Instrument Lesson #11: DME Arcs
|Date||Aircraft||Route of Flight||Time (hrs)||Total (hrs)|
|13 Sep 2012||N21481||5G0 (LeRoy, NY) - local||1.2||1090.2|
DME arcs are airways defined by constant radius turns around a ground-based transponder. Though I do not have a DME (distance measuring equipment) unit in Warrior 481, the GPS is a legal substitute. In fact, glorified DME has been the primary role of my approach-certified Garmin 430W GPS thus far in my training because we have focused on the radio-based backbone of the IFR system (VORs). Although the GPS does not measure slant range distance like a DME, geometry tells us that the differences will be negligible if the arc is of sufficient radius versus altitude.
Tom and I tracked toward the Geneseo VOR at 3000 feet. I was to fly an eight mile radius arc between two radials. Although the unblinking eye of the iFly 700 showed that my "arc" looked more like an elephant ear (kind of oblong), the GPS clearly indicated that my arc was flown well within tolerance (+/- 0.5 mile). At the prescribed terminating radial, we flew back to the VOR, crossed it, and described an arc on the opposite side.
"We can do more of those if you want, but I think you have them nailed. How about we do the VOR-A into Le Roy, then go into the practice area and do something like steep turns that we have not practiced for a while?"
Where's the Airport?
I pulled out the plate for the Le Roy VOR-A approach, climbed to 4000 feet (the minimum starting altitude for the approach), and tracked back toward the VOR. At the VOR, I set up the CDI for the outbound course and started descending for the first leg of the approach. My tracking of the CDI was not good. Though it never reached full deflection, it was certainly not centered.
Eventually, we were at 1400 feet (the minimum descent altitude) and journeying toward a point in the sky 12.6 miles from Geneseo that would put us over the airport. When the GPS read 12.6, Tom said, "ok, look outside and identify the airport for me". When I did, I saw nothing but farmland.
Must have taken a wrong turn at Albuquerque...
The GPS showed the airport to be off my right wingtip. I looked to the north, but could not immediately locate it. At 620 feet above the ground, trees presented a significant challenge to finding the airport. I located the quarries north of the runway, shifted my focus slightly ahead of them, and discerned my hangar through a gap in a treeline. I went to full throttle, pitched for climb, and pointed to the airport out the window. Naturally, Tom already knew where the airport was, he had watched it go by. I knew that my VOR tracking on that approach had been sloppy, but I did not think it was that sloppy.
Once established in the climb, I started troubleshooting.
I had set the CDI to indicate the 313° radial from Genseo. The approach course is actually 323°. Tom, of course, already knew.
"We're going to do that again," I grumbled.
"You bet we are," said Tom. "Not only did you have the wrong radial dialed in, but you didn't track THAT one very well. So, do it again. I want to see that CDI dead nuts on. I want your inbound altitude to be pegged at 4000. Tighten it up." Tom is generally so affable that I was taken aback by the sternness in his voice.
Sometimes, a kick in the seat of the pants is exactly the right approach.
Back to 4000...tracking to the Geneseo VOR...CDI centered...station passage...start timer...tracking outbound...dial in 323° on #1 CDI...one minute reached, intercept 323° radial inbound to Geneseo...station passage, flying outbound...begin cruise descent to 2300 feet...dial in Rochester VOR on Nav2...identify the station...set #2 CDI to the 227° Rochester cross radial to identify UNITS intersection (final approach fix)...descending, still above 2300...#1 CDI centered on 323°...5 miles from Geneseo...2300 feet...apply power, level off...#1 CDI centered...5.6 miles from Geneseo, 2 miles from final approach fix...complete approach checklist...#1 CDI still centered, altitude 2300...#2 CDI centers, 7.6 miles from Geneseo, arrival at UNITS intersection (final approach fix)...reduce power for descent to 1400 feet...advisory radio call on Le Roy frequency...#1 CDI still centered...still above minimum descent altitude of 1400 feet...11.5 miles from Geneseo...#1 CDI centered...
Minimum altitude bust, the cardinal sin.
"DAMMIT!" And though this had become something of a refrain, I said it with new found feeling.
I immediately added power, regained 1400 feet and held it. Moments later, we reached 12.6 miles from Geneseo, the missed approach point.
"Ok, look outside," said Tom. In the shadows of twilight, the lighted runway was directly below. I was directly over the center line. "Now that is how it's supposed to look! Good job!" said Tom. "Though," he added, "you forgot to start the timer at the final approach fix."
I remained silent, grimly advancing the throttle to climb back to the VFR pattern altitude. I flew the pattern and settled the airplane on the runway. I went about my post flight activities with quiet purpose.
"Talk to me," said Tom after we put pen to logbooks.
"I'm frustrated," I said simply.
"Well, I can see that from your body language." Of course he could. Tom is a people person and very perceptive, a quality that makes him such an excellent teacher.
If he assumed the demeanor of drill sergeant after our botched approach attempt, he was now morphing into coach. "Look, I know you're frustrated with yourself for going through the MDA, but you recognized it right away and fixed it. Everything else was spot on. You flew DME arcs for the first time tonight and nailed them. You do a lot of things really well." He proceeded to enumerate my strengths, finishing with, "all that's left is practice and tightening everything up."
After a pause he added, "and do you know what? I kept forgetting about the timer, too, when I was training. You'll get there."
I have 20.3 simulated instrument hours (including a few hours carried over from primary and recurrent training over the years) with 0.3 of those being in actual IFR. There is not much new for Tom to teach me and no more scheduled lesson topics beyond the instrument cross country flight that we must complete together. I would like to build some additional actual IFR time, however.
My primary goal is to refine my abilities and build hours with a safety pilot while getting better-acquainted with the Garmin 430W. I also need to take the FAA written exam, for which I have begun studying again after a lapse during spring and summer. The time I invested earlier this year was well spent; I am running at about 93% on practice exams. With the arrival of September, family obligations have increased, days have become shorter, and work schedules with potential safety pilots are not meshing well (I am also out of vacation - poor planning on my part).
On top of all that, "winter is coming" and icy clouds are not terribly compatible with my humble little ship.
But as Tom said, I'll get there.