Parameter Commissioning Annual / Routine Transmitter to bechecked
Polarisation Only required at the commissioning of an aerial system which is new to the UK.Polarisation error when the aircraft is in a roll attitude of 20° shall be no greater than:Cat I 0.016 ddm (1215).Cat II 0.008 ddm (1216).Cat III 0.005 ddm (1217). As required
Parameter Commissioning Annual/ Routine Transmitter to be checked
AlignmentOf the promulgatedglidepath angle Cat I ± 1.5% (1910)Cat II ± 1.0% (1911)Cat III ± 1.0% (1912) Cat I ± 7.5% (2173)Cat II ± 7.5% (2174)Cat III ± 4.0% (1915) Commissioning 1 & 2Annual 1 & 2Routine 1 & 2
Displacement SensitivityOf the nominal displacement sensitivity Cat I ± 8% (1919)Cat II ± 6% (1920)Cat III ± 5% (1921) Cat I ± 25% (1922)Cat II ± 20%(1923)Cat III ± 15% (1924) Commissioning 1 & 2Annual 1 & 2Routine 1 & 2
Symmetryof upper/lower half sector. Of the measureddisplacement sensitivity Cat I 33% to 67%. (1928)Cat II 42% to 58%. (1929)Cat III 42% to 58%. (1930) Commissioning 1 & 2Annual 1 & 2Routine 1 & 2
Mod Sum SDMSum of the depths ofmodulation of the navigational tones 78% -82% Measured when approaching the facility, where the ddm is approximately zero (1931). 75% -85% Measured when approaching the facility, where the ddm is approximately zero (1932). Commissioning 1 & 2Annual 1 & 2Routine 1 & 2
Below Path ClearanceNormal Operations The clearance below path should be measured close to the edge of the Designated Operational Coverage (DOC).There shall be a smooth increase in ddm from the glidepath angle to an anglewhere 190 μA fly-up (0.22 ddm) is reached. This shall occur at not less than 0.3θ (2165). Where this is achieved at an angle above 0.45θ, the fly-up must not fall below 190 μA (0.22 ddm)between this angle and 0.45θ or to such lower angle, down to 0.3θ, as required to safeguard the promulgated glidepath intercept procedure (2166).Where coverage between 0.45θ and 0.3θ is less than the specified datum, but sufficient current is present to remove the flag alarm, the fly-up shall not fall below 190μA (0.22 ddm) (1230). Commissioning 1 & 2Annual 1 & 2Routine 1 & 2
Parameter Commissioning Annual/ Routine Transmitter to be checked
Below Path ClearanceCourse onlyNote:This check is to ensurethat 2 frequency M- Arrays have beencorrectly set up and that the clearance transmitteris not hiding a problem Cat IBetween the glidepath angle and 0.45θ or to such lower angle, down to 0.3θ, as required to safeguard the promulgated glidepath intercept procedure, the ddm must remain 150 Hzpredominant wherever a useable signal is present. (2167)Cat II / IIISmooth increase in ddm from the glidepath angleto an angle where 150 μA fly-up (0.175 ddm) is reached. Between this angle and 0.452 or to such lower angle, down to 0.3θ, as required tosafeguard the promulgated glidepath intercept procedure, the ddm must remain 150 Hzpredominant wherever a usable signal is present.(2168)Note: With clearance signal removed, there is norequirement to meet any coverage (signal strength) specification. Only the value of ddm is being examined. N/A Commissioning 1 or 2Annual NoneRoutine None
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