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COMMUNICATION, NAVIGATION AND

SURVEILLANCE MANUAL

VOLUME - IV

FLIGHT INSPECTION OF CNS FACILITIES

DEPARTMENT OF CIVIL AVIATION

MYANMAR

1st Edition, 2009

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Department of Civil Aviation, Myanmar CNS Manual Volume IV

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Preface

This Volume IV of CNS Manual consisting of seven volumes is prepared and maintained by the Directorate of CNS, HQ, on behalf of DCA for the use and guidance of executives and staff of DCA. The topics covered under these volumes are as under:-

Volume I – Maintenance of CNS Facilities Volume II – Communication Procedures Volume III – Siting Criteria of CNS Facilities Volume IV – Flight Inspection of CNS Facilities Volume V – Lightning & Surge Protection and Earthing System of CNS Installations Volume VI – Technical Specifications Volume VI – Maintenance Schedules of CNS facilities

This volume contains the Flight Inspection Procedures for navigational facilities. These procedures should be read in conjunction with Doc. 8071 (Flight Inspection Procedures for navigational aids). Wherever there is a difference between a standard prescribed in Doc. 8071 and one in this manual, the standard prescribed in this manual shall prevail.

Although the flight inspection is carried out by FIU aircraft and technical personnel posted in FIU, the field staff should be well versed in carrying out the ground adjustments of navigational aids and tolerance limits of various parameters given in this volume.


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Record of Amendments

No. Amendment Date Incorporated on Incorporated by


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Table of Contents Preface………………………………………………………………………………………………………………………. i Record of Amendments ……………………..………………………………………………………………………. iii Table of Contents ………………………………………………………………………………………………………. v Chapter -1 General 1 Chapter - 2 General Requirements 3

1.0 Introduction ……………………………………………………………………………………………………… 3 2.0 Type of Inspection …………………………………………………………………………………………….. 3 3.0 Periodicity of Flight Inspection ……………………………………………………………………………. 4 4.0 Pre Flight and Post Flight Procedures ………………………………………………………………….. 4 Chapter-3 Flight Inspection Procedure of ILS 7

1. Localizer Flight Inspection …………………………………………………………………………………. 7 1.1 Identification Coding Check ………………………………………………………………….. 7 1.2 Mod Balance and Mod-depth Check ………………………………………………………. 7 1.3 Course Width & Clearance Check …………………………………………………………… 7 1.4 Course Structure Alignment & Fly ability Check ……………………………………… 9 1.5 High Angle Clearance …………………………………………………………………………... 13 1.6 Alignment of Monitor Alarm Check ………………………………………………………. 13 1.7 Width Monitor Alarm Check ………………………………………………………………… 13 1.8 Coverage & Power Monitor Alarm Check ………………………………………………. 14 1.9 Polarization Check ………………………………………………………………………………. 14 1.10 Course Width Symmetry Check …………………………………………………………….. 15 2. Glide Path Flight Inspection ………………………………………………………………………………. 18 2.1 Antenna Null Checks …………………………………………………………………………… 18 2.2 Phasing Check …………………………………………………………………………………….. 19 2.3 Glide Angle and Sector Width Check …………………………………………………….. 20 2.4 Glide Angle & Path Structure Check ……………………………………………………… 21 2.5 Monitor Checks …………………………………………………………………………………… 22 2.6 Azimuth Coverage ………………………………………………………………………………. 23 2.7 Generation of Flight Check Reports ………………………………………………………. 24 Chapter-4 VOR Flight Inspection 29

1. VOR Parameters Checks ……………………………………………………………………………………. 29 1.1 Sensing and rotation ……………………………………………………………………………. 29 1.2 Identification Check …………………………………………………………………………….. 29 1.3 Modulation Levels Check ……………………………………………………………………… 29 1.4 Orbit Checks ……………………………………………………………………………………….. 29 1.5 Radial Checks ……………………………………………………………………………………… 32 1.6 Polarization Check ………………………………………………………………………………. 33 1.7 Coverage Check …………………………………………………………………………………… 33 1.8 Bearing Monitor Alarm Check ……………………………………………………………… 33 1.9 Flyability-Must be Satisfactory …………………………………………………………….. 34 1.10 Receiver Check Points …………………………………………………………………………. 34

2. Flight Inspection Profiles of VOR ………………………………………………………………………. 35

3. Table For Acceptable Limits of VOR …………………………………………………………………… 36


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Chapter-5 Flight Inspection of DME & NDB 37 1. DME Flight Inspection ……………………………………………………………………………………… 37 1.1 Parameters Checker Results and Tolerances …………………………………………. 37 1.2 Ground Adjustments …………………………………………………………………………… 37 2. NDB Flight Inspection ………………………………………………………………………………………. 37 2.1 Desired results and Tolerances …………………………………………………………….. 37 2.2 Needle Oscillations ……………………………………………………………………………… 38 Chapter-6 VGSI Flight Inspection 39 1. VGSI/VASI/PAPI Flight Inspection ……………………………………………………………………. 39 1.1 Color Transition Check ………………………………………………………………………… 39 1.2 Approach Angle Check …………………………………………………………………………. 39 1.3 Azimuth Coverage Check ……………………………………………………………………… 39


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CHAPTER 1

GENERAL

1. Title of the Document:

This document is identified as Communication, Navigation & Surveillance Manual – Volume. IV (CNSM- Vol. IV) “Flight Inspection of CNS Facilities.”

2. Purpose of this Document:

2.1 Purpose of this document is to provide information and guidelines pertaining to flight inspection of CNS facilities, which are essential for the provision of safe and efficient air traffic services by Department of Civil Aviation, Myanmar. It is published for use and guidance of its CNS Maintenance personnel.

3. Responsibility for documentation, review, amendments and publication:

3.1 The Director (CNS), DCA HQ is responsible for development, review and amendments of CNS – Manuals Vol. IV. He will ensure that the information and guidelines pertaining flight inspection of CNS facilities, as detailed in this manual are in conformity with Standards and Recommended Practices (SARPs) given in the Annexes to Convention on International Civil Aviation and National regulations.

3.2 The Director (CNS) is responsible for the approval of documentation & Amendments

and publication of CNS-Manual. 4. Effective Date:

4.1 Effective date of Manual is indicated at the end of this chapter. 4.2 New edition will be indicated by the same date at the end of this chapter. 5. Change History:

5.1 This is version 1 of CNS Manual Vol. IV. Changes, if any, are indicated on ‘Record of Amendments and corrigenda page’.

5.2 Amendments – documentation being inserted in the manual must contain headers

and footers that are consistent with those given in this document. 6. Control of the manual:

6.1 Directorate of CNS will control this Manual electronically through DCA web site. 7 Distribution of the Manual:

7.1 Directorate of CNS may produce hard copies and control the distribution of these Copies, as deemed appropriate.

8 Master Copy:

8.1 An electronic and a hard master copy of each chapter contained in the Manual will be held and maintained by the CNS Directorate.

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9. Checking Currency of Manual:

9.1 A current copy of the Manual will be published on Department of Civil Aviation, Myanmar web site.

10. Enquiries

10.1 Enquiries/Clarifications should be addressed to:

Director (CNS) Department of Civil Aviation, Yangon International Airport, Mingaladon 11021, Yangon, Myanmar Telephone: +95-1-533020 FAX: +95-1-533016 Effective Date: 23 Nov 2009

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Chapter – 2

General Requirements 1.0 Introduction

1.1 Flight Inspection of Radio and Visual 'Navigation aids’ involves flight evaluation and certification of the signal-in-space. The evaluation process utilizes specially equipped instrumented aircraft, which carries out specific flight maneuvers. Data acquired thus on the quality of signal in space, is analyzed to arrive at the specific performance Parameters. These parameters, in turn, determine the certification of facility status. Flight inspection is mandatory as per International Civil Aviation Organization (ICAO).

1.2 The State owns a fleet flight inspection aircrafts which are equipped with semi

automatic computerized flight inspection systems (PFIS – Sierra). All types of Navigation Aids including CAT-III ILS can be inspected with the system available. Directorate of CNS & Directorate of FIU coordinates for scheduling of flight inspection of newly installed facilities and for trans-installed facilities.

1.3 In the planning for flight inspection, a major role is played by the hours, which are

available with the flight inspection aircraft that is being released for purpose. A maximum of 50 flying hours is generally released with the aircraft that is being used for flight inspection purpose. So the Plan is made in such a way that aircraft is able to return to the base after completing the planned tasks within allotted 50 hours.

1.4 The FIU plans flight inspection of facilities as per the specified periodicity. The same

is intimated to concerned stations in advance by Fax/Phone. The stations are expected to be ready with site preparation, ground measurements and necessary tools and equipments for use during flight inspection.

1.5 The flight check profiles required for calibration for various parameters of navigation

facilities are included at the end. 2.0 Type of Inspection

2.1 As needed the flight inspection team may be required to undertake any of the following five types of inspection.

1. Site Evaluation 2. Engineering Support 3. Commissioning / Re-commissioning 4. Routine 5. Special

2.1.1 Site Evaluation Inspection: Site Evaluation flight inspections are carried out to determine the suitability of a site for installation of a nav-aid.

2.1.2 Engineering Support Inspection: Engineering support inspection is done

towards evolving an engineering solution to the imperfect installation site. It may involve, for example, modification to the Antenna system of Glide Path or minor improvement in the site for optimizing “a within tolerance” performance.

2.1.3 Commissioning / Re- Commissioning: Commissioning / Re- Commissioning

inspection is a comprehensive check designed to obtain complete information regarding all aspects of performance of a nav-aid. The facility can not be declared operational before this check.

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2.1.4 Routine Inspection: Routine inspection is carried out to ensure that Nav-aid facility is being maintained within tolerance limits in spite of the inherent drift in the equipment. Routine inspections do not normally involve major adjustments unless the performance is observed to have drifted either close to, or beyond the applicable tolerance limits.

2.1.5 Special Flight Inspection: Special flight inspection is made on special request to

confirm satisfactory performance. It may follow a major maintenance on the equipment especially the antenna system. Special Flight Inspection may also be carried out for investigation purpose after any incident or accident.

3.0 Periodicity of Flight Inspection

3.1 The establishment of generally applicable check interval depends on:

a. The checking method used. b. Reliability of ground equipment. c. Extent and fidelity of monitoring capability. d. Proficiency of maintenance personnel. e. Extent of correlation established between ground check and Flight check.

3.2 A new facility requires shorter interval than a proven one. Valve type equipment and those involving mechanical sub-system need more frequent check than solid-state equipment.

3.3 Following are the periodicities being followed by DCA;

Facility Periodicity a. ILS 150+ 30 days b. DVOR 720+ 60 days c. CVOR 240+ 30 days d. DME As per the associated facility. e. NDB As and when required f. Radar As and when required g. VGSI(VASI/PAPI) As and when required

3.4 Maintenance team can draw a schedule for flight inspection as per the data above. In case the established intervals are exceeded because of weather or other factors the facility status (Certification) shall not be changed for the sole reason that the inspection could not be carried out within the maximum allowable intervals. The facility may continue to remain in service, provided the ground checks indicate normal performance.

4. Pre-Flight and Post Flight Procedures:

4.1 Pre Flight Inspection Preparations: Following are the points to be observed during Preflight Inspection Preparation:

(a). Ensure that the result of all possible ground calibration and checking of equipment are satisfactory.

(b). Competent Maintenance personnel should be available to make corrections and adjustments during flight inspection.

(c). The DGPS and LT Platform should be constructed, as advised by the FIU, along with a suitable Power Point. Such positions should be maintained properly for

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subsequent Flight Checks. The position of LT reference reflector or its bracket should also be maintained properly.

(d). Availability of dedicated transport for equipment and personnel should be ensured during the entire course of flight check.

(e). Ensure all special tools and instruments are available at the site.

(f). Availability of last Flight Inspection Report.

(g). Any requirement of special investigation during flight inspection must be intimated in advance and followed up with FIU during flight inspection.

(h). In case the facility is not expected to be ready as per the regular scheduled inspection, FIU must be advised accordingly.

(i). NOTAM action for withdrawal of facility during Flight Inspection must be taken without fail in coordination with local ATC authorities.

4.1.1 In-Flight Inspection Action by the Ground Personnel:

During the inspection Flight Inspector, will advise maintenance personnel of observed conditions which require adjustment of ground equipment. Request for adjustment will be specific and readily understandable by ground personnel. Normally the Flight Inspector is not expected to diagnose the fault, but will furnish sufficient information to enable the maintenance team to' make the corrective adjustment, when the aircraft is airborne. Record the adjustments done, for post analysis. Take down relevant measurements on ground for establishing a meaningful correlation with the flight check results after each run.

4.2 Post-Flight Inspection Action by the Ground Personnel: Ground maintenance, personnel will complete the following actions:

(a). Take action as per the advice of Flight Inspector.

(b). Take down relevant measurements on ground for establishing a meaningful correlation with the flight check results.

(c). Implement the suggestions contained in the remarks column of “Flight Inspection Report”.

(d). Intimate FIU and all concerned regarding any major change in the facility performance (NOTAM action)

4.2 Airborne FIS Equipment

FIS console fitted on board the flight inspection aircraft may be of one of the following:

(a). Manual System (earlier): Features manual data analysis and computation of results besides supported by a manual theodolite / tracking system.

(b). Semi-Automatic System (present): Features automatic data analysis and computation of results but supported by an operator dependent position reference system / Theodolite.

(c). Fully Automatic System (plan): Features automatic data analysis and computation of results based on self contained automatic position reference systems, like DGPS and Laser Tracker. This system is recently acquired from Germany and fitted in aircraft.

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4.4 PFIS-Sierra 4.4.1 This is a semi Automatic Flight Inspection system which is installed in the Flight

Inspection aircrafts of DCA Flight Inspection Unit. It is procured from Aerospace and Defense, Sierra Research Division, USA.

*****

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Chapter-3

Flight Inspection Procedure of ILS

1. Localizer Flight Inspection: Following are the various Flight Inspection Checks carried on the Localizer equipment:

1. Identification Coding Checks 2. Mod-Balance and Mod-Depth Checks 3. Course width and Clearance Check 4. Course Structure, Course Alignment and Flyability Check 5. High angle clearance check 6. Alignment Monitor Alarm check 7. Width Monitor Alarm check 8. Coverage and Power Monitor Alarm Check 9. Polarization Check 10. Course width Symmetry Check.

In case of Routine / Periodic inspections, adjustments are normally carried out on

one of the transmitters and then: (i). All the monitors are adjusted to "zero". (ii). Transmitter is changed over. (iii). Controls of this transmitter are adjusted to obtain similar readings on the

monitor. (iv). A confirmatory air check is made for this transmitter. It saves time and

ensures that both the transmitters are balanced on monitors.

This procedure is also employed in glide path calibration.

1.1 Identification Coding Check: Ident should have no effect on Cross Pointer. Ident level is adjusted to 10% Modulation.

1.2 Mod Balance and Mod-Depth Check

1.2.1 Purpose: To confirm that mod balance and mod depth are set properly. On centre line of LLZ the DDM should be zero and Mod sum should be 40%.

1.2.2 Flight Procedure: Park the aircraft at Runway Threshold on Centre-line (C/L).

Ground staff asked to Adj. Mod Bal. & Mod Depth controls

Mod. Balance adjusted for 0 ± 5 μ amps (cross pointer current in the FIS console) Mod. Depth adjusted for 40% ± 4% (CAT I & II)

40% ± 2% ( CAT III)

Final adjustments of Mod Balance and Mod depth are carried out during approaches.

1.3 Course Width and Clearance check:

1.3.1 Purpose: (i). To ensure Course Width is satisfactory.

- During Commissioning / Annual flight checks the Course width is adjusted for nominal value.

- During Routine - flight checks, it is ensured that the course width is within tolerance

(ii). To check off-course clearance (in the sector 10°-35° either side of C/L)

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1.3.2 Flight Procedure: Calibration aircraft flies an arc about Runway centre line at approx 5 NM from LLZ & 1500'AGL (Above Ground Level) as shown in fig 1.

1.3.3 Ground Facility Adjustment: Ground staff is required to adjust Course Width

control as advised by the Flight Inspector.

An increase in width DDM monitored on INT Width Mon socket will result in a decrease in Course Width values. In case of Normarc ILS, SBO Power control is adjusted. A clockwise rotation increases the attenuation and thereby increases the course width. In-sufficient clearance may be caused due to:-

(i) Imperfect Phasing (ii) High VSWR in the RF Feeder / Dipoles.

(It should be re-checked and corrected)

1.3.4 Desired Result / Tolerances:

COURSE WIDTH (W) = W ±17% CAT I, II & III

Course width adjustment: Adjustment = DDM (SBO) X Measured CW

Required CW

(i) Clearance current should increase linearly to 175 μ Amps (18% DDM) from centre line and must not fall below this value up to 10° azimuth either side of C/L.

Fig:1 Localizer Course Width and Clearance check

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(ii) Minimum Clearance current should be 150 μ Amps (15.5% DDM) in ±10° to

± 35° sector

During routine check, if width is found outside CW ± 4%, it is adjusted for CW ± 1% value.

1.4 Course Structure, Alignment and Fly ability Check

1.4.1 Purpose:

(i). To check the alignment of electronic centre line with the physical runway centre line

(ii). To check that the quality of course signals is satisfactory. Course bends, Roughness, scalloping (all combined together) should be within tolerance limits of the applicable category

(iii). Fly ability is checked to ensure it is satisfactory that an aircraft following the ILS can fly smoothly "manually" as well as on its "auto pilot".

1.4.2 Flight Procedure

(i). Calibration A/C carries out ILS approaches inbound from 8 NM up to R/W Threshold on LLZ and on Glide Slope (as shown in fig 2) for CAT-I & II facility.

(ii). Calibration A/C carries out ILS approaches inbound from 8 NM and then follows the LLZ approach 50´ above the RWY up to Reciprocal Threshold for CAT-III facility.

1.4.3 Theodolite Tracker

When approaches are made the positional (aircraft position w.r.t. threshold) data correction is given by Theodolite manually. The Calibration Aircraft is manually track by RTT ( Radio Theodolite Transmitter ) Tracker.

In-the case of Tracker, continuous azimuth deviation data of the Air Craft position gets manually transmitted to the console through RTT UHF up-link and course structure is calculated by the computer after the completion of the exercise. The RTT ( Radio Theodolite Transmitter ) Tracker is controlled by the Flight Inspector/PFIS system depending on the chosen exercise.

1.4.4 Ground Adjustment: Normally no adjustment is carried out for above exercise. However light adjustment of MOD BAL & MOD DEPTH may be required to optimize the far field performance, and get acceptable alignment value.

1.4.5 Desired Results and Tolerances

1.4.5.1 Alignment

Tolerance Limits

ILS Category Periodic Commissioning

CAT I + 14.6 μA ± 1.5μA CAT II + 10.5 μA ± 1.1μA CAT III + 4.2 μA ± 0.5μA

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1.4.5.2 Structure

(a) Usable distance to ILS point 'A' 30 micro Amps

(b) ILS Point ‘A’ to ' B' - CAT I Linear decrease from 30micro amps to 15 micro amps.

CAT II Linear decrease from 30micro amps to 5 micro amps.

(c) CAT I - ILS Point B to C maintain 15 micro amps

CAT II - ILS Point B to Threshold 5 micro amps

CAT III - ILS Point B to D 5 micro amps.

CAT III - ILS Point D to E Linear increase from 5 to 10 micro amps

This data is illustrated in fig 3 and 4.

1.4.5.3 Fly ability - Must be Satisfactory. It is subjective assessment of the

pilot for the facility.

1.4.5.4 ILS Points

ILS Point A - On extended C/L, on G/P - 4 NM from (7.5 Km) from threshold

ILS Point B - On extended C/L, on G/P - 3500' (1050M) from Threshold

ILS Point C - On extended C/L. Downward extended straight portion of G/P where it crosses 100 ft above horizontal plane containing threshold

ILS Point T - A point at a specified height located above the intersection of the runway centerline and the threshold and through which downward extended straight portion of the ILS glide path passes ILS Point D - A point 4 m (12’) above the runway centre line and 900 m (3000’) from the threshold in the direction of Localizer ILS Point E - A point 4 m (12’) above the runway centre line and 600 m (2000’) from the stop end of runway in the direction of the threshold

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Fig:2 Course Structure Alignment and Flyability Check

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Fig: 3 LLZ Course and maximum Bend amplitude criteria

Fig: 4 Evaluation of course/path bend amplitude

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1.5 High Angle Clearance 1.5.1 Purpose:

The Combination of ground environment and antenna height can cause nulls or false courses. These may not be apparent at normal instrument approach altitudes. High Angle Clearance should therefore be investigated upon in case of:

a. Initial Commissioning b. Change in location of Antenna c. Change in height of Antenna d. Installation of a different type of Antenna

1.5.2 Procedure: This check is similar to clearance check described earlier in para 5.1.3 except that a/c

flies the arc at 4500' above the AGL or max service altitude of LLZ in use.

1.6 Alignment of Monitor Alarm Check

Monitor alarm limits are cross-checked. Ground maintenance personnel actuate alignment monitor alarm condition with Mod-Balance control. Calibration aircraft detects the deviation to confirm that the deviation is within the tolerance limits.

1.7 Width Monitor Alarm Check

1.7.1 Purpose: To confirm that adjustment of Width, Monitor Alarm is Satisfactory. 1.7.2 FLT Procedure: This exercise is conducted similar to that of CW check. Ground

procedure is different. 1.7.3 Width wide Alarm Check: This check ensures that even during wide width

condition, clearance current does not reduce below the minimum. In this check off- Course Clearance must not fall below 160 micro Amps in the Zone ± 10° & 135 micro Amps in the Zone +10° to + 35°.

1.7.4 Ground Procedure: Inspection of width alarm is carried out on one Tx only.

Decrease in SBO power simulates wide alarm condition. . For narrow alarm condition, increase the SBO power till monitor gives alarm. FIU checks the air performance under this condition. If narrow alarm under the advice of FIU, the alarm limits may be required to be adjusted.

Return the control to earlier position to obtain original value of width DDM.at the end .

1.7.5 Permissible course width (Displacement Sensitivity) change for each

category:

CAT I & CAT II + 17% CAT III ± 10%

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1.8 Coverage & Power Monitor alarm Check

1.8.1 Purpose:

To confirm that Localizer provides coverage to the defined service volume even when operating at Half Power (Monitor Alarm).

1.8.2 Flight Procedure:

The FIU aircraft carries out exercise as shown in the fig 5.

1.8.3 Ground Facility Adjustment

The field strength of the LLZ signal is measured on course at greatest distance at which it is expected to be used (But not less than 18 NM) while operating with 50% of normal power. If the field strength is less than 5 micro volts, the power will be increased to provide at least 5 micro volts and monitor limit adjusted to Alarm at that level. Normalize the power output to the original value after the check is done.

1.8.4 Desired Result –

Throughout the coverage volume:

Minimum field strength 40 μv/m throughout the coverage volume 90 μv/m for CAT-I (from 10 Nm to Point B) 100 μv/m to 200 μv/m for CAT-II (from 10 Nm to Threshold ) 100 μv/m to 200 μv/m for CAT-III (from 10 Nm to 20´ above threshold), above100μv/m at 12´

Minimum AGC 5 μv Minimum SDM 36%Maximum SDM below 95%

1.9 Polarization Check 1.9.1 Purpose:

To confirm that no adverse effect will be encountered while flying on LLZ course due to undesired vertical polarization component.

The desired polarization of LLZ is Horizontal

1.9.2 FLT Procedure: Calibration Air Craft flies in-bound on Localizer at 1500' AGL between 6-10 NM. The Air Craft is made to Bank 20° each side while remaining on centre line as shown in fig 6.

1.9.3 Desired Result

No appreciable deflection of Cross Pointer on Banking.

Tolerance in cross pointer current (DDM)

CAT I + 15 micro amps CAT II + 8 micro amps CAT III + 5 μ amps

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1.10 Course Width Symmetry Check 1.10.1 Purpose:

To confirm that course width an either side of centre line is SYMMETRICAL within prescribed limit.


Fig:7. Shows the flight procedure for the Course Width Symmetry Check. The calibration Air Craft flies in-bound from Outer Marker to Runway threshold at half width (75 + μAmps -offset) point an either side of the LLZ Centre line.

Pilot flies with the help of FIS-CDI. The A/C is tracked automatically by LT.

1.10.3 Desired Result:

Symmetry (half width on 90 Hz side compared to width on 150 Hz side) must be within 10% of the total Sector Width. -

This check is done only during commissioning. After the flight Inspection is completed the ground staff should ensure that both the TX’s are Balanced On Monitors.

Fig: 5 Localizer Usable Airspace Check

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Fig: 6 LLZ Polarization Check

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Fig: 7 Course Width Symmetry Check

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2. Glide Path Flight Inspection

Following are the various Flight Inspection checks.

1. Antenna NULL Check 2. Phasing Check 3. Sector width and Glide Angle Check 4. Glide angle and Course Structure Check 5. Monitor Checks

(i) Position Alarm (ii) Width Alarm

6. Azimuth Coverage 2.1 Antenna Null Checks 2.1.1 Purpose:

To confirm and correct (if required) the height of G/P Antenna elements above ground. This check is performed during commissioning or after major maintenance of antenna.


The calibration aircraft flies at 1000'/1500' AGL on LLZ, from a distance of 8 NM to a point overhead G/P antenna. The a/c positional information is provided by PDGPS (Positional Reference System) as shown in Fig. 8


Dummy load the SBO signal in the Coaxial Distribution Unit /Antenna Changeover Unit. Feed CSB signal to antenna being checked (one antenna at a time). Adjust antenna height appropriately to get correct nulls. Antenna should be raised to decrease the NULL ANGLE and V1CE VERSA.

2.1.4 Desired Results

a. Null Reference System Upper Antenna - θ, 2θ Lower Antenna - 2θ, 4θ b. Side Band Reference System Upper Antenna - 4θ/3, 8θ/3 Lower Antenna - 4θ, 8θ c. M-Array Upper Antenna - 2θ/3, 4θ/3 Middle Antenna - θ, 2θ Lower Antenna - 2θ, 4θ

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Fig:8 Glide Path check

2.2 Phasing Check

2.2.1 Purpose: To establish that correct quadrature phase relationship between CSB and SBO signals

exists.

2.2.2 Flight Procedure: Fig 9 shows the flight procedure for Phasing' Check. The calibration A/C flies

inbound on Centre line at 1000’ AGL (Level Run). The exercise is started at 10 NM from Runway threshold and is terminated at 1 NM before Outer Marker.

2.2.3 Ground Facility Adjustment: In case of Glide Path equipment air phasing is seldom required. Necessary phasing adjustments are made in the Antenna Distribution Unit on ground itself. The details given below pertain to STAN/GCEL ILS. However it is required to know the RF adjustments, which constitute the phasing procedure.

1. Terminate SBO O/P on Dummy load at Antenna Changeover Unit & radiate only CSB. Adjust MOD BAL Control as advised by flight inspector to attain zero cross pointer current in the a/c Console.

2. Insert quarter wave-length (λ / 4) cable in SBO feeder and radiate, both CSB and SBO signals.

(a) Null Reference For proper phasing the ground staff should always be quick and alert to monitor and act on instruction received on VHF R/T set. After radiating CSB and SBO, if the CP current is not zero then Flight Inspector will inform CP current on VHF R/T, to carry out required adjustment in the Side Band Phaser Control.

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Fig: 9 Phasing Check

After phasing, remove λ/4 cable and give normal radiation.

(b) Side Band Reference Put upper antenna on Dummy Load before flying is started Adjust power ratio Control on ADU to achieve equal SBO power to both Antennas.

Put the SBO feed on Dummy Load & radiate only CSB, Check with a/c if CP current is zero. Feed SBO with λ/4 cable. Adjust 'Side Band Phaser' control to attain CP current = 0.

Remove Dummy Load from Antenna feeder and adjust upper ant phase control on ADU as advised by FIU to get CP current as zero. Remove λ/4 cable and normalize the feeds. (c) M-Array Adjust various power ratio controls on ADU as prescribed. Put the Middle and Upper Ant on D/Load. Insert λ/4 cable in SBO feed and put it on D/Load. Radiate only CSB and check for Zero CP current. Radiate SBO also with λ/4 cable. Adjust phase Side Band Control to attain CP current zero. Remove D/Load from Middle Ant and adjust Middle antenna phaser to attain CP current zero. Remove D/Load from Upper Ant and adjust upper antenna phaser to achieve CP current = zero. Finally remove λ/4 cable and NORMALISE the equipment.

While doing phasing by SBO phaser if zero CP current can not be attained, then insert about 3" (3 inch) of extra length in SBO feeder. If phasing comes proper then CSB cable may be cut equal to extra length (3 inch in this case). Extra length of cable can be put in CSB cable also if required to get zero CP current. In this case SBO cable may be cut.

It is advisable to carry out the phasing of M-Array Glide Path system on ground without any requirement of flying the FIU Aircraft.

2.3 Glide Angle and Sector Width check

2.3.1 Purpose: To determine the Glide angle, sector width and adjust glide path equipment, if necessary.

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The calibration aircraft flies in-bound on extended centre line (level run) at 1500′ AGL from 10 NM to MM. the aircraft receives positional information from the PDGPS positional reference system.


(a) Angle: If the angle is out of tolerance and MOD BAL setting is correct, antenna height will have to be adjusted, Minor adjustment of Mod Bal can be made as advised by of Flight Inspector. During the adjustment, put the FTS on CSB course socket. In case the DDM is on 90 side the G/P angle is low and if DDM is on 150 side then G/P angle is High. To increase the glide path angle, obtain a higher DDM predominant on 150Hz and vice versa. . (For 0.01 deg adjustment change DDM on path by 0.02 0.24 % or by 2 μA) (b) Width: Adjust SBO power attenuator. To increase the sector-width reduce the SBO power (or increase the attenuation and vice versa).Carry out adjustment of SBO Power control as per advice of Flight Inspector.

2.3.4 Desired Results

Glide Angle θ (Selected) Lower 1/2 Sector Width 0.12 θ Upper 1/2 Sector Width 0.12 θ

Tolerances

Glide angle

i. Commissioning - No tolerances allowed

ii. Routine Glide Angle - ± 7.5% of θ f or CAT I & II

± 4% of θ for CAT III Half Sector Width CAT I - Lower Half Sector Width 0.07 θ to 0.14θ CAT II & III - Lower Half Sector Width 0.10 θ to 0.14 θ

(Please refer table) 2.4 Glide Angle & Path Structure check 2.4.1 Purpose:

(i) To determine the computed (actual) Glide Angle.

(ii) To confirm that the G.P. bends, roughness and scalloping are within tolerance. 2.4.2 Flight Procedure

The calibration Air Craft flies inbound on Glide Path on extended centre line from 10 NM up to threshold. The pilot follows glide path. The Air Craft is continuously tracked by RTT (Radio Theodolite Transmitter) Tracker. The Path Structure is computed manually . The processed results are displayed by the system, on the screen.


No adjustment is required in ground equipment for path structure but the averaged path angle may be required to be adjusted as given above. If structure results are not

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up to the mark the facility may be down – Categorized or restricted. Site improvements may solve an out-of-tolerance structure situation.

2.4.3 Desired Result

The Computed Glide Angle (average of the samples collected between A to B) should be within Tolerance and Path deviations must meet the following criterions/tolerances.

2.4.4.1 Tolerances

Path Structure: Should not exceed

CAT I up to 'A' - ± 30 micro amps A-B - ± 30 micro amps B-C - ± 30 micro amps

CAT II & III up to A - ± 30 micro amps A-B - Linear decrease from ± 30 μA at A to ± 20 μA

at B B-T - ±20 micro amps

2.4.4.2 Desired Results and Tolerances on Glide Angle and Sector Width

As given in the preceding paragraph. 2.5 Monitor Checks

2.5.1 Angle Alarm

2.5.1.1 Purpose: To confirm that the Angle Alarm is adequately sensitive to detect a change of Glide Angle. This check is carried out using one Tx only.

2.5.1.2 Flight check procedure

It is generally carried out during normal Air Craft approach where in it flies ILS from 8 NM to point C or T.

2.5.1.3 Ground Facility Adjustment

Connect the FTS to course CSB socket in the changeover unit and note the DDM. On request from FlU Air Craft, move MOD BAL in one direction till both Monitor 1 and Monitor 2 just at the threshold of alarm condition. Keep an eye on the C/L DDM display on the monitor. On advice of the flight inspector move the MOD Balance control in the other direction to achieve alarm condition as above. Afterwards, on advice of Flight Inspector, restore the control to obtain original value of DDM on FTS.

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Fig: 10 Glide Path and Maximum Bend Amplitude Criteria

2.5.1.4 Desired Results The change in Glide Angle obtained by calibration Air Craft must be within ± 7.5%

of θ.

2.5.2 Width Alarm

2.5.2.1 Purpose: To confirm that width alarm is adequately sensitive to detect an out-of tolerance change in sector width value.

2.5.2.2 Flight Procedure

Air Craft flies 1000 ft. AGL (level run) along the extended C/L from 10 NM to 2 NM.

2.5.2.3 Ground Adjustment Set Monitor display for DS DDM and note the value. Actuate width (DS) Wide alarm

condition on both monitor 1 and monitor 2 by increasing SBO power attenuator. On advice of flight inspector move the attenuator on the other side to obtain narrow alarm condition. Finally, as advised, restore the control and reconfirm by obtaining the original value of DS DDM.

2.5.2.4 Desired Results

For CAT I lower half sector width, within ± 0.037 θ. For CAT II & III lower half sector width, within 25% of nominal

value of displacement sensistivity

2.6 Azimuth Coverage

2.6.1 Purpose: To confirm that usable signal is available in the ± 8° azimuth zone (With the extended centre line as the reference).

This check is carried out only during commissioning or after major maintenance of the antenna.

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A/C flies in arc at 1500 ft ± 8° of the extended centre line.

2.6.4 Desired Results 2

Glide path signal should have minimum signal strength of -92 dBm/m , minimum 150 μA fly up current and SDM/Mod sum more than 48 %.

2.7 Generation of Flight Check Reports:

2.7.1 The Result of flight inspection is given to maintenance personnel at the station itself. AFTN Signal/FAX message to the effect is given to D(CNS),D(FIU).

2.7.2 The final flight inspection report is prepared after return to the base and is generally

sent to the concerned offices within seven days. The data collected during flight inspection are archived in our records along with the report.

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4. Table for Acceptable limits

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Chapter – 4

VOR Flight Inspection

1. VOR Parameters Checks Following are the various Flight Inspection Checks carried on VOR.

a. Sensing and Rotation check. b. Identification Coding Check c. Modulation Level Check d. Orbit Check e. Radial check f. Polarization Check g Coverage Check h. Monitor Alarm check

1.1 Sensing and rotation: The purpose of this check is to assure proper orientation of the antenna; Proper connection of its RF feed lines. Course azimuth increases in a clockwise direction and ‘TO-FROM’ indications are correct.

Flight Inspection aircraft flies any outbound radial to check sensing. After sensing is checked, Orbit check starts.

If it is found to be incorrect, the most probable cause would be reversed sideband antenna feed cables.

1.2 Identification check

Identification check is carried out to see the correctness, clarity and to ensure that there is no adverse effect on VOR course structure.

This check is performed anytime while flying a radial. 1.3 Modulation Levels Check

1.3.1 Purpose: To confirm that modulation levels of 30 Hz AM, 9960 KHz Sub-carrier and the 30 Hz FM (deviation ratio of 9960 KHz sub-carrier) are set properly.


Calibration aircraft flies on any radial and modulation levels of the parameters are checked and adjusted accordingly Mod. Depth of 30 Hz AM adjusted for 30% ± 2 %

9960 KHz adjusted for 30% ± 2% Deviation ratio 30 Hz FM 16 ± 1

Final adjustments are carried out during Orbit check.

1.4 Orbit Checks

1.4.1 5 Nm Orbit :

1.4.1.1 Purpose: (i) To evaluate the error in azimuth alignment, the roughness and scalloping of

sectors and the signal strength over the orbit.

(ii) To determine the accuracy and overall alignment error distribution of the radials over 360 degrees.

This check is carried out during Commissioning and routine flight checks.


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1.4.1.2 Flight Procedure: Calibration aircraft flies an orbit radius of normally 5 Nm or more in a Counter Clock wise direction at a minimum altitude of 1000’ AGL or above.

1.4.1.3 Position reference system:

Calibration Aircraft is manually tracked by Theodolite and mark tone is plotted on recorder by the VHF transmitter.

1.4.1.4 Ground Facility Adjustment Adjustments are made on the basis of analysis of flight inspection data to establish

and maintain optimum error distribution. Ground staff is required

(1) To adjust modulation levels of 30 Hz AM, 9960 Sub carrier, the FMI of 30Hz FM and 1020 Hz Ident.

(2) To adjust the north bearing for alignment with magnetic north and to optimize the error distribution throughout radials.

Fig:1 VOR Theodolite Orbit Check Flight Procedure


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1.4.2 25 Nm Orbit check:

1.4.2.1 Purpose:

(i) To evaluate Bends ,roughness , scalloping and signal strength.

(ii). To establish Ground check points.

This check is carried out only during Commissioning.

1.4.2.2 Flight Procedure: Calibration aircraft flies an orbit radius of normally 25 Nm in a Counter Clock wise rotation at a minimum altitude of 1000’ AGL.

1.4.2.3 Position reference system: Calibration Aircraft is manually tracked by Theodolite and mark tone is plotted on recorder by the VHF transmitter.

1.4.2.4 Ground Facility Adjustment Normally no adjustment is carried out for above exercise. After the Half the Orbit, a change over of Transmitter is carried out.

1.4.2.5 Ground check points: Ground checkpoints, evenly distributed around the facility are selected from an aeronautical map and transferred over the VOR Orbit. Each checkpoint is marked by the pilot and is compared with actual azimuth reading by the flight inspector. Overall sectoral quality of signal, roughness, scalloping, bend or noise can be detected for the VOR at 25 Nm which could be used during the radial checks. This method also reassures radial alignment through physical matching of ground features.

1.4.2.6 Desired Results and tolerances:

30 Hz AM % mod depth: 30% ± 2 %

9960 KHz % mod depth: 30% ± 2 %

Deviation ratio 30 Hz FM: 15 to 17

Azimuth Alignment: ± 2.0°

Signal Strength: 90 μV/m

Bends: ± 3.5°

Roughness: ± 3.0°

Scalloping: ± 3.0°


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Fig:2 VOR Ground Check Point Orbit Flight Procedure

1.5 Radial Checks

1.5.1 Purpose: (i) To check that the quality of course signals is satisfactory. Course bends,

roughness, scalloping (all combined together) should be within tolerance limits

(ii) Minimum 8 radials with at least one radial in each quadrant including PDRs are checked during commissioning. During Routine inspections, only PDRs are checked.


Calibration Aircraft flies on en-route radials either inbound or outbound along the radial to a distance of 40 Nm. The minimum altitude is 1000ft above the highest terrain. .

1.5.3 Ground Adjustment

Normally no adjustment is carried out for above exercise. 1.5.4 Desired Results and Tolerances

Alignment

Signal strength > 90μv/m Bends: ± 3.5° Roughness: ± 3.0° Scalloping: ± 3.0°


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1.6 Polarization Check 1.6.1 Purpose:

To confirm, that no adverse effect will be encountered, while flying on course due to undesired vertical polarization component. The desired polarization of VOR is HORIZONTAL.

VOR Radial Check

1.6.2 Flight Procedure: Calibration A/C flies in-bound OR out-bound on any radial and The A/C is made to

Bank 30° each side between 5-20 NM. while heading is not changed. 1.6.3 Desired Result

Course deviations as a result of aircraft banking should not exceed 2 degree

Bearing deviation: ± 2 .0° 1.7 Coverage Check

1.7.1 Purpose: To confirm that VOR provides coverage to the defined service volume even when

operating on St-by Power Supply.

1.7.2 Flight Procedure: The FIU Aircraft flies on any radial outbound at a minimum altitude of 1000’AGL. 1.7.3 Ground Facility Adjustment The field strength of the VOR signal is measured on course at greatest distance at

which it is expected to be used while operating with st-by Supply. 1.7.4 Desired Result: –

Throughout the coverage volume:

Minimum Signal Strength: more than 90 μV/m

1.8 Bearing Monitor alarm check Monitor alarm limits are cross checked. Ground maintenance personnel actuate alignment monitor alarm condition with North Alignment Control. Calibration aircraft detects the deviation to confirm that the deviation is within the tolerance limits.


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Calibration Aircraft flies on any radial either inbound or outbound. Give the equipment on alarm with north alignment control when advised by flight inspector. Normalize the equipment after Alarm check.

Tolerance: Bearing Monitor : ± 1 .0°

1.9 FLYABILITY - Must be Satisfactory

Flyability is a subjective assessment by the Pilot during the inspection. Assessment of Flyability is performed on operational radials and during procedures based on the VORs.

1.10 RECEIVER CHECK POINTS: Fixed check points are established both on the ground and in the air where pilots may check the accuracy of their aircraft VOR Receivers. These points are established during Commissioning check.

1.10.1 Airborne Check Points: The aircraft flies either inbound or outbound directly over easily identified ground features at specific altitudes near the airport at a distance between 5 Nm to 30 Nm. The radial and distance above the check point will be published as Receiver air check point azimuth.

1.10.2 Ground Check points: The aircraft position on the ramp or on a taxiway over a

selected location. The indicated radial and distance will be published as Ground check point.


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Chapter – 5

Flight Inspection of DME & NDB

1. DME Flight Inspection All DME Checks are carried out in conjunction with checks on their associated facilities (VOR & ILS).

1.1 Parameters Checks Results and Tolerances:

1.1.1 Identification: The identification code should be clear and correct through out the area of coverage. The ID Code frequency should be 1350 Hz. The ID should be properly synchronized with that of the associated facility.

1.1.2 Distance accuracy: The indicated Slant range distance must be within the limits 1.1.3 Coverage: The area of coverage of the DME will be at least that of its associated

facility (VOR & ILS) 1.1.4 Signal Strength (AGC): The signal strength must be at least –82 dBm throughout

the area of coverage. 1.1.5 Squitter Rate: The normal squitter rate should be 2700 ± 90 pps. On certain type

facilities, rates as low as 700 pps are normal. 1.1.6 False replies : No false replies should be present which could result in false locks-

ons. Within the area of coverage. This may occur at any location especially in the presence of vertical nulls.

1.2 Ground Adjustments:

When the measured distance is out of tolerance, then the system delay of both Transmitters is to be adjusted by the ground personnel. System delay is to be increased to reduce the range error and vice versa. Tolerances:

For Terminal (ILS) DME : ± 75 meters Enroute (VOR) DME : ± 150 meters

2. NDB Flight Inspection The Flight procedures required will consist of an orbit at 1500 ft above the facility elevation at a radius which will be determined by the facility classification or its “rated Coverage”. Radial flights at Minimum enroute altitude (MEA) along published routes, and all published instrument approach and holding procedures.

2.1 Desired results and Tolerances:

2.1.1 Coverage: Minimum coverage for the various classes of facilities 2.1.2 AGC: The receiver AGC should be the equivalent to at least 70 μv/m (or 120μv/meter

between 30 degrees North and 30 degrees South latitude) ± 20% throughout the area of coverage.


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2.1.3 Identification: The identification code should be clear and correct throughout the area of coverage. If voice is installed, it should be readable to at least two thirds of the rated usable distance.

2.2 Needle Oscillations:

2.2.1 Enroute : Needle oscillations will not exceed ± 10 degrees to the maximum usable distance published for the facility.

2.2.2 Approach and Holding : Needle oscillations will not exceed ± 5 degree throughout

the approach or holding procedure.

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Chapter – 6

VGSI CALIBRATION:

1. VGSI/VASI/PAPI Flight Inspection: Following flight Inspection checks are carried out on the PAPI/VASI equipment.

(i) Color Transition check (ii) Approach angle check (iii) Azimuth coverage check

1.1 Color Transition Check:

1.1.1 Purpose: To confirm that the elements of the PAPI/VASI system are properly aligned and the color change is smooth.

1.1.2 Flight procedure: Calibration aircraft flies inbound on centre line at 1000ft.AGL. 1.1.3 Ground Facility Adjustment: With the result of color transition check the

correction required for the elements of the PAPI/VASI are applied to the ground equipment and other necessary adjustments like leveling etc. are carried out by the ground personnel.

1.1.4 Desired result: The color change from one box to the next box should be proper i.e.

the lower boxes should initially show red and turn white gradually as the aircraft approaches.

1.2 Approach Angle Check:

1.2.1 Purpose: To determine the approach slope and adjustment of the angle if required. 1.2.2 Flight procedure: The calibration aircraft flies inbound on the extended centre

line, from 5NM till threshold on glide slope. The aircraft receives the positional information from the PDGPS and the events of on glide-slope conditions (Correct approach colors) are entered under pilots guidance.

1.2.3 Ground Facility Adjustment : If the angle of the PAPI/VASI is incorrect , the

ground personnel are advised to readjust the Bar angles with their alignment equipment(clinometers)

1.2.4 Desired result: Generally the VGSI approach angles are set for 3 degree. The

tolerance applied is ± 0.2 deg. 1.3 Azimuth Coverage check:

1.3.1 Purpose: To verify that azimuth coverage is adequate. 1.3.2 Flight procedure: The calibration aircraft flies a ± 15 deg arc from extended centre

line at a distance of 4 NM from threshold at 1000 ft AGL. The aircraft receives the positional information from the PDGPS. It is required that the events of aircrafts entering VGSI/PAPI Coverage, aircraft on centre line and aircraft leaving VGSI/PAPI coverage are recorded. This procedure is carried out in both clockwise and anti clockwise directions.


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1.3.3 Ground Facility Adjustment : If the azimuth coverage of the PAPI/VASI is not sufficient the ground personnel are advised to readjust the bar positions with their alignment equipment.

1.3.4 Desired result: Generally the VGSI azimuth coverage is set for ± 10 deg unless a

restriction has been imposed due to obstruction limitation.

FIG 1. COLOR TRANSITION CHECK

FIG:2 APPROACH ANGLE CHECK


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FIG:3 AZIMUTH COVERAGE CHECK

*** End of CNS Manual Vol. IV***

communication, navigation and serveillance manual man vol 4.pdfin fiu, the field staff should be...

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