ATC Equipment and Runway Separations Explained

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

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
1a

Typical Navigation,
Communication
and Weather
Equipment at an
Airport
source:
FAA AC 150/5300-13
Chapter 6
1b

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 Airport Beacon
Provides information to pilots on airport location
(specially at night)
ASOS / AWOS
Automated surface observation system
Automated weather observing system
Provides weather information to pilots and ATC personnel
LLWAS Low level wind shear alert system Provides information on dangerous surface wind shear
DME Distance measuring equipment
Provides distance to the airﬁeld information to on-board
instruments
RVR Runway visual range
Equipment to measure forward visibility (important to
pilots and ATC personnel)
Wind Cone Wind Cone Provides visual information on wind direction
TVOR
TerminalVery High Frequency
Omnidirectional Range system
Provides navigation guidance to on-board instruments
1c

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 Precision approach path indicator
Lights that provide guidance to pilots about their glide
slope
VASI Visual approach slope indicator
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
1d

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
1e

Navigation Aids
and
Compatibility
with RSA and
ROFA Areas
1f

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
1g

More Examples of Equipment at the
Airport
• Chapter 6 of the FAA AC 150/5300-13 provides numerous
examples of navigation, surveillance, communication and
weather equipment located at an airport
1h
Localizer
Antenna
Runway
edge lights
Gulfstream III landing at BCB
Taxiway signs

Virginia Tech 2 of 68
Discussion of Flight Rules
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

Airways are Like Highways in the Sky
United States
Blacksburg
Miami
Airways

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

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)

US Air Route Traffic Control Centers (ARTCC
• Twenty one ARTCC facilities in the U.S.
• 30-50 sectors (horizontal and vertical) in each ARTCC
• Control over 200-300 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)

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

Airspace Sectorization to Control Flights
The NAS airspace is divided into Centers to control flights
-88 -86 -84 -82 -80 -78 -76
26
27
28
29
30
31
32
33
34
35
23
24
40
49
51
55
61
62
75
77
84
8687
89
91
93
113
115
119
121
126
129
131
143
Latitude(deg.)
Longitude (deg.)
Jacksonville
Enroute Center
Atlanta
Enroute Center
Miami
Enroute Center
Sector
Washington
Enroute Center

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

• Asia-Europe (South of Himalayas) started RVSM
operations in November 2003 Enroute Separations
(vertical)

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 8400.10). HBAT 03-06 (9/8/03). "Reduced Vertical
Separation Minimum Airspace.î HBAT 03-06 is incorporated into
8400.10 Change 27 (5/25/04). 8400.10, Volume 4, Chapter 1,
Section 5, Paragraph 220 is now ì RVSM Airspace".

ATC Surveillance Mechanisms
Radar (Today)
ADS-B, GPS (2005-2010)
GPS = Global Positioning System
ADS = Automatic Dependent Surveillance

Terminal Approach and Departure Control
Facilities (TRACON)
• Control terminal traffic (both arrivals and departures)
• Typically 50-80 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 120
- UA53 descent and maintain 170 (17,000 ft.)
- Aeromexico reduce to 230 (IAS airspeed)

• 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

Sample TRACON (Roanoke)
Notes:
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
Class C Airspace
R k Ai t
Virginia Tech Airport
5,200 ft.
3,400 ft.
3,800 ft.
1,176 ft.
2,132 ft.
Side View

Sample Flight Paths to and from Miami Airport
-84 -83 -82 -81 -80 -79 -78 -77
Longitude (deg.)
Miami Intl. Airport
Aircraft Tracks
Tampa Bay
Gulf of MÈxico
Atlantic Ocean
TRACON Radar Coverage

Detailed View of Flight Tracks (ETMS Data)
-81 -80.8 -80.6 -80.4 -80.2 -80 -79.8
Longitude (deg.)
Miami Intl. Airport
Arrivals
Departures

Terminal Area Operations in Atlanta
(Departures)

Terminal Area Operations in Atlanta (Arrivals)
Four Corner Post System

Detail of Operations at Atlanta
Arrivals in Blue Departures in Red
Airport

Terminal Area Operations in New York City
One Day of Traffic into 5 New York Area Airports

Terminal Operations in New York
• 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
JFK 31L DEP
LGAARR to 4
LGAARR to 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

Sample Airport (JFK) with Taxiway and Gate
Detail
31L
31R
13L
22R
22L13R
4L 4R
Terminal
Building

CEE 4674 – Airport Planning and Design (A. Trani)
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)
25a

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
25b

Example of In-Trail Wake Airspace Separations
IMC Conditions (ICAO)
Lang, Eriksen and Tittsworth, WakeNet 3 Europe, 2010
25c

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
25d

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
25e

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

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

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)

Climb Procedure Out of BCB
Blacksburg

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

Enroute Part of the Trip

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

Final Approach and Terminal Area
Vero Beach
Miami

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

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

Sample Individual Free Flight Track
Flight plans will be more flexible and allow pilots to save time and
fuel
80
85
90
95
100 26
26.5
27
27.5
28
28.5
29
29.5
0
10
20
30
Longitude (deg) Latitude (deg)
Altitude(kft)
Flight plan way-points
DFW
MIA
Pseudo-globe circle route
Constant heading
segments
ClimbDescent

North Atlantic and Oceanic Operations
• 1963 - Reich and Marks start development of the first Collision
Risk Assessment model
• 1968 - Reich-Marks model accepted for oceanic operations
- Established longitudinal, lateral and vertical separation
minimums to fly over the North Atlantic
- 120 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

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

Composite Rule Changes
• 1971 - First reduction in lateral separation (120/60 composite
rule separation)
2000 ft.
120 nm
60 nm
Sx = 15 minutes

MNPS Changes in NATS
• 1981-1983 Minimum Navigation Performance (MNPS)
• Navigation equipment was more accurate
2000 ft.
120 nm
60 nm
Sx = 10 minutes

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

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

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)

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 767-200 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)

• More recently, Boeing obtained certification for longer
diversion rules for the Boeing 777 family of aircraft
(see article at http://www.boeing.com/news/releases/2007/q2/
070514b_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 : http://
www.tc.gc.ca/civilaviation/commerce/manuals/tp6327v00a/
definitions.htm
• More information about ETOPS from the FAA is found at: http:/
/www.faa.gov/newpress_releasesnews_story.cfm?newsId=7975

ETOPS Trans-Pacific Flights

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"

Sample ETOPS Flight
-140 -120 -100 -80 -60 -40 -20 0 20
0
10
20
30
40
50
60
70
80
Distance traveled (nm) 4359.3772
Longitude (deg.)
Latitude(deg.)
IAH (Houston)
CDG (Paris)
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)

Possible Diversion Points (Airports)
-80 -70 -60 -50 -40 -30 -20 -10 0
30
35
40
45
50
55
60
65
70
75
Distance traveled (nm) 4359.3772
Keflavik
Gander
Santa Maria
Shannon

Have There Been Diversions?
Two very well known cases:
a) Air Transat Airbus A330-200 lost both engines (due to fuel
starvation) over the Atlantic and landed safely at Lajes (in the
Azores)
See report at: http://www.moptc.pt/tempfiles/
20060608181643moptc.pdf or read article at: http://
en.wikipedia.org/wiki/Air_Transat_Flight_236
b) Boeing 767-200ER traveled more than 300 minutes in a flight
from North America to Hawaii (landed safely with engine
operative)

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.

• Modest drag condition (intermediate altitude)
0.5 0.6 0.7 0.8 0.9
1
1.5
2
2.5
3
3.5
4
4.5
x 10
5
Mach Number
DragorThrust(Newtons)
Drag (N) at: 6000 meters
Thrust (N) at: 6000 meters
0.5 0.6 0.7 0.8 0.9
0.5
1
1.5
2
2.5
3
3.5
4
4.5
x 10
5
Mach Number
DragorThrust(Newtons)
Drag (N) at: 6000 meters
Thrust (N) at: 6000 meters
Two Engines One Engine

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

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)

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)

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
Airport Terminal
Independent arrival streams
Runway 1
Runway 2
4,300 ft. or more

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

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)

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
R 2
5,000 ft. or more
Runway 2
Runway 3

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
Runway 2
2,500 ft.

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.
Runway 1
Runway 2
2,500 ft.
Arrival
Stream
Departure
Stream

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
Runway 2
2,300 ft.
1,000 ft.

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
Runway 2
2,700 ft.
1,000 ft.
Overlap
Region

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 2
700 ft. or more
No wake vortex
effect (seldom
the case)
Increase to
1,200 ft. if
aircraft belong to
Design groups V and VI

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

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).
Dependent arrival streams
Runway 1
Runway 2
2,500 ft. or more 1.5 nm 1.5 nm

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)

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

ATC Equipment and Runway Separations Explained

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