These articles were written in 1999. Please refer to current regulatory guidance for compliance purposes.

Global RVSM implementation
A cooperative effort between providers and users.

By Anita Trotter-Cox,
Assessment Compliance Group, Inc.

Published in Professional Pilot Magazine,
March 1999

Exhaustive studies have demonstrated that global reduction of vertical separation is safe, feasible, and cost beneficial and can be implemented without imposing demanding, system-wide, technical requirements. February 24, 2000 is the target date for RVSM (Reduced Vertical Separation Minima) implementation in the Pacific Region with implementation to begin in European airspace in January 2002. Planning is underway to implement RVSM in the WATRS (Western Atlantic Region System) area, however, no target date has been established.

The NAT (North Atlantic) Region was selected for early implementation because traffic flows were mainly unidirectional and the heightkeeping accuracy was better than average due to Minimum Navigation Performance Specifications (MNPS) navigation performance. Phased implementation where aircraft are separated by 1000 feet vertically between FL 290 and Fl 410 inclusive, began in March 1997 (FL 330 - FL 370) and was followed by the next phase in October 1998 (FL 310 - FL 390). The date for full implementation (FL 290 - FL 410) is still under review by the ICAO North Atlantic Systems Planning Group (NATSPG).

RVSM approval

By now, most operators have become very familiar with Interim Guidance 91-RVSM
(www.faa.gov/ats/ato/rvsm1.htm) and 14 CFR Part 91 Appendix G FAR 91 Appendix G as primary references for the approval criteria and process for US registered aircraft. For operators flying under 14 CFR Part 91, the approval is granted in the form of a "Letter of Authorization" and for Part 135 operators, it's a change in the operations specifications.

We've come a long way since 1995 in understanding how to obtain RVSM operational approval for both the aircraft and the operator. There are 840 US General aviation aircraft currently approved. This time last year, more than 80% of the traffic operating in the Shannon Transition Area was RVSM approved NAT traffic. The approval process includes airworthiness, continuing airworthiness approval, operational approval and provisions for monitoring. For a large number of aircraft types, however, monitoring is no longer required prior to operational approval being granted. Specific aircraft types, as well as other valuable RVSM information for the NAT region, can be found on the ARINC website (www.arinc.com). In addition to the location of the HMU (Height Monitoring Unit) in Strumble, you can also find the coordinates for the new Gander HMU.

As part of the operator approval, most of us have had our "formal training" and our RVSM manuals written and submitted. Officially, written manuals are not required for 14 CFR Part 91 operators, but a few FSDOs have required them either as separate RVSM operations and maintenance manuals or as part of an international operations manual. This documentation demonstrates to the FAA that the operator has specific operational procedures in place for flightcrews, operations personnel, and maintenance technicians and that these procedures are coordinated. For example, your procedures should explain who will be the primary responsible authority for developing and monitoring department RVSM requirements, procedures, and directives.

Non-RVSM aircraft (These procedures currently apply only to the NAT Region)

MNPS approved aircraft that are not yet approved for RVSM airspace may still be cleared, subject to traffic, to climb or descend through RVSM flight levels to cruise at flight levels above or below RVSM airspace (currently FL 310 - FL 390). A continuous climb or descent must be made without stopping at intermediate levels and a "Report Leaving" the current level and a "Report Reaching" the cleared flight level must be made.

If you are RVSM approved and become non-RVSM approved due to equipment failure, ATC can provide you with an altitude reservation for an RVSM level for you to return to your base for repair and/or reapproval. You will need to call OAC (Oceanic Area Control Center) by telephone not more than 12 hours or not less than 4 hours prior to the intended departure time. Don't forget to note the approval and flight level in Item 18 of your ICAO flight plan. This exception is also extended to aircraft delivery, humanitarian and mercy flights.

"For operators struggling with the RVSM approval process without the support of the manufacturer or a Service Bulletin, avionics solutions do exist, or will soon become available, for nearly every airframe conducting operations in RVSM flight levels." So says Tony Wiederkehr of AeroMech Inc.(Email: contact@aeromechinc.com) who believes the non-group operator now has several options that were not available, say, 18 months ago.

Our NAT experience - a few operational changes

During the first two implementation phases in the NAT, few difficulties were encountered. With additional flight levels, there are now fewer time restrictions westbound and obviously an increase in operational flexibility. With a greater opportunity for random routing and better altitudes, airspace users have reported an increase in satisfaction. New York Center also noted a flawless implementation while experiencing improved operations and greater efficiency.

Initially, there was some flight planning confusion with the inclusion or exclusion of W in Item 10 (equipment) of the ICAO flight plan. The letter W was chosen by the NAT Region to indicate RVSM approval of the aircraft and operator to conduct RVSM operations. Inflight, pilots have experienced wake turbulence encounters and a NOTAM for Track Offset procedures was issued. These contingency procedures can now be found on the Jeppesen Atlantic Orientation Chart H/L 1/2 (Panel 8). It's important to note that these Track Offset procedures may not be used in the adjacent domestic airspace identified as RVSM Transition Areas (FL 290 - FL 410). Transition Areas have been implemented where different separation standards, RVSM and CVSM (Conventional Vertical Separation Minima), exist between adjacent airspace.

 
Figure 1. Wake Turbulence Report Form

Any pilot who encounters a wake turbulence incident while flying in the NAT MNPS airspace or in the adjacent RVSM Transition Areas should ensure that a detailed report be submitted to the regional CMA (Central Monitoring Agency). A suggested Wake Turbulence Report Form (Figure 1) can be found in the North Atlantic MNPS Airspace Operations Manual - Seventh Edition. The manual can be downloaded from the NBAA website (www.nbaa.org).

Along with an emphasis on heightkeeping equipment and procedural requirements during preflight, inflight, and postflight, flightcrews should be aware that contingency procedures have changed. Primarily, during a contingency maneuver, a 500 ft climb or descent altitude offset is used instead of 1000 ft. Additional requirements for altitude readback and reports of reaching assigned altitudes apply to both RVSM and CVSM altitudes. New York FIR (Flight Information Region) requires a WAH (When Able Higher) Report by all aircraft entering RVSM and/or MNPS airspace. Advising ATC of the time or position the aircraft can accept the next higher altitude will ensure maximum use of available altitudes. This information is important for the controllers to plan the altitudes for the transition from RVSM to CVSM.

Under certain conditions in NAT RVSM airspace, TCAS (Logic Version 6.04a) can issue nuisance TAs (Traffic Alerts) alerting the pilot to another aircraft that is correctly separated vertically by 1000 ft above or below and following the same track. It is recommended that climb and descent rates in RVSM Airspace and Transition Areas be limited to 1000 fpm when operating within five (NM and +/- 2000 feet of other aircraft to minimize the generation of TAs and RAs. However, it is important to note that TCAS should always be operated in the TA/RA mode during all operations in RVSM airspace. The FAA has provided operators and FAA inspectors with supportive training information entitled Training Considerations for Using TCAS in RVSM Airspace posted on their website
(www.faa.gov/ats/ato/rvsm1.htm).

Written reports are necessary for all RAs requiring a change in the existing vertical speed while operating in the RVSM airspace and Transition Areas. Reports on TAs are encouraged but not required. An Altitude Deviation Report Form (Figure 2) can be used and submitted to the CMA (address is on the form). This form should be used for any altitude excursion due to TCAS, turbulence or a contingency procedure greater than 300 ft. In addition, as part of the ongoing TCAS Transition Program, it would be helpful (not mandatory) to fill out a TCAS Pilot Event Questionnaire (Figure 3). These forms can be obtained from Sean Reilly at TTP ARINC, Inc. (410 266 2904). Any information or comments you write will be confidential and not made public.

Why all the paperwork? The information received by the CMA allows a continual assessment of the actual performance of airspace users under RVSM standards. The CMA has been a necessary and integral part of the RVSM implementation process to ensure that the collision risk does not exceed the TLS (Target Level of Safety). When flying in MNPS airspace or airspace in which RVSM may be applied, flightcrews are encouraged to maintain detailed inflight records and report any altitude excursion in RVSM airspace.

RVSM in the Pacific

RVSM will be implemented in the Pacific Region in February 2000. A possible exception to this is the area known as the Central East Pacific (CEP). Work is now underway between the air traffic service providers in the region to develop a common operational concept. You can follow the work of the ICAO RVSM Implementation Task Force (ICAO Asia and Pacific Office) by accessing the agenda and minutes on the FAA website.

In preparation for the implementation of RVSM in the Pacific, a Pacific Monitoring Agency has been established. This agency, the APARMO (Asia Pacific Approvals Registry and Monitoring Organization), is being hosted at the US FAA's WJHTC (Wm. J. Hughes Technical Center). The duties and responsibilities of the APARMO have been modeled on the CMA, which is hosted by the United Kingdom CAA (Civil Aviation Authority).

Any aircraft wishing to fly in PAC (Pacific) RVSM airspace must be approved and must indicate that approval in Item 10 of the ICAO flight plan by entering the letter W. In other words, if you are currently indicating your approval by entering the letter W on your ICAO flight plan for the NAT Region, then you are approved for the Pacific Region.

As in the NAT Region, you may be asked by an Air Traffic Controller if you are approved to operate in PAC RVSM airspace when you request your oceanic clearance. If you can't confirm that you're approved, except in an emergency situation, you will be asked to climb or descend clear of PAC RVSM airspace.

Figure 2. Altitude Deviation Report Form

The same Altitude Deviation Report Form will be required of an altitude deviation of 300 ft or more, including those due to TCAS, turbulence and contingency events. The only difference is that it will be sent to the WJHTC in Atlantic City NJ.

The Guidance Material on the Implementation of a 300 M (1000 ft) Vertical Separation Minimum (VSM) for Application in the Airspace of the Pacific Region has been published to assist in the preparation for implementation of RVSM (www. faa.gov). This guidance material has been developed for the Pacific Region as a basic reference document for use by State authorities in developing procedures and documentation for aircraft and operator approval. It is based on the ICAO Manual on RVSM (DOC 9574), the current work of the RGCSP (Review of the General Concept of Separation Panel), and NAT Doc. 002 (www.icao.org) and should be available in the near future.

The content will look very familiar to those of us who have referenced the FAA Interim Guidance 91-RVSM. Both 91-RVSM and the JAA Temporary Guidance Leaflet-6 (www.nbaa.org) are included as appendices.

RVSM in Europe

Due to its complex nature, the European Air Traffic Services is a more demanding environment to implement RVSM than in the NAT Region. These complexities include its route structure, a wide variety of aircraft types, high traffic density and a high percentage of climbing and descending aircraft. However, key elements from the NAT can still be utilized and any duplication of work should be avoided.

A major challenge, unlike the NAT Region's 5 ATS providers and 7 Provider States, is the fact that Europe has 60 ATC Centers along with 38 ECAC and non-ECAC States with more than 100 Letters of Agreement between ATCCs (Air Traffic Control Centers) to be amended. There will also be about 8000 airframes flying at RVSM levels with some 150 States of Registry for those airframes. And, of course, State aircraft must be accommodated with 2000 ft separation for formation flights, refueling etc. Written commitments are needed from all States involved and implementation must take place on the same day throughout the entire RVSM airspace. If one State does not agree with the Master Plan or does not participate, then it would not be feasible to continue with RVSM implementation. RVSM in Europe will provide 6 additional flight levels between FL 290 and FL 410. You can monitor the progress and obtain additional information through either of the following websites: (www.ecacnav.com) or
(www.eurocontrol.be)

 
Figure 3. TCAS Transition Program-Pilot Event Questionnaire (Logic Version 6.04a)

Unlike the NAT Region, monitoring will not be part of the approval process. There will be monitoring to verify that the TLS has not been compromised but this will be transparent to the airspace user. Along with the HMU at Strumble, which is no longer a demo model, there will be 3 addition sites: Nattenheim, Linz, and Geneva. The coverage area will be 45 miles vs. the 10 miles at Strumble. Strumble HMU coverage measures only one airway while Geneva, for example, will measure at least 10 airways. Twenty-five enhanced GMUs (GPS Monitoring Units - SSR Codes and DGPS) will complement the monitoring process with the CMA continuing to maintain the database. They have received funding priority, which demonstrates serious commitment.

The EBAA (European Business Aircraft Association) has stated that the majority of the European-registered business jet fleet is not long-range. The heavy economical impact on reasonably amortized equipment may prove disastrous. Some are still without a technical solution available to them to comply with RVSM. Nearly 60% will not be able to meet the airworthiness criteria for RVSM. The EBAA's position is that they would like to see some airspace reserved for non-conforming aircraft.

"Aircraft which have been approved in compliance with JAA Information Leaflet No. 23 or FAA Interim Guidelines 91-RVSM satisfy the airworthiness criteria of this TGL No. 6 and credit may be taken for this prior approval." However, there are specific procedures for European RVSM implementation that may have to be incorporated into our pilot training programs, which should include the appropriate RVSM phraseology.

Wake vortex encounters create a larger challenge in the European air environment. This is due to the turning points (airway junctions), mountain turbulence, climbs from and descents to airports, more communications activity, greater traffic density, higher proportion of military operations, and the higher proportion of smaller transport and business jet operations. Unlike the NAT Region, into wind Track Offsets will not be practical. Still, RVSM is not expected to be dangerous or unsafe. When climbing or descending through a flight level ahead of a smaller aircraft, a 30 NM separation is recommended and a 20 NM separation is recommended for the same weight aircraft.

The process of changing separation standards in oceanic airspace has been a dedicated and joint effort of representatives of ICAO (International Civil Aviation Organization) member States over many years. These efforts include representatives from State regulatory agencies, aircraft manufacturers, airlines, and international industry associations conducting regular dialogue with pilots and controllers. They attend and contribute to task force meetings and worldwide educational seminars. ATC interface simulations are conducted along with controller and pilot training. It is a huge task and a challenge to all the Provider states and the Air Traffic Control Centers involved in the planning and implementation of RVSM. Close cooperation for harmonized and progressive information and the use of the NAT experience and data will be required to meet the TLS and provide the benefits of RVSM to all airspace users.

Anita Trotter-Cox is an ATP/CFII pilot with GIV/GI/Westwind 1124 type ratings. She holds a Masters Degree from Washington University. She is President of Assessment Compliance Group, located in Rockville, MD and provides flight departments (Part 91, 135 and 121) with International operations procedures manuals and support for standardized procedures for advanced technologies.
(atc@aviationmanuals.com).

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