VOR/DME Approaches

VOR/DME approaches

VOR/DME approaches differ from the VOR approach in that theyhave distance (DME) information available. Here is a VOR/DME approachplate for Hutchinson, Kansas.

What's new, or different on thisapproach plate?

First off, notice that there is no "timing box" inthe lower left corner. With distance information available, youcan be much more certain of where you are on the approach. Let'slook a few items on this approach plate that were not, or werenot addressed, on the previous one.

TheATIS frequency, 124.25 is shown, operation is not continuous.The frequency for Hutchinson Approach would be shown on the firstplate for Hutchinson, most likely (and indeed true) an ILS approachplate. The Hutchinson Tower and Ground do not operate continuously.The notation "Wichita Radio CTAF" means that the frequency118.5 is the Common Traffic Advisory Frequency when the Toweris not in operation. The last note "When Control Zone noteffective, except for operators with approved weather service,use Wichita altimeter setting." Translation: If the toweris not open, the Control Zone does not exist. Unless you havea certificated weather observer on the ground to take weatherobservations for you when the Tower is closed, you must use thealtimeter setting from the nearest airport, in this case, Wichita.And, of course, if you have to use a remote altimeter setting,the minimums will probably be higher.

Onthe back of the first approach plate for the airport there wouldbe the information necessary to use this service.

The tallest object in the approach area. In this case, a towerthat is 3,049 feet tall.A"spot elevation". The terrain at this point is 1,928feet, msl.

Thepublished minimums for this approach. For a straight-in landingto runway 21, with the tower in operation (Control Zone Effective),the minimums are 458 & 1: 458 feet above the ground (2,000msl), and 1 statute mile of visibility, day or night. If it isnight time, and the Tower is closed, then the minimums bump upto 698 & 2: 698 feet above the ground (2,240msl), and 2 statutemiles of visibility.

OK, I understand all of that. Now,how would I go about shooting this approach?

We're going to go through several different ways that thiscan be done: without radar, with radar, and via a DME arc.

Without radar

You are currently Southwest of the Hutchinson VOR, level at7,000.

At some point, Center will call you. "Red Baron 123, turnright heading 020, descend to an maintain 5,000". "Rightto 020, out of 7 for 5, Red Baron 123." 'Roger Red Baron123, now proceed direct to the Hutchinson VOR, maintain five.""Direct the VOR, maintain five, Red Baron 123." Nav.1 should be set to the HUT VOR, and, as long as there are no intersectionsfor the approach that are based on another navaid, #2 can be setto HUT as a backup. Two miles Southwest of HUT Center calls. "RedBaron 123, contact Approach on 124.55". "124.55, goodnight." "Good evening Approach, Red Baron 123 with you,leveling 5,000, Echo (the current ATIS)." "Good eveningRed Baron 123, you're cleared the VOR/DME approach runway 21 intoHutchinson. Proceed direct to the VOR. Descend to and maintain4,000." "Direct the VOR. Cleared the approach, out offive for four. Red Baron 123." "Roger Red Baron 123.The Tower at Hutchinson is closed for the night. The one hourold altimeter setting for Hutchinson is 29.73, the current altimeterat Wichita is 29.75."

Ah, a little sneaky here. That means that the Control Zonewill not be in effect, and it's night time. What are your minimums?Looking at the plate we see:

So,at night, with the Wichita altimeter setting the "Circle-To-Land"minimums apply in this case.

Thatmakes the minimums for this approach 698 feet (agl) and 2 (statutemiles visibility).

"Red Baron 123, Hutchinson Approach is closing operationsat this time. Make all radio calls on the CTAF, 118.5. In theevent of a Missed Approach, contact Denver Center on frequency118.75. Good night." "Attention all aircraft this frequency,Hutchinson Approach is now closing operations for the day. Alltraffic arriving and departing Hutchinson use the CTAF, 118.5.Good night." At this point the "TO/FROM" flag flipsover to read "FROM". Set the course selector on theHSI to read 033, the outbound radial for the approach, and trackit outbound. You are already level at 4,000 and cannot descendany more until Procedure Turn inbound. Now, where to start thatprocedure turn? The plate states that it must be done within tenmiles of Turky, which is 9 miles from the VOR. That makes youroutside limit at 19 miles DME from the HUT VOR.

Turky is your FAF (note the Maltese Cross), so you know thatyou want to be level at 2,500 feet when you get there, and, youwant the aircraft to be in an approach configuration. Lookingat the chart, it would appear that a couple of miles from Turky,call it 11 DME, would do it. Remember, it's your decision, yourcall. As long as you remain within your altitude limits, and theapproach airspace, no one cares how you make your turn. Some pilotswould turn left 90 degrees for 30 seconds, then make a 180 untilthey intercept the 033 inbound. The DME clicks over from 10.9miles to 11.0. You start your procedure turn by turning to a headingof 348 degrees. Note the time. One minute later, you make a 180degree turn to 168 degrees. All turns are Standard Rate turns.At this time, set your course selector on the HSI to read 213degrees. In about one minute, depending on winds, you should interceptthe 033 degree radial inbound.

As you intercept the 033 degree radial, the DME shows 13.5DME from HUT, 4.5 miles from your FAF of Turky. Now you can descendout of 4,000 for 2,500. And, as a precautionary safety measure,make a blind radio call on the Hutchinson CTAF, 118.5. "HutchinsonTraffic, Red Baron 123 is on the approach into Hutchinson, ProcedureTurn inbound." Why? There could be someone taxing out atHutchinson. He'll be guarding the frequency too. As a matter offact, he should also announce that fact on the CTAF. Your "blindcall" let's him know that there will be landing aircraft,and that he should use caution if he takes the runway before youland. As you approach Turky, approach power should be set, thefirst notch of flaps should be down. The DME counts downward toward9.0 miles.

Turky. The DME reads 9.0 miles, the CDI is centered. Drop thegear, start your descent towards 2,240 feet. And, make a radiocall. "Hutchinson Traffic, is at Turky inbound on the approach."You hear: "Roger Red Baron 123, Midwest 417 is holding shortof the runway, we'll hold for our departure until you land Sir."Hey, a heads-up guy. "Thank you Midwest 417." Levelat 2,240 the DME counts down to 7.4 miles when you see the runway.Adjust your position as necessary for landing. "HutchinsonTraffic, Red Baron 123 is on a one mile final, runway 21, Hutchinson."If, when the DME reads 6.0, you cannot see the runway, it is MissedApproach time.

With radar

You are currently North of the Hutchinson VOR, level at 7,000feet.

Approach Control will vector you for the approach. "Goodmorning approach, Red Baron 123 level at 7,000, information Tango."Roger Red Baron 123, fly heading 090, descend to and maintain5,000." "Out of seven for five, 090 on the heading,Red Baron 123." "Roger Red Baron 123. This will be vectorsfor the VOR runway 21 approach into Hutchinson." "Roger,Red Baron 123." Approach will give you changing headingsuntil they have you outside of the VOR, and more or less linedup with the 033 degree radial from the HUT VOR. You should haveNav. 1 radio set for the HUT VOR, Nav. 2 as well for a back-up.Your DME, tuned by the #1 Nav. radio, will show distance to theHUT VOR. The CDI on the HSI will be set to 213 degrees, as wellas the VOR head on #2. You should be adjusting your power towardsyour approach power settings. "Red Baron 123, fly heading190. Intercept the approach on that heading and track it inbound.Descend to and maintain 4,000." "190 on the heading,track the approach inbound, out of five for four, Red Baron 123."You look at the DME, and it displays 16.5 miles.

The CDI on the HSI centers as the DME counts down to 15.0 miles.Fly headings as necessary to track the 033 degree radial. "RedBaron 123, I show you intercepting the radial at this time, you'resix miles from Turky. Descend to and maintain 2,500. You're clearedthe approach, contact Hutchinson Tower at Turky inbound.""Out of four for 2,500, cleared the approach, Tower at Turky,Red Baron 123."

You are here:Turkyis the FAF (Final Approach Fix) for this approach. Level at 2,500,you watch the DME countdown towards 9.0 miles- Turky. At thispoint the aircraft should be set up completely for the approach.The only item left will be to drop the gear. The DME drops downfrom 6.1 to 6.0. You are at Turky. Drop the gear. Start your descentout of 2,500 for the MDA, 2,000 feet. "Hutchinson Tower,Red Baron 123 is Turky inbound." "Roger 123, not insight, cleared to land runway 21." "Cleared to land,123". Level at 2,000 feet, you watch the DME. When it getsdown to 6.0 you must be able to see the runway in order to land.If you see the runway at any time prior to the 6.0 DME readout,you may position the aircraft as necessary and proceed to land.If you do not see the runway at 6.0 DME, you must go Missed Approach.

Via a DME arc

Flying a DME arc is an effective way to join the final approachcourse. It is also expeditious, as no Procedure Turn is required,even in a non-radar environment.

Note the remarks by the arc. "15 DME Arc, 3,300 No PT."This means that once you are cleared the approach, via the arc,and you are established on a published segment of the DME arc,you may descend to and maintain 3,300, join the final approachcourse, and fly it inbound, without the Procedure Turn.

"Good morning Approach, Red Baron 123 with you, ninerthousand, Romeo" (the current ATIS). "Roger Red Baron123, fly heading 300 and join the 15 mile arc for the VOR 21 approachinto Hutchinson. Once established on the arc, descend to and maintain3,300." "Heading 300, join the arc. 3,300 once established,Red Baron 123." "Roger Red Baron 123, report interceptingthe 033 degree radial." "Report intercepting the 033degree radial, 123."

On your assigned heading of 300 you watch as the DME countsdown towards 15.0. While that is going on, set the course selectoron the HSI to 213 degrees, the inbound radial for the approach.The DME reaches 15.1 miles. Turn right 30 degrees. This is justan arbitrary guess on your part, you know that the 300 headingintercepted the arc, therefore you will have to turn right tokeep from getting closer to the VOR. Watch the DME, does it stayat 15.0? If it does then maintain your heading. If it increasesto 15.1, turn left another 5 degrees. If it goes down to 14.9,turn right another 5 degrees and so on. You know that you willbe flying a circle, with a constantly decreasing heading to theleft. The only thing that you don't know, is how much turn isrequired to maintain the 15 mile distance. Flying an arc is anart, not a science. Constantly changing winds, aircraft groundspeeds and so on make this maneuver an on-going learning experiencefor the pilot. Experiment with flying arcs. After a while youwill develop a sense about how much of a heading change is requiredto maintain a given distance.

Established on the 15 mile arc you make your radio call. "Approach,Baron 123 is established on the 15 mile arc, out of niner thousand.""Roger Red Baron 123 out of nine. Report crossing the 040degree radial." "Report crossing the 040 degree radial,Red Baron 123." You tune Nav. #2 to the HUT VOR, 116.8, andset the OBS on the #2 Nav. display to 040 degrees.

POP quiz. Given your approximate location, and the fact thatyou have not reached the inbound radial for the approach yet,when you select the 040 degree radial in the Nav. #2 display,which way will the CDI be displaced? Left or right? How aboutthe "TO/FROM" indicator? To, or From? Picture your airplanefacing a heading of 040 degrees. The 040 degree radial is to yourleft, you haven't reached it yet. Therefore, the CDI will be displacedto the left. What about the "TO/FROM" indicator? Givenyour location, the indicator would read "FROM".

Leveling at 3,300 feet you prepare for the final approach.Power set as appropriate to get you into the flap operating rangeon the airspeed indicator. Hold off on dropping flaps at thistime however, no sense in dragging out the approach. The DME isholding between 14.9 and 15.1. Hey, this flying an arc stuff isn'tso hard! Your eye catches the #2 VOR display starting to twitch.The CDI starts drifting in from the left. It centers. "Approach,Red Baron 123 is crossing the 040 degree radial at this time,15 DME, level at 3,300." "Roger Red Baron 123. You'recleared the VOR runway 21 approach via the 15 mile arc. ReportTurky inbound to the Tower, 118.5." "Cleared the approach,Tower at Turky, 123." A couple of minutes later the CDI onthe HSI starts to swing towards center. Start your left turn nowto intercept the 033 degree radial inbound. If you wait untilthe CDI centers, you will overshoot the radial. Once establishedon the 033 radial inbound, descend to and maintain 2,500 feet.About 11 miles DME (2 miles from Turky), drop your approach flaps.

The DME drops to 9.0 miles. You are at Turky. Drop your gear.Start your descent to 2,000 feet. "Hutchinson Tower, RedBaron 123 is Turky inbound." "Roger Red Baron 123. Notin sight, cleared to land runway 21. A Cessna 421B that shot theapproach 10 minutes ago reported the bases of the overcast at2,200 feet, with a visibility greater than 2 miles under the overcast."(What a nice guy that fellow in the 421B was!) "Cleared toland, thanks for the report, Red Baron 123." As predicted,the airport pops into view about two miles out. You are in perfectalignment with the runway and proceed to make a first class greaseronto the surface. Good for you! You just shot a VOR/DME approachusing a DME arc. That wasn't so bad, was it?

This ends the tutorial on VOR/DME Approaches.

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