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fsxnate

Minimum speed calculation during Manual NAVRAD entry

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Hi all,

 

before I start please feel free to go READ THE MANUAL and shame me for posting such silliness!  : P

 

 

So to put it as simple as possible:   I have a PMDG 777-200 with Short range fuel and empty (PAX or CARGO version) I take off and do some air work (navigation in the area) planning on either touching down or touch and go back in.  I notice that my minimum VREF is 180 to 190kts on the Tape and won't let me fly any slower with my A/T setting , however if I plan a route with the same Fuel/Payload (150 miles or so not much more different then flying some of the navigation in the area) my Approach REF in the FMC can be 138 (143 VREF + 5) with Flaps 25.  So basically my question is why does it hold a much higher minimum VREF unless you have a route programmed in?

 

thanks!

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That is a funny one.

 

But the FMC really should allways have a departure and destination airport.

 

Why dont you just use the same airport for departure and destination, enter ine waypoint in the area, activate and execute.

 

That should take care of it.

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@777simmer

 

that sounds like a plan, I usually did that on previous aircraft

 

@ollli4740

 

in all honesty I put my fuel/payload in, then set my HDG and ALT SPD turned on the Flight Directors and input they ILS/CRS into the NAV/RAD then went and had fun lol, probably need to do some more FMC programming?

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Thank you! yes ZFW worked like a charm, did a few touch and go's and the VREF was spot on

 

again thank you very much!

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Yeah, ofcourse without a ZFW the aircraft does not know how heavy it is and thus it cant calculate anything.

 

Anywhere where you see empty squares in the FMC you HAVE to put something in (I know this is FS.....you dont have to anything :-) )

But not just anything.....you gotta put the correct values in.

PMDG has made that real easy to do....just click on the line select key next to ZFW twice and it is CORRECTLY entered (same for Cg).

(If you just manually overwrite this value with a fictional ZFW, then the FMC will calculate with that.

All will look good but nothing is right actually.

As in you could stall while flying at Vref 137kt because you are actually much heavier (actual ZFW can be seen and adjusted under the MENU button) then what you entered manually!

 

This is actually a real world danger that has caused accidents in the past!

 

So, adjust your payload and fuel load on the CDU MENU pages and then double click the ZFW line select key to enter the correct, actual ZFW in the FMC performance page.

 

 

Oh, and if you do those short practice flights a lot, then just enter all data correctly once and then save the panel state.

 

Call it something like AIRWORK and from then on you can just load and go with that setup from pretty much everywhere.

Thrust reduction values and V1/V2/VR will not be correct for all conditions, but if you dont care about that (this is FS right) then you will be able to get airborne like that from pretty much anywhere in a sec.

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Wonderful, thanks again! it makes sense to fill everything out.  What would a Pilot do for touch and go's route wise? I guess it depends if they are training, testing the plane out etc?

 

thanks!

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