GPS intercepts confusion
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GPS intercepts confusion
Im really confused about GPS intercepts.
Heres an example, see if im correct:
Say i want to intercept station "X" inbound:
DTK = 045
Say my BRG (BTS) = 200 so my BFS =020, im N/E of the station so i have to fly S/W direction for any kind of inbound intercept.
TRK = doesn't matter
Once i intercept the 045 DTK my GPS would show me:
-BRG = 225
-TRK = 225
-DTK = 045 obvs
so now im flying inbound on the 45 degree track to the station?
but for inbound my DTK=BRG=TRK right? So im really confused. for this to make sense I would have to have started somewhere either N/W or S/W of the station thus when im flying on my DTK =45 my TRK =45 and my BRG = 45.
Heres an example, see if im correct:
Say i want to intercept station "X" inbound:
DTK = 045
Say my BRG (BTS) = 200 so my BFS =020, im N/E of the station so i have to fly S/W direction for any kind of inbound intercept.
TRK = doesn't matter
Once i intercept the 045 DTK my GPS would show me:
-BRG = 225
-TRK = 225
-DTK = 045 obvs
so now im flying inbound on the 45 degree track to the station?
but for inbound my DTK=BRG=TRK right? So im really confused. for this to make sense I would have to have started somewhere either N/W or S/W of the station thus when im flying on my DTK =45 my TRK =45 and my BRG = 45.
Re: GPS intercepts confusion
Once you are on a direct track of 045° to a station you would be south west of it.
As you say, if at the start, your bearing to the station is 200° then you are north east of it, which is an unlikely place to start to intercept a 045° track to it.
As you say, if at the start, your bearing to the station is 200° then you are north east of it, which is an unlikely place to start to intercept a 045° track to it.
DId you hear the one about the jurisprudence fetishist? He got off on a technicality.
- rookiepilot
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Re: GPS intercepts confusion
Sounds to me, pulling away from the Jays losing, like you’d need to turn right, fly SE to intercept a 045 outbound track.ols500 wrote: ↑Wed May 24, 2023 4:39 pm Im really confused about GPS intercepts.
Heres an example, see if im correct:
Say i want to intercept station "X" inbound:
DTK = 045
Say my BRG (BTS) = 200 so my BFS =020, im N/E of the station so i have to fly S/W direction for any kind of inbound intercept.
TRK = doesn't matter
Once i intercept the 045 DTK my GPS would show me:
-BRG = 225
-TRK = 225
-DTK = 045 obvs
so now im flying inbound on the 45 degree track to the station?
but for inbound my DTK=BRG=TRK right? So im really confused. for this to make sense I would have to have started somewhere either N/W or S/W of the station thus when im flying on my DTK =45 my TRK =45 and my BRG = 45.
At 020 from the station, you are NW of a 045 outbound track, BTS would be 225.
I’m assuming you mean you are 020 outbound from the station, and transitioning to an intercept that is 045 from station.
Last edited by rookiepilot on Wed May 24, 2023 5:15 pm, edited 2 times in total.
Re: GPS intercepts confusion
Somebody draw a diagram.
DId you hear the one about the jurisprudence fetishist? He got off on a technicality.
Re: GPS intercepts confusion
By TRK i mean my current track, this will change throughout the intercept:
-My inital track --> my intercepting track (an angle to my DTK, e.g. 30, 45, 60, 90) ---> My TRK=DTK
-My inital track --> my intercepting track (an angle to my DTK, e.g. 30, 45, 60, 90) ---> My TRK=DTK
Re: GPS intercepts confusion
I think im confused on outbound and inbound, can someone give me a full defintion please. thanks.
Re: GPS intercepts confusion
You are confusing something very simple.
DTK is always TO the waypoint.
We don't care about going FROM it (in most case) because we always have another waypoint to go to until we are at our destination.
You're confused about inbound/outbound? It's as you say.. one is toward the waypoint, one is away from it. We can draw or follow lines each way but again we rarely need to go FROM.
There's four ways you can go TO a GPS waypoint. I think.. other than offsets and all of that.
1) Direct. Just like it sounds. Right from your position to the waypoint. Maybe some turn anticipation put into the track so your plane doesn't overshoot.
2) OBS. So this is what you are talking about. OBS or setting an intercept track means that you are going to head to the waypoint on a selected track. 045 would mean yes you'd have to maneuver yourself SW of the waypoint to intercept that track if you were NE. Now... in Garmin land OBSing suspends the waypoint so that once you cross it.. you'd continue that 045 track FROM the waypoint. Not all GPS are like this and some will automatically sequence you to the next waypoint. But this is about the only time you'd be concerned with an outbound track from a waypoint. The other is a Downwind Termination Waypoint on an open star where you just keep going until you get vectored onto the approach.
3) Activate Leg. This is where you make the leg between the active waypoint and the previous waypoint active. This sets the front course of the CDI to the leg and then you can navigate to it (usually by heading or vectors) to intercept it at any point.
4) Vectors to Final. Much like Activate Leg except it doesn't need a previous waypoint and is generally only for approaches
DTK is always TO the waypoint.
We don't care about going FROM it (in most case) because we always have another waypoint to go to until we are at our destination.
You're confused about inbound/outbound? It's as you say.. one is toward the waypoint, one is away from it. We can draw or follow lines each way but again we rarely need to go FROM.
There's four ways you can go TO a GPS waypoint. I think.. other than offsets and all of that.
1) Direct. Just like it sounds. Right from your position to the waypoint. Maybe some turn anticipation put into the track so your plane doesn't overshoot.
2) OBS. So this is what you are talking about. OBS or setting an intercept track means that you are going to head to the waypoint on a selected track. 045 would mean yes you'd have to maneuver yourself SW of the waypoint to intercept that track if you were NE. Now... in Garmin land OBSing suspends the waypoint so that once you cross it.. you'd continue that 045 track FROM the waypoint. Not all GPS are like this and some will automatically sequence you to the next waypoint. But this is about the only time you'd be concerned with an outbound track from a waypoint. The other is a Downwind Termination Waypoint on an open star where you just keep going until you get vectored onto the approach.
3) Activate Leg. This is where you make the leg between the active waypoint and the previous waypoint active. This sets the front course of the CDI to the leg and then you can navigate to it (usually by heading or vectors) to intercept it at any point.
4) Vectors to Final. Much like Activate Leg except it doesn't need a previous waypoint and is generally only for approaches