Flight Training - Course Intercepts

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Basic flight navigation training information based on instruments.

Transcript of Flight Training - Course Intercepts

Eddie Sez:In the days before flight management systems and flight directors,knowing how to efficiently intercept a course the first time and everytime was the coin of the instrument pilot realm. These days mostpilots let the box do the heavy lifting. Knowing how it is done,however, keeps you a step ahead of the airplane and can prevent abad situation when the box is programmed incorrectly, or is simplywrong.This is one of my stories from long ago, but it teaches the concepts . ..Flight LessonsCourse InterceptsPhoto: T37B Cockpit, from Eddie's collectionCourse Intercepts (1979)Grnnch! I heard from the right seat, the evaluator charged with making sure I knewwhat I was doing during my midphase check ride, the first flight evaluation of many tocome. We were both strapped into our ejection seats and tethered together via our ownoxygen masks and a common interphone system. I could hear his every breath, grunt,and sigh. He was grunting as I pulled into my first loop.It was a good loop, I hit the speeds exactly and the Gforces were right out of the textbook. So far the check ride was going quite well.Okay, he said, let me have the airplane for a bit. I released the controls and herolled and stood the airplane on its right wing and let the nose fall. As the nose reachedits nadir he pulled out of the dive and pointed the nose to the sun, all in one continuousmotion. I watched as the airspeed bled from over 250 to 200, to 150, to 100, to 50, to 0,to less than zero. The wings, with no air flow, failed to grab the molecules they neededfor lift and the nose plunged unevenly into a yawcontorted stall. The aircraft wrappeditself into a spin and after the first rotation, the nose tracing a spiral from way up toway down, the evaluator took his hands off the controls and said, simply, recover.I pulled the throttles to idle and centered the stick and rudder. I then pulled the sticksharply back to its aft stop, and watched the earth rotate below me. We were spinningleft and a quick look at the turn needle confirmed that. Satisfied, I stomped on the rightrudder and counted the rotation. After one complete turn I threw the stick full forwardand watched as the spin suddenly stopped. At this point I recovered from the dive.Not Roger, not Sal, I heard from the right seat, perhaps sotto voce.What? I asked.Nothing, he said in a normal volume, that was excellent. Let me see another loop.But this time, show me some finesse. Just because the book says it takes three and onehalf Gs doesnt mean you need those Gs instantaneously. Show me you can fly a loopwith some style.I flew another loop, trying to build the G forces more gradually. To my surprise, I endedup with more speed at the top of the loop and it worked out better than any before it.Very nice, he said, lets head to the pattern.We did so and in the end he passed me with a Good on the grade sheet. That was notas good as an Excellent, but certainly better than a Fair or an Unsatisfactory.There were congratulations all around the flight room and I pondered my promotion intothe next phase while still wondering what Not Roger, not Sal meant.Roger, my table mate, was the smartest guy in the class. He got every test questionright and he grasped every classroom lesson before anyone else. I wanted to be like him.He was also a second lieutenant and also an engineer by education. But he looked thepart. He was an uber geek in the days before that was stylish. Before we hit the flightline I was betting he would be leading the pack.Salvatore, on the other hand, did not exude intelligence. He barely passed every test.If the minimum wasnt good enough, he would say not caring a whit, it wouldnt bethe minimum. If an instructor ever asked him a question in class, perhaps they didntknow better, Sals answer was invariably, I dunno. What Sal had, though, wascharisma. Everybody liked Sal. He was funny and you couldnt help hoping he would joinyour table at the bar. When he came back from a flight after a botched maneuver, hewould give us all the playbyplay.I was watching the spin, counting the rotations, he said with his loud, booming voice,but the instructor didnt say recover. Are we playing chicken here? I started to wonderabout that and by the time he said recover, I forgot which way we were spinning. Wehowled as one, knowing we had all feared that very situation. Perhaps some had beenthere. So I pushed the wrong rudder! Next thing you know, we are spinning upsidedown!Sal had gotten himself into the dreaded inverted spin and was bragging about it. Youhad to love Sal.Not Roger, not Sal.There is a Yin and Yang about military flying, no doubt about it. You had to haveintelligence, discipline, and stickandrudder skills. But you needed something else too.You need a ballstothewall, devil may care, blood thirsty aggressiveness. You had tohave a confidence that made up for all short comings. Your Sal had to overpower yourRoger.I liked Sal, I idolized Roger.During our midphase check rides we were on morning flight rotations. We spent themorning flying and the afternoons in class. On Monday we were greeted with yetanother pilot training memory aid that served more to confuse than to explain.Okay boys and girls, the instructor said to our group of male only studs, write thisdown and commit it to memory. I scribbled dutifully.He explained that when intercepting a course inbound to a radio station, you turned toa heading that put the Course on the further side of the Bearing Pointer and the aircraftheading 30 degrees further still. When intercepting a course outbound, you turned to aheading that put the Tail of the bearing pointer on the further side of the desiredCourse and the aircraft heading 45 degrees further still.To a fledgling pilot with zero instrument time, the idea of a course intercept isdaunting. It is a vital skill basic to all instrument flight, however, and must bemastered. I wasnt mastering anything until Roger drew a few pictures. As it turns out,they were worth a thousand words.If flying a 360 heading south of a 090 course, you would obviously want to turn right.But how far right? The rule said turn right until you have the Course further away fromyou than the Bearing pointer and settle on 30 degrees. In this case the course is alreadyon the correct side of the bearing pointer, so you need only turn right until you have 30degrees offset from the bearing pointer.To intercept a course inbound: Charlie Brown plus 30, the headalways falls.From this point you wait until the bearing pointer falls to the desired course and turn tojoin. Simple.The head always falls, Roger said, waiting for me to laugh. get it?I finally got it. I guess when you had been locked up in a mostly boys school for fouryears, this kind of stuff was hilarious.So too with an outbound example. If you are due west of a 360 degree course flying aparallel heading, you need to turn right. How far right?The rule says to place the Tail of the bearing pointer on the far side of the desiredCourse and fly a 045 offset.To intercept a course outbound: Tom Collins plus 45, the tail alwaysrises.From this point the tail will eventually rise to the 360 course and you can turn left tojoin.The tail always rises, Roger said, waiting.Got it.Before the week was out I had the concepts down and headed for the simulator whereeverything was set in stone. Since I was done with the midphase check ride, I spentmost of the week in the simulator, which made class easier which then made thesimulator easy. Another Yin and Yang kind of thing, not Roger not Sal.Sal passed his midphase on Thursday and on Friday I saw him at the simulator. Howsit going? I asked.I could use a Tom Collins, he said, see you at the bar?Sure, I said, I was going to see if I could drag Roger over for a change.Oh, Sal said, okay.I couldnt find Roger but showed up where a good portion of the flight was alreadycelebrating. The mood was light and we wore the added confidence of meeting anothermilestone on our ways to our wings. As usual, the party didnt really start until Salshowed up. You couldnt help feeling good just talking to him. There was joy in hisevery syllable and even bad news prompted a grin. The mood of any room improvedwhen Sal showed up. I started wanting to be like Sal.Not Roger, not Sal.The next week Roger was gone. My instructor told me, for the first time, that Rogercouldnt think faster than the airplane could fly and while he knew his stuff, he couldntexecute. He was the last in our flight to solo and the last to be put up for the midphasecheck ride. That check ride would be his last flight as an Air Force pilot. I finally had toask.What does it mean when somebody says Not Roger, not Sal?He was surprised by the question but then he finally answered. It seems all ourinstructors recognized that Roger was very smart but not quick. They too recognizedthat Sal was a natural pilot, but too lazy to study. Not Roger, not Sal was actually acompliment of sorts.It was a Yin and Yang kind of thing. Not Roger, not Sal. Charlie Brown, Tom Collins.Our last class of the week was to be our last class on the subject. Why two differentrules, a classmate asked. Why indeed.Because thats the way it works, the instructor said.Pilot training was to be a year filled with these explanations. If you think too muchabout it, the learned instructors would say, you will only confuse yourself. I thoughta little geometry would help solidify the rationale and help me always remember whichrule applies to which inbound or outbound situation.Going inbound, simply put, the rate of change in distance covered increases and itbecomes easier to intercept. Thirty degrees is an ample offset.Going outbound, the rate of change in distance covered decreases and it becomesharder to intercept. A larger offset is needed.Two months later, flying a T38, Charlie Brown and Tom Collins became academicdiscussion points and little more. The T38 had a flight director, a computer that did allthis thinking for us and presented u