Communication Navigation and Surveillance Manual - Volume IV - (Flight Inspection of CNS Facilities)

Airports Authority of India CNS Manual Vol. IV

Communication, Navigation &

Surveillance

Manual

Volume IV

(Flight Inspection of CNS Facilities)

First Edition- 2006

AIRPORTS AUTHORITY OF INDIA

August 1, 2006 - 1 - Version 1.0


Preface

This Volume IV of CNS Manual consisting of seven volumes is prepared and maintained by the Directorate of CNS-OM, CHQ, on behalf of AAI for the use and guidance of executives and staff of AAI. 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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Table of Contents

Chapter -1 General 5 Chapter - 2 General Requirements 7 1. Introduction 7 2. Type of Inspection 8 3. Periodicity of Flight Inspection 9 4. Pre Flight and Post Flight Procedures 10 Chapter- 3 Flight Inspection Procedure of ILS 13 1. Localizer Flight Inspection checks 13 1.1 Identification Coding Check 13 1.2 Mod Balance and Mod-Depth Check 13 1.3 Course Width & Clearance Check 14 1.4 Course Structure Alignment & Fly ability Check 16 1.5 High Angle Clearance 21 1.6 Alignment of Monitor Alarm Check 21 1.7 Width Monitor Alarm Check 21 1.8 Coverage & Power monitor Alarm Check 22 1.9 Polarization Check 23 1.10 Course Width Symmetry check 23 2. Glide Path Flight Inspection Check 28

2.1 Antenna Null Checks 28 2.2 Phasing Check 30 2.3 Glide Angle and Sector Width check 32 2.4 Glide Angle & Path Structure check 34 2.5 Monitor Checks 35 2.6 Azimuth Coverage 37 2.7 Generation of Flight Check Reports: 37 3. Table for Flight Inspection Profiles 38 4. Table for Acceptable Limits 40



Chapter -4 VOR Flight Inspection 44 1. VOR Parameters Checks 44 1.1 Sensing and rotation 44 1.2 Identification check 44 1.3 Modulation Levels Check 44 1.4 Orbit Checks 45 1.5 Radial Checks 49 1.6 Polarization Check 50 1.7 Coverage Check 51 1.8 Bearing Monitor alarm check 52 1.9 Fly ability 52 1.10 Receiver Check Points 52 2. Flight Inspection Profiles of VOR 53 3. Table for Acceptable Limits of VOR 54 Chapter -5 Flight Inspection of DME & NDB 55

1. DME Flight Inspection 55 1.1 Parameters Checks Results and Tolerances 55 1.2 Ground Adjustments 55 2. NDB Flight Inspection 56 Chapter - 6 VGSI Flight Inspection 57 1. VGSI/VASI/PAPI flight inspection 57 1.1. Color transition check 57 1.2 Approach Angle Check 57 1.3 Azimuth Coverage check 55



No. Amendment Date Incorporated on Incorporated by



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CHAPTER - 1

GENERAL

1. Title of the Document: This document is identified as Communication, Navigation & Surveillance Manual – Vol. 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 Airports Authority of India. It is published for use and guidance of its CNS Maintenance personnel. 3 Responsibility for documentation, review, amendments and publication: 3.1 The General Manager (N&S), AAI, CHQ is responsible for development, review and amendments of CNS – Manuals Vol. IV. He will ensure that the information and guidelines e 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 Executive Director (CNS-OM) 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 foot of the page. 4.2 New edition will be indicated by the same date at the foot of the page. 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-OM will control this Manual electronically through AAI web site.



7 Distribution of the Manual: 7.1 Directorate of CNS-OM 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-OM Directorate. 9. Checking Currency of Manual: 9.1 A current copy of the Manual will be published on Airports Authority of India web site. 10 Enquiries 10.1 Enquiries/Clarifications should be addressed to: Executive Director (CNS - OM), Airports Authority of India, Rajiv Gandhi Bhaven, Safdarjung Airport, New Delhi – 110003. Telephone: 011- 24652075 FAX : 011- 24654142



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 organization owns a fleet flight inspection aircrafts which are equipped with fully automatic computerized flight inspection systems (AFIS – 200). All types of Navigation Aids including CAT-III ILS can be inspected with the system available. Directorate of CNS (Planning) & Directorate of (RCDU/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 Dornier 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. 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 AAI

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 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.

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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)

4.3 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 (earlier): Features automatic data analysis and computation of results but supported by an operator dependent position reference system / Theodolite.

c. Fully Automatic System (present): 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 Dornier aircraft.

4.4 AFIS-200 4.4.1 This is a fully Automatic Flight Inspection system which is installed in the Flight Inspection aircrafts of AAI Flight Inspection Unit. It is procured from M/s Aerodata, Germany. The system is fully dependent on GPS for its Positional Reference System. A single GPS system can give positional accuracy, no better than 30 m which is of no use for ILS calibration. So, the system is equipped with P-DGPS for achieving the desired accuracy of around 10cm.It is also supplemented by an automatic laser tracker fully controlled by AFIS System without manual intervention for tracking, locking or transmitting of aircraft positional information. 4.4.2 The system is provided with RASCAL Ground survey kit based on DGPS. At an airport, the first task of FIU is to collect the Survey data for the ILS to be calibrated. Generally the ARP of the airport, whose coordinates are accurately known, is chosen as the DGPS base station for the survey work. The Rover station is then taken to various points of interest like, Runway Thresholds, Localizer antenna centre, GP antenna base, the P-DGPS point and the Laser Tracker point and Coordinates are recorded. Then the laser tracker survey is carried out to set the references for the tracker itself and a point is selected for siting a reference reflector.

4.4.3 With these data in raw form, it is converted into Threshold coordinate system (TCS) using a software kit. The TCS has its origin at Threshold, X-axis along the extended centerline towards outer marker, Y-axis is perpendicular to X-axis in the anticlockwise

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direction and Z-axis directed upwards. These values are then fed to the facility database of the AFIS system . The nominal Course Width of LLZ is calculated using the survey data and is entered in the database of AFIS. 4.4.4 During Flight check, the aircraft receives its positional information from GPS. It also receives the raw GPS information from the DGPS base station antenna from ground through UHF link. Since the surveyed position of DGPS base antenna is known to the system, it calculates the error and applies to reduce the C/A Code error. The system is having a two frequency GPS receiver and can calculate and apply the carrier phase error in its solution. The application of Phase error gives the P-DGPS solution which is capable of giving an accuracy of 5 cm accurate enough to calibrate a cat III ILS. 4.4.5 The Laser tracker is used to track the aircraft during ILS approaches. The Laser Autotracker is fully controlled by the system software for Search, Track and Verify operations. There is no manual intervention during its operation. 4.4.6 The AFIS is a fully menu driven software with defined exercises. The results are calculated by the inbuilt software and out of tolerance values are displayed in red. It can also generate the reports of an inspection in a predefined format. 4.4.7 GROUND MAINTENANCE SUPPORT SYSTEM (GMSS) : GMSS is the Laboratory equipment setup used for maintenance of AFIS-200 System. The hardware units and the software of GMSS are similar to relevant hardware of AFIS-200 fitted in the Flight Inspection Aircraft and can be interchanged. The GMSS is used for calibration, testing and maintenance of AFIS components. In addition to this it is used for :

1. Archival of mission data from MO disk to CD 2. Replaying of Mission data which are recorded during flight Inspection 3. Preparation and up gradation of FIS database 4. Training on ground using the Simulation feature available in the system.

*****

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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)

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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)

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.

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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.

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1.4 Course Structure, Alignment and Flyability 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. Flyability 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 upto Reciprocal Threshold for CAT-III facility.

1.4.3 Laser Tracker / DGPS When approaches are made the positional (aircraft position w.r.t. threshold) data correction is given by DGPS automatically. Calibration Aircraft is automatically tracked by DGPS / Laser Tracker. In-the case of Tracker, continuous azimuth deviation data of the A/C position gets automatically transmitted to the console through RTT UHF up-link and course structure is calculated by the computer immediately after the completion of the exercise. The Laser Tracker is controlled by the Flight Inspector/AFIS-200 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.

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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

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' (l050M) 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

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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 Localiser 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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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% 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%

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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 A/C flies in-bound on Localizer at 1500' AGL between 6-10 NM. The A/C 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

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.

1.10.2 Flight Procedure

Fig 7. Shows the flight procedure for the Course Width Symmetry Check. The calibration A/C 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. -

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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.

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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.

2.1.2 Flight Procedure: 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

2.1.3 Ground Facility Adjustment 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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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 Normarc 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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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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2.3.2 Flight Procedure: The calibration acft flies in-bound on extended centre line (level run) at 1500′ AGL from 10 NM to MM. the acft receives positional information from the PDGPS positional reference system.

2.3.3 Ground Facility Adjustment

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 for CAT I & II

± 4% of θ for CAT III

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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 Acft flies inbound on G/P on extended centre line from 10 NM up to threshold. The pilot follows glide path. The acft is continuously tracked by PDGPS system/Laser Tracker. The Path Structure is computed automatically. The processed results are displayed by the system, on the screen.

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

2.4.4 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

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CAT II & III up to A - ± 30 micro amps

B 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 para.

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 Acft approach wherein 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 A/C, 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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2.5.1.4 Desired Results The change in Glide Angle obtained by calibration A/C 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 A/C 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.

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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 sensitivity.

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.

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

5. Ground facility adjustment

None. 2.6.4 Desired Results Glide path signal should have minimum signal strength of -92 dBm/m2, minimum 150 µA flyup 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 ED (FIU), GM (Region), OIC Station, GM (N&S). 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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3. Table for Flight Inspection Profiles S.No. Flight profile Parameters recording

parameters result evaluation Remarks

Localizer

1 Crossover at 1500’ AGL at 5 NM

Width & CLR 1.Normal 2.Wide alarm 3.Narrow alarm

1.Deviation current 2.Modsum 3. AGC

Width, Proper Modsum and AGC

Ground eqpt is to be set for nominal CW, wide alarm CW and Narrow alarm CW

2

Normal ILS Approach establishing on LLZ at 7 NM & continuing upto 100’ AGL for Cat I, upto 50’ AGL for Cat II & upto the reciprocal Threshold at 50’ AGL along the rwy for Cat III.

Alignment, Modsum & Path Structure. Polarization check, Position alarm.

1. Deviation current 2. Modsum 3. AGC

Path structure value for Different Zones, Modsum on path, AGC on Path & alignment

Ground eqpt is to be set for nominal alignment and shifted right/left for position alarm under instruction. Aircraft to bank 20° on either side on path for polarization check during commissioning.

3

± 35° Crossover at 2000’ AGL at 17 NM under power alarm condition.

AGC and clearance


Proper clearance and AGC

Ground eqpt to be set for Power alarm condition. For a change of -3 dB (50%) for single frequency Localizer- and – 1 dB (80%) for dual frequency Localizer.

4


AGC and clearance


Proper clearance and AGC

Ground eqpt to be set for Power alarm condition. For a change of – 3 dB (50%) for single frequency Localizer- and -1 dB (80%) for dual frequency Localizer.

5

± 35° Crossover at 6000’ AGL at 8 NM (High angle clearance).

AGC and clearance Proper clearance

and AGC

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Glide Path

1 Level run at 1500’ AGL from 10 NM to 1 NM

a. AGC Nulls b. Phasing c. Sector Width & Max Flyup 1. Normal 2. Wide alarm 3. Narrow alarm


a. Ant height evaluation b. LHSW, UHSW, AGC, Max Flyup & above path clearance.

a. Only CSB to be radiated by resp .ant(dummy other ant.) for null chks b. Phasing as per Gnd eqpt using prescribed cable and procedure. C. Ground eqpt is to be set for nominal SW, wide alarm SW and Narrow alarm SW

2

Normal ILS Approach establishing on GP at 5 NM & continuing upto 100’ AGL for Cat I, upto 50’ AGL for Cat II & Cat III.

Approach angle, Modsum & Path Structure, Position alarm.


Path structure value for Different Zones, Modsum on path, AGC on Path & approach angle.

Ground eqpt is to be set for nominal GP angle and shifted up/down for position alarm under instruction.

3


AGC & Flyup 1.Deviation current 2.Modsum 3. AGC

Proper AGC and Clearance.

Ground eqpt to be set for power alarm condition. For a change of – 3 dB (50%) for single frequency Glide Path- and – 1 dB (80%) for dual frequency GP

4

ILS approach at a minimum of 180µa or 150µa flyup from 5 NM to Threshold

Below path Obstruction clearance


Pilot is to advise on encountering reduced obstacle clearance during the approach.

Gnd eqpt to radiate under Wide alarm condition for the check to be done at 150µa flyup condition..

Markers

1 Normal ILS approach

Ident code, Tone freq, Flythrough distance,

Marker AGC(on low sensitivity), code & frequency

Proper AGC and Ident code.

For operationally usable signal under power alarm condition of ground point. For a change of-3 dB (50%) in Carrier Power

2

±150μa Offset LLZ approach on GP from beyond OM to threshold.

Azimuth Coverage

Marker AGC(on low sensitivity), code & frequency

Proper AGC and Ident code.

For operationally usable signal under power alarm condition of ground equipment. For a change of-3 dB (50%) in Carrier Power

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4. Table for Acceptable Limits

S.No. Parameter Lower limit

Ideal value/Result

Upper limit Remarks

Localizer

1 Alignment - in micro amps 8 0 -8 For Cat I (in-house limits)

5 0 -5 For Cat II(in-house limits)

2 4 0 -2 4For Cat III(in-house limits)

2 Mod Sum 36% 40% 44% On path

38% 40% 42% On path, For Cat III(in-house limits)

36% 40% 60 95%

Off course Modsum for installations after year 1999.

3 Coarse Width 0.96*W W 1.04*W (in-house limits)

4 Minimum clearance 150 side, clearance Sector 150

Minimum clearance 90 side, clearance Sector -150

Minimum clearance150 side, course Sector 175

Minimum clearance 90 side, course Sector -175

5 Path Structure -- in micro amps …upto pt. A 30

...between pt. A and B --- for Cat I 15 linear decrease from 30 to 15

--- for Cat II & III 5 linear decrease from 30 to 5

...between pt. B and pt. C -- for Cat I 15 ...between pt. B and pt. T -- for Cat II 5 ...between pt. B and pt. D -- for Cat III 5

...between pt. D and pt. E -- for Cat III 10 linear increase from 5 to 10

6 Polarization check ( micro amps ) 20 Deg acft bank on course.

15 0 -15 Cat I 8 0 -8 Cat II

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Ideal value/Result

Upper limit Remarks

5 0 -5 Cat III

7 Usable distance in NM 25

Sat AGC. CP current & Mod sum.

8 Identification SAT

Subjective assessment for proper keying and no interference on DDM

9 Course Width symmetry-150 : 90 40 50 60

10 Coverage Chkd under pwr alarm condition.

…LLZ at 17 NM +/- 35 Deg

-84dBmW/m2 SAT


…LLZ at 25 NM +/- 10 Deg

-84dBmW/m2 SAT


11 High angle clearance 150µa SAT


12 Monitor check Alignment shift 90 side alarm -15µa Cat I -10.7µa Cat II -8.4µa Cat III Alignment shift 150 side alarm 15µa Cat I 10.7µa Cat II 8.4µa Cat III

Course Width narrow alarm 0.83*W0.85

Course Width wide alarm 1.17*W 1.20

….Minimum clearance, clearance Zone 135µa Under wide CW alarm

….Minimum clearance, course Sector 160µa Under wide CW alarm

…Power monitor 50%

SAT coverage and performance for a single frequency LLZ.

80%

SAT coverage and performance for a dual frequency LLZ.

13 Performance on stby supply SAT approach on stby supply.

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Ideal/ Nominal value

Upper limit Remarks

Glide Path 1 Glide angle 0.925*θ θ 1.075*θ For Cat I & II 0.96*θ θ 1.04*θ For Cat III 2 Sector Width (Nominal) 0.48 *θ ...Upper half Sector Width Cat I & II 0.07*θ 0.12*θ 0.14*θ ...Upper half Sector Width Cat III 0.10*θ 0.12*θ

0.14*θ ...Lower half Sector width Cat I 0.07*θ 0.12*θ 0.14*θ

Value to be Adjusted During

...Lower half Sector width Cat II & III 0.10*θ 0.12*θ 0.14*θ commissioning

Sector Width (maintained within) for both LHSW & UHSW)

Cat I 0.8*Nom Nom 1.33*Nom

Cat II 0.84*Nom Nom 1.25*Nom

Cat III 0.87*Nom Nom 1.17*Nom

Value to be verified and adjusted within during Routine checks

3 Max Fly up current in micro amps 190

4 Above path Clearance in micro amps 150

must not fall below 150 until 1.75*θ

5 Mod Sum 75% 80% 85% 6 Path Structure -- in micro amps …upto pt. A Cat I,II &III 0 30 ...between pt. A and pt. B --- for Cat I 30

--- for Cat II & III 20 linear decrease from 30 to 20

between pt. B and pt. C -- for Cat I 30 between pt. B and pt.T -- for Cat II & III 20

7 Azimuth coverage right/left of rwy

-65dBmW/m2 SAT

Sat AGC and Flyup +/- 8 deg of rwy

8 Obstruction Clearance check on approach SAT

Sat Obs clr at 180μA flyup condition.

9 Performance on stby supply SAT Sat Approach on stby supply

10 Monitor check

…High angle alarm 1.075*θ 1.10

…Low angle alarm 0.925*θ

…LHSW narrow alarm LHSW-0.0375*θ Cat I

0.75*LHS Cat II & III

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W 0.8*Nom

…LHSW wide alarm LHSW+0.0375*θ Cat I

1.25*LHSW 1.33*Nom Cat II & III

Max Fly up current under wide alarm condition. 180

11 Power monitor 50% SAT

SAT coverage and performance for a single frequency GP.

80% SAT

SAT coverage and performance for a dual frequency GP.

Outer Marker 1 Pass through distance in meter 400 600 800 2 Keying SAT da-da-da-dah 3 Performance on stby supply SAT 4 Tone frequency ( in Hz ) 390 400 410

5 Azimuth coverage 150 μA right/left of rwy(LLZ) SAT

SAT coverage under alm condition.

Middle Marker 1 Pass through distance in meter 200 300 400 2 Keying SAT di-dah-di-dah 3 Performance on stby supply SAT 4 Tone frequency ( in Hz ) 1268 1300 1332

5 Azimuth coverage 150 μa right/left of rwy(LLZ) SAT

SAT coverage under alm condition.

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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

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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. 1.3.2 Flight Procedure: 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

scallopingof 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.

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 automatically tracked by GPS available on board with AFIS. Its omnistar GPS receiver receives correctional data from service provider via satellite to give submeter accuracy under DGPS mode.

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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.

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VOR

FIG.1

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

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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 automatically tracked by GPS available on board with AFIS.

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 Tx 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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VOR

1.5 Radial Checks

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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.

1.5.2 Flight Procedure

i Calibration A/C flies on enroute 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 i. Alignment

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

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

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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 Stby Power Supply. 1.7.2 Flight Procedure: The FIU A/C 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 stby Supply.

1.7.4 Desired Result: – Throughout the coverage volume: Minimum Signal Strength : more than 90 μV/m

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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.

Calibration A/C flies on any radial either inbound or outbound. Give the

equipment on alarm with north alignment control when advised by flight inspector. Normalise 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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2. Flight Inspection Profiles of VOR

Flight profile Parameters recording parameters

result evaluation Remarks

(1) Radial1000ft AGL,inbound /outbound, 0-40 Nm/ 40 Nm- 0

1.Alignment 2.Modulation levels 3.Polarisation 4.Coverage on Stby supply 5.Coverage 6.Bearing alarm check

1. Mod depth-30 Hz AM, 9960 Sub carrier, dent 2. frequency deviation 3. AGC 4. Alignment error

Proper modulation Levels, ident ,AGC, Coverage

1.Ground eqpt to be adjusted for proper modulation levels. 2.Enroute & approach radials to be checked. 3.Ground eqpt on Power Alarm Condition Stby supply during any one of the radial checks 4.Gnd eqpt to be set for Bearing Monitor Alarm 1deg on each side under instruction. 5.A/c to Bank 30° on either side on path for polarization check during commissioning radial checks.

(2) 5NMOrbit,CCW, 1000ft/1500ft AGL

1.Errorspread 2.North alignment

1. Mod depth-30 Hz AM, 9960 Sub carrier, Ident 2. frequency deviation 3. AGC 4. Alignment error

Error spread, mod levels, ident, AGC

1.Ground eqpt i.e main and stby tx is to be radiated a) to determine error spread b) to align the magnetic north

(3) 25NMOrbit,CCW, 1000ft/1500ft AGL

1.Roughness, scalloping bends, noise etc 2. error distribution w.r.t. ground check points.

1. Mod depth-30 Hz AM, 9960 Sub carrier, Ident 2. frequency deviation 3. AGC 4. Alignment error

Error spread, AGC, actual azimuth reading over checkpoint

1.Fly the aircraft directly over the selected Ground check point and mark the recording at the checkpoint. and compare the values.

(4) Receiver checkpoint

1. Air Rx.check point 2.Gnd.Rx.check Point

1. AZIMUTH

2. Distance 3. 30Hz AM, SC,FMI,AGC 4. Tx-I & Tx-II

indications should be within ± 1 deg.

Radial and distance

1. Fly the aircraft over Geographical Feature at 15-20 Nm . 2 Park the aircraft on the airport ramp or taxiway at points selected for easy access by aircraft.

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3. Table for Acceptable Limits of VOR


Ideal value/Result

Upper limit Remarks

1 Polarization -2º 0 +2º 2 Pattern Accuracy Alignment -2º 0 +2º Bends -3.5º 0 +3.5º Roughness -3º 0 +3º Scalloping -3º 0 +3º

3 Coverage field strength 90µv/m >= 90µv/m

or -107 dBW/m2 or -77 dBmW/m2

4 9960 Hz deviation 15 16 17 5 9960 Hz Modulation depth 0.28 0.3 0.32 6 30 Hz Modulation 0.28 0.3 0.32 7 Ident Clearly audible 8 Bearing Monitor -1º +1º

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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

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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. 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 glideslope 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 alignement 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.

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1.3.2 Flight procedure: The calibration aircraft fllies 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.

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.

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FIG 1. COLOR TRANSITION CHECK

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FIG 2. APPROACH ANGLE CHECK

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FIG 3 AZIMUTH COVERAGE CHECK

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

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Documents

Communication Navigation and Surveillance Manual - Volume IV - (Flight Inspection of CNS Facilities)