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

8 - 10 June 2005 ICAO Safety Management Seminar - Session 14

1Federal AviationAdministration 1

AGCS Committee – Meeting 96

October 19, 2005

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

Federal AviationAdministration




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OverviewFederal AviationAdministration




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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 1940’s, 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 1980’s

• 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

Pacific2/00

Implemented Planned

NAT 3/97

Canada South1/05

Canada North4/02

WATRS 11/01

CAR/SAM 1/05

Europe 1/02

Domestic US1/05

Pacific2/00

**Western PacificSouth China Sea

2/02

Australia 11/01

Japan/Korea9/29//05

Asia/EuropeSouth of Himalayas 11/ 03

EUR/SAMCorridor 1/02

Mid East 11/03

Africa

Caucasus Area 3/17/05




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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 FAR’s 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/refinement 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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FL 350 Geometric Height

FL 350 = Constant Pressure Altitude

MONITORING PERFORMANCE-THE MAJOR PROBLEM




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FL 350 Geometric Height

HEIGHT-KEEPING PERFORMANCE ERRORS

Aircraft geometric height Total Vertical Error (TVE) = Altimetry System Error + Assigned Altitude Deviation = ASE +AAD




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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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Documents

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