Reading the Sectional
Open the San Francisco Sectional and locate the lower left corner that has 36-degrees with 125-degrees below and to the right. Now fold the chart so that only ocean is visible except at the upper right corner which shows Point Reyes. Leave the Legend to the right out flat as you not that the vertical line is not straight but has a slight curve. The bottom line is also curved, as you should note by the width of the white margins. Note the caution box below the 125-degrees, related to uncharted hazards below 200 feet.
The 36-degree line is the degrees of Northern Latitude it is parallel to the 37-degree; line about 9 inches above. The top of the sectional goes slightly beyond the 40-degree; line of latitude or 40th parallel. The space between every degree on the sectional is divided into 60 divisions and each division is a nautical mile. This is true only on the vertical lines. There are sixty divisions between the vertical lines but they vary in distance from 48 to 45 nautical miles due to the tapering of the distance toward to pole. You never measure distance on the horizontal lines of latitude.
Vertically between 36-degree; and 37-degree; there are divisions and subdivisions. Half way between every degree either vertically or horizontally there is a full line marking the thirty-minute (30')or halfway point between degrees. It is very easy to confuse a 30' line with a degree line. Degree lines will have their numbers to the lower left at every interior intersection. Horizontally each nautical mile is one-minute. There are sixty minutes in every degree. From the degree line every five degrees has a marking that extends farther to the left; every ten degrees has a marking extending farther both left and right. Use of these subdivision markings makes it easier to count degrees.
Go back to the lower left corner of the sectional. Count up the 125-degree; line of west longitude or meridian five spaces. Mark this line and then repeat the process on the 124-degree; meridian. Use a straight edge to connect the two points with a line. This Line is knows as the 36-degrees 05' N. Go back to the left corner and count over on the 36-degree; parallel for 15 spaces and mark the crosshatch. Go up to the 37-degree; parallel and repeat the count and mark. Draw a vertical line between the two marks. This line is known as the 125-degree; 15' W line of longitude or is it the 124-degree; 45' W meridian. Which?
We have created a problem for ourselves. 36-degree; 05' N worked because we were counting toward 37-degree;. By counting from 125-degree; to the right we may tend to use the 15 count when it is actually the 45' point from 124-degree;. I deliberately tried to expose you to one of the most common errors in locating coordinates. You must always start your count for latitude from the bottom and the count for longitude from the right. The next most common error is in not using a long ruler to draw your lines. It is very easy to draw a line between two points that are not going to give a parallel line.
Where these two lines cross is a point that is unique in the world. 36-degrees 05' N-124-degrees; 45' W. Every place on the earth can be so identified and located. Locate Mt. Whitney near Death Valley and see what coordinates you get. Check with the coordinates given on the chart legend. Practice at least ten different locations by giving yourself coordinates that would be located on the San Francisco Sectional. Next mark at least ten airports on both sides of the sectional and determine the coordinates.
To locate a particular airport for which you do not have a designator. You can put the geographical coordinates into your Loran or GPS and the navaids will work just as well. Fifteen years ago I did this while going to Medford, Oregon from the Nut Tree. Crossing the threshold the Loran indicated 1/2 mile to airport center. (I taught LORAN in All airline pilot training, commercial pilot training, air force pilot training, fighter pilot training, pilot training schools, flight training schools, flight attendant training, helicopter flight training, accelerated flight training, airline flight training, flight training florida, flight attendant training schools, instrument flight training, cpl flight flying school training training, flight training simulator, flight training academy, atp flight training, helicopter flight training schools, california flight training, professional flight training, data flight training, orlando flight training, corporate flight attendant training, flight nurse training, warrant officer flight training, flight training device, lufthansa flight training, flight training san diego, alien alien flight flight training, military pilot training, sport pilot training and private pilot training.
The quadrangles bounded by the ticked lines are but 1/4 of the area in a degree square. It isn't a square or a rectangle but it does measure 60' to a side. Every quadrangle is 30 nautical miles high but the width is quite variable. Call them wreckedangles? Each figure that has land has a highest known obstruction elevation. The given figure is rounded upward to the next hundred and then an additional hundred is added. Maximum elevation figures on a sectional have a fudge factor to account for possible errors. After rounding any elevation to the next highest hundred, another hundred is added. In mountains an additional 300' is added. These margins may only partially correct for altimeter setting errors. You are required by FAR to have an altimeter setting from within 100 miles. The closer the setting location the better.
The sectional aeronautical chart is essential to all forms of visual navigation. Your eyes use a comparison of land features to chart features to determine how relationships compare. When comparisons match, you know where you are.
A sectional is aligned to true north. The Lambert Conical Projection of the chart makes all straight lines very nearly the direction you fly before figuring in isogonic variation and deviation. This works very well when you know that the winds given by the FSS and Weather Bureau are also measured by direction from true north.
The lines of longitude and latitude on the sectional divide it into a series of wrecked-angles (sic) with 30 ticks marked on each side. Only the north-south ticks can be used for distance measuring since the lines of latitude are parallel. Each wrecked-angle has a Maximum Elevation Figure, which, within 100', tells the MSL altitude required to over fly all obstacles.
Within many wrecked-angles the topography is shown in eight colors which shade from green to dark brown to indicate altitude. Most chart symbols resemble earth features. Small roads are shown only when deemed useful for navigation. Fly with the chart open and pointed in the direction you are going. In each quarter of a degree depicted there is a maximum elevation figure. In most areas this figure is rounded to the next higher 100' but in mountainous areas it is rounded to the next higher 100' plus an additional 300'.
Airports are either magenta (uncontrolled) or blue (controlled). It is important that the pilot become totally familiar with the chart legend as it applies to information available at the airports and through the use of radios. Airspace depiction is shown by types of line/color combinations to cover Classes B, C, D, E, and G. It is illegal to fly without a current chart for the area.
VOR Box
The Hazardous In-flight Weather Advisory Service is broadcast over VORs that have a Small solid square in the lower right corner of the VOR information box.
Arcata, California VOR gives TWEBs or Transcribed Weather Broadcasts about route information, NOTAMs and special information. A solid circle around a white T in the upper left corner of the VOR box shows this ability.
The altitude of your transponder mated encoder is always based on 29.92 and computer adjusted for the ATC read-out. Nothing you do to your altimeter will make a difference in what ATC sees. Every new radar controller is required to confirm your cockpit altimeter setting to compare with his read-out.
World Aeronautical Charts (WAC)
WACs have half the scale of Sectional Charts so the price is cheaper for the area depicted. Class B and C airspace is only outlined without altitudes. Class D and Class E surface (CZ of non-tower) is not shown at all. Space limits have eliminated many obstacles, towns, and frequencies. Maximum elevation figures (MEF) cover 60 nautical mile wrecked angles (sic). WACs are best for fast airplanes or for long flight planning. (Required Practical Test Knowledge-frequent oral test question) WAC charts show MOAs but do not show MTRs. The width of a MTR can vary up to ten miles to each side. See AIM 3-41 +.
Class Bravo Airspace
Expect to pay a landing fee if landing at a Class B airport. Wake turbulence and extensive taxiing to expensive parking is to be expected. If you do not have the rating and equipment for flying into Class B you can expect to hear from the FAA. FAR 91.129 gives the operational requirements. Most of the large Class B airports do not allow student operations. A student endorsement is required in those Class Bs that allow student operations. You cannot enter Class b unless your are given a clearance.
FAR 91.131 requires you to have an encoding transponder. Your transponder will warn TCAS equipped aircraft of your location and proximity. VFR aircraft are not required to have a VOR but you will be expected to abide by any headings and altitudes assigned regardless of your altitude and location. You are usually free to select your own route and altitude below Class B but you should advise ATC of any changes you Class C or D field that will give the same amenities at far less cost. At any unfamiliar airport you should request progressive taxi instructions. Prior to departures in underlying Class B airspace you will be given specific instructions as to direction and altitude restrictions. Readback all such restrictions as they occur. FAR 91.117 limits speeds below Class B to 200 knots or slower. Speed in Class B has an upper limit of 250 knots.
I have yet to find a reason to fly into a Class B airport. There is always an underlying information and make sure that you understand what is expected.
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