# Questions tagged [dme]

DME (Distance Measuring Equipment) is, as the name suggests, a system for measuring the slant distance between a suitably-equipped aircraft and a ground-based transponder station; DME stations are often colocated with VOR or ILS installations.

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### What are the modulation parameters of a DME?

I am having difficulties finding specific information about DME pulse pair modulation. As far as I understand, the gaussian shaped pulse pairs are modulated using amplitude modulation. The carrier ...
1k views

### Are there benefits in training instrument students how to fly a DME arc?

With more instrument approach procedures being designed for RNAV/GPS equipped aircraft, and considering the high level of radar coverage currently available, is there a need to spend valuable training ...
3k views

### How can the A320 receive 3 DME signals if it has only 2 DME receivers?

How can the A320 receive simultaneously 3 DME signals (VOR1 + VOR2 + ILS) if it has only 2 DME receivers (and antennas)? Does it multiplex them in some way? If yes, does it mean if one DME receiver ...
169 views

### Although the missed approach point in the profile view is 1.1 DME-400 feet, the GS out reference altitude is given as 410 feet in 1.0 DME. HOW?

Although the missed approach point in the profile view is 1.1 DME-400 feet, the GS out reference altitude is given as 410 feet in 1.0 DME. HOW?! Based on GS out reference altitudes, we are expected ...
1 vote
98 views

### Why don't the Altitude-DME values in the approach profile match the Groundspeed-FPM values in the conversion table?

Why don't the Altitude-DME values in the approach profile match the Groundspeed-FPM values in the conversion table? When the calculation is made with the values given in the conversion table, the ...
605 views

### "w/o DME" minimums on DME required approach

I've found this ILS-Y 26 EPBY approach, where there are two LOC minimums: With D3.0 and w/o D3.0 on Jeppesen chart. On the original AIP charts it says "When stepdown fix not received", but ...
413 views

### is DME groundspeed slightly inaccurate due to slant range?

When DME is calculating aircraft ground speed, is it doing it based off of the slant range? Wouldn't this mean that if the aircraft is at sea level and the DME is at sea level that the GS would be ...
2k views

### How can I triangulate a position using two DMEs?

What is the formula for determining an aircraft's position (latitude, longitude) using barometric altitude and the ranges to two DMEs?
283 views

### How does increasing the rate of pulse pairs in DME 'search' mode help?

From How does an airborne DME unit differentiate itself? The higher rate in SEARCH [150 PP/S] gives it more opportunity to detect the replies as it has no knowledge of range in search and thus has to ...
312 views

### How do you calculate the deviation from an RNAV waypoint radial?

As a clarification at the beginning: I'm talking about non-GPS, pure VOR-DME based RNAV devices here. On RNAV devices that use just the selected VOR-DME, not GPS, the phantom radio station is set up ...
1k views

### Are there two navaids on the same frequency close enough to be confused?

Several RTCA DO standards require checks for bad navaid tuning including, "In lieu of using ground-based navigation aid designated operational coverage (DOC), the system should provide, checks ...
558 views

### What does a DME indicator do in HOLD or RNAV mode?

I found this DME indicator on the Cessna 210. Its mode switch has four positions - NAV1, NAV2, RNAV and HOLD. NAV1 and 2 are clear - it uses the NAV1 and 2 freq respectively. I'm wondering what the ...
117 views

### Can an IFR civilian aircraft use a TACAN for DME distances? [duplicate]

Flying the KRDR LOC RWY 35 approach. How do I get my DME distance to HONNE or CANLI? can we pick up DME distance from a TACAN? Just used GPS Overlay but can we get distance from the TACAN?
1 vote
168 views

### How does a VOR or a VORDME affect the coding decision between CF or IF-TF respectively?

I was reading of the following case in ARINC 424-17 spec. Unfortunately the image is copyrighted and I can't paste it here, so here is a low(er) quality image of mine replicating the situation: The ...
1 vote
272 views

### How is DME station ident coded in ARINC 429?

I understand that labels 242,244, 246, 247 are set for DME Station Id or DME Station Ident. they are marked as discrete. How should I convert the station code from alphabet to these 'discretes'? The ...
1 vote
968 views

### What button do I push on the instrument panel to activate DME in VOR navigation? [closed]

For some strange reason I cannot seem to find any information about what button to push on the instrument panel to active the DME. There is plenty of information about how DME works with ...
371 views

### What does it mean to "lock on" to a DME ground station?

I was just reading about the working of the DME the other day and then I read a para which said: The aircraft interrogator "locks on" to the DME ground station once it recognizes a particular ...
2k views

### Why don't aircraft have DME that can automatically convert the slant range to ground range?

Knowing that $a^2 = b^2 + c^2$ where $a = \text{slant range},\ b= \text{ground range},\ c = \text{height}$. Why can't the DME equipment which calculates the slant range then just convert it to the ...
866 views

### How does an airborne DME unit differentiate itself?

The FAA's IFR handbook glosses over a keypoint: The aircraft DME transmits interrogating radio frequency (RF) pulses, which are received by the DME antenna at the ground facility. The signal ...
3k views

### How can I know DME distance? [closed]

When I fly 12000ft, how can I know a distance from DME station? Is there any formula to know or measure distance from DEM?