DME Range

[your_dreamguy]

Does anyone happen to know the range of DME reception when you're at FL350? My guess is around 180 NM. In case you're wondering, it's for an interview coming up. Thx.

 

[tacairlift]

Dude, goto the library and checkout a AIM, you know, Aeronatical Information Manual and study up before the interview. Table 1-1-1, VOR/DME/TACAN Standard Service Volumes: High Altitude 180 to 450 is 130nmi. Good luck.

 

[bubbers44]

You are a lot closer to the answer than Mr know it all. I don't remember exactly but seems to me on trips across Mexico it has been almost 200 NM.

 

[Mea25000]

199nm

 

[Looking]

If I am not mistaking, DME works of a secondary VHF frequency tied up to a VOR frequency;
that means it is line of sight and at FL 350, (ISA) 35000' that would be: the Square root of the altitude times 1.23 = 230 NM.
:beer:

 

[tacairlift]

From table 1-1-1 "From 18,000 feet AGL up to and including 45,000 feet AGL at radial distances out to 130 NM" Here's the link:
http://www.faa.gov/airports_airtraffic/air_traffic/publications/atpubs/AIM/Chap1/aim0101.html

 

[Say Again Over]

Reception and usability are two different things, AC 00-31A can help explain. Signals received beyond published service volumes are not technically usable.

 

[bubbers44]

Standard service volumes range probably is a very conservative range with the transmitting antenna on the ground with average obstructions. DME's which operate on a UHF freq. are line of sight so precluding obstructions would be received at high altitude beyond 200 nm with the same accuracy as closer in. Usually any time you can talk to someone if the DME is co located you can receive the DME too since VHF is also line of sight. Notice how the vor and dme usually come in range at the same time even though one is vhf and dme is uhf? Baffle your interviewers with your knowledge and you will have the job. ID ing the DME signal with the high pitch tone every 3 or 4 repeats will also impress them or think you are anal retentive too.

 

[denny]

good heavens! Who cares? Are they going to ask about range navigation and Loran too?

 

[Lowrider717]

Tell them you don't know jack about DME, but that you built your own laser ring gyro in the fifth grade.

 

[denny]

There you go!!

 

[bubbers44]

I'm getting a hand held gyro stabilized mouse to run my 60 inch monitor through my laptop in a day or two. I think that is more impressive than remembering when DME starts to work. I have no idea how this mouse will work. Good luck on your interview. I am sure it will be great. Never try to impress them too much. Most companies are just trying to find good competent people that can get along.

 

[Say Again Over]

good competent people that can get along

Amen to that.

 

[Tref]

1-1-7. Distance Measuring Equipment (DME) ​

a. In the operation of DME, paired pulses at a specific spacing are sent out from the aircraft (this is the interrogation) and are received at the ground station. The ground station (transponder) then transmits paired pulses back to the aircraft at the same pulse spacing but on a different frequency. The time required for the round trip of this signal exchange is measured in the airborne DME unit and is translated into distance (nautical miles) from the aircraft to the ground station. ​

b. Operating on the line-of-sight principle, DME furnishes distance information with a very high degree of accuracy. Reliable signals may be received at distances up to 199 NM at line-of-sight altitude with an accuracy of better than 1/2 mile or 3 percent of the distance, whichever is greater. Distance information received from DME equipment is SLANT RANGE distance and not actual horizontal distance.

​

http://www.faa.gov/airports_airtraffic/air_traffic/publications/atpubs/aim/Chap1/aim0101.html

 

[Clacker]

If they ask you that question, just shrug your shoulders and say: "I dunno, I'd just ask ATC for a heading."

Works great on a DC-9!