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This chapter introduces the various classifications of airspace and provides information on the requirements to operate in such airspace. For further information, consult the Aeronautical Information Manual (AIM) and 14 CFR parts 71, 73, and 91.
The two categories of airspace are: regulatory and non- regulatory. Within these two categories there are four types: controlled, uncontrolled, special use, and other airspace.
Figure 13-1 presents a profile view of the dimen- sions of various classes of airspace. Figure 13- gives the basic weather minimums for operating in the different classes of airspace. Figure 13-3 lists the operational and equipment requirements. It will be helpful to refer to these figures as this chapter is studied. Also there are excerpts from sectional charts in Chapter 14Navigation, that will show how air- space is depicted.
CONTROLLED AIRSPACE
Controlled airspace is a generic term that covers the different classifications of airspace and defined dimensions within which air traffic control service is provided in accordance with the airspace classifica- tion. Controlled airspace consists of:
- Class A
- Class B
- Class C
- Class D
- Class E
CLASS A AIRSPACE
Class A airspace is generally the airspace from 18, feet mean sea level (MSL) up to and including FL600, including the airspace overlying the waters within 12 nautical miles (NM) of the coast of the 48 contiguous states and Alaska. Unless otherwise authorized, all operation in Class A airspace will be conducted under instrument flight rules (IFR).
CLASS B AIRSPACE
Class B airspace is generally the airspace from the
surface to 10,000 feet MSL surrounding the nation’s busiest airports. The configuration of Class B airspace is individually tailored to the needs of a particular area and consists of a surface area and two or more layers. Some Class B airspace resembles an upside-down wedding cake. At least a private pilot certificate is required to operate in Class B airspace; however, there is an exception to this requirement. Student pilots or recreational pilots seeking private pilot certification may operate in the airspace and land at other than specified primary airports within the airspace if they have received training and had their logbook endorsed by a certified flight instructor in accordance with Title 14 of the Code of Federal Regulations (14 CFR) part
CLASS C AIRSPACE Class C airspace generally extends from the surface to 4,000 feet above the airport elevation surrounding those airports having an operational control tower, that are serviced by a radar approach control, and with a certain number of IFR operations or passen- ger enplanements. This airspace is charted in feet
Nontowered Airport 700 AGL
CLASS A
CLASS B CLASS C CLASS D 1200 AGL
CLASS G CLASS G
CLASS E
CLASS G
FL 600
MSL 18,
14,500 MSL
MSL – mean sea level AGL – above ground level FL – flight level
Figure 13-1. Airspace profile.
BASIC VFR WEATHER MINIMUMS
Airspace Flight Visibility Distance from Clouds
Class A ......................................................................
Class B ......................................................................
Class C ......................................................................
Class D ......................................................................
Class E Less than 10,000 feet MSL ......................................
At or above 10,000 feet MSL .......................................
Not Applicable Not Applicable
3 statute miles Clear of Clouds
3 statute miles
3 statute miles
500 feet below 1,000 feet above 2,000 feet horizontal
500 feet below 1,000 feet above 2,000 feet horizontal
500 feet below 1,000 feet above 2,000 feet horizontal
3 statute miles
5 statute miles 1,000 feet below 1,000 feet above 1 statute mile horizontal
Class G 1,200 feet or less above the surface (regardless of MSL altitude). Day, except as provided in section 91.155(b). ........... 1 statute mile Clear of Clouds
Night, except as provided in section 91.155(b). ........... 3 statute miles 500 feet below 1,000 feet above 2,000 feet horizontal More than 1,200 feet above the surface but less than 10,000 feet MSL. Day ................................................................................
Night .............................................................................
More than 1,200 feet above the surface and at or above 10,000 feet MSL. ..................................................
1 statute mile 500 feet below 1,000 feet above 2,000 feet horizontal
500 feet below 1,000 feet above 2,000 feet horizontal
3 statute miles
5 statute miles 1,000 feet below 1,000 feet above 1 statute mile horizontal
Figure 13-2. Visual flight rule weather minimums.
WARNING AREAS
Warning areas consist of airspace which may contain hazards to nonparticipating aircraft in international airspace. The activities may be much the same as those for a restricted area. Warning areas are estab- lished beyond the 3-mile limit. Warning areas are depicted on aeronautical charts.
MILITARY OPERATION AREAS
Military operation areas (MOA) consist of airspace of defined vertical and lateral limits established for the purpose of separating certain military training activity from IFR traffic. There is no restriction against a pilot operating VFR in these areas; how- ever, a pilot should be alert since training activities may include acrobatic and abrupt maneuvers. MOAs are depicted on aeronautical charts.
ALERT AREAS
Alert areas are depicted on aeronautical charts and are to advise pilots that a high volume of pilot training or unusual aerial activity is taking place.
CONTROLLED FIRING AREAS
Controlled firing areas contain activities, which, if not conducted in a controlled environment, could be hazardous to nonparticipating aircraft. The difference between controlled firing areas and other special use airspace is that activities must be suspended when a spotter aircraft, radar, or ground lookout position indicates an aircraft might be approaching the area.
OTHER AIRSPACE AREAS
“Other airspace areas” is a general term referring to the majority of the remaining airspace. It includes:
- Airport Advisory Areas
- Military Training Routes (MTR)
- Temporary Flight Restrictions
- Parachute Jump Areas
- Published VFR Routes
- Terminal Radar Service Areas
- National Security Areas
AIRPORT ADVISORY AREAS
An airport advisory area is an area within 10 statute miles (SM) of an airport where a control tower is not operating, but where a flight service station (FSS) is located. At these locations, the FSS provides advi- sory service to arriving and departing aircraft.
MILITARY TRAINING ROUTES
Military training routes (MTR) are developed to allow the military to conduct low-altitude, high- speed training. The routes above 1,500 feet AGL are developed to be flown primarily under IFR, and the routes 1,500 feet and less are for VFR flight. The routes are identified on sectional charts by the designation “instrument (IR) or visual (VR).”
TEMPORARY FLIGHT RESTRICTIONS
An FDC NOTAM will be issued to designate a tem- porary flight restriction (TFR). The NOTAM will begin with the phrase “FLIGHT RESTRICTIONS” followed by the location of the temporary restriction, effective time period, area defined in statute miles, and altitudes affected. The NOTAM will also contain the FAA coordination facility and telephone number, the reason for the restriction, and any other informa- tion deemed appropriate. The pilot should check the NOTAMs as part of flight planning.
Some of the purposes for establishing a temporary restriction are:
- Protect persons and property in the air or on the surface from an existing or imminent hazard.
- Provide a safe environment for the operation of disaster relief aircraft.
- Prevent an unsafe congestion of sightseeing aircraft above an incident or event, which may generate a high degree of public interest.
- Protect declared national disasters for humanitarian reasons in the State of Hawaii.
- Protect the President, Vice President, or other public figures.
- Provide a safe environment for space agency operations.
PARACHUTE JUMP AREAS
Parachute jump areas are published in the Airport/Facility Directory. Sites that are used fre- quently are depicted on sectional charts.
PUBLISHED VFR ROUTES
Published VFR routes are for transitioning around, under, or through some complex airspace. Terms such as VFR flyway, VFR corridor, Class B airspace, VFR transition route, and terminal area VFR route have been applied to such routes. These routes are generally found on VFR terminal area planning charts.
TERMINAL RADAR SERVICE AREAS
Terminal Radar Service Areas (TRSA) are areas where participating pilots can receive additional radar services. The purpose of the service is to provide sep- aration between all IFR operations and participating VFR aircraft.
The primary airport(s) within the TRSA become(s) Class D airspace. The remaining portion of the TRSA overlies other controlled airspace, which is normally Class E airspace beginning at 700 or 1,200 feet and established to transition to/from the en route terminal environment. TRSAs are depicted on VFR sectional charts and terminal area charts with a solid black line
and altitudes for each segment. The Class D portion is charted with a blue segmented line. Participation in TRSA services is voluntary; however, pilots operating under VFR are encouraged to contact the radar approach control and take advantage of TRSA service. NATIONAL SECURITY AREAS National security areas consist of airspace of defined vertical and lateral dimensions established at locations where there is a requirement for increased security and safety of ground facilities. Pilots are requested to voluntarily avoid flying through these depicted areas. When necessary, flight may be temporarily prohibited.
This chapter provides an introduction to cross- country flying under visual flight rules (VFR). It contains practical information for planning and executing cross-country flights for the beginning pilot.
Air navigation is the process of piloting an airplane from one geographic position to another while monitor- ing one’s position as the flight progresses. It introduces the need for planning, which includes plotting the course on an aeronautical chart, selecting checkpoints, measuring distances, obtaining pertinent weather infor- mation, and computing flight time, headings, and fuel requirements. The methods used in this chapter include pilotage—navigating by reference to visible landmarks, dead reckoning—computations of direction and dis- tance from a known position, and radio navigation—by use of radio aids.
AERONAUTICAL CHARTS
An aeronautical chart is the road map for a pilot flying under VFR. The chart provides information which allows pilots to track their position and provides avail- able information which enhances safety. The three aeronautical charts used by VFR pilots are:
- Sectional Charts
- VFR Terminal Area Charts
- World Aeronautical Charts
A free catalog listing aeronautical charts and related publications including prices and instructions for
ordering is available at the National Aeronautical Charting Office (NACO) Web site: www.naco.faa.gov.
SECTIONAL CHARTS Sectional charts are the most common charts used by pilots today. The charts have a scale of 1:500, (1 inch = 6.86 nautical miles or approximately 8 statute miles) which allows for more detailed infor- mation to be included on the chart.
The charts provide an abundance of information, including airport data, navigational aids, airspace, and topography. Figure 14-1 on the next page is an excerpt from the legend of a sectional chart. By referring to the chart legend, a pilot can interpret most of the information on the chart. A pilot should also check the chart for other legend information, which includes air traffic control frequencies and information on airspace. These charts are revised semiannually except for some areas outside the conterminous United States where they are revised annually.
VISUAL FLIGHT RULE TERMINAL AREA CHARTS Visual flight rule (VFR) terminal area charts are help- ful when flying in or near Class B airspace. They have a scale of 1:250,000 (1 inch = 3.43 nautical miles or approximately 4 statute miles). These charts provide a more detailed display of topographical information and are revised semiannually, except for several Alaskan and Caribbean charts.
WORLD AERONAUTICAL CHARTS World aeronautical charts are designed to provide a standard series of aeronautical charts, covering land
areas of the world, at a size and scale convenient for navigation by moderate speed aircraft. They are pro- duced at a scale of 1:1,000,000 (1 inch = 13.7 nautical miles or approximately 16 statute miles). These charts are similar to sectional charts and the symbols are the same except there is less detail due to the smaller scale. These charts are revised annually except several Alaskan charts and the Mexican/Caribbean charts which are revised every 2 years.
LATITUDE AND LONGITUDE
(MERIDIANS AND PARALLELS)
The Equator is an imaginary circle equidistant from the poles of the Earth. Circles parallel to the Equator (lines running east and west) are parallels of latitude. They are used to measure degrees of latitude north or south of the Equator. The angular distance from the Equator
to the pole is one-fourth of a circle or 90°. The 48 con- terminous states of the United States are located between 25° and 49° N. latitude. The arrows in figure 14-2 labeled “LATITUDE” point to lines of latitude.
Meridians of longitude are drawn from the North Pole to the South Pole and are at right angles to the Equator. The “Prime Meridian” which passes through Greenwich, England, is used as the zero line from which measurements are made in degrees east and west to 180°. The 48 conterminous states of the United States are between 67° and 125° W. Longitude. The arrows in figure 14-2 labeled “LONGITUDE” point to lines of longitude.
Any specific geographical point can thus be located by reference to its longitude and latitude. Washington, DC for example, is approximately 39° N. latitude, 77° W. longitude. Chicago is approximately 42° N. latitude, 88° W. longitude.
TIME ZONES The meridians are also useful for designating time zones. A day is defined as the time required for the Earth to make one complete rotation of 360°. Since the day is divided into 24 hours, the Earth revolves at the rate of 15° an hour. Noon is the time when the Sun is directly above a meridian; to the west of that meridian is morning, to the east is afternoon.
The standard practice is to establish a time zone for each 15° of longitude. This makes a difference of exactly 1 hour between each zone. In the United States, there are four time zones. The time zones are Eastern (75°), Central (90°), Mountain (105°), and Pacific Figure 14-1. Sectional chart legend. (120°). The dividing lines are somewhat irregular
E Q U A T O R
L o n g i t u de
Latitude
135° W120° W (^) 105° W (^) 90° W
75° W 60° W
45° W
15° W
15° E
30° W
PR IM E M ER ID IA N
90°N 75°N
60°N
45°N
15°N
15°S 30°S
30°N
Figure 14-2. Meridians and parallels—the basis of measuring time, distance, and direction.
As shown in figure 14-5, the direction from A to B would be a true course of 065°, whereas the return trip (called the reciprocal) would be a true course of 245°.
The true heading is the direction in which the nose of the airplane points during a flight when measured in degrees clockwise from true north. Usually, it is neces- sary to head the airplane in a direction slightly different from the true course to offset the effect of wind. Consequently, numerical value of the true heading may not correspond with that of the true course. This will be discussed more fully in subsequent sections in this chapter. For the purpose of this discussion, assume a no-wind condition exists under which heading and course would coincide. Thus, for a true course of 065°, the true heading would be 065°. To use the compass accurately, however, corrections must be made for magnetic variation and compass deviation.
VARIATION Variation is the angle between true north and magnetic north. It is expressed as east variation or west variation depending upon whether magnetic north (MN) is to the east or west of true north (TN).
The north magnetic pole is located close to 71° N. lati- tude, 96° W. longitude and is about 1,300 miles from the geographic or true north pole, as indicated in figure 14-6. If the Earth were uniformly magnetized, the com- pass needle would point toward the magnetic pole, in which case the variation between true north (as shown by the geographical meridians) and magnetic north (as shown by the magnetic meridians) could be measured at any intersection of the meridians.
Actually, the Earth is not uniformly magnetized. In the United States, the needle usually points in the general direction of the magnetic pole, but it may vary in certain geographical localities by many degrees. Consequently, the exact amount of variation at thousands of selected locations in the United States has been carefully deter- mined. The amount and the direction of variation, which change slightly from time to time, are shown on most aeronautical charts as broken magenta lines, called iso- gonic lines, which connect points of equal magnetic
variation. (The line connecting points at which there is no variation between true north and magnetic north is the agonic line.) An isogonic chart is shown in figure 14-6. Minor bends and turns in the isogonic and agonic lines are caused by unusual geological conditions affecting magnetic forces in these areas.
On the west coast of the United States, the compass needle points to the east of true north; on the east coast, the compass needle points to the west of true north. Zero degree variation exists on the agonic line, where magnetic north and true north coincide. This line runs roughly west of the Great Lakes, south through Wisconsin, Illinois, western Tennessee, and along the border of Mississippi and Alabama. [Compare figures 14-7 and 14-8.]
Because courses are measured in reference to geograph- ical meridians which point toward true north, and these courses are maintained by reference to the compass which points along a magnetic meridian in the general direction of magnetic north, the true direction must be converted into magnetic direction for the purpose of flight. This conversion is made by adding or subtracting the variation which is indicated by the nearest isogonic line on the chart. The true heading, when corrected for variation, is known as magnetic heading.
If the variation is shown as “9°E,” this means that mag- netic north is 9° east of true north. If a true heading of 360° is to be flown, 9° must be subtracted from 360°, which results in a magnetic heading of 351°. To fly
A x
x B
Course A to B 065°
Course B to A 245°
065°
245°
Figure 14-5. Courses are determined by reference to meridi- ans on aeronautical charts.
TN
MN
Figure 14-6. Isogonic chart. Magnetic meridians are in black; geographic meridians and parallels are in blue. Variation is the angle between a magnetic and geographic meridian.
east, a magnetic heading of 081° (090° – 9°) would be flown. To fly south, the magnetic heading would be 171° (180° – 9°). To fly west, it would be 261° (270° – 9°). To fly a true heading of 060°, a magnetic heading of 051° (060° – 9°) would be flown.
Remember, to convert true course or heading to mag- netic course or heading, note the variation shown by the nearest isogonic line. If variation is west, add; if east, subtract. One method for remembering whether to add or subtract variation is the phrase “east is least (subtract) and west is best (add).”
DEVIATION Determining the magnetic heading is an intermediate step necessary to obtain the correct compass heading for the flight. To determine compass heading, a correc- tion for deviation must be made. Because of magnetic influences within the airplane such as electrical cir- cuits, radio, lights, tools, engine, and magnetized metal parts, the compass needle is frequently deflected from its normal reading. This deflection is deviation. The deviation is different for each airplane, and it also may vary for different headings in the same airplane. For
instance, if magnetism in the engine attracts the north end of the compass, there would be no effect when the plane is on a heading of magnetic north. On easterly or westerly headings, however, the compass indications would be in error, as shown in figure 14-9. Magnetic attraction can come from many other parts of the air- plane; the assumption of attraction in the engine is merely used for the purpose of illustration.
Some adjustment of the compass, referred to as com- pensation, can be made to reduce this error, but the remaining correction must be applied by the pilot.
Proper compensation of the compass is best performed by a competent technician. Since the magnetic forces within the airplane change, because of landing shocks, vibration, mechanical work, or changes in equipment, the pilot should occasionally have the deviation of the compass checked. The procedure used to check the deviation (called “swinging the compass”) is briefly outlined.
The airplane is placed on a magnetic compass rose, the engine started, and electrical devices normally used (such as radio) are turned on. Tailwheel-type airplanes should be jacked up into flying position. The airplane is aligned with magnetic north indicated on the compass
EASTERLY VARIATION WESTERLY VARIATION 0°
0° 5°
5° 5°
5°
10°
10° 10°
10°
15°
15° 15°
15°
20°
20° 20° 20°
Agonic Line
Figure 14-7. A typical isogonic chart. The black lines are iso- gonic lines which connect geographic points with identical magnetic variation.
West Var
Variation iation
East
Zero Variation
NP MP
SP SP SP
MP MP
NP NP
Compass needle pointing east of true north Compass needle pointing to true north (along agonic line)
Compass needle pointing west of true north
Figure 14-8. Effect of variation on the compass.
Magnetic North Magnetic North
Magnetic North
Compass Deflection Deviation
Compass Deflection Deviation
Magnetized Engine Magnetized Compass Engine
No Deviation
Figure 14-9. Magnetized portions of the airplane cause the compass to deviate from its normal indications.
Assuming no correction is made for wind effect, if the airplane is heading eastward at 120 knots, and the air mass moving southward at 20 knots, the airplane at the end of 1 hour will be almost 120 miles east of its point of departure because of its progress through the air. It will be 20 miles south because of the motion of the air. Under these circumstances, the airspeed remains 120 knots, but the groundspeed is determined by combining the movement of the airplane with that of the air mass. Groundspeed can be measured as the distance from the point of departure to the position of the airplane at the end of 1 hour. The groundspeed can be computed by the time required to fly between two points a known distance apart. It also can be deter- mined before flight by constructing a wind triangle, which will be explained later in this chapter. [Figure 14-13]
The direction in which the plane is pointing as it flies is heading. Its actual path over the ground, which is a combination of the motion of the airplane and the motion of the air, is track. The angle between the head- ing and the track is drift angle. If the airplane’s heading coincides with the true course and the wind is blowing from the left, the track will not coincide with the true course. The wind will drift the airplane to the right, so the track will fall to the right of the desired course or true course. [Figure 14-14]
By determining the amount of drift, the pilot can counteract the effect of the wind and make the track of the airplane coincide with the desired course. If the mass of air is moving across the course from the left, the airplane will drift to the right, and a correction must be made by heading the airplane sufficiently to the left to offset this drift. To state in another way, if the wind is from the left, the correction will be made by pointing the airplane to the left a certain number of degrees, therefore correcting for wind drift. This is wind correction angle and is expressed in terms of degrees right or left of the true course. [Figure 14-15]
To summarize:
- COURSE— is the intended path of an airplane over the ground; or the direction of a line drawn on a chart representing the intended airplane path, expressed as the angle measured from a specific reference datum clockwise from 0° through 360° to the line.
GROUNDSPEED 120 KTS
GROUNDSPEED 100 KTS
AIRSPEED 120 KTS
AIR NOT MOVING
GROUNDSPEED 140 KTS
AIR MOVING AIRSPEED 20 KNOTS
120 KTS
AIRSPEED 120 KTS
AIR MOVING 20 KNOTS
Figure 14-12. Motion of the air affects the speed with which airplanes move over the Earth’s surface. Airspeed, the rate at which an airplane moves through the air, is not affected by air motion.
Distance Covered Over Ground (1 Hour)
Airspeed Effect (1 Hour) 20 Knots
Figure 14-13. Airplane flightpath resulting from its airspeed and direction, and the windspeed and direction.
Heading
Track
Desired Course
Wind
Drift Angle
Figure 14-14. Effects of wind drift on maintaining desired course.
Heading
Track Desired Course
Wind
Wind Correction Angle
Figure 14-15. Establishing a wind correction angle that will counteract wind drift and maintain the desired course.
- HEADING— is the direction in which the nose of the airplane points during flight.
- TRACK— is the actual path made over the ground in flight. (If proper correction has been made for the wind, track and course will be iden- tical.)
- DRIFT ANGLE— is the angle between heading and track.
- WIND CORRECTION ANGLE— is correction applied to the course to establish a heading so that track will coincide with course.
- AIRSPEED— is the rate of the airplane’s progress through the air.
- GROUNDSPEED— is the rate of the airplane’s in-flight progress over the ground.
BASIC CALCULATIONS
Before a cross-country flight, a pilot should make com- mon calculations for time, speed, and distance, and the amount of fuel required.
CONVERTING MINUTES TO EQUIVALENT HOURS It frequently is necessary to convert minutes into equiv- alent hours when solving speed, time, and distance problems. To convert minutes to hours, divide by 60 (60 minutes = 1 hour). Thus, 30 minutes 30/60 = 0. hour. To convert hours to minutes, multiply by 60. Thus, 0.75 hour equals 0.75 x 60 = 45 minutes.
Time T = D/GS To find the time (T) in flight, divide the distance (D) by the groundspeed (GS). The time to fly 210 nautical miles at a groundspeed of 140 knots is 210 divided by 140, or 1.5 hours. (The 0.5 hour multiplied by 60 min- utes equals 30 minutes.) Answer: 1:30.
Distance D = GS X T To find the distance flown in a given time, multiply groundspeed by time. The distance flown in 1 hour 45 minutes at a groundspeed of 120 knots is 120 x 1.75, or 210 nautical miles.
Groundspeed GS = D/T To find the groundspeed, divide the distance flown by the time required. If an airplane flies 270 nautical miles in 3 hours, the groundspeed is 270 divided by 3 = 90 knots.
CONVERTING KNOTS TO MILES PER HOUR Another conversion is that of changing knots to miles per hour. The aviation industry is using knots more frequently than miles per hour, but it might be well to
discuss the conversion for those who do use miles per hour when working with speed problems. The National Weather Service reports both surface winds and winds aloft in knots. However, airspeed indica- tors in some airplanes are calibrated in miles per hour (although many are now calibrated in both miles per hour and knots). Pilots, therefore, should learn to convert windspeeds in knots to miles per hour.
A knot is 1 nautical mile per hour. Because there are 6,076.1 feet in a nautical mile and 5,280 feet in a statute mile, the conversion factor is 1.15. To convert knots to miles per hour, multiply knots by 1.15. For example: a windspeed of 20 knots is equivalent to 23 miles per hour.
Most flight computers or electronic calculators have a means of making this conversion. Another quick method of conversion is to use the scales of nautical miles and statute miles at the bottom of aeronautical charts.
FUEL CONSUMPTION
Airplane fuel consumption is computed in gallons per hour. Consequently, to determine the fuel required for a given flight, the time required for the flight must be known. Time in flight multiplied by rate of consump- tion gives the quantity of fuel required. For example, a flight of 400 NM at a groundspeed of 100 knots requires 4 hours. If the plane consumes 5 gallons an hour, the total consumption will be 4 x 5, or 20 gallons.
The rate of fuel consumption depends on many factors: condition of the engine, propeller pitch, propeller r.p.m., richness of the mixture, and particularly the per- centage of horsepower used for flight at cruising speed. The pilot should know the approximate consumption rate from cruise performance charts, or from experi- ence. In addition to the amount of fuel required for the flight, there should be sufficient fuel for reserve.
FLIGHT COMPUTERS
Up to this point, only mathematical formulas have been used to determine such items as time, distance, speed, and fuel consumption. In reality, most pilots will use a mechanical or electronic flight computer. These devices can compute numerous problems associated with flight planning and navigation. The mechanical or electronic computer will have an instruction book and most likely sample problems so the pilot can become familiar with its functions and operation. [Figure 14-16]
PLOTTER
Another aid in flight planning is a plotter, which is a protractor and ruler. The pilot can use this when determining true course and measuring distance. Most plotters have a ruler which measures in both
nautical and statute miles and has a scale for a sec- tional chart on one side and a world aeronautical chart on the other. [Figure 14-16]
PILOTAGE
Pilotage is navigation by reference to landmarks or checkpoints. It is a method of navigation that can be used on any course that has adequate checkpoints, but it is more commonly used in conjunction with dead reckoning and VFR radio navigation.
The checkpoints selected should be prominent features common to the area of the flight. Choose checkpoints that can be readily identified by other features such as roads, rivers, railroad tracks, lakes, and power lines. If possible, select features that will make useful bound- aries or brackets on each side of the course, such as highways, rivers, railroads, and mountains. A pilot can keep from drifting too far off course by referring to and not crossing the selected brackets. Never place com- plete reliance on any single checkpoint. Choose ample checkpoints. If one is missed, look for the next one while maintaining the heading. When determining position from checkpoints, remember that the scale of a sectional chart is 1 inch = 8 statute miles or 6.86 nauti- cal miles. For example, if a checkpoint selected was approximately one-half inch from the course line on the chart, it is 4 statue miles or 3.43 nautical miles from the course on the ground. In the more congested areas, some of the smaller features are not included on the chart. If confused, hold the heading. If a turn is made away from the heading, it will be easy to become lost.
Roads shown on the chart are primarily the well-trav- eled roads or those most apparent when viewed from the air. New roads and structures are constantly being built, and may not be shown on the chart until the next chart is issued. Some structures, such as antennas may be difficult to see. Sometimes TV antennas are grouped together in an area near a town. They are supported by almost invisible guy wires. Never approach an area of antennas less than 500 feet above the tallest one. Most of the taller structures are marked with strobe lights to make them more visible to a pilot. However, some weather conditions or background lighting may make them difficult to see. Aeronautical charts display the best information available at the time of printing, but a pilot should be cautious for new structures or changes that have occurred since the chart was printed.
DEAD RECKONING
Dead reckoning is navigation solely by means of computations based on time, airspeed, distance, and direction. The products derived from these variables, when adjusted by windspeed and velocity, are head- ing and groundspeed. The predicted heading will guide the airplane along the intended path and the
groundspeed will establish the time to arrive at each checkpoint and the destination. Except for flights over water, dead reckoning is usually used with pilotage for cross-country flying. The heading and groundspeed as calculated is constantly monitored and corrected by pilotage as observed from check- points.
THE WIND TRIANGLE OR
VECTOR ANALYSIS
If there is no wind, the airplane’s ground track will be the same as the heading and the groundspeed will be the same as the true airspeed. This condition rarely exists. A wind triangle, the pilot’s version of vector analysis, is the basis of dead reckoning.
The wind triangle is a graphic explanation of the effect of wind upon flight. Groundspeed, heading, and time for any flight can be determined by using the wind triangle. It can be applied to the simplest kind of cross-country flight as well as the most complicated instrument flight. The experienced pilot becomes so familiar with the fundamental principles that esti- mates can be made which are adequate for visual flight without actually drawing the diagrams. The beginning student, however, needs to develop skill in constructing these diagrams as an aid to the complete understanding of wind effect. Either consciously or unconsciously, every good pilot thinks of the flight in terms of wind triangle.
If a flight is to be made on a course to the east, with a wind blowing from northeast, the airplane must be headed somewhat to the north of east to counteract drift. This can be represented by a diagram as shown in figure 14-17. Each line represents direction and speed. The long dotted line shows the direction the plane is heading, and its length represents the airspeed for 1 hour. The short dotted line at the right shows the wind direction, and its length represents the wind velocity
N
S
Wind Direction and Velocity
Heading and Airspeed
Course and Groundspeed
Figure 14-17. Principle of the wind triangle.
for 1 hour. The solid line shows the direction of the track, or the path of the airplane as measured over the Earth, and its length represents the distance traveled in 1 hour, or the groundspeed.
In actual practice, the triangle illustrated in figure 14- is not drawn; instead, construct a similar triangle as shown by the black lines in figure 14-18, which is explained in the following example.
Suppose a flight is to be flown from E to P. Draw a line on the aeronautical chart connecting these two points; measure its direction with a protractor, or plotter, in ref- erence to a meridian. This is the true course, which in this example is assumed to be 090° (east). From the National Weather Service, it is learned that the wind at the altitude of the intended flight is 40 knots from the northeast (045°). Since the National Weather Service reports the windspeed in knots, if the true airspeed of the airplane is 120 knots, there is no need to convert speeds from knots to miles per hour or vice versa.
Now on a plain sheet of paper draw a vertical line rep- resenting north and south. (The various steps are shown in figure 14-19.)
Place the protractor with the base resting on the verti- cal line and the curved edge facing east. At the center point of the base, make a dot labeled “E” (point of departure), and at the curved edge, make a dot at 90° (indicating the direction of the true course) and another at 45° (indicating wind direction).
With the ruler, draw the true course line from E, extending it somewhat beyond the dot by 90°, and labeling it “TC 090°.”
Next, align the ruler with E and the dot at 45°, and draw the wind arrow from E, not toward 045°, but downwind in the direction the wind is blowing, making it 40 units long, to correspond with the wind velocity of 40 knots. Identify this line as the wind line by placing the letter “W” at the end to show the wind direction. Finally, measure 120 units on the ruler to represent the airspeed, making a dot on the ruler at this point. The units used may be of any convenient scale or value (such as 1 / 4 inch = 10 knots), but once selected, the same scale must be used for each of the linear movements involved. Then place the ruler so that the end is on the arrowhead (W) and the 120-knot dot intercepts the true course line. Draw the line and label it “AS 120.” The point “P” placed at the intersection represents the position of the airplane at the end of 1 hour. The diagram is now com- plete.
The distance flown in 1 hour (groundspeed) is meas- ured as the numbers of units on the true course line ( nautical miles per hour or 88 knots).
The true heading necessary to offset drift is indicated by the direction of the airspeed line, which can be determined in one of two ways:
- By placing the straight side of the protractor along the north-south line, with its center point at
Wind Direction and Velocity Heading and Airspeed
N
S
E P
W
Course and Groundspeed
Figure 14-18. The wind triangle as is drawn in navigation practice. Dashed lines show the triangle as drawn in figure 14-17.
N
S
N
S
N
S
E
E
W
W
TC 090°
TC 090° GS 88
Wind Step 2 and 3
90°
45°
Step 1
Step 4
Mid Point
AS 120
P
Figure 14-19. Steps in drawing the wind triangle.
FLIGHT PLANNING
Title 14 of the Code of Federal Regulations (14 CFR) part 91 states, in part, that before beginning a flight, the pilot in command of an aircraft shall become familiar with all available information concerning that flight. For flights not in the vicinity of an airport, this must include information on available current weather reports and forecasts, fuel requirements, alternatives available if the planned flight cannot be completed, and any known traffic delays of which the pilot in command has been advised by air traffic control (ATC).
ASSEMBLING NECESSARY MATERIAL
The pilot should collect the necessary material well before the flight. An appropriate current sectional chart and charts for areas adjoining the flight route should be among this material if the route of flight is near the bor- der of a chart.
Additional equipment should include a flight computer or electronic calculator, plotter, and any other item appropriate to the particular flight—for example, if a night flight is to be undertaken, carry a flashlight; if a flight is over desert country, carry a supply of water and other necessities.
WEATHER CHECK
It may be wise to check the weather before continuing with other aspects of flight planning to see, first of all, if the flight is feasible and, if it is, which route is best. Chapter 11 on weather discusses obtaining a weather briefing.
USE OF THE AIRPORT/FACILITY DIRECTORY Study available information about each airport at which a landing is intended. This should include a study of the Notices to Airmen (NOTAMs) and the Airport/Facility Directory. [Figure 14-22] This includes location, elevation, runway and lighting facilities, available services, availability of aeronau- tical advisory station frequency (UNICOM), types of fuel available (use to decide on refueling stops), AFSS/FSS located on the airport, control tower and ground control frequencies, traffic information, remarks, and other pertinent information. The NOTAMs, issued every 28 days, should be checked for additional information on hazardous conditions or changes that have been made since issuance of the Airport/Facility Directory.
The sectional chart bulletin subsection should be checked for major changes that have occurred since the last publication date of each sectional chart being used. Remember, the chart may be up to 6 months old. The effective date of the chart appears at the top of the front of the chart.
The Airport/Facility Directory will generally have the latest information pertaining to such matters and should be used in preference to the information on the back of the chart, if there are differences.
AIRPLANE FLIGHT MANUAL OR PILOT’S
OPERATING HANDBOOK
The Airplane Flight Manual or Pilot’s Operating Handbook (AFM/POH) should be checked to determine the proper loading of the airplane (weight and balance data). The weight of the usable fuel and drainable oil aboard must be known. Also, check the weight of the passengers, the weight of all baggage to be carried, and the empty weight of the airplane to be sure that the total weight does not exceed the maximum allowable. The distribution of the load must be known to tell if the resulting center of gravity is within limits. Be sure to use the latest weight and balance information in the FAA-approved Airplane Flight Manual or other perma- nent airplane records, as appropriate, to obtain empty weight and empty weight center-of-gravity information.
Determine the takeoff and landing distances from the appropriate charts, based on the calculated load, ele- vation of the airport, and temperature; then compare these distances with the amount of runway available. Remember, the heavier the load and the higher the
Figure 14-22. Airport Facility Directory.
elevation, temperature, or humidity, the longer the takeoff roll and landing roll and the lower the rate of climb.
Check the fuel consumption charts to determine the rate of fuel consumption at the estimated flight altitude and power settings. Calculate the rate of fuel consump- tion, and then compare it with the estimated time for the flight so that refueling points along the route can be included in the plan.
CHARTING THE COURSE
Once the weather has been checked and some prelimi- nary planning done, it is time to chart the course and determine the data needed to accomplish the flight. The following sections will provide a logical sequence to follow in charting the course, filling out a flight log, and filing a flight plan. In the following example, a trip is planned based on the following data and the sectional chart excerpt in figure 14-23.
Route of flight: Chickasha Airport direct to Guthrie Airport True Airspeed (TAS)...............................115 knots Winds Aloft.....................................360° at 10 knots Usable fuel...........................................38 gallons Fuel Rate....................................................8 GPH Deviation.............................................................+2°
STEPS IN CHARTING THE COURSE The following is a suggested sequence for arriving at the pertinent information for the trip. As information is determined, it may be noted as illustrated in the exam- ple of a flight log in figure 14-24. Where calculations are required, the pilot may use a mathematical formula or a manual or electronic flight computer. If unfamiliar with how to use a manual or electronic computer com- petently, it would be advantageous to read the opera- tion manual and work several practice problems at this point.
First draw a line from Chickasha Airport (point A) directly to Guthrie Airport (point F). The course line should begin at the center of the airport of departure and end at the center of the destination airport. If the route is direct, the course line will consist of a single straight line. If the route is not direct, it will consist of two or more straight line segments—for example, a VOR station which is off the direct route, but which will make navigating easier, may be chosen (radio nav- igation is discussed later in this chapter).
Appropriate checkpoints should be selected along the route and noted in some way. These should be easy-to- locate points such as large towns, large lakes and rivers, or combinations of recognizable points such as towns with an airport, towns with a network of highways, and railroads entering and departing. Normally, choose only towns indicated by splashes of yellow on the
chart. Do not choose towns represented by a small cir- cle—these may turn out to be only a half-dozen houses. (In isolated areas, however, towns represented by a small circle can be prominent checkpoints.) For this trip, four checkpoints have been selected. Checkpoint 1 consists of a tower located east of the course and can be further identified by the highway and railroad track, which almost parallels the course at this point. Checkpoint 2 is the obstruction just to the west of the course and can be further identified by Will Rogers Airport which is directly to the east. Checkpoint 3 is Wiley Post Airport, which the airplane should fly directly over. Checkpoint 4 is a private non-surfaced airport to the west of the course and can be further iden- tified by the railroad track and highway to the east of the course.
The course and areas on either side of the planned route should be checked to determine if there is any type of airspace with which the pilot should be concerned or which has special operational requirements. For this trip, it should be noted that the course will pass through a segment of the Class C airspace surrounding Will Rogers Airport where the floor of the airspace is 2, feet mean sea level (MSL) and the ceiling is 5,300 feet MSL (point B). Also, there is Class D airspace from the surface to 3,800 feet MSL surrounding Wiley Post Airport (point C) during the time the control tower is in operation.
Study the terrain and obstructions along the route. This is necessary to determine the highest and lowest elevations as well as the highest obstruction to be encountered so that an appropriate altitude which will conform to part 91 regulations can be selected. If the flight is to be flown at an altitude more than 3,000 feet above the terrain, conformance to the cruising altitude appropriate to the direction of flight is required. Check the route for particularly rugged terrain so it can be avoided. Areas where a takeoff or landing will be made should be carefully checked for tall obstruc- tions. TV transmitting towers may extend to altitudes over 1,500 feet above the surrounding terrain. It is essential that pilots be aware of their presence and location. For this trip, it should be noted that the tallest obstruction is part of a series of antennas with a height of 2,749 feet MSL (point D). The highest ele- vation should be located in the northeast quadrant and is 2,900 feet MSL (point E).
Since the wind is no factor and it is desirable and within the airplane’s capability to fly above the Class C and D airspace to be encountered, an altitude of 5,500 feet MSL will be chosen. This altitude also gives adequate clearance of all obstructions as well as conforms to the part 91 requirement to fly at an altitude of odd thou- sand plus 500 feet when on a magnetic course between 0 and 179°.
