## **[North Atlantic Region Reduced Vertical Separation Minimum (RVSM)]{.underline}**

## **[Aircraft Height-Keeping Performance Monitoring Procedures]{.underline}**

1\. [Height Monitoring Information for Operators in the North Atlantic
Region.]{.underline} ICAO

Doc 9574 and regional guidance material require monitoring for all
operators of aircraft that have received RVSM operational approval.
Current monitoring goals should be reviewed for actual requirements;
generally 2 or 3 aircraft of each type must be monitored. Specific
monitoring requirements for the North Atlantic Region, as well as other
RVSM information can be found under the RVSM documentation section at
the FAA RVSM web site:

-   **http://www.faa.gov/ats/ato/rvsm1.htm**

1.1 Monitoring can be conducted after RVSM airworthiness approval is
granted for the aircraft. For most aircraft types, monitoring is not
required prior to the grant of RVSM operational approval, however
participation in monitoring is required in accordance with the current
North Atlantic Minimum Monitoring Requirements Chart. In the North
Atlantic Region, two methods of monitoring can be used. Monitoring can
be conducted by overflying a ground-based Height Monitoring Unit (HMU)
or utilizing the portable, airborne GPS-based Monitoring System (GMS).

**2.** [Ground-Based Height Monitoring Unit (HMU) Monitoring
Procedures.]{.underline} **The Gander HMU was decommissioned in January
2005.** The HMU located near Strumble (STU) VOR still serves the North
Atlantic Region. The HMU provides a 13.8 nm radius of horizontal
coverage centered on the site locations. Strumble is situated at N51^o^
56' 00" W004^o^ 40' 00". The HMU can provide simultaneous height
monitoring measurements within the coverage area for multiple aircraft
operating at FLs 290 to 410.

2.1 Pre-Flight Procedures. Operators planning to overfly the Strumble
HMU should verify its operational status. The Stumble HMU Status Line
provides operational information at

44 \*0 189 542 3823 (\*0 not required from U.S. locations). Operators
planning to overfly the Strumble HMU should file via STU. Dispatchers
should ensure flight plans include both aircraft registration and "HMU
FLT STU" in the remarks section.

2.2 In-Flight Procedures. Crews should fly straight and level within the
coverage area when overflying an HMU to permit quality data collection.
Crews planning to overfly Strumble should transmit "for HMU flight" on
initial contact or to London Control.

2.3 Post-Flight Procedures. HMU Monitoring results can be requested from
the NAT Central Monitoring Agency (CMA) via fax at 44 \*0 189 542 3931
(\*0 not required from U.S. locations). The operator should include the
appropriate Mode S or Mode A codes and estimated time of overflight when
submitting a request for monitoring results.

3\. GPS-based Monitoring System (GMS) Monitoring Procedures.

3.1 GMS Administration. The FAA Technical Center is responsible for all
monitoring activity and the operation of the GMS. CSSI Inc. and ARINC
Inc., serve as GMS support contractors and assist the FAA Technical
Center with the monitoring program.

3.2 GMS Description. The GMS is comprised of the equipment and
procedures to collect and process three required data elements: GPS
data, Mode-C data, and meteorological data. The GPS-based Monitoring
Unit (GMU) is used to collect the GPS data during the monitoring flight.
Mode-C and meteorological data is obtained by the FAA Technical Center
without operator involvement.

3.3 Monitoring Flights. Monitoring can be conducted on scheduled
flights, ferry flights, or monitoring-specific flights. To ensure
collection of sufficient position data, the flight must be straight and
level at any altitude from FL290 to FL410, and should be at least thirty
minutes in duration. Monitoring should also be conducted in areas where
Mode-C radar data can be retrieved in a timely manner. If monitoring is
conducted in areas where Mode-C cannot be obtained, the operator should
provide pressure altitude data from the Digital Flight Data Recorder
(DFDR) to the FAA Technical Center for Altimetry System Error (ASE)
calculation.

3.4 GMU Description. The GMU is a portable unit comprised of a Global
Positioning System (GPS) receiver, two GPS antennas, temporarily mounted
on interior windows, and a laptop computer. The unit requires plug in
power from the aircraft (draws 2.0 to 4.0 amperes maximum) and accepts
multiple types of power standard to aircraft. The GMU can be installed
in the aircraft cockpit or cabin, depending upon aircraft type.
Installation time is approximately 15 minutes. For most transport
aircraft, the GMU is best installed using the aft cockpit windows. The
GMS Monitoring Specialist typically occupies a jump seat to monitor GMU
performance. GMU installation is transparent to crew operations.

3.5 Monitoring Process. Upon receiving airworthiness approval, the
operator should contact a monitoring contractor to discuss monitoring
options. The collection of GPS data with the GMU can be accomplished by
a GMS Monitoring Specialist or by an operator representative that has
received GMU training. The operator and the GMS Operations Coordinator
of the respective GMS monitoring contractor will develop a mutually
agreed upon monitoring plan.

3.5.1 If determined in the planning step that Mode C data will not be
available from any ATC facilities, the operator will take the necessary
steps to retrieve pressure altitude data from the digital flight data
recorder. The DFDR data should be sent to the FAA Technical Center as an
electronic file. The specific format of the electronic file should be
obtained from the FAA Technical Center prior to the monitoring flight.

3.5.2 To conduct the monitoring flight, the Monitoring Specialist or
operator representative that has received GMS training, will perform the
following tasks:

-   Submit preflight flight information form (FIF) to FAA Technical
    Center and GMS Support Contractor

-   Operate GMU

-   Submit post-flight FIF to FAA Technical Center and GMS Support
    Contractor

-   Submit GPS data files to GMS Support Contractor

### 3.6 GMS Post-Flight Information. After completion of the monitoring flight, the GPS data will be processed by the GMS Contractor and forwarded to the FAA Technical Center. The operator will be advised by fax of the processing status of the data file. For the computation of the ASE, Meteorological data and Mode C data will be collected and merged with the GPS data at the FAA Technical Center. Final ASE results should be available from the FAA Technical Center within three weeks of the flight. The results will be sent to the State Civil Aviation Authority (CAA).

3.7 North Atlantic Region GMS Contacts:

> FAA Technical Center RVSM Lead
>
> Phone: 1+609-485-5475
>
> Fax: 1+609-485-5078
>
> Email: wayne.smoot@tc.faa.gov
>
> CSSI, Inc. GMS Operations Coordinator:
>
> Phone: 1 866-468-8111 or 1 202-554-1051
>
> Fax: 1+202-863-2398
>
> Email: <monitor@cssiinc.com>

ARINC, Inc. GMU Operations

Phone: 1+410-266-4707

Fax: 1+410-573-3007

Email: [rvsmops@arinc.com](mailto:eanthony@arinc.com)