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Inconsistent and potentially dangerous behavior

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MitchV View Drop Down

Joined: 21 Apr 2024
Location: KROC
Status: Offline
Points: 2
Post Options Post Options   Thanks (0) Thanks(0)   Quote MitchV Quote  Post ReplyReply Direct Link To This Post Topic: Inconsistent and potentially dangerous behavior
    Posted: 20 May 2024 at 1:50pm
Other than the following issue, I have found this a great system, and I have a lot of time in G1000's and other systems, and find this very easy to use in general.

Here is the issue:  When you select an approach on the IFD (540 in my case) the behavior is inconsistent based on whether the destination is the current fix, or a future fix.   

I know there were discussions on this previously but PLEASE READ ON.

If it's a current fix the system works correctly, and places the approach fixes AFTER the destination with a GAP.

If it's a future fix, then the system works incorrectly, and inconsistently and places the fix BEFORE the destination.

Why is this incorrect? -- Because you are not cleared for the approach. --  ATC expects you to fly towards the destination per the flight plan until instructed otherwise.

Therefore the approach should ALWAYS be inserted after the destination.   Then once you are cleared for the approach, or a fix on the approach you can fly to it.  

Furthermore having the software act differently in two different situations can be confusing or even dangerous.

Let me give you two real world examples:


Here is what you would typically be cleared with:  HAAYS HUO V252 GIBBE KROC

Approaching GIBBE you get the ATIS.  Ceilings 800' 2 mi vis, runways 22, 25, 28 are in use.  You set up for RNAV 28 approach with FAULT as the IAF.  The navigator now shows a GAP after GIBBE BECAUSE it has inserted the approach BEFORE KROC instead of AFTER.

Meanwhile before getting to GIBBE you are handed off to ROC approach.  You request RNAV 28, and are told to expect that but no further instructions are given.  Approach expects you to continue towards KROC after GIBBE, but the navigator is showing a GAP.  Unless you do something the plane will pass GIBBE on whatever heading you were on, NOT WHAT YOU WERE CLEARED FOR OR WHAT ATC EXPECTS OR WHAT YOU EXPECT.    

All this because you are trying to get ahead of the plane, and get your approach setup.  And why should it be inconsistent?  What advantage is there?

In this case you can insert  KROC back in after GIBBE, which while is a hassle, fixes the problem.

But how about this case:

KROC -> KHPN with the following clearance KROC -> DNY NOBBI5 -> KHPN

KHPN has digital ATIS so you know to expect RNAV 16  a long way from HPN and 16 is only active runway..  Its 500' ceilings, and NY center fully expects you to know this and have everything set up well in advance, but in this case its really tough.

If you program the RNAV 16 approach with entry at CMK then once again it shoves the approach in at the end of the arrival but BEFORE KHPN.   

But this time for whatever reason the navigator wont let you add KHPN back in between the end of the arrival and before the approach (not sure why, but waypoint does not come up as an option.)

So those are two REAL WORLD situations showing that its simply WRONG to put the approach in BEFORE the airport YOU WERE CLEARED TO.

Of course you can just hold off plugging in the approach until after you are cleared for the approach or a fix on the course.

Really?  Have you flown into NYC when weather is low?  Nobody, the controllers, you, or the other pilots have time for you to fool with that.  NY approach is going to say "Direct FODAK" and expect you to comply ASAP.    You ask for help in this situation and they will give it to you as in "N797HG turn heading 90 degrees" (i.e. away from the airport and out of everybody way) followed by "next time you request an approach please have it programmed and be ready".

Not kidding this has happened.

To make sure I was not mistaken I have sat down with my FSDO and run these scenarios by him.  He agrees that this inconsistency is problematic.

I understand that a change like this may cause some legacy confusion, but could you please at least put this on a config switch (i.e. "Always add approach after destination") which can be defaulted to off.  

There is a thread with a lot of this discussion back in 2015, which may be of some interest:  This is in reference to this thread: http://forums.avidyne.com/unexpected-behavior_topic906_post9967.html?KW=destination+after+approach#9967

PLEASE take this seriously, and consider adding some way to have the approach consistently added after the destination.

Edited by MitchV - 20 May 2024 at 3:19pm
Mitch - N797HG
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