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Don Hudson

Possible 'gotcha' Format As Jeppesen Adds Half-Degree Wpts

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Standard Flight Plan checks and checks at FPlan waypoints when enroute will avoid any problems, but it's still a subtle 'gotcha' and there have been a number of GNE's on the Atlantic lately...

Jeppesen NavData for cycle 1404, effective 3 April 2014, included a large number of new waypoints at half degree latitude/full degree longitude. These new waypoints are causing operational difficulties for customers who were not aware of the additions. The approximate geographic extent for the additions is from 22 degrees north latitude to 67 degrees north latitude and 050 degrees west longitude to 020 degrees west longitude.

The waypoints were added following the industry standard for database preparation, ARINC 424. That convention uses the positioning of an alpha character to denote full degree or half degree of latitude:

5040N – trailing character – full degree of latitude, i.e. 50 00 00N 040 00 00W
N5040 – leading character – half degree of latitude, i.e. 50 30 00N 040 00 00W


THEREFORE, FLIGHT CREWS ATTEMPTING TO ENTER WAYPOINTS USING LATITUDE AND LONGITUDE NEED TO BE AWARE OF THESE CONVENTIONS AND THE FACT THAT BOTH FULL DEGREE AND HALF DEGREE LATITUDE WAYPOINTS ARE INCLUDED IN THEIR NAVDATA FOR CYCLE 1404/1405.

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Wow. What a nightmare.

Haven't entered a waypoint using that 424 convention for a long time. Fortunately, it wasn't taught on the 767 at AC so nobody does it. Not sure about the other aircraft.

Auto-route-load should help and, when you do have to manually enter the waypoints, saving a couple of keystrokes and leaving yourself open to that gotcha isn't worth it. You wonder why they would even introduce it... "Yeah, we came up with this really neat way of saving 2 keystrokes. How could you possibly have been stupid enough to have had a GNE?".

What happens when they go to half-lats on the Pacific? Let's see... 4030N160E will be 406N0... or would that be 4N060.

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We did it on the A330/A340 until I retired. I think autoload is the only way if they're going to shave this close.

Looks like trying to squeeze more aircraft into the same space laterally now that they've done it vertically.

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Thanks Rd. The official announcement is here as a PDF.

This doesn't seem a well-considered implementation of an ARINC 424 change. That's quite shocking really when one considers the immediate effects which have occurred and how obvious they should have been. I wonder where the idea and the pressure to add intermediate waypoints came from? The intent is clearly to put more airplanes in the same space, so who / which group has that as a priority?

I believe any airline pilot could have provided the necessary insight into what could occur. It's obvious to say but essentially this is a change which brings airplanes closer together using a technology in which a typing reversal could bring airplanes closer together. We already have had a number of near misses in the vertical when aircraft technology responds to momentary speed variations.

From the Jeppesen website, "Notices and Alerts", May 03, the notice that the waypoints will be removed on the next cycle has been added to the original Alert:

Publish Date: 29 Apr 2014 alerts-atlantic-supplement.gif Atlantic, and Canada & Alaska

Included Areas: Atlantic Ocean,

North Atlantic Region Cycle 1404 and 1405

Jeppesen NavData for cycle 1404, effective 3 April 2014, included a large number of new waypoints at half degree latitude/full degree longitude. These new waypoints are causing operational difficulties for customers who were not aware of the additions. The approximate geographic extent for the additions is from 22 degrees north latitude to 67 degrees north latitude and 050 degrees west longitude to 020 degrees west longitude.

The waypoints were added following the industry standard for database preparation, ARINC 424. That convention uses the positioning of an alpha character to denote full degree or half degree of latitude:

5040N – trailing character – full degree of latitude, i.e. 50 00 00N 040 00 00W

N5040 – leading character – half degree of latitude, i.e. 50 30 00N 040 00 00W

THEREFORE, FLIGHT CREWS ATTEMPTING TO ENTER WAYPOINTS USING LATITUDE AND LONGITUDE NEED TO BE AWARE OF THESE CONVENTIONS AND THE FACT THAT BOTH FULL DEGREE AND HALF DEGREE LATITUDE WAYPOINTS ARE INCLUDED IN THEIR NAVDATA FOR CYCLE 1404/1405.

The waypoints will be removed from Jeppesen NavData for cycle 1406, effective 29 May 2014.

Half Degree Lat/Long Grid Waypoints

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It's not often Jeppesen gets caught up in something like this. They only re-publish in their own format, data received from ICAO countries' AIP's. How have other chart publishers reacted to this new set of procedures/protocols? Or are there any other independent org's such as JEPP that is widely used? I know Air Canada used to have their own charts - thankfully, they are no more - I recall SAS used to publish charts. It will be interesting to see where the ball got dropped and by which states.

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Personally, I miss the AC charts.

They were tailored specifically to an airline operation and didn't have all the useless crap on them that has to be included in the Jepp Charts for Aztec and Navajo drivers. So you didn't have to do a revision because of a change on a chart that had nothing to do do with airline operations. And they were ordered correctly. And they were printed on higher quality paper. And you could actually read all of the print on them without a magnifying glass. And the enroute charts actually divided up the world the way that AC flew it.... it didn't take 5 charts to get through the Caribbean to South America. And you didn't have to try to locate the legend for the little circled "F" 3 panels over to find out that you missed calling ten minutes ahead before entering an FIR.

One other popular supplier is Lido charts.

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The AC charts were great, for all the reasons offered. It's more than "what you're used to" or "to each his/her own". I found the Jepps cumbersome to use, thick with info I never used, with airline-specific information buried pages away. The one aspect I did like was the profile on the approach chart page.

I'm sure it was $$, and not a technical decision.

These days I'm reading/using the CAP. I'll take the AC charts any day.

Regarding Jepp, though extremely rare at this level of severity, this is pretty fundamental human factors / organizational error which could and should have been anticipated. Someone was sleeping at the switch.

A single, mis-typed/mis-placed character is a high-probability single point of failure which is capable of producing a max nav mid-course error of 30nm on the Atlantic. The flight-plan > FMC check and, as a last backstop, the waypoint-passage SOPs should catch the error but it's already occurred a number of times.

That is a serious failure somewhere in the organization. I'm surprised Jepp is leaving it until the next regular cycle to remove the wpts, but perhaps "regular cycle" is a safer option in terms of logistics and users' processes.

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