Author: 94S
Subject: Issue with Direct To distance count down
Posted: 18 Feb 2015 at 3:08pm
Ditto bellanca1730a.
I understand the math behind ATN, but fail to see the utility of it. I can think of many reasons why one might be flying off of the flight plan. Where, the TO Waypoint distance, as designed, would be confusing because it's not intuitive. Some scenarios would be; ATC vectors, diverting around weather, dealing with an emergency, going to look at that thing over there, etc. One particular use I have for direct distance and bearing is situational awareness at my home airport. I select "Direct To" before departing to go out in the practice area where I monitor the CTAF for other traffic coming and going. The direct bearing and distance to the airport help me understand my relationship to other traffic in the area as well as make position reports to same.
The architecture of FMS might assume that you will always be on the magenta line where this won't be an issue, but if it simply showed direct bearing and distance to the waypoint it would be correct and intuitive when you are on the magenta line and when you are not. I don't see the value in knowing the distance your perpendicular intercept to the magenta line is from a way point. I want to know how far away my airplane is from a waypoint, on or off the magenta line. I understand that you are adding a couple of new data blocks that will provide the direct to information, but I am really puzzled why your keeping the original ATN logic. It seems to me that it could bite somebody already task saturated by the weather, atc, or other extenuating circumstance, not by leading them astray, but by taking valuable mental resources off the primary task of flying the airplane to try to understand why the "number" is not doing what it is intuitively supposed to do.
I think pburger has brought up an issue that requires more attention than just saying "it works the way we want it to".
Sincerely,
David
Subject: Issue with Direct To distance count down
Posted: 18 Feb 2015 at 3:08pm
Ditto bellanca1730a.
I understand the math behind ATN, but fail to see the utility of it. I can think of many reasons why one might be flying off of the flight plan. Where, the TO Waypoint distance, as designed, would be confusing because it's not intuitive. Some scenarios would be; ATC vectors, diverting around weather, dealing with an emergency, going to look at that thing over there, etc. One particular use I have for direct distance and bearing is situational awareness at my home airport. I select "Direct To" before departing to go out in the practice area where I monitor the CTAF for other traffic coming and going. The direct bearing and distance to the airport help me understand my relationship to other traffic in the area as well as make position reports to same.
The architecture of FMS might assume that you will always be on the magenta line where this won't be an issue, but if it simply showed direct bearing and distance to the waypoint it would be correct and intuitive when you are on the magenta line and when you are not. I don't see the value in knowing the distance your perpendicular intercept to the magenta line is from a way point. I want to know how far away my airplane is from a waypoint, on or off the magenta line. I understand that you are adding a couple of new data blocks that will provide the direct to information, but I am really puzzled why your keeping the original ATN logic. It seems to me that it could bite somebody already task saturated by the weather, atc, or other extenuating circumstance, not by leading them astray, but by taking valuable mental resources off the primary task of flying the airplane to try to understand why the "number" is not doing what it is intuitively supposed to do.
I think pburger has brought up an issue that requires more attention than just saying "it works the way we want it to".
Sincerely,
David