RVSM compliance is a multi-step process which includes equipment installation, test flights, pilot training and a letter of authorisation (LOA) from the FAA. The LOA certifies that aircraft and pilots are RVSM qualified. Upgrade costs range from $73,000 to $165,000, with the average falling between $100,000 and $120,000, says Paul Clouse, director of RVSM operations for Annapolis, Maryland-based Arinc. But it is likely that competition will drive prices down, he says.

Basic components of an RVSM upgrade include dual digital air data computers; single or dual digital altimeter (depending on the capability of the aircraft's existing altimeter); and new or modified pitot-static system. Components must be certificated for RVSM use, either under the airframe manufacturer's service bulletin (SB) or, in the case of an independent shop, a supplemental type certificate (STC).

Certifications are granted on either a group or individual basis. A group SB or STC usually applies to most members of a specific aircraft family, while an individual solution caters to those that do not conform to the majority within that group - for example, if the autopilot differs from that used by the other members of the family. An individual solution is often specific to an aircraft's factory serial number.

John Sotak, vice president engineering for Dassault Falcon Jet, says group solutions are the easiest to install, and require less downtime because they are already available. An individual solution requires a special engineering and certification plan that must be developed for one aircraft. For both types of solutions, the aircraft's air data system must be upgraded to meet the tighter altitude tolerances. This involves a ground and flight test programme to verify that the upgraded system will work with RVSM.

Whether the operator takes the group or individual upgrade route, it must apply for certification to fly the aircraft in RVSM airspace. This involves a height monitoring flight, to be performed by an FAA-approved organisation. These flights use a GPS monitoring unit (GMU) to verify the accuracy of the equipment. The unit also monitors the autopilot to make sure it keeps the aircraft within RVSM tolerances - ±6ft of the designated altitude.

The 30min test flight is usually carried out at 29,000ft (8,850m). Data collected by the GMU is downloaded to a laptop by a technician monitoring the flight, then emailed to the FAA technical centre in Atlantic City, New Jersey, where data is compared to the meteorological conditions at the time and place of the test flight. The FAA then informs the owner if the aircraft maintained height within tolerances.

An LOA application involves the preparation of a multi-document package describing the modification process. "You have to provide documentation that the components - and the shop that installed them - meet the FAA's requirements," says Clouse. Applicants must verify that the systems passed the height-keeping test and will be maintained in airworthy condition.

Operators must prove there is an ongoing training programme for those who will maintain the aircraft and fly it within RVSM airspace. "That includes emergency training to operate the aircraft if any of the RVSM equipment fails," says Clouse. The FAA requires renewal of the LOA every two years.

Source: Flight International