Air Traffic Control and Runway Separations. Dr. Antonio A. Trani Professor of Civil and Environmental Engineering

Transcription

1 Air Traffic Control and Runway Separations Dr. Antonio A. Trani Professor of Civil and Environmental Engineering Airport Planning and Design (Antonio A. Trani)

2 Why learning About Air Traffic and Runway Separations? ATC provides the operating rules of the airport Airport operational rules influence airport capacity Runway separations influence airport capacity and safety Many types of ATC equipment are located at the airport site Airport Planning and Design (Antonio A. Trani) 1a

3 Typical Navigation, Communication and Weather Equipment at an Airport source: FAA AC 150/ Chapter 6 Airport Planning and Design (Antonio A. Trani) 1b

4 Some Nomenclature Acronym Name Purpose ASDE Airport surface detection equipment Provides aircraft position information to ATC tower controllers (aircraft on the ground) ALS Approach lighting system Provides visual guidance to pilots in bad weather Airport Beacon ASOS / AWOS Airport Beacon Automated surface observation system Automated weather observing system Provides information to pilots on airport location (specially at night) Provides weather information to pilots and ATC personnel LLWAS Low level wind shear alert system Provides information on dangerous surface wind shear DME RVR Distance measuring equipment Runway visual range Provides distance to the airfield information to on-board instruments Equipment to measure forward visibility (important to pilots and ATC personnel) Wind Cone Wind Cone Provides visual information on wind direction TVOR Terminal Very High Frequency Omnidirectional Range system Provides navigation guidance to on-board instruments Airport Planning and Design (Antonio A. Trani) 1c

5 Some Nomenclature (cont.) Acronym Name Purpose GS Glide slope antenna Part of the instrument landing system ATCT Air traffic control tower Houses ATC personnel and equipment ASR Airport surveillance radar Radar surveillance system use by ATC controllers (aircraft in the air) REIL Runway end identifier lights Lights that denote the end of the runway RWSL Runway status lights Lights that indicate if a runway is used (used by pilots) PAPI VASI Precision approach path indicator Visual approach slope indicator Lights that provide guidance to pilots about their glide slope Al o;der version of lights used by pilots to know their approach glide path WAAS Wide area augmentation system Provides navigation guidance to pilots PRM Precision runway monitor Fast scan radar used for aircraft surveillance RTR Remote transmitter and receiver Communication equipment used in air-to-ground communicatons Airport Planning and Design (Antonio A. Trani) 1d

6 Siting Criteria of Navigation, Surveillance and Communications Equipment Siting criteria Every piece of equipment requires specific siting criteria to function adequately Separation and clearances Each device requires separation and clearances to work Critical areas Some equipment require protected areas (critical areas) to function correctly Airport Planning and Design (Antonio A. Trani) 1e

7 Navigation Aids and Compatibility with RSA and ROFA Areas Airport Planning and Design (Antonio A. Trani) 1f

8 Example: Approach Lights and REILs By design, they are located inside the RSA and ROFA areas of a runway MALS system at DCA runway 19 REIL MALS Airport Planning and Design (Antonio A. Trani) 1g

9 More Examples of Equipment at the Airport Chapter 6 of the FAA AC 150/ provides numerous examples of navigation, surveillance, communication and weather equipment located at an airport Gulfstream III landing at BCB Localizer Antenna Runway edge lights Taxiway signs Airport Planning and Design (Antonio A. Trani) 1h

10 Flight Rules Discussion of Flight Rules IFR - instrument flight rules (ATC controlled flights) VFR - visual flight rules (> 3 nm visibility and 1000 ft. from clouds) Weather conditions VMC - visual meteorological conditions IMC - instrument meteorological conditions An airliner could fly in VMC conditions but always under IFR flight plan rules Virginia Tech 2 of 68

11 Airways are Like Highways in the Sky Blacksburg United States Airways Miami Virginia Tech 3 of 68

12 The Role of Air Traffic Control Air traffic controllers maintain aircraft separations and help pilots navigate to their destination providing verbal and datalink instructions Virginia Tech 4 of 68

13 Classification of ATC Services There are 3 control components of ATC and one support component. These components interact all time among themselves via telephone or microwave data links. Control Components: Air Traffic Control Systems Command Center (ATCSCC) Air Route Traffic Control Centers (ARTCC) Terminal Approach/Departure Control Facilities (TCA - TRACON) Airport Traffic Control Tower (ATCT) Support Component (Information) Flight Service Stations (FSS) Virginia Tech 5 of 68

14 US Air Route Traffic Control Centers (ARTCC Twenty one ARTCC facilities in the U.S sectors (horizontal and vertical) in each ARTCC Control over nm from radar sites (use of multiple radars to track targets at long distances) Use of long range radars for surveillance (12 seconds between scans or update rate) The size of the ARTCC varies because traffic density vary over NAS (see Figure) Virginia Tech 6 of 68

15 Enroute Control Sectors in the US A well organized and hierarchical system Communications are via Voice channels (one per controller) source: FAA Instrument Procedure Handbook Virginia Tech 7 of 68

16 Airspace Sectorization to Control Flights The NAS airspace is divided into Centers to control flights Latitude (deg.) Atlanta Enroute Center Jacksonville Enroute Center Miami Enroute Center Washington Enroute Center Sector Longitude (deg.) Virginia Tech 8 of 68

17 Enroute Separations (Vertical) In January 20, 2005 the FAA instituted Reduced Vertical Separation Minima (RVSM) in the domestic US airspace Canada and Mexico (and Gulf of Mexico) also implemented the same RVSM rules on the same day The new vertical separations allow six new flight levels to be selected every 1,000 between flight levels 290 and 410 North Atlantic operations use RVSM since March 1997 and Pacific operations since February 2000 Europe started RVSM operations in January 2002 Virginia Tech 9 of 68

18 Asia-Europe (South of Himalayas) started RVSM operations in November 2003 Enroute Separations (vertical) Virginia Tech 10 of 68

19 RVSM Issues Aircraft are required to comply with tighter altimetric capability (not all aircraft in NAS are equipped in 2005) Aircraft not meeting new altimetric capabilities can still operate in NAS (below FL 290 or above FL 410 if authorized by ATC) Literature on RVSM 1. Guidance 91-RVSM, Change 2 (2/10/04) - Guidance Material on the Approval of Operators/Aircraft for RVSM Operations 2. Air Transportation Operations Inspectorís Handbook (FAA Order ). HBAT (9/8/03). "Reduced Vertical Separation Minimum Airspace.î HBAT is incorporated into Change 27 (5/25/04) , Volume 4, Chapter 1, Section 5, Paragraph 220 is now ì RVSM Airspace". Virginia Tech 11 of 68

20 ATC Surveillance Mechanisms Radar (Today) ADS-B, GPS ( ) ADS = Automatic Dependent Surveillance GPS = Global Positioning System Virginia Tech 12 of 68

21 Terminal Approach and Departure Control Facilities (TRACON) Control terminal traffic (both arrivals and departures) Typically nm from the aircraft Some TRACON control more than one airport (SW California) TRACONs are divided into sectors to ease workload for controllers TRACONs meter traffic approaching an airport facility Heavy use of verbal advisories ( vectors ) - AA52 turn right heading UA53 descent and maintain 170 (17,000 ft.) - Aeromexico reduce to 230 (IAS airspeed) Virginia Tech 13 of 68

22 Minimum separation inside TRACON is either 5 nm (>40 nm from radar antenna) or 3 nm (if < 40 nm from radar antenna) assuming no wake vortex effect is present Virginia Tech 14 of 68

23 Sample TRACON (Roanoke) Side View 5,200 ft. Class C Airspace 3,800 ft. 3,400 ft. Notes: 2,132 ft. Virginia Tech Airport R k Ai t 1,176 ft. 1) The volume of airspace controlled by ROA Approach control looks like an inverted wedding cake 2) Typical of many TRACONs in the U.S. 3) The complexity of the TRACON increases as traffic increases Virginia Tech 15 of 68

24 Sample Flight Paths to and from Miami Airport Tampa Bay Atlantic Ocean TRACON Radar Coverage Aircraft Tracks Gulf of MÈxico Miami Intl. Airport Longitude (deg.) Virginia Tech 16 of 68

25 Detailed View of Flight Tracks (ETMS Data) Arrivals Departures Miami Intl. Airport Longitude (deg.) Virginia Tech 17 of 68

26 Terminal Area Operations in Atlanta (Departures) Virginia Tech 18 of 68

27 Terminal Area Operations in Atlanta (Arrivals) Four Corner Post System Virginia Tech 19 of 68

28 Detail of Operations at Atlanta Airport Arrivals in Blue Departures in Red Virginia Tech 20 of 68

29 Terminal Area Operations in New York City One Day of Traffic into 5 New York Area Airports Virginia Tech 21 of 68

30 Terminal Operations in New York LGA ARR to 31 LGA ARR to 4 JFK 31L DEP Approaches to La Guardia Airport (LGA) (dark green color lines) are executed in close proximity with departures from JFK Airport (light green color lines) Operations at LGA, JFK and EWR require coordination Virginia Tech 22 of 68

31 Air Traffic Control Tower Control aircraft traffic (both arrivals and departures) at the airport (includes ramps near gates, taxiways, runways, and airspace up to 5 nm from airport) Three controller posts - Local controller (runways and landing areas) - Ground control (taxiways and aprons) - Clearance delivery (provides information on flight plans) Some ATCT divide workload into East-West operations Use of short and precise language - AA52 taxi to RWY 36 via alpha-3 - UA53 clear for takeoff, wind 040 at 12 - Aeromexico clear to land RWY 36 Virginia Tech 23 of 68

32 Sample Airport (JFK) with Taxiway and Gate Detail 13L 13R Terminal Building 22R 31R 22L 31L 4L 4R Virginia Tech 24 of 68

33 Aircraft Wake Categories Used in Air Traffic Control FAA aircraft groups (at maximum takeoff weight) Small (< 41,000 lb) Large (< 255,000 lb) B757 (255,000 to 300,000 lb) Heavy (> 255,000 lb) Superheavy (Airbus A380 and Antonov 225) ICAO groups Light (< 7 metric tons) Medium (> 7 tons but < 136 tons) Heavy (> 136 tons) Superheavy (A380 and Antonov 225) CEE 4674 Airport Planning and Design (A. Trani) 25a

34 Issues in Separating Aircraft Near Runways Airspace criteria are intrinsically used for runway separations: Minimum radar separations (driven by the ability to differentiate targets in a radar display) Wake vortex separations - driven by the hazard created by flying behind the wake of a lead aircraft Runway occupancy time (ROT) Can also be an important factor in separations on final approach If ROT is small (i.e., due to high speed runway exits), the airspace separations may need to be increased to avoid simultaneous occupancy of the runway CEE 4674 Airport Planning and Design (A. Trani) 25b

35 Example of In-Trail Wake Airspace Separations IMC Conditions (ICAO) Lang, Eriksen and Tittsworth, WakeNet 3 Europe, 2010 CEE 4674 Airport Planning and Design (A. Trani) 25c

36 Typical Minimum Values of Aircraft Separations ( in the United States under IMC Conditions Radar is Available Highlighted values are minimum radar separations Values behind Superheavy vary from 8-10 nm CEE 4674 Airport Planning and Design (A. Trani) 25d

37 VMC Separations Under visual meteorological conditions, pilots are expected to be responsible for separations Data collected at airfields in the United States indicates that VMC separations are 10% below those observed under IMC conditions Therefore: Runways have more capacity under VMC conditions for the same fleet mix Higher runway utilization is possible under VMC conditions Runway occupancy times and VMC airspace separations are closer in magnitude CEE 4674 Airport Planning and Design (A. Trani) 25e

38 A Hypothetical Flight Suppose we fly a Cessna Citation II from Virginia Tech Airport to Miami International The flight takes us across four ARTCC Centers in the U.S. (Washington, Atlanta, Jacksonville, and Miami) The aircraft is under continuos control of ATC services even if the day is clear (CAVU conditions) Cessna Citation II Virginia Tech 26 of 68

39 The Flight Plan (Current NAS) The current plan uses high-altitude Jet Routes (Jet airways) A codified instrument approach procedure (Heath II) is used during the transition into the Miami TRACON Virginia Tech 27 of 68

40 Activities of the Flight Pilots arrive to VPI Airport (BCB) an hour before the flight (to review weather and submit a flight plan) Few minutes before departure they contact Roanoke ATC for flight plan approval BCB has no control tower (but a UNICOM frequency is used to establish intent - blind verbal statements) Out of BCB pilots contact Roanoke TRACON for climb instructions (to intercept J-48 a Jet Route) At FL 100 (10,000 ft.) the pilots contact Washington Center - ZDC (briefly) A few minutes later ZDC hands-off the flight to ZTL (Atlanta ARTCC) Virginia Tech 28 of 68

41 Climb Procedure Out of BCB Blacksburg Virginia Tech 29 of 68

42 Flight Activities ZTL controllers (4 sectors total for this trip) direct this flight to switch to J-53 to Spartanburg VOR (a NAVAID facility) The aircraft reaches its enroute cruising altitude of FL 350 (heading is around 187 degrees - South) The flight then moves over to J-81 West of Augusta, GA 100 nm North of Jacksonville ZTL controllers hand-off the flight to ZJX controllers (Jacksonville Center) The flight takes J-45 and passes a few miles West of Daytona Beach (flies over Daytona Beach VOR called DAB) The flight is handed-off to ZMA (Miami ARTCC Center) ZMA controllers start descending the flight 100 nm from MIA VOR near Vero Beach VOR Virginia Tech 30 of 68

43 Enroute Part of the Trip Virginia Tech 31 of 68

44 Final Part of the Trip (Activities) The flight is handed over to MIA TRACON 60 nm from the airport East of the West Palm Beach VOR The flight progresses inside the MIA terminal area flying a codified Standard Terminal Arrival Route (STAR) The flight is continuously given vectors inside the 50 nm radius from MIA The TRACON controller sequences our flight behind a ì heavyî (Boeing 757 of American Airlines) and establishes 6 nm of separation 5 nm from MIA airport the flight is handed-off to MIA tower The flight lands on RWY 27 R per local controller instructions The flight taxis to the ramp following instructions of a ground controller Virginia Tech 32 of 68

45 Final Approach and Terminal Area Vero Beach Miami Virginia Tech 33 of 68

46 Aircraft Instrumentation and Navigation Modern transport aircraft have plenty of instrumentation to navigate across the U.S. and over the oceans Virginia Tech 34 of 68

47 Navigation in Free Flight In Free Flight a pilot navigates directly from an origin to a destination using Satellite Navigation (SATNAV) systems GPS Network of Satellites Virginia Tech 35 of 68

48 Sample Individual Free Flight Track Flight plans will be more flexible and allow pilots to save time and fuel Flight plan way-points Constant heading segments 30 Descent Climb Altitude (kft) MIA 85 Longitude (deg) 90 Pseudo-globe circle route DFW Latitude (deg) Virginia Tech 36 of 68

49 North Atlantic and Oceanic Operations Reich and Marks start development of the first Collision Risk Assessment model Reich-Marks model accepted for oceanic operations - Established longitudinal, lateral and vertical separation minimums to fly over the North Atlantic nautical mile lateral separation (90 nm separation considered unsafe using the model) - The longitudinal separation was 20 minutes initially - 15 minutes in-trail adopted in 1978 Virginia Tech 37 of 68

50 Reich-Marks Model Reich- Marks model (target level of safety at 2.5x10e-9 collisions per flight hour) 2000 ft Sx = 20 minutes 120 nm Virginia Tech 38 of 68

51 Composite Rule Changes First reduction in lateral separation (120/60 composite rule separation) 2000 ft. 60 nm Sx = 15 minutes 120 nm Virginia Tech 39 of 68

52 MNPS Changes in NATS Minimum Navigation Performance (MNPS) Navigation equipment was more accurate 2000 ft. 60 nm Sx = 10 minutes 120 nm Virginia Tech 40 of 68

53 MNPS Changes Avionics/aircraft equipment needs to be certified under stricter rules to operate in NATS (North Atlantic Track System) Lateral NAV Error PDF µ = 0 ft.! = 3000 ft. Vertical Error PDF µ = 0 ft.! = 82 ft. Virginia Tech 41 of 68

54 RVSM Rule Changes In 1990 a new study concluded that 1000 ft. vertical separation was acceptable over the North Atlantic 1000 ft. Sx = 10 minutes 60 nm Virginia Tech 42 of 68

55 New Separations over NATS (North Atlantic Organized Track System) 1000 foot vertical separation between flight levels 290 and 390 (implemented in March 1997) 60 nm lateral separation between adjacent flight tracks 10 minute longitudinal separation between successive aircraft (about 150 km if flying at Mach 0.80) Requires strict enforcement of Minimum Equipment Lists (MLE) and RVSM (Reduced Vertical Separation Measures) certification (aircraft specific) Wake turbulence and issue sometimes (pilots are given the freedom to deviate 2 miles off the track to avoid wake turbulence) Virginia Tech 43 of 68

56 Extended Range Twin-Engine Over the Water Operations ETOPS is the acronym of extended range, twin-engine over the water operations ETOPS operations with twin engine aircraft started in 1985 with Boeing flights (between Europe and North America) Today more than 90% of the North Atlantic flights are conducted using twin-engine aircraft Airlines worldwide conduct 1,700 ETOPS flights per day More than 5.5 million ETOPS flights since 1985 using twin engine aircraft (source: Boeing 2007) These aircraft have demonstrated high reliability and thus are certified to fly over the oceans with 180 to 207 minute diversion rules (time to a nearest airport at single engine speed) Virginia Tech 44 of 68

57 More recently, Boeing obtained certification for longer diversion rules for the Boeing 777 family of aircraft (see article at b_nr.html) Boeing expects to certify newer versions of Boeing 777 aircraft to fly 330 minute diversion rules More information at Transport Canada web site : definitions.htm More information about ETOPS from the FAA is found at: / Virginia Tech 45 of 68

58 ETOPS Trans-Pacific Flights Virginia Tech 46 of 68

59 ETOPS Requirements (Transport Canada) 1) Required aeroplane limitations including airline procedures for ETOPS certification 2) Revision to the performance section including fuel consumption rates; 3) Flight crew procedures; 4) Aircraft certication - "the aeroplane has been found to meet the type design reliability and performance criteria for ETOPS operations in accordance with this document. Compliance with these type design criteria alone does not constitute approval to conduct ETOPS operations" Virginia Tech 47 of 68

60 Sample ETOPS Flight Distance traveled (nm) Latitude (deg.) IAH (Houston) CDG (Paris) Longitude (deg.) Note: There are critical sections of this flight where the aircraft could be ~120 minutes away from the nearest airport (assuming a single engine speed) Virginia Tech 48 of 68

61 Possible Diversion Points (Airports) 75 Distance traveled (nm) Keflavik Shannon Gander Santa Maria Virginia Tech 49 of 68

62 Have There Been Diversions? Two very well known cases: a) Air Transat Airbus A lost both engines (due to fuel starvation) over the Atlantic and landed safely at Lajes (in the Azores) See report at: moptc.pdf or read article at: en.wikipedia.org/wiki/air_transat_flight_236 b) Boeing ER traveled more than 300 minutes in a flight from North America to Hawaii (landed safely with engine operative) Virginia Tech 50 of 68

63 Types of Critical Failures in ETOPS Operations Pressurization failure Pressure vessel (fuselage) no longer maintains a low-altitude cabin conditions (<8,000 ft) at cruise altitude Aircraft is required to descend to 10,000 ft. allowing passengers to breathe normally High drag condition (high density due to low altitude cruise) Fuel reserves are critical because two engines are running Engine failure Engine failure requires a descent to a suitable one-engine cruise altitude Modern twin engine aircraft have single-engine service ceilings of 21,000-29,000 ft. Virginia Tech 51 of 68

64 Modest drag condition (intermediate altitude) 4.5 x Drag (N) at: 6000 meters Thrust (N) at: 6000 meters 4.5 x Drag (N) at: 6000 meters Thrust (N) at: 6000 meters Drag or Thrust (Newtons) Two Engines Drag or Thrust (Newtons) One Engine Mach Number Mach Number Virginia Tech 52 of 68

65 Separations in the National Airspace System Much smaller than over NATS (5 nm for distance > 40 nm from radar) Positive control (radar control for all IFR flights) 2000 ft. above 41,000 ft. (flight level 410) 1000 ft. below FL 410 Above FL 290 RVSM requires aircraft equipment certification Free Flight introduces a new dimension in complexity NASA / FAA want to reduce incidents and collisions by a factor of 5-10 in the next decade Need to assess the collision risk over NAS if reduced separation criteria is used Virginia Tech 53 of 68

66 Implications for Air Transportation Engineering NAS system capacity is typically constrained at the airport level Many ATC services housed at the airport - Airport surveillance radars - VOR - very high frequency omnidirectional range and TACAN systems - ILS - instrument landing systems - Distance Measuring Equipment (DME) ATC aircraft separations dictate the capacity of the airport and in some cases that of the airspace Runway separation criteria are dictated by ATC technology (more on this later) Virginia Tech 54 of 68

67 Runway Separations at Airports Depend on Airport Surveillance Technology The same technology used to establish the position of aircraft in the airspace is used to perform surveillance activities near airports Radar technology has inherent weaknesses for surveillance The farthest from the antenna, the larger the uncertainty to determine accurate positions Primary radar (skin paint) Secondary radar (transponder inside aircraft - Modes C and S) Virginia Tech 55 of 68

68 Independent ILS or Precision Approaches IFR operational conditions 4,300 ft. between runway centerlines Standard radar systems (scan rate of 4.8 seconds or more) Radar surveillance is available Independent arrival streams Runway 1 Airport Terminal 4,300 ft. or more Runway 2 Virginia Tech 56 of 68

69 Independent Parallel Approaches using the Precision Runway Monitor (PRM) in IFR The purpose of this standard is to use the Precision Runway Monitor (PRM) to allow independent ILS approaches to parallel runways separated down to 3,000 feet (FAA, 1998) This standard currently applies with PRM (fast-scan technology) Radar scan rate of 1 second or less Virginia Tech 57 of 68

70 What is a PRM - Precision Runway Monitor? Two pieces of software and hardware comprise the PRM system: Air Traffic Controller display (shows the aircraft blips plus the NTZ - No Transgression Zone (NTZ) Fast scanning radar (with tau <= 1.0 seconds) This system reduces the uncertainty of knowing where aircraft are (i.e., thanks to its fast scan rate) Virginia Tech 58 of 68

71 Independent Triple and Quadruple Approaches To Parallel Runways (IFR) The idea behind this concept is to allow triple and quadruple parallel approaches to runways separated by 5,000 feet using standard radar systems (scan update rate of 4.8 seconds) at airports having field elevations of less than 1,000 feet Increase to 5,300 ft. spacing between runways for elevations above 5,000 ft. p Runway 1 Runway 2 Runway 3 5,000 ft. or more R 2 Virginia Tech 59 of 68

72 Independent Departures in IFR Conditions and Standard Radar (" => 4.8 s.) Simultaneous departures can be conducted if two parallel runways are located 2,500 ft. p Runway 1 2,500 ft. Runway 2 Virginia Tech 60 of 68

73 Independent Departures and Arrivals in IFR Conditions and Standard Radar (" => 4.8 s.) Simultaneous departures and arrivals can be conducted if two parallel runways are located 2,500 ft. Departure Stream Runway 1 2,500 ft. Runway 2 Arrival Stream Virginia Tech 61 of 68

74 Staggered Runways Rule (Decreasing Separation) If two parallel runways are staggered (i.e., their runway thresholds are offset) use: Decrease runway centerline separation by 100 ft. for every 500 ft. of stagger Runway 1 2,300 ft. 1,000 ft. Runway 2 Virginia Tech 62 of 68

75 Staggered Runways Rule (Increasing Runway Centerline Separation) If two parallel runways are staggered (i.e., their runway thresholds are offset) use: Increase runway centerline separation by 100 ft. for every 500 ft. of stagger Runway 1 2,700 ft. 1,000 ft. Runway 2 Overlap Region Virginia Tech 63 of 68

76 Independent Arrivals under VFR Conditions Independent simultaneous arrivals can be conducted with at least 700ft between runway centerlines if: VFR conditions (visibility > 3 nm) No wake vortex effect is present Independent arrival streams Runway 1 Runway ft. or more No wake vortex effect (seldom the case) Increase to 1,200 ft. if aircraft belong to Design groups V and VI Virginia Tech 64 of 68

77 Independent Simultaneous Approaches to Converging Runways Procedures governing independent converging approaches require that the distance between the missed approach points be 3 n.m. apart and that the Terminal Instrument Procedures (TERPS) surfaces not overlap. Because of these restrictions, minimums are high, thereby limiting the number of airports NTZ - No Transgression Zone Assumes the Missed Approach Envelopes are Non-overlapping Virginia Tech 65 of 68

78 Dependent Approaches to Parallel Runways (IFR) Procedures exist to conduct dependent arrivals when runway separation is below 4,300 ft. and above 2,500 ft. (standard radar). Runway 1 Dependent arrival streams 2,500 ft. or more 1.5 nm 1.5 nm Runway 2 Virginia Tech 66 of 68

79 Simultaneous Offset Instrument Approaches (SOIA) Allows siimultaneous approaches to runways spaced less than 3,000 ft. but more than 750 ft. San Francisco International airport is the first airport approved for the procedure (see diagram) Requirements: Pilot training Dual communications ATC software/hardware (PRM radar) Virginia Tech 67 of 68

80 Simultaneous Offset Instrument Approaches (SOIA) SFO International 9,000 ft. ILS Approach 3,000 ft. LDA Approach No Transgression Zone Virginia Tech 68 of 68