SID RNAV overlay -- EDDK NOR7E

[bookworm]

Departing Cologne-Bonn yesterday, we departed 14R (the shorter parallel runway) on a NOR7E SID.

The conventional SID depiction (http://www.ead.eurocontrol.int/eadbasic/pamslight-74CD52749CC4B84FEA8B036CEE2E0B9A/OODUMTUY4LXFU/EN/Charts/AD/NON_AIRAC/ED_AD_2_EDDK_5-7-9_en_2010-06-03.pdf) and the RNAV overlay (http://www.ead.eurocontrol.int/eadbasic/pamslight-74CD52749CC4B84FEA8B036CEE2E0B9A/OODUMTUY4LXFU/EN/Charts/AD/AIRAC/ED_AD_2_EDDK_5-7-10_en_2010-03-11.pdf) have significant differences. (Jepp depcitions also differ in the same way.)

The SID text form is: "Direct LV NDB (5.0 DME KBO); RT, on track 200° to 7.2 DME KBO (CAT D replace track 200° by continuous RT); RT, on R106 NOR to NOR." and this is illustrated on the chart.

The RNAV overlay shows LV as a fly-over, then a track of 174° to a fly-by waypoint DK148, then a track of 249 to a fly-by waypoint DK149 on the required 286 inbound to NOR.

I can think of a number of possibilities:

A) there's an error in the RNAV overlay
B) the RNAV overlay overlay is charted only for CAT D, even though there is no note to that effect on the chart
C) I'm making too much fuss about a relatively small difference which no one cares about
D) I'm missing something about the way the overlay should be flown.

Perhaps the key question is, as a CAT B aircraft, what should I fly? (Please don't say "look in your Ops manual" -- I have no Ops manual.)

[cosmo kramer]

Can't speak for the particular departure, but this is quite common problem. I suspect answer B) to be correct. The RNAV overlay is only there for your convenience. But ATC expects you to fly the conventional SID. Pure RNAV departures on the other hand should follow the RNAV points.

There are several ways to go about this. Fly the departure in heading select, or by hand. Fly the departure with the FMC and monitor for gross deviation and intervene as necessary. Or... fly the overlay since German ATC doesn't seem to care if you do one or the other.

[Denti]

Pretty sure it is B), the LIDO-map of the departure shows a continous left turn from LV via DK148 to DK149. However as the speed is restricted to 220kts during turns anyway there is not that much difference between D and C (and probably B).

Biggest problem for most C and D aircraft would be the 12,1% climb gradient though.

[rudderrudderrat]

Hi Denti,
the LIDO-map of the departure shows a continous left turn from LV via DK148 to DK149
Last time we flew that departure we turned Right.

I'd go for answer C. The RNAV routings have a couple of coded places during the turn which are impossible to specify if using conventional aids. I bet the RNAV routing avoids the noise monitoring sensors, by flying the published track over the ground, compensating for wind by varying the bank angle to achieve it.

[Denti]

Right, i probably shouldn't write after a 16 hour duty and a couple beers :P Seems i lose my sense of direction first .P

[FE Hoppy]

Problem is if your database procedure doesn't match the published plate you shouldn't use it. If you're cleared a non RNAV departure then an overlay is a convenient way to fly it but doesn't supersede the published version. Report the error to your provider and fly the charted version until the Database is corrected.

[421C]

Hi BW

I think it's "C" but with some caveats. Here's how I understand it:

I think the 2 points to note are

1. The difference between a “database overlay” and a “published overlay”
If the overlay is published, then it is a normal published procedure. The fact it’s called “overlay” is informational – it tells you it is not a native RNAV procedure and that it follows a conventional procedure. This is important information because in the event of an RNAV failure, the pilot knows there is a conventional back-up.
A published overlay should not be confused with the database depiction of a conventional radio procedure (ie. a “database overlay”). The latter is purely advisory for most GA operators (I know little about the case of getting operational approval to fly database overlays) and any conflict between the database overlay and the radio procedure must be resolved by following the published radio procedure, as FE Hoppy says.

2. The naming of the procedure
From an ATC clearance point of view, the procedure is uniquely specified by the published name in RTF and database designator in the case of FPL transmissions (ie. Norevenich Seven Echo and NOR 7E respectively)
If, in the case of a conventional procedure and published overlay, the procedure name is the same, then the pilot may elect which to fly. One would expect the differences to be trivial from an ATC point of view – which they are in the case of the NOR7E and that the use of either alternative complies with the separation and terrain/airspace rules to which traffic is worked. It’s a bit like a Cat A/B vs Cat C/D depiction on an approach – ATC don’t always necessarily know which one you’ll fly and it doesn’t matter to them.

One reason for the difference is that the conventional leg from LV to 7.2d is an “FD” Path-Terminator (fix to DME distance) which is not an RNAV type – ie if used in an database overlay, many FMS would not support it other than as a “Pilot Nav” leg. It is more desirable to use a Track-to-Fix path-terminator (TF), which is what has been done in the published overlay.

It’s actually a sensible solution when there are reasons not to have distinct RNAV procedures (perhaps traffic complexity or just the hassle of design and environmental consultation?). What ATC are saying is “we are happy that the Overlay we’ve published is sufficiently similar to the conventional version that the two are identical for our purposes. However, for pilot purposes, the published overlay may be preferable and we’ve tweaked it to make it a better procedure than a ‘straight’ database coding of the conventional one”. There is also likely to be an improvement in track accuracy and consistency for considerations such as noise abatement.

brgds
421C

[Admiral346]

I remember an ATC publication to us pilots via our company from some ten years ago.
It showed older radarplots of departing aircraft using conventional nav in FRA, and a newer one showing plots after the Rnav overlay had been introduced.
DFS (german ATC) encouraged us to use the Rnav procedure as the plots showed much less deviation from the desired min noise tracks.
I don't fly to CGN much, but I do use the Rnav overlays for many german airports and have never gotten any complaints.

But maybe just ask them next time you're there... that usually helps a lot.

Nic

PS: They also have telephones in CGN, you could call from wherever you are at right now.

[bookworm]

Thanks all for your input.

PS: They also have telephones in CGN, you could call from wherever you are at right now.

True enough, but in my limited experience of such calls, I usually end up talking to someone who neither understands nor cares about the issue, but feels obliged to give me a definitive answer nevertheless. And I suspect I'd get passed from Cologne to Langen to Braunschweig. I rarely get the clarity of reply that I've had on this thread. I'm particularly grateful to 421C for pointing out the “FD” Path-Terminator issue.