Garmin Set OBS and Hold

drgwentzel

drgwentzel

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Flyers,

I have a Garmin 796. Let's say I'm given a clearance to, "Hold North at ABC on the 360 degree radial..."

I enter Direct to ABC and press Menu > Set OBS and Hold. Next I enter 360 in the OBS field. Then what I'm presented with confuses me.

The pink line emanating out of ABC is along the 180 degree radial!? Can someone explain to me why this is? I basically told the unit that I want to fly to ABC via the 360 degree radial, but it put the line on its inverse. :confused:

BTW, the 696 did this too, but drew the pink line through the fix on both the 360 and 180 radials. But the active leg was the 180 degree radial. Very confusing.
 
To hold north of a fix on the 360 degree radial your inbound course would be 180, and the OBS would be set to 180, no?
 
dmspilot said:
To hold north of a fix on the 360 degree radial your inbound course would be 180, and the OBS would be set to 180, no?
Click to expand...

Yes, because you're flying "on" the 360 degree radial to the station with a 180 degree heading, and IF I was doing this with a VOR receiver that is what I'd have to do to set it up. BUT, I am flying a GPS and I'm trying to speak "GPS". It appears the programmers want me to speak to the GPS in VOR / NAV radio language.

Example: it would seem intuitive that if I was told to fly to ABC VOR via the 270 degree radial, I would think I would set the GPS to go Direct To the VOR and simply set the radial I wish to fly upon...in this case...270.

We seem to be taking the simple nature of the GPS and dragging the counter intuitive elements of the VOR / NAV / TO / FROM / OBS / Reverse sensing / radial verses heading elements that have befuddled pilots new and old since the system was implemented.
 
dmspilot said:
To hold north of a fix on the 360 degree radial your inbound course would be 180, and the OBS would be set to 180, no?
Click to expand...

Maybe what I'm saying is, "SET OBS AND HOLD" should be changed to "SET RADIAL AND HOLD" or simply "SET DESIRED RADIAL". That would be more intuitive.
 
drgwentzel said:
Flyers,

I have a Garmin 796. Let's say I'm given a clearance to, "Hold North at ABC on the 360 degree radial..."

I enter Direct to ABC and press Menu > Set OBS and Hold. Next I enter 360 in the OBS field. Then what I'm presented with confuses me.

The pink line emanating out of ABC is along the 180 degree radial!? Can someone explain to me why this is? I basically told the unit that I want to fly to ABC via the 360 degree radial, but it put the line on its inverse. :confused:

BTW, the 696 did this too, but drew the pink line through the fix on both the 360 and 180 radials. But the active leg was the 180 degree radial. Very confusing.
Click to expand...

no, you told it to fly TO ABC via a course of 360. GPS only goes TO something. it might draw a FROM line but only navigates TO a waypoint.

Sent from my Nexus 7 using Tapatalk
 
drgwentzel said:
Maybe what I'm saying is, "SET OBS AND HOLD" should be changed to "SET RADIAL AND HOLD" or simply "SET DESIRED RADIAL". That would be more intuitive.
Click to expand...
It would also be wrong.

I'm not sure what's particularly "intuitive" about anything dealing with aircraft navigation, but it's up to the pilot to know that it's the holding course inbound to the waypoint that you want to fly and that

==============================
"Hold North at ABC on the 360 degree radial..."
==============================

translates to an inbound holding course of 180 and that's the course you enter in the OBS, whether GPS, VOR, NDB, DME distance or an made up intersection in the middle of nowhere.
 
You want to set the inbound COURSE when selecting the OBS. With a COURSE of 180 set, you will be given GPS course guidance along the 360 degree radial.
 
Direct to XYZ, OBS hold, select inbound course (recip heading of radial) enter
Now fly yourself on to the pink line
 
drgwentzel said:
I have a Garmin 796. Let's say I'm given a clearance to, "Hold North at ABC on the 360 degree radial..."

I enter Direct to ABC and press Menu > Set OBS and Hold. Next I enter 360 in the OBS field. Then what I'm presented with confuses me.

The pink line emanating out of ABC is along the 180 degree radial!? Can someone explain to me why this is?
Click to expand...
It's because you entered a 360 course TO the station, which means you would be flying the 180 radial inbound. If you use the Garmin OBS function to fly a hold at a VOR, intersection, waypoint, or other fix, you have to enter the inbound holding course, not the radial, in the OBS window or on the OBS of the CDI -- just as you'd do with a VOR.
 
HPNPilot1200 said:
You want to set the inbound COURSE when selecting the OBS. With a COURSE of 180 set, you will be given GPS course guidance along the 360 degree radial.
Click to expand...

I am a CFII too. I know that, and THAT is why sooo many students struggle in visualizing holds while they are flying and they struggle to enter the hold properly. Even pilots with over a 1000 hours, who only fly IFR occasionally, have a difficult time wrapping their heads around hold visualization.

ATC says, "Hold SW at XXX on the 250 degree radial,..." I can see the student write it down and then I see them trying to fly, talk, and noodle the hold in their head and then noodle the hold entry.

I can see them struggle with this every time, so they turn to their faithful VFR GPS for situational awareness...and what does it ask us?? The same questions that make the visualization hard to see in their heads in the first place.

THEY HAVE TO THINK ABOUT COURSE VERSES RADIAL VERSE THE NUMBER AT THE TOP OF THE DIAL, OR THE BOTTOM OF THE DIAL, THEY HAVE TO USE THE INVERSE OF THE RADIAL THEY WERE TOLD TO HOLD ON, OR a TO INDICATION OR a FROM INDICATION...BLAH BLAH BLAH.

ENTER THE GPS! VFR OR IFR Certified, it doesn't matter. VFR can be used for situational awareness, which is EXACTLY what these pilots need at the moment.


They wrote down the Hold particulars: the fix, SW, 250, EFC. No more thinking is needed if the GPS would only ask for those particulars!!

The GPS should ask you to enter the fix ID and the RADIAL you were cleared to hold upon. PERIOD! Because that was the number ATC gave you...you even wrote it down!

It should then draw the pink line off that fix along the RADIAL you just entered and if so, I think the rest of the story is easy.

That pink line is the inbound course to the fix, and you already know which way to turn, and you already know the leg lengths in time or distance. End of story!

You still have to visualize the hold entry, which is easy now that you have the overhead view of the fix, the inbound radial and your airplane position.

After that your head is clear; you understand the picture and now you can enter the VOR frequency and inbound course, ID the station, relax and enjoy your flight.

So why do students and many pilots get this screwed up so much? Because they were told and only remember, "HOLD 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, ...) I see this mistake time and time again. All they can think of is "2 - 5 - 0". So I think, that is what the GPS should ask for..."What is the RADIAL you were told to hold on...in this case 2- 5- &^%$ 0!
 
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Fearless Tower said:
You don't need SVT either, but like you say, why not use technology that is available?
Click to expand...

Well, if the VOR radio and magenta line on the VFR don't coincide, what do you get out of it? There's a difference between using certified and non certified equipment in an IFR environment. For situational awareness you're as well off with just the map and placement.
 
I don't know of a GPS or FMS that asks for the desired radial to hold on, but I suppose that may be useful. Our FMS in the CJ3 asks us for the inbound course. In the case of a hold with an assigned radial, that would just be the reciprocal value.
 
I would kill for a future IFR GPS to have the ability to hit a softkey which gives you a prompt to create a holding pattern on the fly.
 
drgwentzel said:
So why do students and many pilots get this screwed up so much?
Click to expand...
Because CFIIs over-complicate it when teaching holds.

To each his own but "you need to determine the inbound course for every navigational system you use except GPS" sounds like an invitation to far more confusion.

Because they were told and only remember, "HOLD 250, 250, 250, 250, 250, 250, 250, 250, 250, 250, ...)
Click to expand...
Too bad they were told to focus on the number by their instructors to the exclusion of learning what it meant. I wonder what that poor pilot would do with the holding instruction I once received - with no numbers at all. Just a "hold southeast of the XYZ VOR."
 
Henning said:
Well, if the VOR radio and magenta line on the VFR don't coincide, what do you get out of it?
Click to expand...

99 times out of 100, the GPS is correct. At least now you know something is wrong and needs to be checked out before you make a mistake...a mistake that could be only embarrassing if you're lucky or deadly if it's not you day.

Who would care if the GPS isn't IFR certified if it catches an incorrectly entered OBS? That is a mistake that could blindly direct you into cumulous granous or an otherwise undesirable object sticking out of the ground? This is why the shuttle and most aircraft have redundant systems that cross check each other.

The problem with a VOR, a map and a human, as you suggest, is that there's only one failure point...the human.
 
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drgwentzel said:
99 times out of 100, the GPS is correct. At least now you know something is wrong and needs to be checked out before you make a mistake...a mistake that could be only embarrassing if you're lucky or deadly if it's not you day.

Who would care if the GPS isn't IFR certified if it catches an incorrectly entered OBS? That is a mistake that could blindly direct you into cumulous granous or an otherwise undesirable object sticking out of the ground? This is why the shuttle and most aircraft have redundant systems that cross check each other.

The problem with a VOR, a map and a human, as you suggest, is that there's only one failure point...the human.
Click to expand...

Well, in this instance it shows that it's just as easy to get the input wrong on the GPS. If you believe that a difference between a VOR that's been checked for accuracy per IFR rules and a non certified GPS is going to favor the GPS 99% of the time, I believe you're in grave error. If you want to fly IFR on GPS, get an IFR GPS.
 
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