Adding a SID after activating the flight plan
Printed From: Avidyne
Category: Avidyne General
Forum Name: IFD 5 Series & IFD 4 Series Touch Screen GPS/NAV/COM
Forum Description: Topics on Avidyne's IFD 5 Series and IFD 4 Series Touch Screen GPS/NAV/COM
URL: http://forums.avidyne.com/forum_posts.asp?TID=1175
Printed Date: 19 May 2024 at 10:00pm
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com
Topic: Adding a SID after activating the flight plan
Posted By: jhbehrens
Subject: Adding a SID after activating the flight plan
Date Posted: 13 Nov 2016 at 5:15am
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When a departure is added after the flight plan has been activated, as might happen when you enter the flight plan without the departure procedure initially, activate it and then add the departure when you get you clearance, the IFD still keeps the leg to the first waypoint after the departure active. The has now happened to me a few times. After take-off I click on the autopilot and the airplane makes a completely unexpected turn to the initial waypoint. I feel this is unsafe behaviour. When you add a departure procedure on the ground, the IFD should activate the first leg of that departure, not the first leg of the flight plan without the departure.
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Replies:
Posted By: Catani
Date Posted: 13 Nov 2016 at 10:43am
| While it may or may not be a good idea for Avidyne to default to behavior as you suggest (I can think of reasons why it should not), I don't think it's a good idea to fiddle with the active flight plan route in any way without confirming where the box has interpreted what you've done by checking the active go-to fix and route as a last step. FMS's (and computers in general) are notorious for doing exactly what you told them to do even when you thought you told them something else. The American Airlines Cali crash comes to mind - it's not just a GA issue. If you don't confirm after making a change, you could be going anywhere. |
Posted By: mfb
Date Posted: 13 Nov 2016 at 11:08am
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I absolutely agree with Catani. There are many instances when the IFD or any other FMS system does not do what you expect it to. It doesn't matter whose "fault" it is - you just thought that whatever you put in would cause it to act differently than it did. It happens every day and it will continue to do so. It's particulary likely to happen when setting up approaches, arrivals, and departures. Most airline FMS boxes have an Execute or Enter button that will allow you to make flight plan edits and check them before they take effect. This allows the operator (usually the non-flying pilot) to go through a program-confirm-execute cycle, where both crewmembers make sure that the new flight plan is correct before the Execute button is pushed. We IFD users don't have the luxury of a second crewmember and we don't have an Execute button. Flight plan changes take place immediately and we must check them ourselves. Therefore, we must use a different protocol. A good one might be: 1) Put the autopilot in Heading mode to de-couple it from the IFD. (So the airplane won't go the wrong way if the new flight plan is wrong.) 2) Enter the flight plan changes. 3) Confirm the changes, paying particular attention to the new magenta "active" leg. That's where the FMS wants to go. 4) Re-couple the autopilot and confirm that it's turning properly to the new course. As Humpty-Dumpty said in Alice in Wonderland: "The question is - Who is to be master?" The PIC must be master, not the FMS. Mike |
Posted By: oskrypuch
Date Posted: 13 Nov 2016 at 12:01pm
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Step (1), putting it in heading mode first, can be a life saver, if you are making major changes. The CNX-80 has the EXECute logic, but it seems that most folks hate it. * Orest |
Posted By: Royski
Date Posted: 14 Nov 2016 at 9:13am
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For those with GPS steering, don't forget to turn that off if you are going into heading mode while messing with the flight plan. |
Posted By: jhbehrens
Date Posted: 14 Nov 2016 at 10:51am
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The scenario I describe above happens when you modify on the ground, before take-off, while you get your clearance or amended clearance including a departure you didnt expect. If you add it to an already activated flight plan its basically ignored. That is not what is expected. It either needs to be routed to or the unit needs to ask me what I want.
Obviously I should have checked and noticed but if this happens while holding for the active runway and you also get your take-off clearance at the same time its a high workload situation and you might be -at least I was- caught out.
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Posted By: Catani
Date Posted: 14 Nov 2016 at 2:16pm
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This was all learned by me the hard way flying with FMSs over the past 30 years, so don't feel like the Lone Ranger: Don't let yourself get rushed when programming an FMS. ATC can wait. Your IFD didn't ignore you; you didn't complete the update by telling the FMS to activate a different route. It cannot assume that anytime you load an approach or a SID or STAR that you want to activate it and proceed immediately off your current route to any random fix the FMS thinks makes the most sense, unless you are already proceeding to the first fix in the procedure. An FMS is not smart enough to question your intentions in context as if it were a copilot. It's not going to warn you, you have to check the route yourself after every entry that you make. If you don't it's going to take you to places unknown, causing you to put your head down and try to puzzle it out, all the while nobody is paying attention to the aircraft. Here's a now-famous video if you haven't seen it already that shows how American Airlines realized it had a problem with FMSs that do the unexpected, and what a pilot should do about it. Good advice for us all. https://www.youtube.com/watch?v=pN41LvuSz10
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Posted By: oskrypuch
Date Posted: 14 Nov 2016 at 3:56pm
Yes, that is an excellent video, "Children of Magenta", even more relevant today. Everyone should watch it. * Orest |
Catani wrote:Posted By: MarkZ
Date Posted: 14 Nov 2016 at 7:39pm
| +1! |
Posted By: DavidBunin
Date Posted: 18 Nov 2016 at 9:15am
For what it's worth, you never need to activate a flight plan in the IFD. Just program it, and the box will self-activate it when you accelerate for takeoff (30 knots?). I believe that omitting the "activate it" step in the statement above would have solved your problem. The problem being the insertion of a procedure prior-to the active waypoint in the plan. David Bunin |