Flynavy From United States, joined Mar 2002, 3265 posts, RR: 20 Posted (3 months 1 week 3 days 7 hours ago) and read 1035 times:
I'm working on a navigation discrepancy on one of our simulators and I need some input.
Refer to the latest Jeppesen chart for the VOR DME Rwy 31 approach at KJAX.
My question is simple. Since runway 31's magnetic heading is 314°, why would the approach plate have you tracking the 316° from CRG and then also have the final approach course as 316°?
PhilSquares From Ireland, joined Mar 2004, 3566 posts, RR: 53 Reply 1, posted (3 months 1 week 3 days 7 hours ago) and read 1029 times:
Quoting Flynavy (Thread starter): My question is simple. Since runway 31's magnetic heading is 314°, why would the approach plate have you tracking the 316° from CRG and then also have the final approach course as 316°?
The bearing from CRG to the runway threshold is 316. The runway heading has nothing to do with the final approach course. If CRG were moved slightly so it coincided with the extended runway centerline, then you would have the final approach course and the runway heading aligned.
IIRC the final approach can be -/+ 15 degrees and still be a straight in approach.
Flynavy From United States, joined Mar 2002, 3265 posts, RR: 20 Reply 3, posted (3 months 1 week 3 days 7 hours ago) and read 1019 times:
I forgot to mention that this wasn't the original problem. The original discrepancy was that the aircraft was tracking right of the VOR's 316 radial. Turns out the runway wasn't aligned correctly in the ground station data file, shiprz.dat.
Flynavy From United States, joined Mar 2002, 3265 posts, RR: 20 Reply 5, posted (3 months 1 week 3 days 6 hours ago) and read 1010 times:
PhilSquares - it would appear that the angle of convergence can not exceed 30 degrees, as per the following paragraph:
Quote: When DME is included in the title of the VOR approach, operable DME must be installed in the aircraft in order to fly the approach from the FAF. The use of DME allows for an accurate determination of position without timing, which greatly increases situational awareness throughout the approach. Alexandria, Louisiana, is an excellent example of a VOR/DME approach in which the VOR is off the airport and a FAF is depicted. [Figure 5-50 on page 5-60] In this case, the final approach course is a radial or straight-in final approach and is designed to intersect the runway centerline at the runway threshold with the angle of convergence not exceeding 30 degrees.
PhilSquares From Ireland, joined Mar 2004, 3566 posts, RR: 53 Reply 7, posted (3 months 1 week 2 days 23 hours ago) and read 951 times:
Quoting Flynavy (Reply 5): PhilSquares - it would appear that the angle of convergence can not exceed 30 degrees, as per the following paragraph:
To be honest, I couldn't remember. There some places where it's +/- 15 degrees from the runway heading and others it's 30. Biggest thing to be aware of is a NP is just that, it can bring you in from a bearing other than the runway heading. A good thing to brief during the approach briefing.
DeltaGuy From United States, joined Sep 2001, 4078 posts, RR: 18 Reply 8, posted (3 months 1 week 2 days 15 hours ago) and read 889 times:
Oftentimes you'll break out on an approach, only to see the runway at an odd angle and having to align yourself. Another example is Cecil Field in Jax (VQQ), VOR RW 9R...puts you at 20 or so degrees off runway heading, IIRC.
I liked doing this approach back during my instrument training in Jax, the approach takes you right over my house, near the VOR.
DeltaGuy
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IAHFLYR From United States, joined Jun 2005, 2915 posts, RR: 16 Reply 10, posted (3 months 1 week 22 hours ago) and read 751 times:
Quoting Flynavy (Thread starter): My question is simple. Since runway 31's magnetic heading is 314°, why would the approach plate have you tracking the 316° from CRG and then also have the final approach course as 316°
Might want to check out the airport diagram and see what this shows for Runway 31!!
Also food for future thought....there a some airports where a NAVAID does not have the same mag var as the airport even when the NAVAID is located on the airport (not the case with JAX and CRG), all depends on the year of the survey.
HOU airport is 4E while HUB VOR/DME located on top of the terminal parking garage is 5E.
Flynavy From United States, joined Mar 2002, 3265 posts, RR: 20 Reply 12, posted (3 months 1 week 8 hours ago) and read 681 times:
Quoting IAHFLYR (Reply 10): Might want to check out the airport diagram and see what this shows for Runway 31!!
The runway heading in the FMS NDB shows 314, the latest Jeppesen version of the airport diagram shows the runway heading as 315, and the latest data on AirNav.com shows 311 true, 314 magnetic.
Zeke From Hong Kong SAR, PRC, joined Dec 2006, 3636 posts, RR: 49 Reply 13, posted (3 months 1 week 6 hours ago) and read 674 times:
Quoting Flynavy (Thread starter):
My question is simple. Since runway 31's magnetic heading is 314°, why would the approach plate have you tracking the 316° from CRG and then also have the final approach course as 316°?
Jepp 10-9 shows 315°
Quoting Flynavy (Reply 12): The runway heading in the FMS NDB shows 314, the latest Jeppesen version of the airport diagram shows the runway heading as 315, and the latest data on AirNav.com shows 311 true, 314 magnetic.
Depends on the FMS how this is done, the magnetic heading you see there can come from a lookup table in the FMS provided by the FMS manufacturer, rather than from the navigational database.
Should add the reason why some some FMS do this is they use lat/long for points and calculate a great circle track between the points which give you the true track, then apply the lookup magnetic variation to get magnetic bearings.
[Edited 2008-07-08 01:46:11]
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IAHFLYR From United States, joined Jun 2005, 2915 posts, RR: 16 Reply 14, posted (3 months 1 week 3 hours ago) and read 656 times:
Quoting Flynavy (Reply 12): The runway heading in the FMS NDB shows 314, the latest Jeppesen version of the airport diagram shows the runway heading as 315, and the latest data on AirNav.com shows 311 true, 314 magnetic.
Not tossing any daggers at any particular entity, but Jepps charts/data from time to time has been known to be less than correct, and the same with AirNav. Not that the NACO charts are always correct either! I only attempted to provide current data for ya to peruse!
Flynavy From United States, joined Mar 2002, 3265 posts, RR: 20 Reply 15, posted (3 months 1 week 3 hours ago) and read 652 times:
Quoting IAHFLYR (Reply 14): Not tossing any daggers at any particular entity, but Jepps charts/data from time to time has been known to be less than correct, and the same with AirNav. Not that the NACO charts are always correct either! I only attempted to provide current data for ya to peruse!
Wouldn't be the first time an "official" publication wasn't exactly accurate. Thanks though!
CosmicCruiser From United States, joined Feb 2005, 1401 posts, RR: 8 Reply 16, posted (3 months 1 week 2 hours ago) and read 642 times:
Quoting IAHFLYR (Reply 14): Jepps charts/data from time to time has been known to be less than correct, and the same with AirNav.
When we made the transition from Jepp to LIDO there was a lengthy period where we collected data on differences between the two from pilot input since we were using both in the cockpit. Checking the AIP for the correct info found Jepp wrong a lot domestically. LIDO had errors as well.
IAHFLYR From United States, joined Jun 2005, 2915 posts, RR: 16 Reply 17, posted (3 months 1 week 2 hours ago) and read 640 times:
Quoting CosmicCruiser (Reply 16): Checking the AIP for the correct info found Jepp wrong a lot domestically. LIDO had errors as well.
Makes ya want to go out and find some nice mountainous terrain and fly an approach to mins doesn't it!
I haven't flown using Jepps in a while but they were well respected in the industry at that time, not sure these days, but I'm thinking those respected days are gone for the most part.
CosmicCruiser From United States, joined Feb 2005, 1401 posts, RR: 8 Reply 18, posted (3 months 1 week 2 hours ago) and read 636 times:
Quoting IAHFLYR (Reply 17): they were well respected in the industry at that time,
I always liked Jepp but we made the move to LIDO because the presentation for the EFB was MUCH better and that was the eventual goal. Both have pluses and minuses. Jepp can be very cluttered and their EFB presentaion was no more than what looked like a scanned Jepp plate. Lido has color added and is laid out very nicely but in order to keep clutter down one must often go to more than one book for info which is time consuming. The EFB eliminates a lot of this but for our 727s, for example, the LIDO books are much bigger than Jepp and very cumbersome in the cockpit. In the EFB equipped jets we still carry the paper ver. as well and I really like product. There were many other little nitnoid things that would confuse you with LIDO and it took about a year for everyone to get accustom to knowing where to go for info.
AAH732UAL From United States, joined Mar 2008, 896 posts, RR: 0 Reply 19, posted (3 months 1 week ago) and read 618 times:
You got to admit that the Jepp plain and profile views are better then NACO.
Like for a PT, NACO just puts a BARB while Jepp draws it out. Also the steps and the VNAV DH in lieu on Jepps compared to one straight line on NACO.
Besides not showing the steps.... the (GPS) and (RNP) look about the same between NACO/JEPP.
I will say I love the small airport diagram w/ declared distances and possible taxi routes and stuff on all NACOs compared to having to look at the AD for all the runway info. I will give NACO that..... but I prefer jepps over NACO any day
DME/DME RNP0.3 NA -Escalators don't break---- they just become stairs!
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