geedub

Routes mismatch P2A IXEG

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Hello Dave,

Congratulations on this excellent piece of kit.

Several weeks now trying off and on for the 'perfect' flight. Been fun trying albeit time-consuming. I spent a lot of time in NZ so using NZAA-NZWN as my trial route, I've flown it several times.

A few challenges to date. First, the main one which I hope you can put me straight on.

MY PLANNED ROUTE:

1. Manually plan a simple route in P2A. NZAA 23L via CLARK1 SID to TPAP3B STAR into NZWN Rwy 16.  Gives me CLARK - LIMES - KARRL - TPAPA - BRUDA - HUWIT - WITBY - CANES.
2. Identical Route entered in IXEG FMC. (Using AIRAC 1708 thoughout,) 

ENROUTE:

Visually the tracks appear identical WPT to WPT. However, when letting the 737CL Lat NAV manage the plane horizontally I observe that my track south (168 deg approx) is turning me gradually north of the Route depicted in P2A, revealing a mismatch and resulting in frequent demands from ATC to fly a correction hdg (140 deg.) This in turn results in a deviation from the magenta route depicted on the IXEG Nav display. ATC soon instructs me to use 'own NAV' and so the process repeats itself.  Could it be a Mag. Var. issue? 

I'm happy to take one thing at a time ... but the other thing I have been struggling with is something I've see elsewhere in the forum: descent profile. Too high, too late, too fast - leading to a rushed or missed approach. Even despite my editing both P2A  and the IXEG altitude targets leg by leg, matching the New Zealand published AIP.  ATC appears to ignore at least some of those restrictions. My best flight was when I used VNAV to control my descent path by seat of pants - a method I am very familiar with from my early training days. 

Of course, I have much to learn with regard to both P2ATC and the wonderful IXEG B737 Cl and would sure appreciate your observations/pointers.

Best regards

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5 hours ago, geedub said:

Too high, too late, too fast - leading to a rushed or missed approach.

Sounds familiar :)

What's your Descent Rate set to in P2A? I had mine at 1800fpm, but since I changed it to 1500fpm my approaches are much better (using the PMDG 737 in P3D and zibo's 737 mod in XP11).

When P2A gets it right, it's brilliant.

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Hi Matt,

I went for 2500 initially but dropped to 2000 fpm. I think that helped. 15000? Interesting. I'll certainly try it. Maybe it'll encourage P2ATC to get me down earlier.

I just tried a reality checkride KLAX to KSFO and it went without incident and a nice auto-land in the IXEG 737 just for fun. I really must find out how to set up an external view of the landing in XP11 like I used to with the PMDG. For drooling purposes you understand. :-) 

For some strange reason the mismatched routes thing wasn't so much of an issue. Magnetic Variation is 20-23 i the North Island of NZ, double that of California. I'm just guessing of course. But I want to get to the bottom of that. Here Dave can help perhaps.

So far I totally agree, this is a terrific piece of software, brilliantly conceived and clearly a labour of love for its creator. Glad I went for it. 

All the best.

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Glad you're enjoying the software.

The TOD is calculated using the Planned Descent rate, so if you are getting the descent a little late, lowering the descent rate will make it occur earlier.

Another common problem is the descent is planned at 250 kts below 10000 ft, and also following any speed restrictions in the STAR.  So if you are speeding, like I normally do, you'll be covering more lateral ground than planned on and will end up high.

As for the mismatch between P2A and the aircraft navigation, that can happen if the AIRAC cycles are mismatched or if the flight plans are similar, but not exactly the same.  If it's just a matter of being off course, but parallel to the track, increasing the Allowed Course Deviation setting can help reduce the number of Off Course calls.

Dave

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Definitely helps if you set the descent lower to 1,500 fpm maybe even 1,000 and set the ground speed higher that will put the TOD point earlier in the flight plan especially if you are flying jets above FL300 and 500knts. Also try setting the Approach control radius to like 200 miles so that communications start earlier. For me that was key. You really have to experiment using this program to see what works for the type of flying you do. It's not one size fits all

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