Final Approach Attitude

[Flexman 30]

What is exactly, the best time to set up Vref on the Approach page? The checklist shows that it should be done just before decent, but would it be better to do it later in the approach?

It really depends. Imagine you selected the VREF calculated 10 minutes before TOD. In that case, the difference in mass between that moment and touchdown would probably only mean a 200Kg difference which would result in no more than 1 knot difference (but remember for each extra knot, landing distance required could be increased in 200ft if not lost during flare). Now imagine that after TOD there's a complex standard approach ahead. Say that ATC requires you to hold for 10 minutes. All of those "contingencies" should be considered for they can result in differences of maybe some 1000kg between your calculated VREF and the actual one. VREF is, on these airplanes, 1,3Vso. As mass increases, so does Vso. The higher your VREF, the longer your landing distance required will be, and every know counts. I dont know precisely how much 1000Kg would increase your VREF, though it's not hard to calculate. Say that gives you 5 extra knots... it would result in 1000ft of added braking distance. "Not very elegant". So, the procedure is to, when selecting the VREF, you first subtract the fuel mass that will be lost during approach by comparing total FOB with the destination fuel show in the box. Subtract the difference to the Gross Mass and enter the resulting figure in LSK1L, and let VREFs be recalculated. Only then you can select the correct VREF for the config you are going to use. Of course, if ATC needs you to hold for 30 minutes (sorry about you), then you will need to update your VREF accordingly. The important thing to know is that the gross mass value shown in the approach reference page, is at an input field that can and should be modified if necesary. When I did this the first time in the real airplane, the pilots were suprised to know that I learned this with the old PMDG. I was trying really hard to impress them, so that they'd grant me more flight student cockpit passes :)

[XPX64man 130]

It really depends. Imagine you selected the VREF calculated 10 minutes before TOD. In that case, the difference in mass between that moment and touchdown would probably only mean a 200Kg difference which would result in no more than 1 knot difference (but remember for each extra knot, landing distance required could be increased in 200ft if not lost during flare). Now imagine that after TOD there's a complex standard approach ahead. Say that ATC requires you to hold for 10 minutes. All of those "contingencies" should be considered for they can result in differences of maybe some 1000kg between your calculated VREF and the actual one. VREF is, on these airplanes, 1,3Vso. As mass increases, so does Vso. The higher your VREF, the longer your landing distance required will be, and every know counts. I dont know precisely how much 1000Kg would increase your VREF, though it's not hard to calculate. Say that gives you 5 extra knots... it would result in 1000ft of added braking distance. "Not very elegant". So, the procedure is to, when selecting the VREF, you first subtract the fuel mass that will be lost during approach by comparing total FOB with the destination fuel show in the box. Subtract the difference to the Gross Mass and enter the resulting figure in LSK1L, and let VREFs be recalculated. Only then you can select the correct VREF for the config you are going to use. Of course, if ATC needs you to hold for 30 minutes (sorry about you), then you will need to update your VREF accordingly. The important thing to know is that the gross mass value shown in the approach reference page, is at an input field that can and should be modified if necesary. When I did this the first time in the real airplane, the pilots were suprised to know that I learned this with the old PMDG. I was trying really hard to impress them, so that they'd grant me more flight student cockpit passes :)

Thank you Omar. I'm going to start trying it this way. I notice that sometimes I seem to land a little too fast. This might help. Bob

[Flexman 30]

I too noticed that the NGX is too "slippery". If you want you can hoover just above the ground for a long long way with idle power and a minimum reduction of airspeed. I think the flight model is very accurate in the climb, cruise and descent, but far from realistic in the lower regions in approach configs. Hopefully PMDG will address this issue for SP1.

Oooh, the real plane does really floats. These things need to be gently flown into the runway, unlike General Aviation airplanes in which landings are "controlled stalls".

[michal 44]

but far from realistic in the lower regions in approach configs. Hopefully PMDG will address this issue for SP1.

I am not sure whether they address this or not but in any case if some feeel the plane has too much lift it seems there is an easy practical remedy - carry slightly less speed on final. Instead of VREF+10 or VFRE+5, fly it at VREF or whatever adjustment you feel is needed. And don't tell me this is going to completely ruin your flight experience

[Flexman 30]

I am not sure whether they address this or not but in any case if some feeel the plane has too much lift it seems there is an easy practical remedy - carry slightly less speed on final. Instead of VREF+10 or VFRE+5, fly it at VREF or whatever adjustment you feel is needed. And don't tell me this is going to completely ruin your flight experience

It's a matter of technique. Flare pitch up should not be greater than 2º or 3º. Fly the plane to the runway, don't stall it to the runway like you do on a cessna. A landing is a painless CFIT :)

[henkie 0]

I am not sure whether they address this or not but in any case if some feeel the plane has too much lift it seems there is an easy practical remedy - carry slightly less speed on final. Instead of VREF+10 or VFRE+5, fly it at VREF or whatever adjustment you feel is needed. And don't tell me it completely ruins your flight experience

Yes, that is a work around for it. And I don't want to sound too negative because this NGX is still an unbelievable simulation! I enjoy it every time I start it. Actually, I'm always losing my slot time because I can't get enough looking around in the cockpit staring at all the nice little details! I'm very hopeful that PMDG will do everything to make the NGX even better and look again to this issue we are talking about!

[Guest tonyf38]

I'm very hopeful that PMDG will do everything to make the NGX even better and look again to this issue we are talking about!

It's not an issue, it's completely accurate..

[henkie 0]

It's not an issue, it's completely accurate..

Well, according to Boeings own manuals its not. Take a look in this thread: http://forum.avsim.net/topic/345263-touchdown-attitude-incorrect/

[Guest tonyf38]

Well, I'm not having this issue, at Vref+5 my pitch attitude has always been about 2+ degrees nose up.. Did you contact PMDG about this??

[xgunther 1]

I usually find these threads ridiculous, but I think I may have to agree with the OP. I feel like I'm barely flaring and almost landing flat.

Agreed. It is off, but it is very very slight. If you've ever driven on the 405 past LAX, you'll notice that, for example, the SWA 737's seem to be a bit nose down vs. a 757-76-etc which glide almost 5 degrees nose up attitude. I find this only to be a problem when executing an autoland, but if you fly it manually, the last few hundred feet you can pitch for speed and power for altitude to get a realistic flare.

[Paul_Smith 92]

PMDG have given you the Boeing manuals. They have also given you FPV indicators and AoA displays that behave exactly like the real thing.You can use them to measure exactly how this aircraft flies and compare that to exactly how the manuals say it should fly, and you can show the exact differences if there are any, but only by reading and understanding what the manuals say the real thing should do. If you are having problems telling the difference between pitch, attitude and angle of attack, or are not familiar with FPV, then perhaps you have not yet finished reading and understanding the manuals and so perhaps you are not (yet) well qualified to judge when something is actually wrong, or when it is just not the way you expected it to be.

[Vladtop 0]

PMDG have given you the Boeing manuals. They have also given you FPV indicators and AoA displays that behave exactly like the real thing.You can use them to measure exactly how this aircraft flies and compare that to exactly how the manuals say it should fly, and you can show the exact differences if there are any, but only by reading and understanding what the manuals say the real thing should do. If you are having problems telling the difference between pitch, attitude and angle of attack, or are not familiar with FPV, then perhaps you have not yet finished reading and understanding the manuals and so perhaps you are not (yet) well qualified to judge when something is actually wrong, or when it is just not the way you expected it to be.

Dear Paul! You can see comparison with FCTM: post #20 http://forum.avsim.net/topic/345401-final-approach-attitude/page__view__findpost__p__2075807

[Av-Fan 0]

I also think the pitch attitude on final is a bit off.

[tcas_climb 45]

I too noticed that the NGX is too "slippery". If you want you can hoover just above the ground for a long long way with idle power and a minimum reduction of airspeed. I think the flight model is very accurate in the climb, cruise and descent, but far from realistic in the lower regions in approach configs. Hopefully PMDG will address this issue for SP1.

Im sure pmdg will be happy to fix that, but how do you know it isnt realistic? What are you comparing this to?

[Tokitaumelie 164]

It's a matter of technique. Flare pitch up should not be greater than 2º or 3º. Fly the plane to the runway, don't stall it to the runway like you do on a cessna. A landing is a painless CFIT :)

Best advice so far Jay Cargo