One of the requirements for aircraft RVSM certification is Height / Altitude Monitoring. What this means is that the aircraft must undergo testing which tracks and validates the ability of the onboard equipment to accurately determine and report the altitude of the aircraft within the strictly defined tolerances required for RVSM operations.
This is to be done within six months of the RVSM approval. Check with CSSI below for specific time requirements. You do not need to fly your aircraft someplace else for a check.
Quick Info: CSSI is the choice for height monitoring. Basically, they charge a flat fee of about $1,750 per aircraft, plus travel cost to your location. They have folks all over the country so travel costs may vary. The flight takes about two hours or less total on the aircraft with at least 30 minutes of that being in straight flight. They bring the equipment to you on your schedule, you fly, and the results are passed to the FAA along with the other paperwork. We know they sometimes try to group several tests in one location to save travel costs.
FAA Height Monitoring Procedures
For European Operations:
http://www.faa.gov/ats/ato/150_docs/Europe_Mntr_Mar29.doc
Depending on the aircraft, this testing requirement may be met by one of these methods.
- HMU Flight
- GMU Flight
- Group Certification
The following information about HMU and GMU appears on the EUR/RVSM Official Web Site for the European Reduced Vertical Separation Minimum Programme
http://www.ecacnav.com/content.asp?CatID=25
1. HMU Flight - Height Monitoring Unit (Ground-Based)
The HMU is a passive ground based system that measures aircraft height keeping within its area of cover. Each system consists of a set of ground stations arranged as a central site with four additional receivers arranged in a square. Each site receives aircraft SSR (Secondary Surveillance Radar) replies (Modes A, C and S) from which the 3D position of the aircraft is derived. Using meteorological information and the Mode C/S height data it is possible to calculate the altimetry system error.
The European HMUs locations are:
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Linz in Austria [centre 48�12’N, 014�18’E]
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Nattenheim in Germany [centre 49�57’N, 006�28’E]
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Geneva in Switzerland [centre 46�22’N, 005�56’E] |
Note: The HMUs developed and implemented in the context of NAT RVSM (such as the HMU near Strumble, Wales) may also be used for monitoring.
European Height Monitoring
http://www.ecacnav.com/content.asp?CatID=25
2. GMU Flight - GPS Monitoring Unit Flight
A GMU is portable, contained in a 12x29x26cm sized case containing 2 independent GPS receivers with 2 separate antennas and a device for storing the GPS three dimensional positioning data. The GMU is positioned on the relevant aircraft and functions independently of the aircraft's systems. Following the flight, the recorded data is sent to a central site where, using differential post processing, the aircraft altimetry system error is determined.
The characteristics of the GMU are:
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Portable device for easy installation |
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Independent from all aircraft systems |
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Reception of GPS signals by 2 GPS antennae attached to windows on either side of aircraft |
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Reception and processing of mode A/C, mode S transponder signals with integrated antenna |
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Onboard recording of GPS and transponder data during flight on disk |
GMU monitoring is intended for those operators which have aircraft for which it is impractical to overfly an HMU.
3. RVSM Group Certification
It is possible that an aircraft which carries a group RVSM certification may not need flight testing. Group RVSM certification may be granted by one of these methods:
Service Bulletin
Service Letter
STC (Supplemental Type Certificate)
Please note that group certification is very limited at this time. Also note that just because one aircraft of a certain type may be RVSM group certified, another aircraft of the same type may not be RVSM group certified. Group certification is noted by aircraft serial number. Check with the aircraft manufacturer if you think that your aircraft might be included under a RVSM group certification.
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