Question for IFR smarty pants
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Question for IFR smarty pants
Any ideas why an up to date certified GPS (KLN94) would cycle from Jezze straight to wavvs (map) skipping CUCAV on the RNAV (GPS) Y RWY 26 approach linked below?
https://flightaware.com/resources/airport/KCMA/IAP/RNAV+(GPS)+Y+RWY+26
https://flightaware.com/resources/airport/KCMA/IAP/RNAV+(GPS)+Y+RWY+26
No idea.
Does CUCAV show up as a waypoint in the active plan when you load the procedure?
I have seen similar things on other brands of units where the plate shows a waypoint but its not in the database, though this has been mainly with overlay style approaches for VOR or NDB approaches.
In the case you mention I'd imagine it's not a show stopper as the critical waypoints are there. It's just a bit of a surprise the first time you experience it.
Does CUCAV show up as a waypoint in the active plan when you load the procedure?
I have seen similar things on other brands of units where the plate shows a waypoint but its not in the database, though this has been mainly with overlay style approaches for VOR or NDB approaches.
In the case you mention I'd imagine it's not a show stopper as the critical waypoints are there. It's just a bit of a surprise the first time you experience it.
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here's the problem...
yes but I had to google it. As ever, Max Trescott is the man... I didn't know he did any books on the KLN94, but his G1000 stuff and his instrument book is great. As a kln94/IR owner myself I was keen to know what the issue was...
This is the issue....
Max Trescott Aviation Trends Aloft: KLN 94 Gotcha Flying RNAV GPS Y and Z Instrument Approaches
And, yep definitely a show stopper as there is a 1700 ft crossing height for CUCAV
This is the issue....
Max Trescott Aviation Trends Aloft: KLN 94 Gotcha Flying RNAV GPS Y and Z Instrument Approaches
And, yep definitely a show stopper as there is a 1700 ft crossing height for CUCAV
And, yep definitely a show stopper as there is a 1700 ft crossing height for CUCAV
It's pretty simple, 4 miles from WAVVS. No different to how hard heights are depicted on VOR or NDB/DME approaches.
It's not as if there was a track change CUCAV, then I might agree with you.
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If you are flying strictly by the book, or say a commercial operator and this happened, is the correct course of action to go missed or just read the mileage to the missed and continue descent to the MDA?
Looking at that plate a little closer, I have to ask the question as to why CUCAV has the note 4 NM to WAVVS both on the plan and profile views. This makes me think CUCAV may not always be depicted in the GPS screen.
None of the other waypoints are annotated like this.
On an other note. It's certainly a steeper profile than is usual. Nearly 6.2% as opposed to the more usual 4.9% or sometimes 5.2%
None of the other waypoints are annotated like this.
On an other note. It's certainly a steeper profile than is usual. Nearly 6.2% as opposed to the more usual 4.9% or sometimes 5.2%
If you are flying strictly by the book, or say a commercial operator and this happened, is the correct course of action to go missed or just read the mileage to the missed and continue descent to the MDA?
In my opinion CUCAV isn't important, yes there's the hard height but that's easily monitored without CUCAV. Certainly a discussion point but in my opinion you can descend to MDA.
I've seen other quirks where the approach was flown all the time without issue.
If I was flying it for the first time and it caught me by surprise and created confusion I'd go missed.
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What's the significance of the point marked on the profile with a V 1.1nm to WAVVS? It's not on the plan but the profile shows the descent stops there followed by a short level segment to th MAP.
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V=VDP
Visual descent point (U.S.) Edit
A concept related to the missed approach point is the visual descent point, or VDP. Determination of its location is done by the designers of the instrument approach procedure, but typically this is a point on the final approach course of a non-precision approach, from which the aircraft would be able to continue its descent from the MDA to the runway threshold while maintaining a standard 3° descent angle while being assured obstacle clearance.[5] In other words, usually it is the point (on the profile view of the approach) where a line depicting a 3° descent angle would intercept the horizontal line at the MDA. If the pilot does not have the required visual reference to continue the descent from the MDA at this point, he/she must continue to fly at or above the MDA, and the rapidly steepening descent angle required to complete a successful landing on the runway means that a safe and successful approach becomes less likely.
The concept of VDP was developed by the FAA to encourage pilots to decide to initiate a missed approach prior to reaching the MAP, in a situation where the runway or its environment is not visible at a normal descent angle. Conversely, if the runway is visible at the VDP, the pilot may continue descent, following a standard descent angle to the runway, while being assured terrain and obstacle clearance.[5] The VDP is always located prior to reaching the MAP, and is a more useful checkpoint for making the decision whether to continue on the approach or to go around than the MAP itself.[6]
The following is the official FAA definition of VDP:
"A defined point on the final approach course of a nonprecision straight-in approach procedure from which normal descent from the MDA to the runway touchdown point may be commenced, provided the approach threshold of that runway, or approach lights, or other markings identifiable with the approach end of that runway are clearly visible to the pilot."[1]
Visual descent point (U.S.) Edit
A concept related to the missed approach point is the visual descent point, or VDP. Determination of its location is done by the designers of the instrument approach procedure, but typically this is a point on the final approach course of a non-precision approach, from which the aircraft would be able to continue its descent from the MDA to the runway threshold while maintaining a standard 3° descent angle while being assured obstacle clearance.[5] In other words, usually it is the point (on the profile view of the approach) where a line depicting a 3° descent angle would intercept the horizontal line at the MDA. If the pilot does not have the required visual reference to continue the descent from the MDA at this point, he/she must continue to fly at or above the MDA, and the rapidly steepening descent angle required to complete a successful landing on the runway means that a safe and successful approach becomes less likely.
The concept of VDP was developed by the FAA to encourage pilots to decide to initiate a missed approach prior to reaching the MAP, in a situation where the runway or its environment is not visible at a normal descent angle. Conversely, if the runway is visible at the VDP, the pilot may continue descent, following a standard descent angle to the runway, while being assured terrain and obstacle clearance.[5] The VDP is always located prior to reaching the MAP, and is a more useful checkpoint for making the decision whether to continue on the approach or to go around than the MAP itself.[6]
The following is the official FAA definition of VDP:
"A defined point on the final approach course of a nonprecision straight-in approach procedure from which normal descent from the MDA to the runway touchdown point may be commenced, provided the approach threshold of that runway, or approach lights, or other markings identifiable with the approach end of that runway are clearly visible to the pilot."[1]
Looking at that plate a little closer, I have to ask the question as to why CUCAV has the note 4 NM to WAVVS both on the plan and profile views. This makes me think CUCAV may not always be depicted in the GPS screen.
1) introduce a named waypoint like CUCAV to the sequence
2) just annotate the approach plate with the SDF based on distance to threshold, without an explicit waypoint
From what I recall, when GPS approaches were first developed, some were coded in one way, some in the other. In operational practice, once past the FAF pilots found it easier to have the distance to threshold directly displayed (2), rather than having to do the math associated with a distance to a SDF plus a distance to the threshold after that (1). So the modern trend, certainly in Europe, is to avoid waypoints between the FAF and the threshold (i.e. 2).
It may be that the transition from one policy to the other (or at least from a mix to a standard way of designing them) involved taking the previous waypoints out of the coding table but leaving the named waypoint on the plate, with a note.
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Interesting, thanks. Seems more relevant to larger ac (smaller ones could happily join the visual low level cct if too high at the MAP to land)
