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Guest A32X

INIT REF question

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Guest A32X

Sirs,Under GROSS WT, I can't change the weight value i.e. it is fixed. Is this true to real life operations for the NG? I know in the 767 this value is changed to the landing gross weight in the cruise so you can calculate Vref for landing.Cheers-Paul

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Guest Ross

Paul,Don't take this as gospel but as far as I know, the FMC calculates the gross weight by adding the Zero Fuel Weight that you input to the weight of the fuel in the tanks. The gross weight should decrease as your flight progresses.

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Guest Zapper

The NG 'knows' the weight of fuel and the ZFW figure is entered on the INIT/REF page before flight. This is totalled with Fuel Weight to give Gross Weight. You will see the GW reduce in flight as fuel is burnt.Rgds,Brad Marsh

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Guest A32X

Yea, but by that logic you can only find out your Vref/approach bugs on final approach as your weight changes to your landing GW.In the 767, you change your GW manually approaching T/D on the INIT page to your estimated landing GW to calculate your approach speeds.I guess in the NG you'd have to keep changing them as your weight reduced? -Paul

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Guest bawheavy

Hey PaulThe PROG page shows predicted fuel at your destination. Add that to your ZFW and voila!Happy Flying ;)Liam

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Guest Ray CYYZ

>Yea, but by that logic you can only find out your>Vref/approach bugs on final approach as your weight changes to>your landing GW.>>In the 767, you change your GW manually approaching T/D on the>INIT page to your estimated landing GW to calculate your>approach speeds.>>I guess in the NG you'd have to keep changing them as your>weight reduced? >>-PaulPaul, on the approach page, once you set your flaps/Vref, it locks in the setting. If you plan on touring around for a while burning off lots of fuel, then you will need to reset your flaps/Vref to deal with the fuel burnoff change in weight. This is pretty consistant in all Boeings, not just the NG.Ray

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Guest A32X

I've calculated my landing GW for landing at 114.7, line selecting that number, it will not allow me to enter it into "GROSS WT" see pic; http://forums.avsim.net/user_files/70321.jpg(You can do this on the 767 FMC) is it impossible in real life to do this with an NG FMC?Cheers,Paul

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Okay, well I know that you can do this on a 767 and a 737 classic 300/400/500 however I'm not sure on the NG.I would say that you are supposed to be able to change it.Rob? Steve? Ian? Joe? Randy? Andrew? anyone?regards,Travis

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Hi,According to Bill Bulfer (what would I do without him?...lol) you should actually be able to enter any GW into LSK 1L and the FMC will then caculate new Vref speeds for that GW. DELeting any manually enterd value will revert back to show present GW.I'll forward this to the team! Thanks!Hope it helps,

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The 767 and 737NG approach ref pages are quite different in operation folks. Both generate approach speeds for particular weights & flap settings, but... with the NG, the resultant Vref speed (+5kts) is transferred to the LEGS page. With the 767, there is no transfer. Also, any manual entry of GW on the 767 automatically reverts to the calculated value (ZFW+Fuel Weight) when you leave the APP REF page. Hope this makes sense :-)Cheers.Ian.

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Guest A32X

I noticed that too, however one final question;In the descent if you have an engine failure how do you get into the engine out pages?CheersPaul

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Guest Zapper

Gents and Ladies,First of all this whole process is to get obtain a Vref for teh weight at which we expect to land.On the real NG (haven't checked the PMDG sim):You can definitely change the GW on INIT/REF at any stage of flight.When flying the real aircraft out on the line it goes something like this:When you are setting up your arrival (STAR APP etc) ( and hopefully before ToD)you go to PROG and subtract the 'Fuel at Dest' figure from the current 'Fuel on Board' figure. This tells you how much the Burn-Off between that time and landing will be. We then go to the INIT/REF page and look at the current GW (at L1) and mentally subtract the expected Burn-Off from teh current GW. Enter the result in teh scratchpad and then Line Select to L1. This will then change the Vrefs and you then LS the speed for the flap setting you intend to use (this is called 'Hardening Up' by some ppl as it cause that speed to remain the commanded Vref even if you now deleted the GW)This sound better?Brad Marsh

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Guest pagotan

Hi Brad,I fully agree with the procedure you described. This is how we proceed generally. I say generally because the timing for "hardening up" may vary from airline to airline depending on their own calculation (overall fuel saving, engines and gear stress etc..).The question is: can this be reproduced with the same effects in the PMDG 737 NG. Let's hope it can be implemented as soon as the nezt release.DISCLAIMER:The above reflects only a personal opinion and was written without any intend to offend, harm or criticize in any way or manner any individual, institution, association or company including PMDG.Michael

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