Final Approach Attitude

[Vladtop 0]

Hello! I thought that this problem only with me. But I have watched this video http://forum.avsim.n...uring-approach/ and undestood that everybody has it. What I mean? See this video from 06:12. Vref30=141knots. IAS=146knots (Vref+5). Flaps position=30. Vertical speed=900ft/min. And... Attitude=0 degrees. According to FCOM, attitude for final approach with IAS=Vref+5 must be more then 2 degrees.Dear PMDG Team, could you chek it? Screen from that video:

[Humpty 751]

you have to maintain a 3 degree glide slope. If you want to check your glide slope but just for reference than check those VASI/PAPI lights before the threshold , all yellow means you are high and red means you are low , two yellow and two reds mean you are on a proper glide slope but use these lights only for reference. hmmm actually you approach looks right on the left runway. What is your descent rate ? Hey you already must be knowing all this.

[Flexman 30]

Assuming a 3º GP, 900 feet per minute sounds a bit high for that that speed. ROD for a 5,2%GP at 150knots should be around 790fpm. What is FAF to MAPT ROD on the published IAC? Also, ignoring the ROD, at what point did you calculate VREF. If during cruise, did you subtract the fuel for the remaining flight time? (ALM=GW-(FOB-fuel at landing). If you don't do that and calculate VREF too early without considering the mass loss, you'll end up using a VREF for a heavier airplane.

[jncgn 0]

I think he's wondering why the nose isn't pitched up.Well, I THINK that the pitch during approach doesn't matter and really depends on your weight, while the pitch doesn't tell anything about the glideslope at all.You can maintain your glideslope (which is mostly somehthing around 3 degrees) regardless of the pitch.

[Vladtop 0]

Thanks for reply. But you can change this on your system in any airports with glideslops 2,5 or 3 degree. You will see same attitude - zero. This is not correct.

[Flexman 30]

you have to maintain a 3 degree glide slope. If you want to check your glide slope but just for reference than check those VASI/PAPI lights before the threshold , all yellow means you are high and red means you are low , two yellow and two reds mean you are on a proper glide slope but use these lights only for reference. hmmm actually you approach looks right on the left runway. What is your descent rate ? Hey you already must be knowing all this.

That's far from what he's asking. What you say about what's found in the FCOM is right. Having said that and assuming a 3º GP, 900 feet per minute sounds a bit high for that that speed. ROD for a 5,2%GP at 146knots should be around 790fpm, so this might actually be an FS problem with glide paths, rather than PMDG's.Try testing this. Maintain 3ºattitude, VREF30+5 and check both rate of descent and glide path. Also, ignoring the ROD, at what point did you calculate VREF. If during cruise, did you subtract the fuel for the remaining flight time? (ALM=GW-(FOB-fuel at landing). If you don't do that and calculate VREF too early without considering the mass loss, you'll end up using a VREF for a heavier airplane.

[Vladtop 0]

...Also, ignoring the ROD, at what point did you calculate VREF. If during cruise, did you subtract the fuel for the remaining flight time? (ALM=GW-(FOB-fuel at landing). If you don't do that and calculate VREF too early without considering the mass loss, you'll end up using a VREF for a heavier airplane.

See CDU display on the screen. Actual calculated Vref is 141 knots.

[Flexman 30]

See CDU display on the screen. Actual calculated Vref is 141 knots.

Yes, but that is often something that people ignore. VREF on the box is calculated for the current Gross Mass of the airplane. If calculated right at top of CLIMB, that VREF will only make sense at that point and is not necesarily suitable for what the airplane will mass at landing (some hours ahead). So, to counteract this you can calculate VREF when the flight is almost over, which is not very elegant since all 5 items should be prepared before TOD, or you can calculate VREF knowing that you will have to subtract the mass loss of the rest of the flight and you do it like this: Check actual gross weight for which VREF is being calculated on the box. Then, notice the diffrence bewteen current fuel on board and landing fuel. That difference you will have to subtract to the gross mass and enter it on the approach page (LSK1L). Correct VREFs will show. But again, this doesn't look to be the problem. I think the problem is more trigonometrical. 900fpm at 146knots ground speed simply doesn't result in a 5,2% glide path.

[Vladtop 0]

...Try testing this. Maintain 3ºattitude, VREF30+5 and check both rate of descent and glide path...

Good idea! I'll try that in few hours.

[Humpty 751]

" while the pitch doesn't tell anything about the glideslope at all" i second that. The best way to calculate your GS , 5x (what ever speed) or more simple if your speed is 140 kts half 140 which = 70 and just a zero behind 70 = 700 fpm. I just fly the Baron 58 not got to any heavies so If am making things confusing than I apologize I have not idea about the 737.

[Vladtop 0]

Yes, but that is often something that people ignore. VREF on the box is calculated for the current Gross Mass of the airplane. If calculated right at top of CLIMB, that VREF will only make sense at that point and is not necesarily suitable for what the airplane will mass at landing (some hours ahead). So, to counteract this you can calculate VREF when the flight is almost over, which is not very elegant since all 5 items should be prepared before TOD, or you can calculate VREF knowing that you will have to subtract the mass loss of the rest of the flight and you do it like this: Check actual gross weight for which VREF is being calculated on the box. Then, notice the diffrence bewteen current fuel on board and landing fuel. That difference you will have to subtract to the gross mass and enter it on the approach page (LSK1L). Correct VREFs will show. But again, this doesn't look to be the problem. I think the problem is more trigonometrical. 900fpm at 146knots ground speed simply doesn't result in a 5,2% glide path.

Ok Sir. But as far as I know FMC is recalculating Vref speeds all the time according actual weight and fuel consuption.

[Flexman 30]

Ok Sir. But as far as I know FMC is recalculating Vref speeds all the time according actual weight and fuel consuption.

It recalculates the one that shows you as Gross Mass decreases, but it will never modify the one that you have selected.The fuel mass subtraction is standard procedure. (I don't fly 737, but during my frozen ATPL training i was working as a flight attendant in Spain and among the few things the pilots would let me do in flight, was setting up the box for approach, so i've done that quite a few times)

[Humpty 751]

Damn I didn't know the big girl calculates every thing that's nice .

[Flexman 30]

Damn I didn't know the big girl calculates every thing that's nice .

Has been doing that since the 80s ;)

[Humpty 751]

Has been doing that since the 80s ;)

Ah Ok , did not know that. what is the 910 below the G/S in the AI ? I hope that is not the ROD as it is completely wrong looking at the speed. and he has 2-3 kts tail wind.