5 Measurement Method
5.1 Reference checkpoint
A checkpoint shall be selected during the commissioning inspection at a point in space where the signal is stable. This checkpoint shall be used in establishing course alignment, 30 Hz Modulation Depth, 9960Hz Modulation Depth and Field Strength to be recorded on the Flight Inspection report (1964).
The position of the reference checkpoint should be recorded in terms of azimuth, distance from the facility, and the mean sea level (MSL) altitude (1965).
5.2 Alignment
The mean alignment shall be determined by flying a 360 degree orbit of the VOR (1966). The altitude selected for the flight should place the aircraft in the main lobe of the VOR (1967).
Alignment shall be recorded at the reference check point (1968).
5.3 Bends Bends shall be determined on all flown radials (1969).
5.4 Roughness and Scalloping Roughness and Scalloping shall be determined on all flown radials (1970).
5.5 Coverage
Measured as close to the edge of DOC as possible whilst flying either a radial or an
orbit (1971).
Field strength shall be recorded at the reference check point (1972).
At commissioning useable signals shall be established by two level flights, separated
by approximately 90 degrees (1973).
5.6 Modulation 30Hz and 9960Hz
The mean modulation depth shall be determined by flying a 360 degree orbit of the VOR (1974). The altitude selected for the flight should place the aircraft in the main lobe of the VOR (1975).
Modulation shall be recorded at the reference check point (1976).
5.7 Voice Checked as close to the edge of DOC whilst flying either a radial or an orbit (1977).
5.8 Identification Checked as close to the edge of DOC whilst flying either a radial or an orbit (1978).
5.9 Polarization The vertical polarization effect shall be checked when flying a radial at a distance of
18.5 to 37 km (10 to 20 NM). The aircraft should be rolled to a 30 degree bank, first to one side, then to the other, and returned to a straight level flight. Track and heading deviations should be kept to a minimum. Course deviation, as measured on the recording, is the indication of vertical polarization effect (1979).
6 Profiles to be checked
6.1 The following table gives details of the Profiles, which shall be checked.
Profile Commissioning Routine
Transmitter to be checked
Radials 1 or 2 (1980) 1 or 2 (1981)
Approach Procedures 1 & 2 (1982) 1 & 2 ** (1983)
Cross check radials 1 or 2 * (1984) None
Intersections 1 or 2 as required (1985) None
Holds 1 & 2 as required (1986) None
** For routine inspection of dual transmitter Doppler VORs, where it can be demonstrated that the alignment error between the transmitters is small i.e. . 0.5 degrees, then only one transmitter needs to be checked.
* Flight inspection of cross-check radials is not required provided there is sufficient flight inspection data to support the use of those radials.
6.2 Radials
A selection of radials, which support Instrument Flight Procedures other than
Instrument Approach Procedures, should be inspected (1987).
The selection should be based on the following:
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