Implementation of The Reduced Vertical Separation Minimum (RVSM) In Domestic U.S. Airspace

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Implementation of The Reduced Vertical Separation
Minimum (RVSM) In Domestic U.S. Airspace
Meeting No. 96 Aerospace Control And Guidance
Systems Committee October 18 21 , 2005
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Overview
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Overview

• (1) What Is the Reduced Vertical Separation
  Minimum (RVSM)?
• (2) RVSM History
• (3) Domestic U.S./North American RVSM
• (5) Safety Challenge Monitoring Aircraft
  Height-Keeping Performance

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What Is the Reduced Vertical Separation Minimum
(RVSM)?
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What is the Reduced Vertical Separation Minimum,
the RVSM?

• The Reduced Vertical Separation Minimum (RVSM) is
  the introduction of a 1000-foot vertical
  separation standard, or minimum permissible
  vertical spacing between aircraft on the same
  route, from flight altitude 29000 ft to flight
  altitude 41000 ft, inclusive, in place of the
  existing 2000-foot value, introduced in 1958
• The RVSM provides fuel-burn reduction benefits to
  aircraft operators and operational flexibility to
  air traffic controllers, when compared to the
  2000-ft value
• The FAA has played a major typically leading -
  role in several RVSM implementations to date, and
  the FAA Technical Center has been a partner in
  these activities

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RVSM History
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Early Vertical Separation Practices

• In 1940s, vertical separation minimum was
  1000-ft in virtually all cases
• Operation of turbojet military aircraft and
  anticipated advent of turbojet civil aircraft led
  the International Civil Aviation Organization
  (ICAO) to form Vertical Separation Panel in June
  1954 in order to
• identify those factors likely to contribute most
  to loss of vertical separation and propose steps
  that should be taken to reduce or eliminate their
  influence
• Vertical Separation Panel concluded (1957), based
  on state-of-the-art in altimetry system design,
  that 29000 feet of pressure altitude should be
  upper limit for 1000-ft vertical separation
  minimum and that 2,000 ft should be used above
  that level

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Establishment of Global Separation Minima

• At a 1958 meeting of ICAO States, it was agreed
  internationally that
• Based on work of Vertical Separation Panel
  vertical separation minimum between aircraft
  operating under air traffic control shall be a
  nominal 1000 ft below an altitude of 29000 ft, or
  flight level 290 (FL290), and a nominal 2000 ft
  at or above this level, except where, on the
  basis of regional air navigation agreements, a
  lower level is prescribed.
• Subsequently, ICAO Regional Planning Groups,
  particularly North Atlantic Systems Planning
  Group, initiated activities to increase the
  ceiling at which the 1000-ft minimum would apply

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FAA and ICAO Work During 1980s

• In February 1982, the FAA announced plan which
  would lead to introduction of 1000-ft vertical
  separation minimum between FL290 and FL410
• Benefit-cost analysis indicated substantial value
  to change
• Fostered establishment of RTCA Special Committee
  150 to bring industry and government experts
  together to develop standards leading to reduced
  vertical separation standard value at high
  altitude
• In same year, ICAO Review of the General Concept
  of Separation Panel (RGCSP) now Separation and
  Airspace Safety Panel adopted as its primary
  task the global reduction in high-altitude
  vertical separation minimum

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ICAO RGCSP Contributions

• States contributing to Panel work conducted data
  collection and standards development work from
  1983 through 1986
• In December 1988, RGCSP concluded that 1000-ft
  vertical separation minimum between FL290 and
  FL410 was technically feasible without causing
  undue burden to operators.
• In November 1990, RGCSP completed draft guidance
  material and submitted document to ICAO Air
  Navigation Commission
• Approved guidance material published as ICAO
  manual in March 1992 basis for all RVSM
  implementations

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First Implementation

• ICAO North Atlantic Region followed RGCSP
  developments and agreed at 1992 Regional Air
  navigation Meeting to introduce the Reduced
  Vertical Separation Minimum (RVSM) into Minimum
  Navigational Performance Specification airspace
  in September 1996
• North Atlantic Operations and Airworthiness
  Subgroup, led by FAA Flight Standards, developed
  State RVSM approval process applicable to
  operators and aircraft
• Published in draft form as AC 91-RVSM in 1994
• First aircraft approved in late 1995
• Large numbers of aircraft not approved until mid-
  to late 1996

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First Implementation - Continued

• Air traffic providers in North Atlantic developed
  RVSM procedures and identified transition
  airspace in 1996
• By late 1995, North Atlantic Reduced Separation
  Standards Implementation Group, with substantial
  FAA Technical Center participation, had developed
  novel systems to monitor aircraft height-keeping
  performance as quality-control check that
  aircraft requirements of AC 91-RVSM were met
• RVSM introduced into North Atlantic in March 1997

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Subsequent RVSM Implementations

• All Pacific international airspace February
  2000
• FAA led multi-State ICAO Pacific RVSM Task Force
• FAA Technical Center chaired Safety and Airspace
  Monitoring Working Group of Task Force
• Europe January 2002
• Western Pacific/South China Sea February 2002
• FAA led ICAO Asia-Pacific RVSM Task Force
• Technical Center again chaired Safety and
  Airspace Monitoring Working Group

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RVSM Implemented PlannedAs of October 2005
Canada North 4/02
Japan/Korea 9/29//05
Canada South 1/05
Europe 1/02
Domestic US 1/05
Caucasus Area 3/17/05
NAT 3/97
Pacific 2/00
Mid East 11/03
EUR/SAM Corridor 1/02
Pacific 2/00
WATRS 11/01
Western Pacific South China Sea 2/02
Asia/Europe South of Himalayas 11/ 03
Africa
CAR/SAM 1/05
Australia 11/01
Implemented
Planned
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Domestic U.S./North American RVSM
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Domestic U.S. RVSM

• RVSM introduced into U.S. domestic airspace on
  January 20, 2005
• The most significant change in U.S.
  high-altitude airspace since the introduction of
  the Jet Route structure in 1963
• Canada implemented RVSM south of 57 degrees north
  latitude and Mexico implemented RVSM in all
  sovereign and delegated airspace on same date at
  same time, resulting in North American RVSM
• All States of ICAO Caribbean and South American
  (CAR/SAM) Regions also introduced RVSM on same
  date, at same time
• Technical Center supported North American RVSM in
  safety and operator readiness areas
• Technical Center also supported CAR/SAM RVSM

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Overview of FAA RVSM Program

• Mid-2001 FAA makes commitment to industry to
  implement RVSM in Domestic U.S. airspace in
  December 2004
• Late 2001 FAA Flight Standards, Air Traffic
  Services and Research and Acquisitions begin
  intense preparations for Domestic RVSM
• February 2002 FAA begins series of Domestic
  RVSM seminars
• October 2003 RVSM Change to FARs approved
  after rulemaking process
• December 2003 Canada and Mexico agree to North
  American RVSM implementation (formal bi-lateral
  agreements signed in June 2004)
• September 2004 Decision to implement North
  American RVSM

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FAA Elements Contributing to Domestic RVSM
Implementation

• Flight Standards
• Challenge Approve as many 20 000
  U.S.-registered aircraft, starting from June 2002
  base of 3 700 aircraft approved in connection
  with RVSM implementations up to that point
• (9 000 U.S.-registered aircraft currently
  approved for RVSM operation)
• Air Traffic Organization Enroute (ATO-E)
• Challenge Develop operational concept, new
  procedures, train more than 7 000 controllers,
  modify automation system, ensure RVSM
  compatibility with current National Airspace
  System operations and other planned changes

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FAA Elements Contributing to Domestic RVSM
Implementation - Continued

• Air Traffic Organization Operations Planning
  (ATO-P)
• FAA Technical Center
• Challenge Support ATO-E in development/refinemen
  t of operational concept, assist in controller
  training
• Support Flight Standards in tracking aircraft
  approvals, monitoring aircraft height-keeping
  performance to ensure compliance with aircraft
  height-keeping performance requirements,
  conducting operator readiness and safety
  assessments

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Safety Challenge Monitoring Aircraft
Height-Keeping Performance
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Background

• First implementation of the RVSM was 1997 ICAO
  promulgated 2000-ft standard in 1958
• So..Why did it take so long to make the change?
• Answer Developing sufficient, reliable
  information on aircraft height-keeping
  performance is formidable task
• Aircraft height-keeping performance is the result
  of the the performance of two aircraft systems
  altitude-keeping system and altimetry system

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Aircraft Height-Keeping Systems

• Altitude-keeping system
• Feedback control system designed to keep pressure
  altitude flown by aircraft at a commanded value
• Performance of system can be observed by both
  flight crew (altimeter reading) and air traffic
  control (secondary surveillance radar Mode C)
• Common practice in RVSM work to refer to error in
  altitude keeping system as Assigned Altitude
  Deviation (AAD), akin to flight technical error

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Aircraft Height-Keeping Systems - Continued

• Altimetry system
• Barometric pressure sensor/transducer which
  translates ambient static pressure measured at an
  orifice on aircraft to geopotential feet
  (pressure altitude) by means of ICAO Standard
  Atmosphere
• Performance of system cannot be observed by
  either flight crew or air traffic control
• Error in this system referred to as altimetry
  system error (ASE)

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Technical Challenge Obtaining Empirical
Evidence Concerning Aircraft Height-Keeping
Performance

• Empirical evidence of height-keeping performance
  informs requirements-development process
• Must know limits on feasible height-keeping
  performance in order to develop meaningful
  standards
• Empirical evidence of height-keeping performance
  permits assessment of individual-aircraft
  compliance with requirements
• Assessment process is termed monitoring
  height-keeping performance
• Empirical evidence of height-keeping performance
  supports overall assessment of airspace system
  with RVSM safety goals

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Technical Challenge Obtaining Empirical
Evidence Concerning Aircraft Height-Keeping
Performance - Continued

• Aircraft assigned to fly a constant pressure
  altitude are attempting to adhere to an isobaric
  surface
• A constant-pressure surface, but not a
  constant-geometric-height surface
• Obtaining empirical evidence concerning
  height-keeping performance requires estimation of
  geometric height of aircraft and estimation of
  geometric height of isobaric surface defining the
  constant pressure altitude to which the aircraft
  is assigned by air traffic control

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Technical Challenge Obtaining Empirical
Evidence Concerning Aircraft Height-Keeping
Performance - Concluded

• Overall error in adhering to flight level is
  termed total vertical error (TVE)
• Because of the statistically independent and
  additive nature of the two height-keeping system
  error sources
• TVE ASE AAD
• or
• ASE TVE - AAD
• Figure illustrating difficulties of obtaining
  empirical evidence of aircraft height-keeping
  performance for aircraft assigned to 35,000-ft
  pressure altitude (FL350)

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MONITORING PERFORMANCE-THE MAJOR PROBLEM
FL 350 Constant Pressure Altitude
FL 350 Geometric Height
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HEIGHT-KEEPING PERFORMANCE ERRORS
FL 350 Geometric Height
Total Vertical Error (TVE)
Altimetry System Error Assigned
Altitude Deviation ASE AAD
Aircraft geometric height
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Meeting The Technical Challenge

• FAA Technical Center developed process to
  estimate TVE, ASE and AAD to support RVSM
  implementation in North Atlantic international
  airspace
• Refinements have been added
• Recall need to estimate
• Geometric height of aircraft
• Geometric height of flight level
• AAD

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Meeting The Technical Challenge Geometric
Height of Aircraft

• Technical Center completed development of GPS
  Monitoring Unit (GMU) in 1995
• Placed on aircraft for one flight via a temporary
  installation on flight deck
• Collects GPS pseudoranges which are later
  processed to yield estimates of geometric height
  using archived information from International GPS
  Service for Geodynamics

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GPS Monitoring Unit (GMU)
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Enhanced GPS Monitoring Unit (EGMU)
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Typical GMU Installation
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Meeting The Technical Challenge Geometric
Height of Aircraft - Continued

• Ground-based Aircraft Geometric Height
  Measurement Element (AGHME) developed in 2004 to
  estimate geometric height of many aircraft
  operating over a relatively small area
• Listens passively for (at present) Mode S pulse
  trains of aircraft operating within service
  volume of 5-AGHME constellation
• Uses time-difference-of-arrival technique to
  determine aircraft geometric height
• AGHME constellations deployed at five locations
  in U.S. and two in Canada

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Meeting The Technical Challenge Geometric
Height of Flight Level

• Use UK Met Office (Bracknell) and NOAA Global
  Meteorological Model Outputs
• Variables
• - geopotential height (meters) at 10 mb levels
  referenced to MSL
• - virtual temperature (Kelvin) at 10 mb
  levels
• Data Coverage
• - latitude -90,90, longitude -180,180
  in 1.25 x 1.25 degree increments
• - time periods 00Z (back cast) 06Z (forecast)
• 12Z (back cast) 18Z
  (forecast)

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Meeting The Technical Challenge Estimation Of
AAD

• Use FAA secondary surveillance radar collected
  with Enhanced Radar Intelligent Tool (ERIT)
  hardware/software system
• Transfer radar data each night from all 20 FAA
  Air Route Traffic Control Centers to FAA
  Technical Center using internal FAA systems
• Example of radar coverage

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Overview of ERIT Data Collection in CONUS
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Example Of Estimation of Height-Keeping
Performance

• Varig Flight 8923 VRG8923
• Boeing 737-800
• Monitored on June 28, 2005 in flight over Brazil
  while in revenue service

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