Navigation Guidance & Control

Why Isn't It Faster To Fly West?

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Since the earth is spinning to the east, why doesn’t flights to the west take less time than one going east?</div>
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According to this video from Minute Physics, it’s kind of complicated.</div>
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<span style="line-height: 23.8px;">Every planet/moon has global wind that are mostly determined by the way the planet/moon rotates and how evenly the Sun illuminates it. On the Earth the equator gets much more Sun than the poles. resulting in warmer air at the equator than the poles and creating circulation cells (or "Hadley Cells") which consist of warm air rising over the equator and then moving North and South from it and back round.</span></div>
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The Earth is also rotating. When any solid body rotates, bits of it that are nearer its axis move slower than those which are further away. As you move north (or south) from the equator, you are moving closer to the axis of the Earth and so the air which started at the equator and moved north (or south) will be moving faster than the ground it is over (it has the rotation speed of the ground at the equator, not the ground which is is now over). This results in winds which always move from the west to the east in the mid latitudes.</div>
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Why Isn't It Faster To Fly West?

Since the earth is spinning to the east, why doesn’t flights to the west take less time than one going east? According to this video fro...

Solving Root Locus

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A system with feedback becomes stable when equations describing that system possess roots that follow certain patterns.</div>
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Otherwise, the system will become unstable. Example of such an unstable system is when microphones create screeches. Part of the loudspeaker voice feedbacks to microphone and becomes amplified by amplifiers and then goes into the loudspeakers and again feds into the microphone and loops again and again until it saturates amplifiers into creating a high pitched noise.</div>
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Feedback sometimes keeps the system just in the margin of instability and starts to make the system oscillating. This might be useful in electronics and elsewhere to have a steady oscillation; in a device such as a clock. But if the margin has not been carefully calculated a small change might devastate the system into the destruction. This is seen when some bridges have collapsed due to become oscillating and then into the instability runaway when people or cars or trains are passing over them. A newly constructed London bridge opened for pedestrians for millennium was near to this runaway in the first day of its inauguration but as it was still under careful observation of the constructors was shut down and disaster did not happen. Root locus helps engineers to predict specification of their system to meet stability criteria. Although all academia are full of a plethora of software for drawing the "Root Locus" still it is fascinating for all learners of engineering to know the conceptual sketch of this method.</div>
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Root Locus: Example</h1>
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Transfer function</h2>
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<img src="http://lpsa.swarthmore.edu/Root_Locus/Example1/imgAC.gif" /></div>
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<a href="https://www.blogger.com/null" name="BckGrnd"></a>Function Info</h2>
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For the open loop transfer function, G(s)H(s):<br />We have n=2 poles at s = 0, -3.  We have m=0 finite zeros.  So there exists q=2 zeros as s goes to infinity (q = n-m = 2-0 = 2).<br /><br />We can rewrite the open loop transfer function as G(s)H(s)=N(s)/D(s) where N(s) is the numerator polynomial, and D(s) is the denominator polynomial. <br />N(s)= 1, and D(s)= s<sup>2</sup> + 3 s.<br /><br />Characteristic Equation is 1+KG(s)H(s)=0, or 1+KN(s)/D(s)=0,<br />or D(s)+KN(s) = s<sup>2</sup> + 3 s+ K( 1 ) = 0</div>
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Completed Root Locus</h2>
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<img alt="RLTot" src="http://lpsa.swarthmore.edu/Root_Locus/Example1/RLTotal.png" /></div>
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<a href="https://www.blogger.com/null" name="RuleSym"></a>Root Locus Symmetry</h2>
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As you can see, the locus is symmetric about the real axis</div>
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<a href="https://www.blogger.com/null" name="RuleNum"></a>Number of Branches</h2>
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The open loop transfer function, G(s)H(s), has 2 poles, therefore the locus has 2 branches. Each branch is displayed in a different color.</div>
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<a href="https://www.blogger.com/null" name="RuleStart"></a>Start/End Points</h2>
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Root locus starts (K=0) at poles of open loop transfer function, G(s)H(s).  These are shown by an "x" on the diagram above<br /><br />As K→∞ the location of closed loop poles move to the zeros of the open loop transfer function, G(s)H(s).  Don't forget we have we also have q=n-m=2 zeros at infinity.  (We have n=2 finite poles, and m=0 finite zeros).</div>
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<a href="https://www.blogger.com/null" name="RuleReal"></a>Locus on Real Axis</h2>
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The root locus exists on real axis to left of an odd number of poles and zeros of open loop transfer function, G(s)H(s), that are on the real axis.   These real pole and zero locations are highlighted on diagram, along with the portion of the locus that exists on the real axis.</div>
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Root locus exists on real axis between:<br />0 and -3<br /><br />... because on the real axis, we have 2 poles at s = -3, 0, and we have no zeros.</div>
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<a href="https://www.blogger.com/null" name="RuleInf"></a>Asymptotes as |s| goes to infinity</h2>
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In the open loop transfer function, G(s)H(s), we have n=2 finite poles, and m=0 finite zeros, therefore we have q=n-m=2 zeros at infinity.<br /><br />Angle of asymptotes at odd multiples of ±180°/q, (i.e., ±90°)<br /><br />There exists 2 poles at s = 0, -3, ...so sum of poles=-3.<br />There exists 0 zeros, ...so sum of zeros=0.<br />(Any imaginary components of poles and zeros cancel when summed because they appear as complex conjugate pairs.)<br /><br />Intersect of asymptotes is at ((sum of poles)-(sum of zeros))/q = -1.5.<br />Intersect is at ((-3)-(0))/2 = -3/2 = -1.5 (highlighted by five pointed star).</div>
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<a href="https://www.blogger.com/null" name="RuleBrk"></a>Break-Out and In Points on Real Axis</h2>
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Break Out (or Break In) points occur where N(s)D'(s)-N'(s)D(s)=0, or 2 s + 3 = 0. (details below*)<br /><br />This polynomial has 1 root at s = -1.5.<br /><br />From these 1 root, there exists 1 real root at s = -1.5.  These are highlighted on the diagram above (with squares or diamonds.)<br /><br />These roots are all on the locus (i.e., K>0), and are highlighted with squares.<br /><br />* N(s) and D(s) are numerator and denominator polynomials of G(s)H(s), and the tick mark, ', denotes differentiation.<br />N(s) = 1<br />N'(s) = 0<br />D(s)= s<sup>2</sup> + 3 s<br />D'(s)= 2 s + 3<br />N(s)D'(s)= 2 s + 3<br />N'(s)D(s)= 0<br />N(s)D'(s)-N'(s)D(s)= 2 s + 3<br /><br />Here we used N(s)D'(s)-N'(s)D(s)=0, but we could multiply by -1 and use N'(s)D(s)-N(s)D'(s)=0.</div>
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<a href="https://www.blogger.com/null" name="RuleDep"></a>Angle of Departure</h2>
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No complex poles in loop gain, so no angles of departure.</div>
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<a href="https://www.blogger.com/null" name="RuleArv"></a>Angle of Arrival</h2>
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No complex zeros in loop gain, so no angles of arrival.</div>
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<a href="https://www.blogger.com/null" name="RuleImag"></a>Cross Imag. Axis</h2>
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Locus crosses imaginary axis at 1 value of K.  These values are normally determined by using Routh's method.  This program does it numerically, and so is only an estimate.<br /><br />Locus crosses where K = 0, corresponding to crossing imaginary axis at s=0.<br /><br />These crossings are shown on plot.</div>
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<a href="https://www.blogger.com/null" name="RuleFindPole"></a>Changing K Changes Closed Loop Poles</h2>
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Characteristic Equation is 1+KG(s)H(s)=0, or 1+KN(s)/D(s)=0,<br />or D(s)+KN(s) = s<sup>2</sup> + 3 s+ K( 1 ) = 0<br /><br />So, by choosing K we determine the characteristic equation whose roots are the closed loop poles.<br /><br />For example with K=2.25225, then the characteristic equation is<br />D(s)+KN(s) = s<sup>2</sup> + 3 s + 2.2522( 1 ) = 0, or<br />s<sup>2</sup> + 3 s + 2.2522= 0<br /><br />This equation has 2 roots at s = -1.5 ±0.047j.  These are shown by the large dots on the root locus plot</div>
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<a href="https://www.blogger.com/null" name="RuleFindK"></a>Choose Pole Location and Find K</h2>
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<img alt="RLFG" src="http://lpsa.swarthmore.edu/Root_Locus/Example1/RLFindGain.png" /></div>
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Characteristic Equation is 1+KG(s)H(s)=0, or 1+KN(s)/D(s)=0, or<br />K = -D(s)/N(s) = -( s<sup>2</sup> + 3 s ) / ( 1 )<br />We can pick a value of s on the locus, and find K=-D(s)/N(s).<br /><br />For example if we choose s= -1.6 + 1.6j (marked by asterisk),<br />then D(s)=-4.87 + -0.243j, N(s)= 1 + 0j,<br />and K=-D(s)/N(s)= 4.87 + 0.243j.<br />This s value is not exactly on the locus, so K is complex, (see note below), pick real part of K ( 4.87)<br /><br />For this K there exist 2 closed loop poles at s = -1.5 ± 1.6j.  These poles are highlighted on the diagram with dots, the value of "s" that was originally specified is shown by an asterisk.<br /><br />Note: it is often difficult to choose a value of s that is precisely on the locus, but we can pick a point that is close.  If the value is not exactly on the locus, then the calculated value of K will be complex instead of real. Just ignore the the imaginary part of K (which will be small). </div>
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Note also that only one pole location was chosen and this determines the value of K. If the system has more than one closed loop pole, the location of the other poles are determine solely by K, and may be in undesirable locations.</div>
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<u>Reference:</u> http://www.wikihow.com/Draw-Root-Locus-of-a-System</div>
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Solving Root Locus

A system with feedback becomes stable when equations describing that system possess roots that follow certain patterns. Otherwise, th...

PAPI and VASI

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A PAPI and a VASI are very similar in the the information they provide. The only functional differences between the VASI and PAPI is that the VASI has the red over the white, the PAPI the white actually goes to the right of the red, and the PAPI offers higher precision (or more glideslopes depending how you look at it a larger airliner with a high cockpit may elect to fly a slightly higher glidepath). The concept is the same though.</div>
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A <strong style="border: 0px; margin: 0px; padding: 0px;">VASI</strong> looks like this:</div>
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 <img alt="enter image description here" src="http://i.stack.imgur.com/SGBaq.jpg" style="border: 0px; margin: 0px; max-width: 630px; padding: 0px;" /></div>
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<strong style="border: 0px; margin: 0px; padding: 0px;">Usage</strong>:</div>
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As the saying goes,</div>
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Red over White, you're alright. (on glidepath)</div>
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Red over Red, you're dead. (too low)</div>
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White over White, you're out-of-sight (too high)</div>
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<img alt="enter image description here" src="http://i.stack.imgur.com/Ygdlp.jpg" style="border: 0px; margin: 0px; max-width: 630px; padding: 0px;" /></div>
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A <strong style="border: 0px; margin: 0px; padding: 0px;">PAPI</strong> like this: <img alt="enter image description here" src="http://upload.wikimedia.org/wikipedia/commons/7/7b/PAPI_Jersey_Airport.JPG" style="border: 0px; margin: 0px; max-width: 630px; padding: 0px;" /></div>
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A regular VASI only offers one glide slope and is designed for an aircraft where the cockpit isn't so high up. <em style="border: 0px; margin: 0px; padding: 0px;">However</em>, there is a such thing as two-light PAPI, and a three-bar VASI. So either of them can really be tailored to fit the costs and types of aircraft flying to that airport.</div>
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In the case of a four-bar PAPI it is higher precision. Since the PAPI systems uses a narrower beam of light you must fly the glide path more precisely than the VASI to stay on the beam. The PAPI, with its extra lights, forewarns you when you are drifting from the desired glide path.</div>
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<img alt="enter image description here" src="http://airportlightingcompany.com/images/PAPI-Diagram.gif" style="border: 0px; margin: 0px; max-width: 630px; padding: 0px;" /></div>
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So one red light would indicate slightly above glide slope, two and two would indicate the normal glide slope, and three red lights would indicate slightly below the glide slope on a 4-bar PAPI. A Three bar VASI works in similar fashion except there are only two glide paths with two reds being the lower, two whites the higher.</div>
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<b><u>Reference:</u></b> http://aviation.stackexchange.com/questions/1493/whats-the-functional-difference-between-papi-and-vasi</div>
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PAPI and VASI

A PAPI and a VASI are very similar in the the information they provide. The only functional differences between the VASI and PAPI is that ...

The Global Positioning System (GPS)

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<span style="color: #191919; font-family: Helvetica Neue, Helvetica, Arial, sans-serif;"><span style="line-height: 23px;">The global positioning system, or GPS as it is commonly known, is a vital component to modern air navigation, and an invaluable component to the FAA's NextGen program.</span></span></div>
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<span style="color: #191919; font-family: Helvetica Neue, Helvetica, Arial, sans-serif;"><span style="line-height: 23px;">GPS data allows pilots to obtain precise three-dimensional or four-dimensional location data. The GPS system uses triangulation to determine an aircraft's exact location, as well as speed, track, distance to or from checkpoints, and time.</span></span></div>
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<span style="color: #191919; font-family: Helvetica Neue, Helvetica, Arial, sans-serif;"><span style="line-height: 23px;"><b>History of GPS: </b></span></span><span style="color: #191919; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; line-height: 23px;">The United States military first used GPS as a navigation tool in the 1970s. In the 1980s, the U.S. government made GPS available to the general public, free of charge, with one catch: A special mode, called Selective Availability, would be enabled to purposefully reduce the accuracy of GPS for public users, reserving only the most accurate version of GPS for the military.</span></div>
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<span style="color: #191919; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; line-height: 23px;">In 2000, under the Clinton administration, selective availability was turned off, and the same accuracy that the military had benefited from was made available to the general public.</span></div>
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<span style="color: #191919; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; line-height: 23px;"><b>GPS Components:</b></span></div>
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<span style="color: #191919; font-family: Helvetica Neue, Helvetica, Arial, sans-serif;"><span style="line-height: 23px;">The GPS system has three components: The space segment, control segment and user segments.</span></span></div>
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<span style="color: #191919; font-family: Helvetica Neue, Helvetica, Arial, sans-serif;"><span style="line-height: 23px;">The space component consists of about 31 GPS satellites. The United States Air Force operates these 31 satellites, plus three to four decommissioned satellites that can be reactivated if needed. At any given moment, a minimum of twenty-four satellites are operational in a specially designed orbit, ensuring that at least four satellites are in view at the same time from almost any point on earth.</span></span></div>
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<span style="color: #191919; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 16px; line-height: 23px;">The complete coverage that satellites offer makes the GPS system the most reliable navigation system in modern aviation.</span></div>
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The control segment is made up of a series of ground stations used to interpret and relay satellite signals to various receivers. Ground stations include a master control station, an alternate master control station, 12 ground antennas and 16 monitoring stations.</div>
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The user segment of the GPS system involves various receivers from all different types of industries. National security, agriculture, space, surveying and mapping are all examples of end users in the GPS system. In aviation, the user is typically the pilot, who views GPS data on display in the cockpit of the aircraft.</div>
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<span style="background-color: initial; font-weight: 700;">How it Works:</span></div>
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GPS satellites orbit about 12,000 miles above us, and complete one orbit every 12 hours. They are solar powered, fly in medium Earth orbit and transmit radio signals to receivers on the ground.</div>
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Ground stations use the signals to track and monitor satellites, and these stations provide the master control station (MCS) with data. The MCS then provides precise position data to the satellites.</div>
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The receiver in an aircraft receives time data from the satellites' atomic clocks. It compares the time it takes for the signal to go from the satellite to the receiver, and calculates distance based on that very accurate and specific time. GPS receivers use triangulation -- date from at three satellites --to determine a precise two-dimensional location. With at least four satellites in view and operational, three-dimensional location data can be obtained.</div>
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<b>Practical Use of GPS:</b></div>
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<span style="color: #191919; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; line-height: 23px;">GPS is widely used in aviation today. Almost every aircraft built today come with a GPS unit installed as standard equipment. General aviation, business aviation and commercial aviation have all found valuable uses for GPS.</span></div>
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<span style="color: #191919; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; line-height: 23px;">From basic navigation and position data to airspeed, tracking and airport locations, GPS is a precious tool for aviators.</span></div>
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<span style="color: #191919; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; line-height: 23px;">Installed GPS units can be approved for use in IMC and for other IFR flights. Instrument pilots find GPS to be extremely helpful in maintaining situational awareness and flying instrument approach procedures. Handheld units, while not approved for IFR use, can be a helpful back-up for instrument failures, as well as a valuable tool for maintaining situational awareness in any situation.</span></div>
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<span style="color: #191919; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; line-height: 23px;">Pilots flying VFR also use GPS as a navigation tool and a back-up to traditional pilotage and dead reckoning techniques.</span></div>
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<span style="color: #191919; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; line-height: 23px;">All pilots can appreciate GPS data in emergency situations, as the database will allow them to search for the nearest airport, calculate time en route, fuel on board, time of sunset and sunrise, and much, much more.</span></div>
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<span style="color: #191919; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; line-height: 23px;">Most recently, the FAA has enabled WAAS GPS procedures for approaches, introducing a new precision approach to pilots in the form of a Localizer Performance with Vertical Guidance (LPV) approach. This is a precision approach that will enable the national airspace system to become much more efficient and assist in meeting the needs of the national airspace system in the future.</span></div>
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The Global Positioning System (GPS)

The global positioning system, or GPS as it is commonly known, is a vital component to modern air navigation, and an invaluable component ...

How Do Pilots Navigate?

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<span style="background-color: white; color: #191919; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 16px; line-height: 23px;">Air navigation is accomplished by various methods. The method or system that a pilot uses for navigating through today's </span>airspace system<span style="background-color: white; color: #191919; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 16px; line-height: 23px;"> will depend on the type of flight that will occur (VFR or IFR), which navigation systems are installed on the aircraft, and which navigation systems are available in a certain area.</span><br />
<span style="background-color: white; color: #191919; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 16px; line-height: 23px;"><br /></span>
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<span style="background-color: white; color: #191919; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 16px; line-height: 23px;">At the most simple level, navigation is accomplished through ideas known as dead reckoning and pilotage.</span><br />
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Pilotage is a term that refers to the sole use of visual ground references. The pilot identifies landmarks, such as rivers, towns, airports, and buildings and navigates among them. The trouble with pilotage is that often times, references aren't easily seen and can't be easily identified in low visibility conditions or if the pilot gets off track even slightly. Therefore, the idea of dead reckoning was introduced.</div>
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Dead reckoning involves the use of visual checkpoints along with time and distance calculations. The pilot chooses checkpoints that are easily seen from the air and also identified on the map, and then calculates the time it will take to fly from one point to the next based on distance, airspeed, and wind calculations. A flight computer aids pilots in computing the time and distance calculations, and the pilot typically uses a flight planning log to keep track of the calculations during flight.</div>
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<span style="background: 0px 0px; border: 0px; box-sizing: border-box; font-weight: 700; margin: 0px; padding: 0px; vertical-align: baseline;">Radio Navigation</span><br />
With aircraft equipped with radio navigation aids (NAVAIDS), pilots can navigate more accurately than with dead reckoning alone.</div>
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Radio NAVAIDS come in handy in low visibility conditions and act as a suitable back-up method for general aviation pilots that prefer dead reckoning. They are also more precise. Instead of flying from checkpoint to checkpoint, pilots can fly a straight line to a "fix" or an airport. Specific radio NAVAIDS are also required for IFR operations.</div>
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There are different types of radio NAVAIDS used in aviation:</div>
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<li style="background: 0px 0px; border: 0px; box-sizing: border-box; list-style-type: none; margin: 0px 0px 8px; padding: 0px; vertical-align: baseline;">ADF/NDB: The most elementary form of radio navigation is the ADF/NDB pair. An NDB is a nondirectional radio beacon that is stationed on the ground and emits an electrical signal in all directions. If an aircraft is equipped with an automatic direction finder (ADF), it will display the aircraft's position in relation to the NDB station on the ground. The ADF instrument is basically an arrow pointer placed over a compass card-type display. The arrow always points in the direction of the NDB station, which means that if the pilot points the aircraft in the direction of the arrow in a no-wind situation, he will fly directly to the station.<div style="background: 0px 0px; border: 0px; box-sizing: border-box; padding: 0px; vertical-align: baseline;">
The ADF/NDB is an outdated NAVAID, and it's a system prone to errors. Since its range is line-of-sight, a pilot can get erroneous readings while flying in mountainous terrain or too far from the station. The system is also subject to electrical interference and can only accommodate limited aircraft at once. Many are being decommissioned as GPS becomes the primary navigation source.</div>
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VOR: Next to GPS, the VOR system is probably the most commonly used NAVAIDS in the world. VOR, short for VHF Omnidirectional Range, is a radio-based NAVAID that operates in the very-high-frequency range. VOR stations are located on the ground and transmit two signals -- one continuous 360-degree reference signal and another sweeping directional signal.</div>
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The aircraft instrument (OBI) interprets the phase difference between the two signals and displays the results as a radial on the OBI (omni-bearing indicator) or HSI (horizontal situation indicator), depending on which instrument the aircraft uses. In its most basic form, the OBI or HSI depicts which radial from the station the aircraft is located on, and whether the aircraft is flying toward or away from the station.</div>
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VORs are more accurate than NDBs and are less prone to errors, although the reception is still susceptible to line-of-sight only.</div>
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DME: Distance Measuring Equipment is one of the most simple and valuable NAVAIDS to date. It's a basic method using a transponder in the aircraft to determine the time it takes for a signal to travel to and from a DME station. DME transmits on UHF frequencies, and computes slant-range distance. The transponder in the aircraft displays the distance in tenths of a nautical mile.</div>
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A single DME station can handle up to 100 aircraft at one time, and they usually co-exist with VOR ground stations.</div>
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<li style="background: 0px 0px; border: 0px; box-sizing: border-box; list-style-type: none; margin: 0px; padding: 0px; vertical-align: baseline;">ILS: An instrument landing system (ILS) is an instrument approach system used to guide aircraft down to the runway from the approach phase of flight. It uses both horizontal and vertical radio signals emitted from a point along the runway. These signals intercept to give the pilot precise location information in the form of a glideslope -- a constant-angle, stabilized descent path all the way down to the approach end of the runway. ILS systems are widely in use today as one of the most accurate approach systems available.</li>
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<span style="background-attachment: initial; background-clip: initial; background-image: initial; background-origin: initial; background-position: 0px 0px; background-repeat: initial; background-size: initial; border: 0px; box-sizing: border-box; display: block; font-weight: 700; margin: 0px 0px 17px; padding: 0px; vertical-align: baseline;">GPS</span>The global positioning system has become the most valuable method of navigation in the modern aviation world. GPS has proven to be tremendously reliable and precise, and is probably the most common NAVAID in use today.</div>
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The global positioning system uses 24 U.S. Department of Defense satellites to provide precise location data, such as aircraft position, track, speed, and to pilots. The GPS system uses triangulation to determine the aircraft's exact position over the earth. To be accurate, a GPS system must have the ability to gather data from at least three satellites for 2-D positioning, and 4 satellites for 3-D positioning.</div>
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GPS has become a preferred method of navigating due to the accuracy and ease of use. Though there are errors associated with GPS, they are rare. GPS systems can be used anywhere in the world, even in mountainous terrain, and they aren't prone to the errors of radio NAVAIDS, such as line-of-sight and electrical interference.</div>
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<span style="background: 0px 0px; border: 0px; box-sizing: border-box; font-weight: 700; margin: 0px; padding: 0px; vertical-align: baseline;">Practical Use of NAVAIDS:</span><br />
Pilots will fly under visual flight rules (VFR) or instrument flight rules (IFR), depending on the weather conditions. During visual meteorological conditions (VMC), a pilot might fly by using pilotage and dead reckoning alone, or he might use radio navigation or GPS navigation techniques. Basic navigation is taught in the early stages of flight training.</div>
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<span style="color: #191919;">In instrument meteorological conditions (IMC) or while flying IFR, </span><span style="color: #191919;">a pilot will need to rely on cockpit instruments, such as a VOR or GPS system. Beca</span>use flying in the clouds and navigating with these instruments can be tricky, a pilot must earn an <span style="background-attachment: initial; background-clip: initial; background-image: initial; background-origin: initial; background-position: 0px 0px; background-repeat: initial; background-size: initial; box-sizing: border-box;">FAA Instrument Rating</span> in order to legally fly in IMC conditions.</div>
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Currently, the FAA is emphasizing new training for general aviation pilots in<span style="background-attachment: initial; background-clip: initial; background-image: initial; background-origin: initial; background-position: 0px 0px; background-repeat: initial; background-size: initial; box-sizing: border-box;">technologically advanced aircraft (TAA)</span>. TAA are aircraft that have advanced highly technical systems on board, such as GPS. Even <span style="background-attachment: initial; background-clip: initial; background-image: initial; background-origin: initial; background-position: 0px 0px; background-repeat: initial; background-size: initial; box-sizing: border-box;">light sport aircraft</span> are coming out of the factory with advanced equipment these days. It can be confusing and dangerous for a pilot to attempt to use these <span style="background-attachment: initial; background-clip: initial; background-image: initial; background-origin: initial; background-position: 0px 0px; background-repeat: initial; background-size: initial; box-sizing: border-box;">modern cockpit systems</span> in-flight without additional training, and current FAA training standards haven't kept up with this issue.</div>
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The FAA's updated <span style="background-attachment: initial; background-clip: initial; background-image: initial; background-origin: initial; background-position: 0px 0px; background-repeat: initial; background-size: initial; box-sizing: border-box;">FITS program</span> finally addressed the issue, although the program is still voluntary.</div>
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How Do Pilots Navigate?

Air navigation is accomplished by various methods. The method or system that a pilot uses for navigating through today's airspace s...

Basic Geography: Latitude and Longitude

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<span style="color: #000066; font-family: verdana, geneva, helvetica;"><strong>Basic Geography: Latitude and Longitude</strong></span></div>
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<b style="box-sizing: border-box;">Latitude</b> defines how far north or south a point is on the globe relative to the equator. As many of us are aware, the <b style="box-sizing: border-box;">equator</b> is an imaginary line drawn around the earth equally distant from both poles, dividing the earth into Northern and Southern hemispheres. To put it plainly, latitude lets you know how far north or south a point is on the globe.</div>
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Latitude is expressed in degrees, with the equator sitting at 0° latitude. As you move north, the degrees go from 0 to 90°. However, they go up to 90 as you move south as well. Therefore, in order to tell whether a point is north or south, you would say its latitude is so and so degrees North, as in north of the equator, or so and so degrees South, as in south of the equator.</div>
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Before we move onto longitude, here's one little tip: in order to keep latitude lines straight from longitude ones, I like to link the 'a' in latitude to the 'a' in the word 'across', helping me to remember that <i style="box-sizing: border-box;">latitude lines go across the globe</i>. Another great way to remember latitude is to link it to a ladder whose rungs run across it.</div>
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<b style="box-sizing: border-box;">Longitude </b>defines how far east or west a point is on the globe relative to the prime meridian. The <b style="box-sizing: border-box;">prime meridian</b> is, again, an imaginary line drawn around the earth that separates it into eastern and western hemispheres. To state it simply, the prime meridian is to east and west what the equator is to north and south.</div>
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Interestingly, the prime meridian is believed to pass directly through Greenwich, England. Therefore, it is often also called the Greenwich meridian.</div>
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Like latitude, longitude is also expressed in degrees. However, as latitude only goes from 0 to 90° north or south, longitude goes from 0 to 180° east or west. Again, just like latitude, longitude will be expressed as so and so degrees east or so and so degrees west.</div>
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<span style="background-color: white; color: red; font-family: Verdana;">So</span><span style="background-color: white; font-family: Verdana;"> you're looking at a map and you want to know where a city or a place is. And you want to tell someone else. How do you do it?</span><span style="background-color: white;"></span></div>
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<span style="color: red; font-family: Verdana;">Let's</span><span style="font-family: Verdana;"> say you want to tell your friend where Paris is.</span></div>
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<span style="color: red; font-family: Verdana;">You</span><span style="font-family: Verdana;"> could say, "Well, it's in France." That's general.</span></div>
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<span style="color: red; font-family: Verdana;">You </span><span style="font-family: Verdana;">could say, "OK, find the Seine River." That might work.</span></div>
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<span style="color: red; font-family: Verdana;">But</span><span style="font-family: Verdana;"> what if your friend wants to know <i>exactly</i> where Paris is? You need to use <b>latitude</b> and <b>longitude</b>.</span></div>
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<span style="color: red; font-family: Verdana;">Latitude</span><span style="font-family: Verdana;"> and longitude are two of the most basics terms in all of geography. To understand them, you need to think of Earth as a globe. Further, you need to think of the globe as divided into lots of little sections. Some go east. Some go west. Some go north. Some go south.</span></div>
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<span style="font-family: Verdana;"><span style="font-family: Verdana;">(</span><span style="color: red; font-family: Verdana;">Note</span><span style="font-family: Verdana;">: A little bit of math is coming. Don't be scared!)</span></span></div>
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<span style="color: red; font-family: Verdana;">So</span><span style="font-family: Verdana;">, you know how a circle has 360 degrees? Well, that's true for Earth as well. If you put your finger on the city of Paris and trace all the way around the globe, from right to left, you will trace the full 360 degrees. Go just halfway and you get 180 degrees.</span></div>
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<span style="color: red; font-family: Verdana;">You</span><span style="font-family: Verdana;"> have just traced 360 degrees of <b>longitude</b>. Longitude is lines that run north and south that measure east or west. The Prime Meridian, in Greenwich, England, is at 0 degrees longitude.</span></div>
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<span style="color: red; font-family: Verdana;">Put</span><span style="font-family: Verdana;"> your finger on Paris again. Trace around the globe, this time going around the top of the globe, then around the bottom, and back to Paris. You've just traced the full 180 degrees of <b>latitude</b>. Latitude is only 180 degrees. Latitude lines run east and west and measure north or south. The Equator is at 0 degrees latitude.</span></div>
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<span style="color: red; font-family: Verdana;">What</span><span style="font-family: Verdana;"> does all this give us? Well, you want to tell your friend exactly where Paris is, right? So check out a map that has latitude and longitude marked on it. You'll find that the latitude and longitude markings are every 10 degrees. (Some maps have markings for every 15 degrees or even every 5 degrees.)</span></div>
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<span style="color: red; font-family: Verdana;">See</span><span style="font-family: Verdana;"> how Paris is almost halfway between 45 degrees and 50 degrees markings? You'll have to estimate here. It's probably about 47.5 degrees. Let's call it 48.</span></div>
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<span style="color: red; font-family: Verdana;">That's</span><span style="font-family: Verdana;"> latitude. What about longitude? Well, the Prime Meridian is at 0 degrees. That's in England. France is just east of England (for the most part). See how Paris is just less than halfway between the 0 degrees and 5 degrees markings? You'll have to estimate here, too. It's probably about 2 degrees.</span></div>
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<span style="color: red; font-family: Verdana;">So</span><span style="font-family: Verdana;">, what is the exact location of Paris? Well, geographers tell us that Paris is indeed at 48 degrees north and 2 degrees east.</span></div>
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<span style="color: red; font-family: Verdana;"><b>Latitude</b></span><span style="font-family: Verdana;"> and <b>longitude</b> are big words, but now you know what they mean. Amaze your friends!</span></div>
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Basic Geography: Latitude and Longitude

Basic Geography: Latitude and Longitude Latitude defines how far north or south a point is on the globe relative to the equator. ...

Six Pack – The Primary Flight Instruments

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There are six traditional flight instruments in most aircraft cockpits. Many of these instruments have taken on a more modern appearance over time, but even technologically advanced aircraft have traditional instruments to use as back-ups in case the primary system fails.</div>
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The following instruments make up what's called the "six-pack" in a traditional cockpit where three instruments are stacked on top of three more instruments.<br />
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<span style="background-attachment: initial; background-clip: initial; background-image: initial; background-origin: initial; background-position: 0px 0px; background-repeat: initial; background-size: initial; border: 0px; box-sizing: border-box; display: block; font-weight: 700; margin: 0px 0px 17px; padding: 0px; vertical-align: baseline;"></span><span style="background-attachment: initial; background-clip: initial; background-image: initial; background-origin: initial; background-position: 0px 0px; background-repeat: initial; background-size: initial; border: 0px; box-sizing: border-box; display: block; font-weight: 700; margin: 0px 0px 17px; padding: 0px; vertical-align: baseline;"><span style="font-weight: normal;">These six </span>basic flight instruments<span style="font-weight: normal;"> are the main source of cockpit flight information for pilots, and are divided into two categories: Static (or pitot-static) instruments and gyroscopic instruments. </span></span><span style="background-attachment: initial; background-clip: initial; background-image: initial; background-origin: initial; background-position: 0px 0px; background-repeat: initial; background-size: initial; border: 0px; box-sizing: border-box; display: block; font-weight: 700; margin: 0px 0px 17px; padding: 0px; vertical-align: baseline;">Gyroscopic Instruments </span><span style="background-attachment: initial; background-clip: initial; background-image: initial; background-origin: initial; background-position: 0px 0px; background-repeat: initial; background-size: initial; border: 0px; box-sizing: border-box; display: block; font-weight: 700; margin: 0px 0px 17px; padding: 0px; vertical-align: baseline;"><span style="background-attachment: initial; background-clip: initial; background-image: initial; background-origin: initial; background-position: 0px 0px; background-repeat: initial; background-size: initial; border: 0px; box-sizing: border-box; display: block; margin: 0px 0px 17px; padding: 0px; vertical-align: baseline;">Static/Pitot-Static Instruments:</span></span></div>
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<li style="background: 0px 0px; border: 0px; box-sizing: border-box; list-style-type: none; margin: 0px; padding: 0px; vertical-align: baseline;"><span style="background: 0px 0px; border: 0px; box-sizing: border-box; font-weight: 700; margin: 0px; padding: 0px; vertical-align: baseline;">1. Airspeed Indicator</span>: The airspeed indicator tells the pilot the indicated airspeed in knots (or in some cases, a Mach number). Airspeed is sometimes also depicted in true airspeed, which is valuable information for flight planning. True airspeed is the actual speed of the airplane in relation to the air, and is corrected for temperature and density effects. It's usually just a few knots different than indicated airspeed in small aircraft.<div style="background: 0px 0px; border: 0px; box-sizing: border-box; margin-bottom: 17px; padding: 0px; vertical-align: baseline;">
In a nutshell, the airspeed indicator works by comparing ram air pressure to static air pressure. The diaphragm inside the instrument casing measures the pressure differential and depicts it on the instrument pointer.</div>
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Airspeed indicators are color coded so the pilot can easily identify ranges such as the normal operating range, flap-operating range, and caution range. Minimum and maximum speeds, as well as other important speeds (known as V-speeds) are marked as well.</div>
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<img alt="Cessna 172 Airspeed Indicator" src="http://learntofly.ca/wp-content/uploads/2010/03/Cessna-172-Airspeed-Indicator.jpg" /></div>
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<span style="background: 0px 0px; border: 0px; box-sizing: border-box; font-weight: 700; margin: 0px; padding: 0px; vertical-align: baseline;">2. Altimeter</span>:  <span style="background-color: initial;">The altimeter reflects the aircraft's vertical height above MSL </span>(mean sea level<span style="background-color: initial;">) corrected for outside air pressure. The pilot sets the appropriate pressure setting (a local setting for those flying below 18,000 feet) and the altimeter will depict the corresponding altitude above MSL.</span></div>
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The altimeter works similar to a basic barometer, by comparing the static pressure inside of a sealed aneroid capsule to the expanding or contracting pressure surrounding it. When the airplane ascends or descends, the air pressure will decrease of increase, respectively. This outside air pressure is constantly being compared to the pressure inside the aneroid capsule, and with the help of linkage and a pointer, the altitude is displayed on the cockpit instrument.</div>
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<span style="background: 0px 0px; border: 0px; box-sizing: border-box; font-weight: 700; margin: 0px; padding: 0px; vertical-align: baseline;">3. Vertical Speed Indicator</span>:  <span style="background-color: initial;">Vertical speed is the rate of the aircraft's climb or descent, usually depicted in feet per minute (fpm) </span>on the vertical speed indicator<span style="background-color: initial;"> (VSI). In level flight, the VSI needle points to '0' feet.</span></div>
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The VSI works by measuring and comparing the static pressure inside of an expandable capsule to the metered static pressure outside of the capsule. The pressure inside the capsule changes very quickly as the plane climbs or descends, while the pressure outside of the capsule changes very slowly due to the metered leak. During climbs and descents, the capsule compresses or expands, respectively. The pressure difference is measured and linked to the pointer, where it's depicted on the instrument face.</div>
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The VSI is valuable in determining if the airplane is climbing or descending and the rate of the climb or descend. There can be a slight lag in information depicted on the VSI if the aircraft is maneuvered abruptly. In turbulence, the indications can be slightly erratic.</div>
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<img alt="Cessna 172 Vertical Speed Indicator" src="http://learntofly.ca/wp-content/uploads/2010/03/Cessna-172-Vertical-Speed-Indicator.jpg" /></div>
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<span style="background-attachment: initial; background-clip: initial; background-image: initial; background-origin: initial; background-position: 0px 0px; background-repeat: initial; background-size: initial; border: 0px; box-sizing: border-box; display: block; font-weight: 700; margin: 0px 0px 17px; padding: 0px; vertical-align: baseline;"><br /></span><span style="background-attachment: initial; background-clip: initial; background-image: initial; background-origin: initial; background-position: 0px 0px; background-repeat: initial; background-size: initial; border: 0px; box-sizing: border-box; display: block; font-weight: 700; margin: 0px 0px 17px; padding: 0px; vertical-align: baseline;">Gyroscopic Instruments</span></div>
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<span style="background: 0px 0px; border: 0px; box-sizing: border-box; font-weight: 700; margin: 0px; padding: 0px; vertical-align: baseline;">1. Attitude Indicator</span>: The attitude indicator is possibly the most important instrument for pilots. In one glance, a pilot can tell if the aircraft is climbing, descending, turning or straight and level. It gives a direct indication of changes to pitch attitude and bank.</div>
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The attitude indicator consists of an artificial horizon that is a background for a miniature airplane. The instrument is meant to depict the sky (usually blue in color) and the ground (typically brown), with a miniature airplane positioned on the artificial horizon (a white line) in level flight. In most cases, the miniature airplane is attached to the instrument viewing case, and it moves with the airplane. The artificial horizon senses movement from the gyroscope and remains suspended in relation to a self-erecting gyroscope, which "holds" its position in reference to the actual horizon. The gyroscope itself can be vacuum-driven or electric.</div>
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<img alt="Cessna 172 Attitude Indicator" src="http://learntofly.ca/wp-content/uploads/2010/03/Cessna-172-Attitude-Indicator.jpg" /></div>
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<span style="background: 0px 0px; border: 0px; box-sizing: border-box; font-weight: 700; margin: 0px; padding: 0px; vertical-align: baseline;">2. Heading Indicator</span>: A basic tool for navigation, the heading indicator provides directional information to the pilot similar to the way a magnetic compass does. The heading indicator itself is not north-seeking, but can depict an accurate heading when aligned to a magnetic compass. The heading indicator is a gyroscopic instrument and can be vacuum-driven or electrically powered.</div>
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As the aircraft turns left or right, the heading indicator will change to depict a new heading between zero and 359 degrees on a compass card. A miniature aircraft is located in the center of the indicator and turns with the airplane while the gyroscope (and coinciding linkage) turn the compass card on the instrument. In a left turn, the miniature airplane appears to turn left while the compass card turns right.</div>
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<img alt="Cessna 172 Heading Indicator" src="http://learntofly.ca/wp-content/uploads/2010/03/Cessna-172-Heading-Indicator.jpg" /></div>
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<span style="background: 0px 0px; border: 0px; box-sizing: border-box; font-weight: 700; margin: 0px; padding: 0px; vertical-align: baseline;">3. Turn Coordinator</span>: The turn coordinator is another gyroscopic instrument that can be either electric or vacuum-driven. It's one of the simplest instruments, with a miniature airplane that dips its wings one way or another to show rate of turn or rate or roll. When a pilot rolls the airplane into a turn, the miniature airplane quickly shows a corresponding roll. There are tick marks on the instrument that are calibrated to depict a standard rate turn for an airplane (a 360-degree standard-rate turn takes two minutes).</div>
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The turn coordinator also includes an inclinometer, which is a ball suspended in fluid that reacts like a pendulum during turning flight. The ball acts in response to gravity and turning forces and will depict a coordinated or uncoordinated turn. The pilot can then counteract an uncoordinated turn with the use of rudder movement, avoiding a slipping or skidding turn.</div>
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<img alt="Cessna 172 Turn Coordinator" src="http://learntofly.ca/wp-content/uploads/2010/03/Cessna-172-Turn-Coordinator.jpg" /></div>
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Six Pack – The Primary Flight Instruments

There are six traditional flight instruments in most aircraft cockpits. Many of these instruments have taken on a more modern appearance o...