AOPA Pilot Magazine - March 1958 - (Page 66)

nefcic," "cottpasa," and "relative," eachm denoting measurements with respect tom true north, magnetic north, compass north, or aircraft heading, respectively. These adjectives are cornonly abbreviated as T,M, C, or R, respectively. The nouns used are the directions themselves, heading, course, track, and bearing which are commonly abbreviated as H, C, T, and B, respectively. The following examples will illustrate how to interpret the various combinations of these terms: to true north, MT-Magnetic Track-the actual direction of travel measured with respect to magnetic north. TT-True Track-the actual direction of travel measured with respect to true north. CH-Compass Heading-the direction in which an aircraft is pointing measured wtib respect to compass north. KBÃ‘Relativ B e a r i n g 4 6 direction of some object from the aircraft measured with respect to aircraft beading. MBÃ‘ agnetic BearingÃ‘th tion of one object from another, ured with respect to magnetic no In order to navigate, a pi1 perform certam geometrical tmns to determine the relatio tween heading, wind, and track or Really keeps aircraf windshields clean !4 4 * Non-Glare (hand use) * Contains no injurious abrastw 12 dispaflien froe 2 cases MGH-10 Plasticcleaner 1 case MGA-1 Aircraft Cleaner * Won't craze or cloud * Non-static 4 CASE PACKAGE PLAN 1 case MGA-3 Reseal Glaze 12 pints to a case complete $4688 ppd. I Enc. check for $46.80 (less 2% earns discount) I Ship 4 case ptan and bill ma I Send Information and name of near* dealer AMâ DMPANV DDRESS ITY SAE TT. mmmm~mmmmmnmmmmmmmmmn~ course. Also, in order to fix his poaition. he frequently plots on a map his bearing from two or mom radio stetions or other landmarks. The importaut point t o make here is that the pilot must always measure, plot, or denote all o f his flight directions with respect to the same reference before he performs any geometrical calculations with them. It .makes no difference what reference is iiaed, but it must be the same one for all directions. For example, i a pilot knows his f course, the estimated wind. and his airspeed, he may calculate his proper heading by solution of what is cornrnonly called the "wind triangle." If be plots his true course and true wind, he will get his solution in terms of true heading. On the other hand, if he plots magnetic course he should also use magnetic wind (wind direction measured with respect to magnetic north), and his solution will praTide the magnetic heading. As another example, he may plot his magnetic bearing from two points, measuring direction from magnetic north, or he may plot. his true bearing from the same two points, measuring from true north. In either case his solution will provide the same identical position, However, if he performs geometrical calculations using directions measured with respect to different references, he will distort the geometrical relationships by introducing errors of variation or deviation, and consequently he will get an incorrect solution. A pilot must frequently convert vari- colatiom. Now when you tackle that CAA exam you can slyly chuckle #a you hand your paper to the chic secretary. That "other guy" will still be mumbling, "East is least, and drift is s h i f t " while he fumbles with a pencil whose smudgy eraser he has already rubbed to nothing. As (or you, you know which way you're going. Bon voyage! END THE AUTHOR Capt. John G EUiÃˆ Jv., auth01- of . 'Are YOUCompass Punchy?" w m e d his p r i v a t e license at a small d h t strip in MartvnsvHle, Va., in 1#47- He now k licensed as an airline itÂ¥anvm pilot and ground in8tmtor. After Joining the WnS. Air Force in 1050, he flew a combat twtr vti F-86 Sabrejets with the 4th Fighter-Interceptor Group in Korea. From 19,5$ to I f f S S , he studied h a ertia2 navigation, insttwmentatim a& control systems at the Massachusetts Institwte of Technology where he received his SSmter's degree. Cttpt. Ellis is ,(ts8igned to the Air Force Missile Test Center at Patrtek Air Form Base, Flo., where he is still active i n civil aviation activities. Bis wife, Barbara, (AOPA SSS89), is a +wage pilot and member of the Florida chapter of 9 9 ' ~ s . THE AOPA PILOT + T C Ã ‘ C o a r s e ~ t h e direction of intended travel measured with respect wind to calculate true heading. However, to fly this heading, he m s use ut a compass. Therefore, after completing the geometrical calculation, he must convert true heading to magnetic heading by applying the variation correction and then convert magnetic heading to compass heading by applying the deviation correction, As another example, he may fly a constant compass heading for a while and determine hi8 true track by obaerving the landmarks he passes on a map. 1 In order to find his drift, the difference between headmg and track, he must either convert his eompaaa heading to true heading or convert his true trade to coaipasa track in order to compare both directions with reap& to the same reference and thus get the correct drift. We can stunmarbe the important features of this study of directions, as follows': (1) Know your basic flight d i r e tions; heading, course, track, and bearings. (2) Enow the differences between these directions, drift and d i t corrf rection. (3) In order to measure your Bight directions, know the reference directions; true north, magnetic north, compass north, and a d a f t heading. (4) Understand (he differences between the reference directions, variation and deviation, and we them to convert flight direction measurements to the most useful reference system. (6) Always convert a l flight direcl tions to the same reference system before performing any geometrical ad- oua direction rneaaÂ¥areca#t from one reference system to another. For example, he may use hia true course and I

Table of Contents for the Digital Edition of AOPA Pilot Magazine - March 1958

AOPA Pilot Magazine - March 1958
Contents
Calendar
Legally Speaking
Editorial
What About Airspace Use, Mr. Pyle?
10,000 Seconds Under the Hood
Flying Weather One Month Ahead
AOPA Weathercast
AOPA 185579
Air-Age Teenagers Give City a Lift
Your Radio and You
Operation Cost Cut
Put Your Fabric to the Test
Are You "Compasss Punchy?
Yankee Duster in Latin America
South American Challenge
I Lived Through a Graveyard Spiral
Safety Corner and Accident Report
On the Airways
Travel
What's New?
Classified Department

AOPA Pilot Magazine - March 1958

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