Jepp Approach Charts
02-13-2010, 02:38 AM
#1
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Jepp Approach Charts
I wanted to know if anyone knew why some Jepp approach plates are different in their DH/MDA altitudes for the same airport from NACO charts. I love my jepps and it seems like when I do a sim ride for IPC purposes my instructor makes me uses his NACO charts for it. For example for CCO you have a DH or 881ft in the Jepp plates while NACO has 800ft on it (dont quote me it might be the other way around I dont have them on hand at the moment). I know its only a foot difference, however as far as whose charts are correct and how that applies to the regs. I dont want to bust altitude for having the wrong information. My Jepp charts are current per Jeppessen and its correct per the last revision. So maybe someone here has some insight.
Thanks
Thanks
02-13-2010, 07:02 AM
#2
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Does it really matter?
Mexi,
I think you meant 880 and 881 in your post, as you referenced a 1 foot difference. Lets look at what is allowable. Your altimeter can be 75 feet off of field elevation, so the 1 foot difference is kind of moot.
I think you meant 880 and 881 in your post, as you referenced a 1 foot difference. Lets look at what is allowable. Your altimeter can be 75 feet off of field elevation, so the 1 foot difference is kind of moot.
02-13-2010, 08:26 AM
#3
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I usually see this discrepancy on end/threshold elevations on airport diagrams (Jepp vs NACO), but hadn't seen it on approach plates. I can look into this Monday and let you know which one is correct and why they are different. It could be because it changed by a foot, and one of them hasn't been updated yet.
02-14-2010, 06:31 AM
#5
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Sorry didn't have the right approach plate(too many local Georgia fields) I meant, LGC ILS31 NACO has a DH/MDA of 880ft and Jepp is 881ft. Good point on the 75ft difference as far as the altimeter. I just find it as an interesting observation.
02-14-2010, 07:17 AM
#6
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I don't think the altimeter tolerances make any difference as far as what DH you use! Those tolerances are already accounted for when the FAA uses TERPS to build the approaches and set the DH/MDA.
If I had to guess I'd say the field elevation changed and one of the charts didn't get updated correctly. The actual source data for the approaches is text...both NACO and Jepp build pictoral charts from that.
If I had to guess I'd say the field elevation changed and one of the charts didn't get updated correctly. The actual source data for the approaches is text...both NACO and Jepp build pictoral charts from that.
02-15-2010, 07:09 AM
#7
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Just checked with terminal charting at Jeppesen, and they said that 881’ (the Jepp chart) is correct. Here is something else that I noticed: the TDZE on the Jepp chart is 681’ and NACO has 680’. Also, if you look at the VOR DME RNAV or GPS RWY 31 approach (Jepp or NACO), the TDZE is 680’ as well. So, when I asked about the discrepancy between the two Jepp plates (ILS RWY 31 with TDZE 681’; and VOR DME RNAV or GPS RWY 31 with 680’), they told me that a foot change in elevation is not enough reason to update a chart, and that the ILS RWY 31 plate was updated last due to other changes, so they updated the TDZE as well.
02-15-2010, 08:01 PM
#8
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I'd be worried if they didn't think they were right.
I'm not worried about one foot. As mentioned, altimeters can be off by more than the difference. Also, I've not seen a controller or radar system that could identify when a pilot is one foot off assigned altitude or a published altitude.
I'm not worried about one foot. As mentioned, altimeters can be off by more than the difference. Also, I've not seen a controller or radar system that could identify when a pilot is one foot off assigned altitude or a published altitude.
02-15-2010, 08:17 PM
#9
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It's not limited to approach charts...it also occurs on the low enroute charts as well. I can't remember which victor airway it is (V528 or V95) off of PHX on the L-5 chart, but the Jepp and NACO have differing MEAs...sometimes off by a couple hundred feet. Could be the difference between required O2 depending on which chart you use.
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