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francisleung

77L SP1B VNAV/LNAV problem flying OCK4B STAR to EGLL

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After installing the SP1b I recently flew from LPPT to EGLL and encountered the following problems which are reproducible on my computer at least. 
I then reflew the route without ASN and cleared the weather same result. I reflew without FSUIPC the same. I created a new short flight from LEBB to EGLL starting from free flight, choose 77L, airport, runway, clear sky then Flynow, no default panel, then request the route, enter fuel, etc. same result as follows:
 
OCK4B STAR to RWY 9L, we are to cross KATHY at FL180 and HAZEL at FL130, I assume it is a continuous descend path.
 
1. Flight progress normally until at KATHY 14707102139_b2c0affacb_m.jpg, 14707142528_2c86e5f755_m.jpg
 
VNAV will hold the plane level with cruise power at FL180 for 13.7nm 
14893393162_be0e433be7_m.jpg before continue descending again to reach FL130 at HAZEL. 
2. When the plane approaches OCK 14890677901_f41b0190c9_m.jpg it is supposed to fly the magenta line, there are no discontinuity. However, it will try to overfly OCK
14707101499_27c2abbb1e_m.jpg
3. After the left turn, there is no next waypoint on ND 14707195967_1915c44773_m.jpg, the plane seems to try to fly to ock-8
4. After reaching ock-8, D290L appears on the ND,14893394482_a28d328bf4_m.jpg
however the plane will do a 360 degree R turn to try to reach it!14890681161_800cc507f6_m.jpg
5. After passing D290L, it tracks to GWC35 and CI09L apparently on course 14893719365_9b10cd5ec2_m.jpg
6. However, near CI09L, the plane will do another right turn for no good reason while FI09L is the next waypoint on the ND14893395092_a7b8fc443c_m.jpg
7. After about doing 150 right turn off course, the plane suddenly decided it has passed FI09L and decided to do a left turn instead 14707198617_dc3110e8d4_m.jpg
and ending up nowhere, I was expecting runway 09L on ND but nothing 14890681651_4136f1ea9e_m.jpg
 
I'll submit a ticket and am interested to know if any of you have flown the OCK4B star with any issues.
 
Francis Leung
 
 

Apparently I've only copied the link for the small jpg, here are the large ones:

14707102139_b2c0affacb_b.jpg2

14707142528_2c86e5f755_b.jpg3 hold

14893393162_be0e433be7_b.jpg4 ock4b

14890677901_f41b0190c9_b.jpg

5 ock

14707101499_27c2abbb1e_b.jpg

6 ock8

14707195967_1915c44773_b.jpg

7 d290L

14893394482_a28d328bf4_b.jpg

8 turn

14890681161_800cc507f6_b.jpg

9 gwc

14893719365_9b10cd5ec2_b.jpg

10 ci09L

14893395092_a7b8fc443c_b.jpg

11 FI L turn

14707198617_dc3110e8d4_b.jpg

12 nowhere

14890681651_4136f1ea9e_b.jpg

 

Francis

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I flew BNN4A this morning without issue although not quite your problem. I'll fly the OCK4B to 09L now starting KATHY FL180 and see how it goes. What Navdata are you using, I'll be trying with Navigraph 1408. I usually go into HDG for landing at EGLL because it is very rare they aren't vectored onto the ILS nowadays.

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Same issue after (OCK-8), this is probably a problem with the STAR in the Navdata.

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same Navigraph 1408 here, I understand that in real life full SID/STARs are never flown but is LNAV supposed to be able to fly the magenta line without dancing around?

 

BTW, Ryan commented on FB that the VNAV is not a bug but a new T/D should have appear after Kathy for the descend to Hazel.

 

Francis


The entries in egll.txt in sidstars looks fine to me:

 

STAR OCK4B FIX DOMUT FIX KATHY 18000 FIX HAZEL 13000 FIX D230L SPEED 250 FIX OCK
  RNW 09L RNW 09R RNW 27L RNW 27R
 
APPROACH ILS09L FIX CI09L 3000 FIX FI09L 2500 RNW 09L TRK 091 UNTIL 1580 TRK 038 UNTIL 3000
 
 TRANSITION OCK TRK 290 UNTIL 8.0 FROM FIX OCK SPEED 220 FIX OVERFLY D290L AT OR ABOVE 6000 FIX OVERFLY GWC35 AT OR ABOVE 3500
 
Francis

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I have flown in from the West and Southwest on the OCK arrivals, don't remember which ones specifically, and I overrode VNAV by using MCP to control speed/altitude and V/S with no problem. The VNAV in the 777 will not solve the geometry problems in the same way that the 737NG does (it's generally older) and you have to be the pilot in command instead of observer on occasion. Very realistic I've read.

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Well, I got a suspicion that as RSR has said before, in order to fix somthing, at times, something else might be broken! I revert back to the RTM version (Sep 13) and reflown the route, same airac 1408, LNAV tracks faithfully as follows:

 

1. the plane will initiate a turn 2.4 nm before OCK almost following the magenta line

14717808409_1d8290f35a_o.jpg

 

2. tracking nicely to OCK-8

14717808799_e2e5a92656_o.jpg

 

3 no more R turn 360, tracking to D290L

14717807629_d07832a457_o.jpg

 

4. to cut a long story short, finally track nicely to FI09L for landing

14881453916_ec03c945cc_o.jpg

 

PMDG guys the SP1b has to be fixed  :P

 

Francis Leung

 

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