IFR Diary, Day 7: Friday, Sept 3

Gunslingers in the Sky

     Charles had told me to file for Salinas, but to make our departure
     one hour later than usual.  He had told me to read up on DME arcs so
     I could practice them on the PC before I flew them.  I studied the
     technique described in the Dogan and Thom books.  Both authors
     advocate the conventional method referred to as the "tangent"
     method, where the arc to be flown is divided into twenty degree
     segments.  One then flies the arc by making 20 degree turns toward
     the center of the arc.  The pilot knows when to make the turn by
     monitoring VOR radials twenty degrees apart.

     To start our session, Charles set the simulator up for the ILS 31 at
     Salinas, which uses a 22-DME arc as an initial approach fix.  He
     quietly watched as I turned and twisted around the gentle arc to the
     localizer.  Without fanfare he then set the simulator up for the
     Watsonville VOR approach, whose initial approach fix is an inverted
     8-DME arc from the Salinas VOR to the South.  By "inverted," I mean
     that the final approach course you arc around to the approach
     radial, then turn outbound from the VOR.

     As one would expect, the tighter 8-DME arc required faster work than
     the 22-mile arc. A lot more.  After about forty-five minutes, I got
     the inevitable, "Let's go fly."

     The 22-DME at Salinas went passably, but I discovered that if you
     ever let yourself get the outside of the arc, it's a real struggle
     to get back inside the course using the lead radial method.  I found
     it necessary to restart the entire procedure.  On the 8-DME arc at
     Watsonville, a fairly stiff wind put me to the outside almost
     immediately and the tight radius kept the work load fairly high.  A
     question from Monterey Approach caused me to lose track of the arc
     and I had to ask for vectors back to it. 

     "Let's go land at Monterey and talk about DME arcs," said Charles.
     Monterey ATIS was calling 300 feet ceiling, one-half mile  in fog.
     While being vectored to ILS 10R, we heard the controller say,
     "Skyhawk 1234, cleared for the approach, blah, blah, blah. Maintain
     110 knots to the Outer Marker."  The Cessna rogered. We could hear
     the controller working a turbo-prop aircraft behind him.  In a few
     minutes, the controller said, "Cessna 1234, Sir, final warning...I
     need 110 knots and now I'll need it inside the marker as well."
     Again the Skyhawk rogered.  In a few moments, the controller said,
     Cessna 1234 turn left heading of 360, climb maintain 3300."

     "Gee," I said, "these guys don't fool around."  My incredulity
     didn't last long, however, because soon it was my turn in the
     barrel.  A 737 reported in behind us and I knew the chase was on.
     "Grumman 613, say your maximum forward speed."  I swallowed hard.
     "Charles, we're in no hurry, let's let this jet play through."
     Charles' voice took on a "damn-the-torpedoes" sternness.  He
     promptly keyed up the mike and said "Grumman 613 can give you 130
     knots to minimums if you'll authorize a mid-field landing."  Runway
     10R is 7600 feet long.  "613, Long landing approved...turn left
     heading...blah, blah, blah, cleared for the approach."

     It worked--he's taking us!  This is great. 

     In a second, though, reality fought its way back into the room. What
     a fine predicament you've gotten us in, Charles.  Charles remained
     quiet, which by now I knew meant that I was being tested. My mind
     dithered to come up with something sensible.  For some reason I was
     using a NOS book today, so I couldn't just take the numbers off my
     Jepp plate.

     OK, I thought,  I'm going about 50 per cent faster than usual, so my
     descent rate needs to be 50 percent faster.  I'll shoot for 750 feet
     per minute.  Seemed sensible. I subtracted a few seconds from the time
     for 120 knots and punched it in the timer.  Now, how do I set up for
     the approach.  No setting up--130 thirty knots is the Tiger's cruise
     speed, so I won't need flaps (stupid thought).

     Jeez, is this bare-back or what?  Gunslingers in the sky.

     I took off my Foggles a few seconds before glide slope intercept and
     went IMC just as I started down.  I just guessed about the amount of
     power to pull back, then I riveted my attention on the DG to keep
     from losing the heading.  When I had the heading nailed, I checked
     the glide slope and saw that I was a dot or so low.  When the Outer
     Marker sounded, I started the timer(!).  Punching in just a decibel
     more power, it suddenly dawned on me that aside from the numbers on
     the gauges and the noise from the engine, this was no different from
     flying the approach at 90 knots. I knew that both needles would
     become sensitive sooner than usual, so I concentrated on not letting
     things get away.

     I broke out at about 350 feet, concentrating got so hard that my
     hair could have been on fire and I wouldn't have noticed it.  I was
     surprised by the sight-picture caused by doing 130 knots this close
     to the ground.

     ...Power all the way back, then carb heat...level off at about 50
     feet... stay level while the air speed bleeds down low enough for
     flaps...steady...steady. OK! Full flaps...don't balloon...don't
     hurry...90 knots...wait, wait..70 knots...BINGO!

     Seventy knots is the magic number on the Tiger. It gets very
     peaceful--then starts coming down faster than Madonna's undies. If
     you're in landing position at 70 knots, you've got it made.

     I touch down mid-field, roll out, turn off, and pull over the hold
     bars. Tower says, " Good job, 613. Ground point-niner."  As I was
     cleaning up the airplane, Charles said, "Are you starting to feel
     like an instrument pilot?"

     Inside the FBO, I was still wound tighter than a two-dollar watch.
     Charles asked, "Now you know why we calibrated the Tiger at 130
     knots."  I looked askance for a moment then confessed, "Uh, I
     totally forgot about that."  He looked quizzically at me, "Then what
     did you rely on?" I bit my lower lip to suppress a grin and said
     coolly, "Oh, I just did something sensible."

     "Get outta my face," he laughed.  "Anyway, no one cares how slow you
     fly the cow-pasture approaches.  But if you're going to mix it up
     with the big boys, you'd better learn to fly the approaches fast.
     This Tiger gives you a real advantage over Skyhawks and Cherokees--
     make the most of it."

     After my self-esteem poisoning wore off, we talked about DME

     "Believe it or not, a lot of people who bust DME arcs do so because
     their initial turn is in the wrong direction.  So let's make certain
     there ain't no doubt in your military mind whether that initial 90
     degree turn is in the right direction."

     "Now, assume you're positioned on the 270 radial and the final
     approach course is 360.  For the sake of argument, let's say you
     want your first turn to be 90 degrees to your current position.
     What heading do you turn to?"  Without hesitation I answered,

     "Good," he said, "that's easy to see."  I could tell he was starting
     to build a web.  "Now you're on the 023 radial and the final
     approach course is 340.  To what heading would your initial turn
     be?"  I did a little arithmetic and said, "either 113 or..." I
     paused to do the reciprocal, "...293."

     The spider asked, "OK. Which one do you turn to?  And don't you dare
     say left or right."

     "I'd turn to 113," answered the fly, obviously guessing.  If I had
     thought about it more than a second or two I would have said 293,
     but I was more interested in seeing him spin his pedagogy.

     "Nope," he said. "Watch this."  He drew a rose, putting us at 023.
     "Don't make this a mental exercise. Look at the dial.  With our
     current position of 023, the headings 113 and 293 are at the 90
     degree positions, right?  To find out which one will take us to the
     final approach course, just move the OBS a tiny bit toward the
     inbound course.  The needle will move over toward one side,

     I nodded assent. I now saw how this was going to come out.

     "Then you're going to turn to the heading that will be on the side
     of the needle after when you've dialed in the final course.  In this
     case the needle moves toward the side with 293."  He never grew
     tired of showing how simple this stuff is.

     After a few more examples, he said, "All right. You've got the hard
     part wired." He now grew quiet and mock-thoughtful.

     "Now I want you to forget everything you've learned about doing the
     rest of the arc.  I think that the conventional method--the one you
     were trying today--is way too complicated.  Believe me, anything
     that complicated disappears unless you practice it a lot.  Worse, if
     you blow it and wander off, there is no sensible way to recover--
     you're just stuck with a DG and a VOR full of meaningless numbers.
     Besides, doesn't all that activity--all that twisting and turning,
     turning and twisting--seem out of proportion to the job?"

     I had gotten so used to Charles' apostatic prologues that I no
     longer felt an urge to protest.

     "So let's pick up where we left off.  You've just turned 90 degrees
     in a direction dictated by the inbound course.  You've dialed in the
     final approach course on the OBS.  Now, just watch the DME and wait
     for the first change, which will come very quickly.  The number will
     get larger, so turn heading 30 degrees in the direction toward the

     "Now wait again for the DME to change.  When the DME changes, turn
     again, but take a 10 degree cut.  Just repeat the process using 15-
     or-so degree turns. After a couple of turns, the DME will change to
     a smaller number. And guess what? You're now established on the

     Once established, you'll have a sense of whether you need to take
     slightly larger or smaller cuts. You'll be amazed--with a little
     practice you can get the DME to oscillate plus or minus a tenth on
     either side of the arc.  Once established in this manner, you can
     get really accurate by making tiny turns to keep the ground speed at

     This sounded too good to be true.  He said, "Compared to the FAA-
     approved method, this method is intuitive. What could be more
     natural: turn toward something to get nearer to it, turn away to get
     farther away from it.  And all the headings that you fly are written
     right on the airplane."

     I couldn't wait to give this a try, so we launched again and headed
     out to do some arcing around the Salinas VOR.  After a couple of
     errors on my first tries, I always made the correct initial turn.
     The rest is easy. I practiced all sizes of arcs, from 7- to 20-DME.
     Charles would have me close my eyes while he maneuvered me to a
     strange heading, then give me only the final course.  I would arc in
     one direction then reverse course, intercept a different arc, an
     follow it for a while.

     The procedure is as easy as it sounds.  After I got the hang of it,
     and once established on the arc, it was easy to hold plus or minus
     two tenths of a mile and, most of the time, one tenth.  Of course,
     the tighter the arc, the harder it is to hold.

     Before stowing this procedure in my brain, I had one final question:
     why make a 90 degree initial turn, when by definition it's certain
     to be too big.  A 60 degree cut seemed to work much better and gets
     you established on the arc much faster.

     "Simple, said Charles.  On any dial there are two interpretations of
     every angle.  For example, I had a student who would take the 60
     degrees from the top of the dial if there was a FROM indication,
     but--and who knows why--she'd take it off the bottom of the dial if
     there was a TO indication.  I teach 90 degrees because there's only
     one of them."

     My biggest concern was that an examiner would see this technique,
     freak out, and bust me.  Charles assured me, "He can't bust you
     until you're a mile from the arc or it's clear that you're not
     correcting in the right direction.  The worst thing that's ever
     happened is that an examiner gave the student a second DME arc to do
     just to make sure that he knew what he was doing. But he flew it
     perfectly, too.  Unless you obviously can't control the aircraft,
     things such as altitude, heading, and DME arcs are judged on
     performance, not on technique.  And the good old Practical Test
     Standard requires only that you stay within a mile of the arc--it
     doesn't say how.  Beside, by now all the examiners have seen my
     students do this. Once they see you get established and make
     corrections in the correct direction, they'll be satisfied. Maybe
     not happy, but satisfied. I absolutely guarantee it."

     Absolute guarantee, eh?  "So if I get busted on this you'll give me
     all the instruction I need for free?"

     "Hey, let's not get carried away," he said.

back next