Distance measuring equipment (DME) is a radio navigation technology that measures the slant range (distance) between an aircraft and a ground station by timing the propagation delay of radio signals in the frequency band between 960 and 1215 megahertz (MHz). When flying a DME arc such as that illustrated in Figure 8-19, it is important that you keep a continuous mental picture of your position relative to the facility. 1/2 to 1 mile is acceptable, so you don’t have to go crazy. The FAA Instrument Flying Handbook suggests flying slightly inside the DME arc, so as to always fly toward it If you get outside the arc, it’s turning away from you, necessitating a greater correction change of course On arc => turn 10° Inside => maintain heading Our sincere thanks to pilots such as yourself who support AskACFI while helping themselves by using the awesome The way I fly it, all you really *need* are the radial you are using to join, a confirmation radial after the turn, a lead radial, and the radial you are going to turn to. Flying DME arc using RMI If no wind, can theoretically fly precise arc by maintaining relative bearing of 90° or 270° In actual practice, fly a series of short legs With RMI bearing pointer on wingtip reference (90° or 270° position), maintain heading and allow bearing pointer to move 5° to 10° behind wingtip am doing my basic IR training and i have a questions regard DME arc entry and leaving procedures, what are the formulas to calculate the distance of the dme arc from the fix in nm and degrees?in another word, if dme arc not published, how to find when should i start circling on the arc from the fix point?i saw alot of formulas online but couldnt understand any...appreciate the helpI believe it is best to just used fixed numbers. 10 NM arc, DME reads 10.6, turn toward the arc. Unless you are in no-wind conditions, the amount of correction you will need will change as you go around the arc (another problem with trying to calculate the flying – it will continually change and require a new calculation) . Faster airspeed obviously needs a proportionally earlier turn, but unless you are travelling better than 240 kts, it won’t be more than 1 nm. I am just a simple minded pilot and I like to keep it as simple as possible. Click on a term to see its definition from the Dauntless Aviation JargonBuster Glossary. The Basics In its simplest form, a DME arc means flying a track that is a constant dis- tance from a VORTAC or VOR/ DME facility. given a few quick and easy tips they can be as easy as tracking any course Flying a DME arc (even without GPS) is simple (far simpler than the complicated way it is taught – KDS is probably right that 1/2 mile will work for 160 too). After the turn (good situational awareness meas you can do it during the turn but you don’t have to) make any necessary correction to give you the arc distance you want. There’s no advanced math required beyond 1st grade. At ground speeds up to about 120 kts (that’s the number the FAA Instrument Flying Handbook uses), turn 90 degrees standard rate in the direction of the arc when 1/2 nm out. So I’m wondering if you are interested in the design of arcs, in which case, I’d refer you to TERMS or other FAA publications which go into excruciating design detail. I’m sure there are also some advanced arc math sites, but you already said you didn’t understand them. Confirm you have turned in the correct direction with a 10 degree twist of the OBS.Once on the arc, it’s just a simple matter of adjusting and maintaining the DME distance and monitoring your progress until you get to the lead radial (published or not). I’m guessing they are taking IAS, converting it to true, adding wind and mixing it all together with rate of turn. I’m also not sure what you mean by “if it’s not published,” but even if a roll-your-own arc (some instructors do there in areas where there are no published ones) , published or unpublished makes no difference.FWIW, here’s how I teach DME arcs. Line-of-visibility between the aircraft and ground station is required. so divide the distance of the arc from the navaid by 60 & multiply by the number of degrees of arc travelled. The good news is that a DME arc is simple once you understand how to execute it. If this is your first visit, welcome! If the DME is 0.1 greater than the arc, turn 10° toward the arc If the DME is 0.1 less than the arc, maintain your current heading until the DME increases to the assigned DME distance, then turn 10deg; toward the arc To help maintain positional orientation and situational awareness, use the OBS to determine your position along the arc In some cases, wind can be used in returning to the desired track. If you are flying something that requires a higher speed, you are probably going to have equipment that is going to do all those calculations for you.I find that the most common serious mistake people make is forgetting to turn inbound when they get near the course. Many pilots are taught “twist 10” to monitor progress, but it’s not really necessary.