That hold is charted on every IAP to runway 11 except NDB 11.
Maybe Garmin follows the old saying “in case of doubt turn to South”
😉
On both flights, Antonio’s and mine, the outbound leg was exactly opposite, which should only happen in rare cases. When I look at my track I’d say a left turn would have been 178 degrees…
Peter wrote:
Not sure what MA Hold is.
I meant Missed Approach Hold, feel free to edit title as required
Airborne_Again wrote:
suddenly the navigator had a flight plan with an approach starting at NORAY and going in the direction of SNR – opposite of the direction from which the aircraft was arriving. Then it (the navigator) planned a track that would make the aircraft arrive over NORAY in the opposite direction
Excellent logic, and I can envision situations where that can happen, but not this case.
The main issue that drove this thread is what the navigator did. My FPL route ended at the end of the STAR at SNR, and then there was the destination airport LEXJ. If I did not suspend sequencing, then after SNR it would do a 170deg LH turn back to LEXJ (or would it have maintained course after SNR?). Since I had been cleared for the approach before SNR I selected “activate approach” just upon passing SNR. Without thinking as much as we are doing in this thread, this sounded logical to me and almost always works “after XXX cleared for the approach” means upon passing XXX I “activate” the approach in the navigator.
This action, AFAIK on all Garmin navigators, will go DCT from present to the IAF preselected on the loaded approach. If instead “vectors” (vs an IAF) was selected then it will intercept the final approach course from current position.
So I did not explicitly select DCT NORAY, I activated the pre-selected approach with identical immediate result. At the same time, the navigator inserted the course reversal into the next approach leg (formally IAF DCT IF , now turned into IAF-reversal-IF, with “reversal” not being listed on the FPL but depicted with dashed white course on the display as depicted in the second post’s actual inflight picture )
“It” overflew the IAF on the wrong course, then reversed course on the wrong side of the hold as I knew it would, then avoiding the IAF entirely set inbound course to the IF, precisely following the formerly dashed white, now turned magenta curved reversal to the IF.
The same procedure on my IPad GTN simulator derives the same (erroneous) result.
If I do the same for VOR 11 with IAF at NORAY, then the simulator inserts the same type of reversal (avoiding the IAF inbound) but with a correct RH turn.
Does this point to something other than a DB coding issue?
Peter wrote:
Probably the navigator didn’t know the hold is a part of the approach.
It does list the hold at the end of the missed approach , but not at the start.
@Peter the Jeppesen chart you have shared does show sectorized MSA with 4000ft MSA North of the SNR 267 radial, but the AIP chart I was using shows unsectorized FL80 for 25NM all around the ARP, making it much more restrictive outside published procedures. That is a + for the Jepp chart
Looking at the Jeppesen approach chart for LEXJ RNP Y (or Z) Rwy 11, the hold is not part of the procedure except as the missed approach hold, so from the IAF at NORAY, there isn’t a course reversal depicted. If that were charted in the US, the hold would be considered an arrival hold and would require separate permission from ATC to fly it to lose altitude or to do a course reversal. On the Jeppesen approach chart, the hold is not using a heavy weight track, which if it did, then the hold is mandatory and would have been a part of the procedure. ATC in the US would have required either vectors to the IAF and an intercept of the FAC at 90 degrees or less. So it looks to me that the procedure is not intended to perform a course reversal and that the procedure begins at the IAF NORAY with the next fix being the IF at XJ07W on a track of 113 degrees. Without a course reversal in the DB, the GTN just turned around the most efficient means to join the inbound track. The track from SNR to NORAY appears to me to be 292, so that makes the LT the shortest direction for turning back to 113, or 179 degrees vs to the right, it is 181 degrees. So I think the left turn is what the GTN would do.
I think I would have asked for the course reversal using the hold and in ForeFlight or on the GTN would have wanted this to be the flight plan:
[SNR] [NORAY(4000)] [NORAY 112 LT 1 Min Hold] [NORAY RNP Z RWY 11 (LPV ONLY)]
Here is what it would look like using ForeFlight:
Antonio wrote:
“It” overflew the IAF on the wrong course, then reversed course on the wrong side of the hold as I knew it would, then avoiding the IAF entirely set inbound course to the IF, precisely following the formerly dashed white, now turned magenta curved reversal to the IF.
Ah. This is so odd that I misunderstood what had happened. I thought the navigator commanded a turn before NORAY so that you arrived over NORAY on the final approach track!
Then I guess the behaviour was because NORAY was a fly-by waypoint. So no matter from what direction you approached NORAY, the navigator would compute a turn to the final approach course without overshooting. As you were arriving over NORAY on the reciprocal of the final approach course, you got this wide turn. From what I can make out of the plots, you intercepted the final approach well before the IF which is the important thing. The terrain clearance is something else, of course
It looks like @NCYankee spotted it and @Airborne_Again logic matches and explains why the simulator (and probably the aircraft although I did not try) does a RH turn after NORAY when reversing course from SNR for the overlay VOR11, but LH turn for the RNP11. It has nothing to do with DB coding as I thought.
Although in both cases the outbound course SNR-NORAY is 291, the difference is that for the VOR the inbound course is 111 (exactly the reciprocal back to SNR) whereas for RNP11 the inbound course is 112. This almost negligible difference of one degree is what causes the navigator to turn the shortest route LH vs RH.
Of course one cannot be expected to note those details while flying or even flight planning: you simply use available tools (like a published hold on the other side and the GTN graphical depiction of planned route) to decide and take control of your routing. The navigator plotting something different is no excuse for PIC not being in control, and graphical cockpit tools including NAV and terrain displays are great to that effect.
