In my estimation, the differences are not worth mentioning. At FedEx we have just transitioned from Jeppesen products to LIDO products. In the process we discovered that the numbers printed on the charts can vary based on who is doing the measuring, and how they're measuring, and how long ago they did it. It's not unusual to find differences of several degrees. But guess what? When it comes to airways and such, the courses aren't as important as the pionts. J42 is defined as the line between MEM and BNA, not the XXX degree radial outbound and the YYY course inbound. Just point to point.


We've got the new Arrivals in a NOTAM-like format. Let me compare, for example, the WLDER 4 arrival with the RNAV arrival for the same quadrant, the LTOWN 1.

From SPKER we go to WLDER then LTOWN, MRCEL, and CLARK. That's the same for both arrivals. The Feeder Routes are the same, as well. Pocket City (PXV), Bowling Green (BWG), Nashville (BNA), McKellar-Sipes (MKL), and Jacks Creek (JKS) are all Feeder Routes for the WLDER 4. The LTOWN 1 (RNAV) only uses Bowling Green (BWG), Pocket City (PXV) and Nashville (BNA). While the published courses are, as you mentioned, up to 3 degrees different, the fact of the matter is the RNAV airplanes will be flying a straight line between the points, which have not changed. (Reviewing your post, I see you've said you noticed a difference in points of up to ten miles. I don't see that. I see the same points as before. What discrepancies do you see, specifically? Could there be an error in your charts?)

I'm a bit puzzled why the holding patterns are different, though. On the WLDER 4, the inbound course for the published holding pattern at SPKER is 225 degrees. On the corresponding RNAV arrival, the LTOWN 1, the inbound course is 226 degrees. I don't understand why these would differ. The holding pattern at MRCEL is the same on the WLDER 4 and the LTOWN 1 (RNAV). Oh, there's one more thing. The LTOWN 1 (RNAV) specifies an OUTBOUND leg length of 7 NM for both patterns. I've never seen that before.


Anyway, that gets us to the last part of the arrival. The WLDER 4 drops us off at CLARK with a magnetic heading. As you know, ATC often adjusts this heading for winds, so that we generally parallel the north/south runways. The LTOWN 1 (RNAV) uses the "last" for the arrival "pair" to the south as the next point. OLIVV is the last point on the HOLLY arrival, so it's the point after CLARK on the LTOWN 1. (Similarly, CLARK is the point after OLIVV on the LARUE 1 (RNAV), the RNAV "complement" to the HLI Arrival.) So, back on the LTOWN 1 (RNAV), we hit CLARK, then go to OLIVV (roughly parallelling the north/south runways), and then to a new point, NDREA. (Using the terminology you used above, we go from one pivot point to another, and then to a new point.)


Unless there's a strong crosswind, I don't see how flying either procedure will place the airplane in a much different place. Back up to the feeder routes, even. Whether it's a 727 wandering left and right of a VOR signal, or a DC-10 going point to point with an INS, or and MD-11 with RNP of 2.0, I don't think you'll see much variation from what you see today. We're all trying to get from one point to the next with whatever tools we have on board.


Now, that's just my take on it from the perspective of having looked at the procedure on paper. Give us a chance to fly it and I might see something different.

(I don't know about the other operators in MEM, but the FedEx 727s and DC-10s won't be doing the RNAV arrivals. Count on the MD-11/10s and that Airbuses.)




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