case of V1 cut, go-distance and stop-distance are the same. For every given set of ATOW and actual available thrust (incl. derates and enviro factors), there is only one such V1 and field length. 

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You need your performance data entered and the departure runway selected. Furthermore, T/O speeds don't show until the ADIRS is fully aligned.

 

This is the post that answers the OP.

  • Performance Data (Weight, temp, derates, flap selection etc)
  • Departure runway selected
  • ADIRS Alligned

any one of those 3 missing, the Vspeed autofill will be missing.

 

This is different from NGX, where the IRS didn't have to be completed alignment for the data to be inserted.

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Balanced field calculations are always done without it... by definition.

 

Balanced field is such a field, that in case of V1 cut, go-distance and stop-distance are the same. For every given set of ATOW and actual available thrust (incl. derates and enviro factors), there is only one such V1 and field length.

Whoops. I was thinking derate.

 

So why does the FMC need a runway selection?

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It's all about filling the correct info into the FMC.  If info is missing or the execute not executed then there will be problems with V Speeds and configuration settings.

 

Read the manuals that accompanied the aircraft.

 

Rob

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Whoops. I was thinking derate.

 

So why does the FMC need a runway selection?

 

At least for heading information that combined with wind info will affect v speeds.

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At least for heading information that combined with wind info will affect v speeds.

 

*face palm* thanks, should have known.

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