Air Traffic Control System Structure PDF

Air Traffic Control System Structure / 139 Airspace Classification The airspace above the United States has been categorized by the FAA into dif- ferent classes, with specific requirements and different operating rules for each. The intent of the classi...

Air Traffic Control System Structure / 139 Airspace Classification The airspace above the United States has been categorized by the FAA into dif- ferent classes, with specific requirements and different operating rules for each. The intent of the classification scheme is to provide maximum pilot flexibility with acceptable levels of risk appropriate to the type of operation and traffic density within that class of airspace. Different airspace classifications and rules permit the FAA and other national agencies to provide varying levels of security and control. In general, the classification scheme is designed to provide maximum sep- aration and active control in areas of dense or high-speed flight operations. In areas of light traffic, if acceptable weather conditions exist, pilots can provide much of the needed traffic separation themselves. General The airspace classification scheme essentially provides four general categories Categories of airspace. of Airspace The first category is one in which ATC separates all aircraft, whether IFR or VFR, known as positive controlled airspace (PCA). The second category is airspace in which ATC separates IFR aircraft but, weather permitting, VFR pilots provide their own separation, generally known as controlled airspace. The third category is airspace within which the pilots provide all separation, known as uncontrolled airspace. The fourth and final category is airspace within which there are special operating restrictions and rules; known as special use airspace. Positive Controlled Airspace Within positive controlled airspace, the FAA either absolutely prohibits VFR flight operations, or if permitted, separates both VFR and IFR aircraft. PCA is reserved for either very high-altitude flights at or above 18,000 feet mean sea level (MSL) or around high-density airports. Controlled Airspace Within airspace generally designated as controlled air- space, which is most but not all of the airspace overlying the continental United States, ATC separation services are provided to IFR aircraft by the FAA. IFR aircraft are authorized to fly into clouds or areas of reduced visibility and are provided ATC assistance to remain separated from other IFR aircraft. IFR aircraft, when operating in areas where weather conditions and traffic density permit other aircraft to be safely observed and avoided, are still responsible for separating themselves from VFR aircraft. VFR aircraft operating in controlled airspace are also responsible for separating themselves from all other aircraft. VFR flight operations are permitted so long as the weather conditions are suf- ficient to enable pilots to “see and avoid” other aircraft. 140 / CHAPTER 3 Uncontrolled Airspace In uncontrolled airspace, ATC separation services are not provided by the FAA. Whether IFR or VFR, all aircraft must provide their own separation, regardless of the weather conditions. Special Use Airspace Special use airspace has been designated by the FAA as airspace where activities that must be confined to specific areas are conducted or where restrictions must be imposed on nonparticipating aircraft. Some spe- cial use airspace, such as prohibited and restricted areas, are regulatory special use airspace and are established and described in FAR Part 73. Other areas, such as warning, military operations, alert, and controlled firing areas, are nonregulatory special use airspace that has been described in FAA Order 7400.8, Special Use Airspace. Special use airspace can lie within either controlled or uncontrolled airspace and can potentially affect both IFR and VFR aircraft. Controlled One of the primary differences between airspace types is that air traffic control versus separation services can be offered only to pilots operating in controlled air- Uncontrolled space. Additional services, such as traffic advisories and safety alerts, can be Airspace offered to aircraft flying in uncontrolled airspace but only on a workload per- mitting basis. Early in this century, most of the airspace above the United States was designated as uncontrolled. Only the federal airways and the airspace around very busy airports were controlled. But as air traffic increased, and the technical air traffic control capabilities of the federal government improved, additional segments of the nation’s airspace have been designated as controlled airspace. The only uncontrolled airspace left in the domestic United States exists below 1,200 feet above ground level (AGL) away from busy airports. Various names for these airspace categories and the rules for operation within each area have evolved as they were created. In time, due to the unique development of ATC within the United States, the names and rules of operation within each area became inconsistent with ICAO standards in use throughout the rest of the world. By 1992, the FAA identified and created operational rules for close to twenty different categories of airspace. Airspace In 1982, in an effort to standardize and simplify U.S. airspace, the FAA and Review representative industry groups formed the National Airspace Review (NAR) committee to begin a comprehensive review of the nation’s airspace system. In conjunction with an ICAO review commission, the NAR committee recom- mended that airspace over the United States be reclassified into one of six classes. These recommendations were accepted by the FAA, and implementa- tion began in 1993. These categories of airspace are known as Class A, B, C, D, E, and G airspace. Class F airspace exists as an ICAO classification, with no equivalent existing in the United States. As currently defined, Class A, B, C, D, and E airspace is generally a form of controlled airspace. Class G airspace is designated as uncontrolled. In general,  Air Traffic Control System Structure / 141 Figure 3–1. Sample flight plan form. Class A airspace is the most restrictive, where ATC provides maximum services and separation. Class G airspace, on the other hand, is the least restrictive, and few ATC services are provided. Class B, C, D, and E airspace spans the range of services. Special use airspace as defined by the FAA does not follow specific ICAO as such and is peculiar to U.S. airspace. IFR Flight in Within controlled airspace, air traffic controllers are required to separate IFR Controlled aircraft and participating VFR aircraft using the procedures specified in the Air Airspace Traffic Control Handbook. (These procedures are discussed in detail in (Class A, B, C, Chapters 7 and 9.) Since VFR aircraft may be permitted to operate in areas of D, and E) controlled airspace (sometime without contacting ATC), it remains the respon- sibility of IFR pilots to see and avoid these aircraft, regardless of the services being provided by the air traffic controller. Before beginning an IFR flight in controlled airspace, the pilot is required to file a flight plan (see Figure 3–1) with the FAA and receive a clearance from an ATC facility. A general aviation or corporate pilot usually files the IFR flight plan with a flight service station specialist, using the Internet or tele- phone, and the information is then forwarded to the air route traffic control center (ARTCC) with jurisdiction over the departure airport. Airline flight plans are typically filed directly with the FAA using stored flight plan infor- mation. If a pilot needs to file a flight plan while airborne, the ATC facility in contact with the pilot transmits the flight plan information to the proper ATC facility. 142 / CHAPTER 3 The information required on a flight plan includes the following: 1. Type of flight plan. This will be VFR, IFR, or DVFR (which is a special type of VFR flight plan used if an aircraft is entering, leaving, or transiting U.S. airspace). 2. Aircraft identification number. This is either the aircraft’s assigned serial number, if it is a general aviation or corporate flight, or the airline call sign and flight number. 3. Aircraft type and navigation equipment installed on the aircraft. The aircraft type is abbreviated, using the codes found in the Air Traffic Control Handbook. An expanded list is included in the Appendix to this book. Examples of these abbreviations include the following: Aircraft FAA Identifier Airbus A-380-800 A388 Beech 200 King Air BE20 Boeing 737-900 B739 Cessna Citation 650 C650 Cirrus SR-22 SR22 Diamond DA-42 DA42 Embraer EMB-190 E190 Gates Learjet 55 LJ55 General Dynamics F16 Falcon F16 Piper PA-28 Warrior P28A The pilot must also identify the navigational capabilities of the aircraft by appending a unique suffix code to the aircraft type. The equipment codes are found in the handbook. The aircraft type is separated from the equipment code with a slash. The equipment codes are as follows: Suffix Equipment Capability NO DME /X No transponder /T Transponder with no Mode C /U Transponder with Mode C DME /D No transponder /B Transponder with no Mode C /A Transponder with Mode C TACAN ONLY /M No transponder /N Transponder with no Mode C /P Transponder with Mode C  Air Traffic Control System Structure / 143 Suffix Equipment Capability AREA NAVIGATION (RNAV) /Y LORAN, VOR/DME, or INS with no transponder /C LORAN, VOR/DME, or INS, transponder with no Mode C /I LORAN, VOR/DME, or INS, transponder with Mode C ADVANCED RNAV WITH TRANSPONDER AND MODE C /E Flight Management System (FMS) with DME/DME and IRU position updating /F FMS with DME/DME position updating /G Global Navigation Satellite System (GNSS), including GPS or Wide Area Augmentation System (WAAS), with enroute and terminal capability /R Required Navigational Performance (RNP). The aircraft meets the RNP type prescribed for the route segment(s), route(s), and/or area concerned REDUCED VERTICAL SEPARATION MINIMUM (RVSM) /J /E with RVSM /K /F with RVSM /L /G with RVSM /Q /R with RVSM /W RVSM 4. The aircraft’s cruising true airspeed in knots. 5. The abbreviation for the departure point. This is normally the departure airport but can be an en route fix. 6. The proposed time of departure. 7. The pilot’s requested cruising altitude. 8. The requested route of flight. This must include the airway and navigation aid identifiers. The entire route of flight must be specified. When changing from one airway to another, the intersection fix must be specified. If no airway is being used, only the navaids need to be specified. For example, the route ALB J37 BUMPY J14 BHM would be interpreted as departing Albany, New York, flying via Jet Route 37 until reaching the BUMPY intersection, transitioning to Jet Route 14 at BUMPY intersection, then flying via Jet Route 14 to the destination which is Birmingham, Alabama. The route ALB BHM would be interpreted as departing Albany and flying in a straight line (direct) to the destination airport at Birmingham. 9. The destination airport. 144 / CHAPTER 3 10. The estimated time en route in hours and minutes. 11. Any pertinent remarks. 12. Fuel on board the aircraft expressed in hours and minutes. 13. The pilots selected alternate airport if on an IFR flight plan and if required by the appropriate FARs. 14. Name and address of the pilot in command. 15. Number of people on board. 16. Color of the aircraft. 17. Contact information at destination airport. Air Traffic The flight plan is then filed and processed by the FAA. A VFR flight plan is kept Control as a record for possible search and rescue if the aircraft is reported lost or over- Clearance due. An IFR flight plan is processed and an air traffic clearance is generated. Pilots operating IFR in the air traffic control system must then be issued a clear- ance by ATC prior to beginning their flight. This clearance must include the fol- lowing information and should be communicated to the pilot in this sequence: 1. Aircraft identification. Sample phraseology: “Cherokee five one four papa uniform,” “United seven thirty-one,” “JetBlue fifteen forty-three.” 2. Clearance limit. This is the farthest location to which the aircraft is cleared to fly. Although the clearance limit is typically the destination airport, it may be an intermediate navigation aid or intersection located along the route of flight. If the clearance limit is not the destination airport and the pilot does not receive an additional clearance before reaching the clearance limit, the aircraft will enter a holding pattern at that point. (“Cleared to the Lafayette Purdue University Airport,” “Cleared to the Boiler VOR,” “Cleared to the Staks intersection.”) 3. Departure procedure. If the assigned route of flight does not begin at the departure airport, it is necessary for the controller to assign a departure procedure (DP) so that the aircraft can intercept the route of flight. Departure procedures may also be used to ensure that the aircraft avoids areas of obstructions or high-density traffic. Departure procedures direct the pilot to turn or fly a particular heading or route. If a particular departure instruction is routinely issued to most of the departing aircraft, it may be incorporated into and published as a charted DP (see Figures 3–2 and 3–3). DPs are constructed by the FAA and are published and sold by the same agencies that publish instrument approach charts. Routine use of DPs relieves controllers from repeating the same departure clearance to every aircraft. If a DP is to be used in a departure clearance, the controller assigns the DP procedure by simply including its name in the clearance. (“After departure, turn left heading three five zero,” “After departure, fly runway heading,” “O’Hare one departure.”) 4. Route of flight. The route of flight issued includes any airways or VOR radials that the pilot will use when navigating to the clearance limit (“Via victor two fifty- one,” “Via direct Danville,” “Via the Boiler one eight five radial and the Danville zero niner radial.”). The route of flight must include at least two fixes (departure and arrival airports) and the route to be flown between each fix. Intermediate fixes along the route to be flown are not routinely included as part of the clearance. The only time an intermediate fix is included in a clearance is when the fix defines a transition from one route to another (see Figure 3–4).  Air Traffic Control System Structure / 145 Figure 3–2. Standard departure procedure (vector) for Atlanta Airport. 146 / CHAPTER 3 Figure 3–3. Departure procedure (pilot navigation) for Alton, Illinois.  Air Traffic Control System Structure / 147 B OIL E R 11 5. 1 B V T 98 13 5 186 158 Z O F RI BV B V T V7 P BV T T V9 V3 7 99 V3 ZI POTES 99 PP VH Y OTES P VH V2 O CKEL P0 4- 17 12 8 VH P V1 V9 28 JA K K S 7 VH P V2 4- 12 8- 39 9 V7 J E LLS ZIP P Y A D VAY 017 31 1 RD B R IC K Y A P 11 0 11 6.3 V H Figure 3–4. Sample route of flight. 148 / CHAPTER 3 5. Altitude assignment. The controller should attempt to issue the pilot an altitude that conforms to the procedures contained in the ATC handbook. The proper use of such altitudes will organize the flow of traffic and reduce the hazard of midair collisions, since each aircraft operating at the same altitude will be traveling in roughly the same direction. If circumstances require that a different altitude be issued to an aircraft, the controller is permitted to assign a nonstandard altitude, but advance coordination with adjacent ATC facilities must be accomplished, advising the next controller that the aircraft is not at the proper altitude. Table 3–1 provides handbook guidelines for altitude assignment. When issuing clearances, a controller should never assign an altitude lower than the minimum en route altitude (MEA). The controller should also attempt to assign an altitude as close as possible to that filed in the original flight plan. To meet these two requirements, the controller may assign a sequence of cross- ing altitudes that will ensure that the aircraft is never below the MEA. These altitude instructions should be issued to the pilot in the order that they will be flown. If an altitude lower than an en route MEA is assigned initially, the pilot should be told the expected final altitude and when that altitude assignment can be expected. In case of radio failure, the pilot will remain at the assigned altitude until the time has elapsed and will then climb to the higher altitude. (“Maintain six thousand,” “Maintain four thousand until Danville, then main- tain six thousand,” “Maintain niner thousand. Cross Danville at or above five thousand,” “Maintain four thousand; expect six thousand one zero minutes after departure.”) Table 3–1. Guidelines for Altitude Assignment Aircraft On course Operating Degrees Magnetic Assign Examples Below 3,000 Any course Any altitude feet above surface At and below 0 through Odd cardinal altitude or flight 3,000, 5,000, FL 410 179 levels at intervals of 2,000 feet FL 310, FL 330 180 through Even cardinal altitude or flight 4,000, 6,000, 359 levels at intervals of 2,000 feet FL 320, FL 340 Above FL 410 0 through Odd cardinal flight levels at FL 450, FL 179 intervals of 4,000 feet beginning 490, FL 530 with FL 450 180 through Odd cardinal flight levels at FL 430, FL 359 intervals of 4,000 feet beginning 470, FL 510 with FL 430  Air Traffic Control System Structure / 149 6. Holding instructions. If it is necessary to hold an aircraft over a particular fix while en route to the destination airport, the following information must be included in the holding instructions (see Figures 3–5 and 3–6). The direction of holding from the fix, using the eight points of the compass: north, northeast, east, southeast, and so on. The name of the holding fix. Abeam Holding side Outbound Fix end Outbound end Inbound Reciprocal Fix Nonholding side Holding course Figure 3–5. Holding-pattern description. L OM L MM Runway Typical procedure on an ILS outer marker VOR VOR Typical procedure at intersection of VOR radials Holding course Holding course away from navaid toward the navaid VORTAC 15 n mi DME fix 10 n mi DME fix Typical procedure at DME fix Figure 3–6. Examples of holding. 150 / CHAPTER 3 The radial, course, bearing, azimuth, airway, or route on which the aircraft is to hold. The direction of the turns in the holding pattern if a nonstandard holding pattern will be used. A standard holding pattern requires right-hand turns; a nonstandard pattern uses left turns. The holding-pattern length if a nonstandard holding pattern is being used. A standard holding pattern has a 1-minute inbound leg length (1 ½ minutes inbound leg length if the aircraft is holding above 14,000 feet). The Expect further clearance (EFC) time. If pilots lose radio contact with ATC, they are expected to remain in the holding pattern until the EFC time, after which they will depart the holding pattern and continue along the route of flight issued in the last clearance. (“Hold northwest of Boiler on the three two three radial. Expect further clearance at one five three five,” “Hold southwest of Vages on victor two fifty-one. Expect further clearance at two three four one.”) The pilot is expected to enter the holding pattern using the procedures described in the Aeronautical Information Manual. The pilot will maneuver the aircraft so as to track inbound on the assigned course and will attempt to make the inbound leg 1 minute in length. This is the only way in which a pilot can hold and accurately time the inbound leg length. Air traffic controllers should never issue holding instructions that require a pilot to hold outbound from the holding fix. Since the inbound leg would not be located along any defined course, it would be impossible for the pilot to hold properly. Any additional clearance information. This information might include position reports or arrival procedures. Required reports include crossing certain navigational fixes or changes in altitude. Arrival procedures may also be included in this portion of a clearance. An arrival clearance could be either a standard instrument approach procedure or a standard terminal arrival route (STAR) clearance (see Figures 3–7 and 3–8). STARs are similar to departure procedures and describe a common arrival procedure. (“Via the Indy one arrival.”) 7. The departure control frequency and transponder code assignment. (The operation and use of a transponder are covered in Chapter 8.) (“Departure control frequency one two three point eight five. Squawk zero three four five.”) An entire IFR clearance to an aircraft operating in controlled airspace will usu- ally include most of the preceding components. The proper phraseology that should be used when issuing an IFR clearance is included in Chapter 4. A few examples of IFR clearances are as follows: “United six eleven cleared to the Chicago O’Hare Airport via direct Boiler, victor seven, Chicago Heights, direct. Maintain seven thousand. Departure frequency one two three point eight five. Squawk five five four five.” “Cherokee two three two papa alpha cleared to the Indianapolis Airport via the Chicago eight departure over Boiler, victor ninety-seven and the Indy seven arrival. Maintain three thousand, expect eight thousand five minutes after departure. Departure frequency one two eight point zero five, squawk five five four three.”  Air Traffic Control System Structure / 151 Figure 3–7. Standard terminal arrival route chart for Orlando, Florida. 152 / CHAPTER 3 U.S. TERMINAL PROCEDURES PUBLICATION: Aeronautical Information 58 STANDARD TERMINAL ARRIVAL (STAR) CHARTS STANDARD TERMINAL ARRIVAL (STAR) CHARTS DEPARTURE PROCEDURE (DP) CHARTS DEPARTURE PROCEDURE (DP) CHARTS RADIO AIDS VOR TACAN ROUTES TO NAVIGATION VOR/DME NDB/DME VORTAC LOC/DME LOC NDB (Non-directional Beacon) LMM, LOM (Compass locator) Marker Beacon Localizer Course SDF Course SPECIAL USE AIRSPACE ALTITUDES 5500 2300 4800 2200 Mandatory Minimum Maximum Recommended Altitude Altitude Altitude Altitude (Cross at) (Cross at (Cross at or above) or below) AIRPORTS Localizer Offset STAR Charts REPORTING POINTS/FIXES WAYPOINTS DP Charts NOTES (NAME) (" " omitted when it conflicts with runway pattern) WAYPOINT (Compulsory) WAYPOINT (Non-Compulsory) FLYOVER POINT MAP WP (Flyover) W WAAS VNAV outages may occur daily due to initial system limitations. WAAS VNAV NOTAM service is not provided for this approach. Figure 3–8. Standard terminal arrival route chart legend.  Air Traffic Control System Structure / 153 Clearance Amendments As the IFR flight progresses toward the destination airport, the clearance may need to be amended by ATC. The entire clearance need not be repeated, only those items that have been changed by the controller. For example: “Five four papa uniform, climb and maintain seven thousand.” “United six eleven cleared to the Indianapolis airport via victor ninety-seven west.” “American two thirty-one, descend and maintain four thousand, cross two zero DME southeast of Boiler at or below niner thousand.” IFR Flight in IFR flight in uncontrolled airspace is permitted so long as the pilot and aircraft Uncontrolled are properly certified. The FAA does not provide any air traffic control services Airspace however. It is up to the pilot to maintain separation from other aircraft and from obstacles on the ground. In general, aircraft seldom make long IFR jour- neys in uncontrolled airspace, but sometimes they need to transit uncontrolled airspace while landing or departing from small, uncontrolled airports. Control- lers must be aware that the pilots might be maneuvering or flying a specific course that provides terrain and/or aircraft separation while within uncon- trolled airspace and that the controller should never issue instructions that would negate the pilot’s need to conform to VFR flight regulations while within uncontrolled airspace. ATC clearances to operate are never issued to aircraft (either VFR or IFR) flying in uncontrolled airspace. VFR Flight in In controlled airspace, the FAA offers both separation and additional ATC Controlled services to pilots. However, depending on the type of flight and the category of Airspace airspace involved, the pilot may not be required to use these services or even to contact air traffic control facilities. Within controlled airspace, IFR flights are required to receive these services, but VFR flights may not be. In general, as long as VFR pilots can meet the weather minima outlined by Federal Aviation Regulation (FAR) 91 and are not entering any special use airspace, no contact with ATC is required. VFR pilots may fly in controlled airspace as long as they comply with the following regulations included in FAR 91: 1. VFR pilots must generally provide their own separation from other VFR and IFR aircraft and the terrain. 2. VFR pilots are not required to file a flight plan or contact ATC unless they are planning to enter an area of restricted class airspace where contact is mandatory. VFR flight plans are voluntary and are used by the FAA only to assist in locating lost or overdue aircraft. 3. The weather conditions during flight must meet the criteria specified in FAR 91.155. VFR pilots must also maintain the minimum cloud distance stipulated in the FARs. The minimum visibility and distance from the clouds vary with the aircraft’s cruising altitude and the class of airspace within which the flight is operating. See Table 3–2. 154 / CHAPTER 3 Table 3–2. VFR Weather Minima for Operations in Controlled Airspace Airspace Flight Visibility Distance from Clouds Class A airspace Not Applicable Not Applicable Class B airspace 3 statute miles Clear of Clouds Class C airspace 3 statute miles 500 feet below 1,000 feet above 2,000 feet horizontal Class D airspace 3 statute miles 500 feet below 1,000 feet above 2,000 feet horizontal Class E airspace Less than 10,000 3 statute miles 500 feet below 1,000 feet above feet MSL 2,000 feet horizontal At or above 10,000 5 statute miles 1,000 feet below 1,000 feet above feet MSL 1 statute mile horizontal These minima are designed to maximize the chances of a VFR pilot seeing and avoiding other VFR and IFR aircraft. If the pilot is unable to comply with these minima, VFR flight cannot legally be conducted. The pilot must then either land or receive an IFR or a special VFR clearance to continue the flight. There are additional regulations governing special VFR flights with which pilots must conform. In general, a special VFR clearance permits a VFR pilot to fly in certain weather conditions that do not meet minimum VFR criteria. VFR aircraft operating under special VFR clearances are afforded IFR separation from both VFR and IFR aircraft by ATC, however. 4. VFR pilots operating in controlled airspace are required to fly at the proper altitude for the direction of flight unless otherwise requested by ATC. FAR 91.159 describe the approved cruising altitude or flight levels to be used by VFR aircraft in controlled airspace. An aircraft operating under VFR in level cruising flight more than 3,000 feet above the surface is required to maintain the appropriate altitude or flight level prescribed here, unless otherwise authorized by ATC: When operating below 18,000 feet MSL and on a magnetic course of zero degrees through 179 degrees, any odd thousand foot MSL altitude !500 feet (such as 3,500, 5,500, or 7,500) or When operating below 18,000 feet MSL and on a magnetic course of 180 degrees through 359 degrees, any even thousand foot MSL altitude !500 feet (such as 4,500, 6,500, or 8,500) These altitudes were chosen to minimize the potential for midair colli- sions between two aircraft flying in opposite directions. Whenever assigning altitudes to VFR aircraft, controllers should attempt to comply with this regu- lation. However, if traffic conditions dictate, controllers are permitted to assign a nonstandard cruising altitude to VFR aircraft receiving ATC services. When these ATC services are terminated, however, the VFR pilot should be advised to return the aircraft to the proper altitude as soon as it is feasible.  Air Traffic Control System Structure / 155 Table 3–3. VFR Weather Minima for Operations in Uncontrolled Airspace Airspace Flight Visibility Distance from Clouds Class G: Daylight flight at 1,200 feet or less AGL 1 statute mile Clear of clouds Nighttime flight at 1,200 feet or less 3 statute miles 500 feet below AGL 1,000 feet above 2,000 feet horizontal Daylight flight at more than 1,200 feet 1 statute mile 500 feet below AGL but less than 10,000 feet MSL 1,000 feet above 2,000 feet horizontal Nighttime flight at more than 1,200 feet 3 statute miles 500 feet below AGL but less than 10,000 feet MSL 1,000 feet above 2,000 feet horizontal Any VFR flight at more than 1,200 feet 5 statute miles 1,000 feet below AGL at or above 10,000 feet MSL 1,000 feet above 1 statute mile horizontal VFR Flight in In uncontrolled airspace, the FAA does not provide separation services to pilots, Uncontrolled and clearances are never issued. In general, as long as VFR pilots can meet the Airspace weather minima outlined by FAR 91 (see Table 3–3), and are not entering any special use airspace, no contact with ATC is required to fly in uncontrolled airspace. In uncontrolled airspace: 1. VFR pilots must generally provide their own separation from other VFR and IFR aircraft and the terrain. 2. VFR pilots are not required to file a flight plan or contact ATC. 3. The weather conditions during flight must meet the criteria specified in FAR 91.155. Airspace Classes In addition to the general operating rules and procedures previously stated, additional flight requirements and ATC services are provided depending on the airspace classification. All the airspace above the U.S. has been designated by the FARs into one of six classes (see Table 3–4). Table 3–4. Airspace Classification Airspace Class A Class B Class C Class D Class E Features Dimensions Altitudes at and Surrounding Surrounding Surrounding Airspace floor above 18,000' high-density medium-density nonradar control between the su MSL airports up to airports up to towered airports of the Earth, 70 an altitude of an altitude of up to an altitude of 1,200' AGL. Ai about 10,000' about AGL about AGL extends up to b AGL not including 1 MSL Level of Positive Positive Controlled Controlled Controlled Control controlled controlled Flight IFR only IFR and VFR IFR and VFR IFR and VFR if IFR and VFR if Operations if weather if weather weather conditions weather condit Permitted conditions conditions permit permit permit permit Aircraft ATC clearance ATC clearance ATC clearance ATC clearance ATC clearance Entry required for both required for required for required for IFR. required for IF Requirements IFR and VFR both IFR and IFR. VFR VFR aircraft must VFR aircraft ar VFR aircraft must make radio contact required to con make radio prior to entry. ATC. contact prior to entry. Services Standard Standard Standard Standard Standard separ Provided by separation (5 nm separation separation separation between between IFR ATC to IFR or 1000') applied between IFR between IFR IFR aircraft. (3 nm aircraft. (3 nm Aircraft to all aircraft aircraft. (3 nm aircraft. (3 nm or 1000' vertical or 1000' vertic or 1000' or 1000' radar separation or radar separatio vertical) vertical) standard nonradar standard nonra separation). separation). Services VFR aircraft not Aircraft will be Aircraft will Provide traffic None required. Provided by permitted separated from be separated information traffic conditio ATC to VFR large or jet from IFR or concerning IFR permit, VFR ai Aircraft IFR aircraft by VFR aircraft and known VFR might be provi either 1 ½ nm by either target aircraft traffic advisori or 500' resolution, flight following separation. visual, or 500' vertical separation. Aircraft will be separated from small IFR or VFR aircraft by either target resolution, visual or 500' vertical separation. Minimum VFR not allowed 3 statute miles 3 statute miles 3 statute miles 3 statute miles Visibility for VFR Aircraft Minimum VFR not allowed Clear of clouds 500' below, 500' below, 1,000' 500' below, 1,0 Distance from 1,000' above, above, and 2,000' above, and 2,0 Clouds for and 2,000' horizontal. horizontal. VFR Aircraft horizontal. Airspace Airspace Description and Use Entry Requirements IFR Restrictions VFR Restric Prohibited Flight of aircraft is prohibited Flight not permitted IFR flight not VFR flight Area based on security or other reasons permitted permitted associated with the national welfare. Airspace Airspace Description and Use Entry Requirements IFR Restrictions VFR Restric Restricted Flight of aircraft, while not wholly Aircraft entry might be If the restricted The pilot m Area prohibited, is subject to restrictions. permitted if restricted area is not contact the Restricted areas denote the existence area not in use (cold). active and has controlling of unusual hazards to aircraft such Aircraft entry not been released, to determin as artillery firing, aerial gunnery, or permitted when area is ATC will allow areas, statu guided missile practice. “hot.” the aircraft restricted a to operate in active, VFR the restricted may operat airspace without restricted a issuing specific without spe clearance for it to clearance to do so. If the restricted If the restri area is active, area is activ ATC will issue is the VFR clearances which responsibili ensures IFR avoid the a aircraft avoidance. Temporary TFRs are issued to protect persons The amount of airspace IFR aircraft are A notice to Flight and property within the vicinity of an needed to protect not normally will be issu Restrictions emergency on the ground. Examples persons and property or routed into or restricting V include: gas leaks or spills; volcanic provide a safe environ- through a TFR flight. It is t eruptions; hijacking incidents, aircraft ment for rescue/relief unless its mission responsibili accident sites; wildfire suppression; aircraft operations is specifically remain clea disaster areas; aerial demonstrations is normally limited related to the TFR airspa or major sporting events; or reasons to within 2,000 feet TFR. of national security. above the surface and within 3-nautical miles Incidents occurring within Class B, Class C, or Class D airspace will normally be handled through existing procedures and should not require the issuance of temporary flight restrictions. Military MOAs consist of airspace of defined No restrictions on VFR If the MOA is Pilots opera Operations vertical and lateral limits established aircraft. IFR aircraft not active and under VFR Area for the purpose of separating certain might be permitted has been released, permitted t military training activities from entry if MOA is ATC will allow an MOA w IFR traffic. Examples of activities cold but will not be the aircraft to clearance b conducted in MOAs include, but are permitted when area is operate in the exercise ext not limited to, air combat tactics, “hot”. airspace without caution. air intercepts, aerobatics, formation issuing specific training, and low-altitude tactics. clearance for it to Military pilots flying in an active do so. MOA are exempted from the FAR which prohibits aerobatic flight within Class D and Class E airspace and within Federal airways. DoD aircraft operating within an MOA are authorized to operate aircraft at airspeeds in excess of 250 knots. If the MOA is Pilots can c active, ATC will any FSS wi issue clearances miles of the which insures obtain accu IFR aircraft time inform avoidance. concerning hours of op Depending ATC capab and worklo VFR pilots able to con controlling for traffic a ADIZ An area of airspace over land or Flight plan must be Routine IFR VFR pilots water, extending upward from the filed. Aircraft must flight plan/ D/VFR flig surface, within which the ready make contact with clearance and IFR and initiate identification, location, and control ATC prior to ADIZ communications with ATC p of aircraft are required in the interest entry. meet ADIZ entering AD of national security. requirements Airspace Airspace Description and Use Entry Requirements IFR Restrictions VFR Restric Terminal TRSAs were originally established as Airspace surrounding TRSAs primarily Pilots opera Radar part of the Terminal Radar Program designated airports affect VFR under VFR Service at selected airports. TRSAs precede wherein ATC provides flights; therefore, encouraged Area the establishment of class C airspace. radar vectoring, IFR aircraft on contact the (TRSA) It was envisioned originally that sequencing, and an IFR clearance approach c all TRSAs would be converted to separation on a full- are not affected. and avail th Class C airspace, but some were not. time basis for all IFR of the TRSA TRSAs do not fit into any of the U.S. and participating VFR which inclu airspace classes but continue to be aircraft. No clearance advisories a operated where participating pilots required. arrival sequ can receive additional radar. However, participatio voluntary o part of the Domestic An ADIZ over U.S. metropolitan After 9/11, a more or Routine IFR VFR opera ADIZ areas, which is activated and less permanent ADIZ flight plan/ within, into deactivated as needed, with was established over clearance out of an A dimensions, activation dates, the Washington D.C. and IFR is permitted and other relevant information metropolitan area. communications pilots file a disseminated via NOTAM. At various times, meet ADIZ entry plan, establ temporary domestic requirements. maintain ra ADIZs have also been There are communica delineated. and continu additional transmit a d security transponde equipments assigned by established for There may flights into and be addition out of a domestic security equ ADIZ. established flights into of a domes Alert Area Alert areas are depicted to inform A clearance is not IFR flights will VFR flight pilots of areas that may contain a required to enter an be routinely permitted. A high volume of pilot training or an alert area. All flight routed through aircraft sha unusual type of aerial activity. activity within an alert alert areas. IFR equally resp area is conducted in aircraft as well for collision accordance with FARS. as participating avoidance. aircraft shall be equally respon- sible for collision avoidance. Airport Airport advisory service is operated The FSS provides a Routine IFR VFR pilots Advisory within 10 statute miles of an complete local airport flight plan/ select to co Service airport where a control tower is advisory service, which clearance the FSS on not operating, but where an FSS is includes known airport and IFR appropriate located on the airport. AAS is not and traffic information communications frequency t regulatory airspace. to arriving and permits airport adv departing aircraft. service. Military MTRs were developed for use by Military aircraft VFR no IFR yes Training the military for the purpose of operating VFR will Routes conducting low-altitude, high-speed operate using VFR training. The routes above 1,500 feet rules. IR training AGL are developed to be flown, to routes require an ATC the maximum extent possible, under clearance from ATC. IFR. The routes at 1,500 feet AGL and below are generally developed to be flown under VFR. There are both IFR and VFR MTRs: Operations on these routes are conducted in accordance with VFR except flight visibility shall be 5 miles or more, and flights shall not be conducted below a ceiling of less than 3,000 feet AGL. Airspace Airspace Description and Use Entry Requirements IFR Restrictions VFR Restric Controlled CFAs contain activities that, if Firing Area not conducted in a controlled environment, could be hazardous to nonparticipating aircraft. CFA activities are suspended immediately when spotter aircraft, radar, or ground lookout positions indicate an that aircraft might be approaching the area. National National security areas are Pilots are requested Security established at locations where to voluntarily avoid Areas there is a requirement for increased flying through the security and safety of ground depicted NSA. When facilities. it is necessary to provide a greater level of security and safety, flight in NSAs may be temporarily prohibited by regulation. Warning A warning area is similar to a Alert: The purpose If the alert area The pilot m Area restricted area, but it is offshore of such warning is not active and contact the of the United States located in areas is to warn has been released, controlling international airspace, and flight nonparticipating pilots ATC will allow to determin cannot be legally restricted. of the potential danger. the aircraft to areas status operate in the aircraft can airspace without fly through issuing specific areas. clearance for it to do so. If the area is active, ATC will issue clearances which ensures IFR aircraft avoidance.