Question about GPS/DME during holds

[Av8or72Dan]

When performing a GPS hold at an intersection, will the DME reach 0.0 or will it reach 1.0? Will your altitude change the distance? I know that this is a stupid question but I have been told by my flight instructor that it will go to zero but the chief flight instructor said it would only go to 1.0. I know from experience that I will get a flag flip (using an HSI) when I cross the fix but I have also noticed that the DME never went below 1.0. Please someone set me straight. ty

 

[Fly Navy]

A GPS waypoint should read 0.0 when directly over it. It is not affected by altitude, not in an enroute mode anyway.

 

[Squid]

so, uh, what are you flying??? in t-34 land, as I remember, when you toggle to GPS, you still get tacan dme with a gps #2 needle.

 

[squeeze]

dme on the gps will read 0 at the point

if you're 6000 ft up, directly over the station, and reading tacan dme, the needle will probably spin and indicate ~1.0 (assuming you don't get some weird COC issues... but dme seems to work in the COC 99% of the time).

 

[Brett327]

When performing a GPS hold at an intersection, will the DME reach 0.0 or will it reach 1.0? Will your altitude change the distance? I know that this is a stupid question but I have been told by my flight instructor that it will go to zero but the chief flight instructor said it would only go to 1.0. I know from experience that I will get a flag flip (using an HSI) when I cross the fix but I have also noticed that the DME never went below 1.0. Please someone set me straight. ty

Yeah, kind of a cryptic question. Are you holding at a fix which is defined by a TACAN radial/DME? Obviously, slant range will be an issue. Does your GPS system allow you to select between range and distance (Alt corrected slant range or not). If your GPS is not accounting for slant, then it will take the L/L posit for the fix you've entered and base your GPS distance from that point in space.

Good times,

Brett

 

[Kolja]

what's holding? :icon_lol: :eyebrows_

 

[Brett327]

what's holding? :icon_lol: :eyebrows_

An even more poignant question!

Brett

 

[jarhead]

what's holding? :icon_lol: :eyebrows_

don't you "hold" when you hit the marshal stack at the boat?

S/F

 

[Av8or72Dan]

Sorry for the confusion, but I did not mean to lead you to believe that I was using a tacan. I'm flying just a 172SP with GPS and trying to hold off of a VOR that does not have a cross radial. If anyone has an L-22 IFR low alt chart (Virginia), look at the Norfolk VOR. My question pertains to the PSALM intersection off of the 233 out of Norfolk.

I believe that when you are holding at an intersection like this, VOR DME does not matter since you have selected exactly which point you will be holding from. If you press DIRECT TO- NEAREST INT- and find the int, you will fly to the fix. The question was, will the DME go to zero or 1.0 at an int like this? I wasn't sure if altitude would have an affect.

Thanks for all of the help.

 

[Brett327]

Sorry for the confusion, but I did not mean to lead you to believe that I was using a tacan. I'm flying just a 172SP with GPS and trying to hold off of a VOR that does not have a cross radial. If anyone has an L-22 IFR low alt chart (Virginia), look at the Norfolk VOR. My question pertains to the PSALM intersection off of the 233 out of Norfolk.

I believe that when you are holding at an intersection like this, VOR DME does not matter since you have selected exactly which point you will be holding from. If you press DIRECT TO- NEAREST INT- and find the int, you will fly to the fix. The question was, will the DME go to zero or 1.0 at an int like this? I wasn't sure if altitude would have an affect.

Thanks for all of the help.

Sounds like it will read zero, anyway, what's +/- a mile or two among friends?

Brett

 

[petescheu]

Whoever said ATC was your friend... ha.

 

[saltpeter]

Altitude has no effect on GPS, however, it does on VOR navigation. When close to the station VOR's display your altitude. If your holding via an intersection then a VOR will read correctly regradless of your altitude (slant range), i.e. turn when the DME read a specific distance, say 15 miles or when the two CDI's center, if your not using DME. It sounds like your confusion GPS and VOR navigation, or more correctly your instructor is.

 

[saltpeter]

He's Fired.

 

[Av8or72Dan]

Thanks again for the help. Yeah, you can be a mile or two off course....who cares...besides the person that you crash into.

 

[Kolja]

don't you "hold" when you hit the marshal stack at the boat?

S/F

I nap.
:sleep_125