Emergency Quick-Diagnosis

Equipment / System

Constant Current Regulator and its protection system, assessed under time pressure to support an immediate operational decision rather than a full root-cause investigation.

Possible Causes

Required Tools

Safety Precautions

• Do not reset a tripped CCR more than once without at least a basic isolation check — repeated resets onto a live fault risk equipment damage and delay a safe outcome.
• Notify ATC/airfield operations of the affected circuit's status before and immediately after any reset attempt so NOTAM action can be issued without delay if needed.

Diagnostic Procedure

1. ObservationRead the CCR's trip indicator/fault code immediately to determine the trip type (overcurrent, earth fault, thermal, manual) without waiting for a full log review.
2. DecisionTrip type indicates a likely transient (e.g. a single earth-fault trip with no prior history) → proceed to a single controlled reset attempt. Trip type indicates a hard fault (overcurrent, repeated trips) → do not reset; escalate directly to fault isolation.
3. MeasurementIf a reset is attempted, monitor CCR output immediately after reset for a clean, stable start with no immediate re-trip.
4. Fault LocationIf reset holds, continue monitoring and schedule full root-cause investigation per Division 01 without further delay to normal operations. If reset fails or re-trips, keep the circuit out of service and begin systematic fault isolation.
5. Root CauseCommunicate the confirmed operational status (restored, or out of service) to ATC/airfield operations immediately so any required NOTAM can be issued or lifted without delay.

Test Points

Root Cause Verification

Confirm circuit status is correctly reflected in ATC/NOTAM systems and hand off to the standard CCR troubleshooting procedure for full root-cause investigation once the immediate operational decision is made.

Corrective Action

• Perform a single controlled reset only where the trip pattern indicates a likely transient.
• Keep the circuit out of service and proceed to systematic fault isolation where the trip indicates a hard or repeated fault.
• Escalate to backup/alternate lighting configuration per local contingency procedure if the affected circuit is safety-critical and cannot be quickly restored.

Preventive Action

• Maintain an up-to-date, quick-reference trip-response decision aid at every CCR location for use under time pressure.
• Ensure ATC/airfield operations communication protocols for lighting status changes are rehearsed and readily actionable.
• Feed every emergency reset event back into the full Division 01 root-cause process rather than closing out on the reset alone.

Related References

SOP: SOP-EMR-01 (CCR Trip Emergency Response Procedure)

Standards: FAA AC 150/5340-30, ICAO Annex 14 Vol I (NOTAM requirements)

Diagram: CCR Emergency Trip-Response Decision Flow

Case Study: Division 01 — CCR Troubleshooting

Equipment / System

The full runway lighting circuit set (edge lights, centreline, threshold/end lights) and their common upstream supply, assessed at the system level for a total-loss event.

Possible Causes

Required Tools

Safety Precautions

• Notify ATC and issue or request a NOTAM/runway closure action immediately given the safety-critical nature of a total runway lighting loss, before completing detailed diagnosis.
• LOTO and follow standard electrical safety procedures once on-site, but treat the initial notification and closure action as the first priority.

Diagnostic Procedure

1. ObservationImmediately confirm with ATC/airfield operations the full scope of the outage — which runway, which light types, and whether it is total or partial — and ensure the runway is taken out of service for the affected operation type if required.
2. MeasurementOn arrival at the vault, check the main incoming power supply status before checking individual CCRs, since a total loss most commonly traces to a common upstream cause.
3. MeasurementIf incoming power is confirmed present, check ALCMS command/status log for an all-off command, then check each CCR's individual status.
4. DecisionUpstream power loss confirmed → escalate to the utility/facility electrical team while keeping the runway closed. Power present but ALCMS/CCR-level cause found → proceed to targeted restoration of the specific fault.
5. Fault LocationPrioritise identifying whether the cause is common (vault/power/ALCMS) or coincidental (multiple independent circuit faults) to guide the restoration approach.
6. Root CauseConfirm full restoration of all affected lighting and coordinate with ATC to lift the NOTAM/closure only once verified.

Test Points

Root Cause Verification

Conduct a full visual/night verification that all previously affected lighting is restored and operating correctly before coordinating with ATC to lift any closure or NOTAM.

Corrective Action

• Restore upstream power supply or escalate to the responsible utility/facility team if the cause is external.
• Correct the ALCMS command/control fault if identified as the cause.
• Repair the specific vault-level or duct-bank fault identified.
• Coordinate with ATC throughout to keep the runway status accurately reflected until full restoration is confirmed.

Preventive Action

• Maintain a documented, rehearsed total-lighting-loss response procedure with clear roles for notification, diagnosis, and restoration.
• Ensure backup/emergency power provisions for the vault are tested on a defined schedule.
• Review common-cause single points of failure (shared power feed, shared conduit) in system design to reduce total-loss risk.

Related References

SOP: SOP-EMR-02 (Total Runway Lighting Failure Response Procedure)

Standards: ICAO Annex 14 Vol I, FAA AC 150/5340-30

Diagram: Runway Lighting Circuit and Vault Supply Diagram

Case Study: Division 01 — CCR Troubleshooting

Equipment / System

The full taxiway lighting circuit set for the affected section and its common upstream supply, assessed at the system level for a total-loss event.

Possible Causes

Required Tools

Safety Precautions

• Notify ATC/apron control immediately given the operational impact of a total taxiway lighting loss on ground movement, particularly at night or in low visibility.
• LOTO and follow standard electrical safety procedures once on-site.

Diagnostic Procedure

1. ObservationConfirm with ATC/apron control the full scope of the outage — which taxiway section and whether total or partial — and coordinate any necessary restriction on ground movement through that section.
2. MeasurementOn arrival at the serving vault, check the main incoming power supply status before checking individual CCRs.
3. MeasurementIf incoming power is confirmed present, check ALCMS command/status log for an all-off command, then check each CCR's individual status for that section.
4. DecisionUpstream power loss confirmed → escalate to the utility/facility electrical team while the restriction remains in place. Power present but ALCMS/CCR-level cause found → proceed to targeted restoration.
5. Fault LocationPrioritise identifying whether the cause is common or coincidental to guide the restoration approach.
6. Root CauseConfirm full restoration of all affected lighting and coordinate with ATC/apron control to lift any ground-movement restriction only once verified.

Test Points

Root Cause Verification

Conduct a full visual/night verification that all previously affected lighting is restored and operating correctly before coordinating with ATC/apron control to lift any restriction.

Corrective Action

• Restore upstream power supply or escalate to the responsible utility/facility team if the cause is external.
• Correct the ALCMS command/control fault if identified as the cause.
• Repair the specific vault-level or duct-bank fault identified.
• Coordinate with ATC/apron control throughout to keep taxiway status accurately reflected until full restoration.

Preventive Action

• Maintain a documented, rehearsed total-lighting-loss response procedure for taxiway sections with clear roles for notification, diagnosis, and restoration.
• Ensure backup/emergency power provisions for taxiway-serving vaults are tested on a defined schedule.
• Review common-cause single points of failure in taxiway circuit design to reduce total-loss risk.

Related References

SOP: SOP-EMR-02 (Total Lighting Failure Response Procedure)

Standards: ICAO Annex 14 Vol I, FAA AC 150/5340-30

Diagram: Taxiway Lighting Circuit and Vault Supply Diagram

Case Study: Division 07 — Taxiway Light Troubleshooting

Equipment / System

Runway centreline lighting circuit, its serving CCR, and its criticality to Category II/III or low-visibility operations at that runway.

Possible Causes

Required Tools

Safety Precautions

• Notify ATC immediately given the direct impact on low-visibility operational minima — centreline failure typically requires an immediate NOTAM restricting Cat II/III operations until restored.
• LOTO the circuit before any fault investigation.

Diagnostic Procedure

1. ObservationConfirm with ATC the exact extent of the centreline outage (full circuit or specific segments) and its immediate impact on published operational minima.
2. MeasurementCheck the CCR serving the centreline circuit specifically for its trip status and fault code, isolating it from other runway circuits that may be operating normally.
3. MeasurementIf the CCR shows a circuit-side fault, proceed directly to segment-by-segment fault location using the series circuit fault locator, prioritising speed given the operational impact.
4. DecisionFault isolated to a specific segment → proceed to targeted repair at that point. CCR-internal fault → escalate to CCR-level troubleshooting while considering a backup CCR or alternate feed if available.
5. Fault LocationUse the fastest available fault-location method (TDR, segment isolation) given the operational urgency of restoring centreline guidance.
6. Root CauseConfirm full restoration and photometric compliance before coordinating with ATC to lift the Cat II/III restriction.

Test Points

Root Cause Verification

Verify photometric intensity meets the required standard for the operational category being restored, and confirm with ATC before the Cat II/III restriction is lifted.

Corrective Action

• Repair the specific cable, connector, or fixture fault identified at the fault-located segment.
• Switch to a backup CCR or alternate feed if available and the primary CCR requires extended repair.
• Restore the ALCMS command state if an erroneous command was the cause.

Preventive Action

• Maintain a rapid fault-location capability (TDR, trained crew) specifically available for centreline and other Cat II/III-critical circuits given their operational sensitivity.
• Ensure backup CCR or alternate feed arrangements exist and are tested for centreline circuits at runways with low-visibility operations.
• Prioritise centreline circuit PM and insulation trending given the operational consequence of any failure.

Related References

SOP: SOP-EMR-03 (Critical Circuit Emergency Fault Location Procedure)

Standards: ICAO Annex 14 Vol I (Cat II/III lighting requirements), FAA AC 150/5340-30

Diagram: Runway Centreline Circuit Diagram

Case Study: Division 05 — Runway Centreline Light Troubleshooting

Equipment / System

Approach Lighting System (ALS) circuits, including centreline bars, crossbars, and sequenced flashers, and their serving CCR(s).

Possible Causes

Required Tools

Safety Precautions

• Notify ATC immediately given the direct impact on approach minima — ALS failure typically requires an immediate NOTAM restricting the approach category until restored.
• LOTO the circuit before any fault investigation, noting the ALS structure may extend into an area requiring additional access coordination.

Diagnostic Procedure

1. ObservationConfirm with ATC the exact extent of the ALS outage (full system, specific bars, or the sequenced flashers only) and its immediate impact on published approach minima.
2. MeasurementCheck the CCR(s) serving the ALS for trip status and fault code, and separately check the sequenced flasher controller if flashers are affected.
3. MeasurementIf a circuit-side fault is indicated, proceed directly to segment-by-segment fault location given the extended cable run typical of ALS installations, prioritising speed given the operational impact.
4. DecisionFault isolated to a specific segment or bar → proceed to targeted repair. CCR or flasher-controller-internal fault → escalate to the relevant equipment-level troubleshooting while considering any available backup configuration.
5. Fault LocationUse the fastest available fault-location method given the operational urgency of restoring approach guidance.
6. Root CauseConfirm full restoration before coordinating with ATC to lift the approach-minima restriction.

Test Points

Root Cause Verification

Verify all bars/crossbars and, if applicable, the sequenced flashers are operating correctly, and confirm with ATC before the approach-minima restriction is lifted.

Corrective Action

• Repair the specific cable, connector, or fixture fault identified at the fault-located segment.
• Repair or reset the sequenced flasher controller if that was the cause.
• Switch to a backup CCR or alternate feed if available and the primary requires extended repair.

Preventive Action

• Maintain a rapid fault-location capability specifically available for ALS circuits given their operational sensitivity and extended cable runs.
• Ensure backup CCR arrangements exist and are tested for ALS circuits at runways with precision approach operations.
• Prioritise ALS circuit PM and insulation trending given the operational consequence of any failure.

Related References

SOP: SOP-EMR-03 (Critical Circuit Emergency Fault Location Procedure)

Standards: ICAO Annex 14 Vol I (approach lighting requirements), FAA AC 150/5340-30, FAA AC 150/5345-56

Diagram: ALS Circuit and Structure Diagram

Case Study: Division 17 — Installation & Commissioning Faults (incorrect approach light installation)

Equipment / System

Stop bar lighting circuit (typically red, elevated or in-pavement, at a runway-holding position), its controller/interlock logic, and its serving CCR.

Possible Causes

Required Tools

Safety Precautions

• Notify ATC immediately — a stop bar failure, whether dark or stuck in the wrong state, is a direct runway incursion risk and normally requires immediate alternate traffic control measures (e.g. positive ATC control of that holding position) until restored.
• LOTO the circuit before any fault investigation, coordinating timing with ATC given the safety-critical nature of the location.

Diagnostic Procedure

1. ObservationConfirm with ATC the exact nature of the fault — fully dark, stuck illuminated, or an inconsistent/conflicting indication with the associated lead-on light — and ensure alternate traffic control measures are in place at that holding position.
2. MeasurementCheck the CCR serving the stop bar circuit for trip status, and separately check the controller/interlock panel for its logic state and any communication fault with ALCMS/tower control.
3. MeasurementIf a circuit-side fault is indicated, proceed to fault location prioritising speed given the direct safety impact.
4. DecisionFault isolated to the circuit/CCR → proceed to targeted repair. Fault isolated to the controller/interlock or communication link → escalate to controller-level troubleshooting while alternate traffic control measures remain in place.
5. Fault LocationPrioritise identifying whether the fault is circuit-level (dark) or logic-level (stuck/conflicting), as these require different corrective paths.
6. Root CauseConfirm the stop bar responds correctly to a test selection command in both states before coordinating with ATC to remove alternate traffic control measures.

Test Points

Root Cause Verification

Test the stop bar through both selection states (on/off) and confirm correct, consistent response before coordinating with ATC to remove alternate traffic control measures at that holding position.

Corrective Action

• Repair the specific circuit, connector, or fixture fault identified.
• Repair or reset the controller/interlock logic fault, or restore the ALCMS/tower communication link.
• Verify and correct the associated lead-on light interlock if an inconsistent indication was found.

Preventive Action

• Maintain a rapid-response capability specifically for stop bar faults given their direct runway incursion safety role.
• Test stop bar interlock logic and communication links on a defined PM schedule, not only when a fault is reported.
• Ensure ATC has a clear, rehearsed alternate traffic control procedure for a stop bar failure at every runway-holding position.

Related References

SOP: SOP-EMR-04 (Stop Bar Emergency Response Procedure)

Standards: ICAO Annex 14 Vol I (stop bar / runway incursion prevention requirements), FAA AC 150/5340-30

Diagram: Stop Bar and Interlock Logic Diagram

Case Study: Division 07 — Taxiway Light Troubleshooting

Equipment / System

Multiple independent lighting circuits and their common upstream infrastructure (shared vault, shared power feed, shared control system), assessed collectively for a coincident-failure event.

Possible Causes

Required Tools

Safety Precautions

• Notify ATC/airfield operations of the full scope of affected circuits immediately, since a multi-circuit failure often has greater operational impact than any single circuit loss would suggest.
• LOTO all affected circuits before investigation, and treat the possibility of a common hazardous cause (fire, major fault) as requiring extra caution on initial approach.

Diagnostic Procedure

1. ObservationList every circuit reported affected and cross-reference against the site single-line diagram to identify any shared upstream infrastructure (power feed, vault, duct bank, control system).
2. MeasurementCheck the shared infrastructure first — main power supply, vault condition, ALCMS command log — before investigating each circuit individually.
3. MeasurementIf no common cause is found at the shared-infrastructure level, proceed to independently investigate each affected circuit per its relevant division procedure.
4. DecisionCommon cause identified → prioritise restoring the shared infrastructure, which should restore multiple circuits simultaneously. No common cause found → treat as coincidental independent faults and allocate resources to investigate each separately.
5. Fault LocationUse the single-line diagram systematically to avoid missing a shared point that is not immediately obvious from the affected circuit list alone.
6. Root CauseConfirm all affected circuits are individually verified restored, since a common-cause fix does not guarantee every downstream circuit recovers without an additional local issue.

Test Points

Root Cause Verification

Individually verify and photometrically/functionally check every circuit initially reported affected, even after a common cause is corrected, to confirm each has fully recovered.

Corrective Action

• Restore the identified shared infrastructure fault (power feed, vault equipment, ALCMS/control system).
• Investigate and repair each circuit individually if no common cause is found.
• Coordinate with ATC/apron control to reflect the true operational status of each affected area throughout.

Preventive Action

• Maintain an up-to-date single-line diagram showing shared infrastructure for rapid reference during a multi-circuit event.
• Review system design for excessive common-cause risk (e.g. too many critical circuits sharing a single feed) and address through capital planning where practical.
• Rehearse a multi-circuit failure response scenario as part of emergency response training.

Related References

SOP: SOP-EMR-05 (Multiple Circuit Failure Triage Procedure)

Standards: FAA AC 150/5340-30

Diagram: Site/Vault Single-Line Diagram

Case Study: Division 01 — CCR Troubleshooting

Equipment / System

Circuit insulation system and earthing/bonding path, assessed under emergency conditions for a severe, actively hazardous earth-fault event rather than a marginal or trending fault.

Possible Causes

Required Tools

Safety Precautions

• Treat any indication of smoke, arcing, or burning smell as a potential fire hazard and follow site fire/emergency response procedure before or in parallel with electrical isolation.
• LOTO the circuit immediately and do not attempt any reset given the severity indicators; verify zero energy before any physical approach to the suspected fault point.

Diagnostic Procedure

1. ObservationAssess the severity indicators reported (trip type, any smoke/arcing/smell, location) to confirm this is a major event requiring emergency-level response rather than routine earth-fault investigation.
2. MeasurementWith the circuit confirmed isolated and safe to approach, megger the circuit segment-by-segment to localise the fault as quickly as possible given the operational and safety urgency.
3. MeasurementUse TDR/fault-locating equipment in parallel to cross-confirm the approximate fault distance and speed up physical location.
4. DecisionFault localised to an accessible point → proceed directly to excavation/repair. Fault location remains ambiguous → escalate for additional specialist fault-location resource given the urgency.
5. Fault LocationPrioritise speed and safety together — do not compromise isolation verification even under operational pressure to restore the circuit quickly.
6. Root CauseConfirm full insulation resistance recovery and clean re-energisation before returning the circuit to service, and coordinate with ATC on the restored status.

Test Points

Root Cause Verification

After repair, re-megger the full circuit and confirm a clean, stable re-energisation with no immediate re-trip before returning the circuit to full service and notifying ATC.

Corrective Action

• Excavate and repair the located cable/connector fault.
• Address any fire-risk conditions found before re-energising.
• Escalate to specialist fault-location resource if the fault cannot be localised promptly with standard equipment.

Preventive Action

• Maintain rapid-response fault-location equipment and trained personnel available for major earth-fault events, distinct from routine PM resourcing.
• Ensure fire/emergency response coordination procedures are rehearsed for electrical fault scenarios.
• Investigate whether the severity of the event indicates a broader condition (e.g. a flood or lightning event) requiring wider system checks beyond the single fault point.

Related References

SOP: SOP-EMR-06 (Major Earth Fault Emergency Response Procedure)

Standards: IEC 60364, FAA AC 150/5340-30, site fire/emergency response procedure

Diagram: Emergency Fault Location Quick-Reference Guide

Case Study: Division 08 — Taxiway Centreline / Guidance Lighting Troubleshooting (cable insulation faults)

Equipment / System

Primary series or feeder cable, assessed under emergency conditions where the scale or cause of the fault (severance, major excavation damage, widespread event) requires a coordinated rapid response.

Possible Causes

Required Tools

Safety Precautions

• Coordinate with civil/excavation teams and confirm no other utilities are at risk before any excavation begins, particularly following a known excavation strike event.
• LOTO the circuit and confirm zero energy before any physical access to a severed or damaged cable, treating any exposed conductor as live until proven otherwise.

Diagnostic Procedure

1. ObservationEstablish the known cause and approximate location of the major fault from the reporting party (excavation crew, fire response, flood report) to focus the initial response.
2. MeasurementWith the circuit isolated, use TDR/fault-locating equipment to confirm the fault distance and cross-check against the reported location and the as-built cable route drawing.
3. MeasurementAssess the full extent of affected cable — a single point severance versus an extended damaged length — before committing to a repair scope.
4. DecisionFault confirmed as a single, accessible point → proceed to excavation and splice/repair. Fault extends over a significant length or the cable is otherwise compromised along its run → plan for a full segment replacement rather than a single splice.
5. Fault LocationCoordinate fault-location results with civil/excavation teams to minimise excavation extent while ensuring the full damaged length is addressed.
6. Root CauseConfirm the repaired or replaced segment passes full insulation and continuity testing before re-energising and returning the circuit to service.

Test Points

Root Cause Verification

Fully test the repaired or replaced cable segment (insulation resistance, continuity, and a clean re-energisation with no immediate fault) before returning the circuit to full service.

Corrective Action

• Splice-repair a single confirmed fault point using a rated below-grade splice kit.
• Replace an extended damaged segment rather than attempting multiple splices where the damage is widespread.
• Coordinate with civil teams to properly reinstate pavement/surface following excavation.

Preventive Action

• Maintain emergency cable repair materials (splice kits, spare cable reels) in stock for rapid major-fault response.
• Establish clear coordination protocols with civil/excavation contractors and utility locate services to reduce the risk and speed the response to future strikes.
• Review as-built cable route accuracy periodically so emergency fault-location efforts are not delayed by inaccurate records.

Related References

SOP: SOP-EMR-07 (Major Cable Fault Emergency Response Procedure)

Standards: FAA AC 150/5340-30, local utility damage-prevention/excavation coordination requirements

Diagram: Emergency Cable Repair Kit Reference

Case Study: Division 17 — Installation & Commissioning Faults (cable routing/burial/protection)

Equipment / System

Multiple base cans, pull boxes, and potentially the equipment vault, assessed collectively following a confirmed significant water ingress event.

Possible Causes

Required Tools

Safety Precautions

• Treat all affected circuits and equipment as energised hazards until isolation is confirmed at the CCR/vault level, given the scale of the event.
• Coordinate with the responsible utility or civil team to stop the water source, in parallel with electrical isolation, since continued inflow will undermine any electrical remediation.

Diagnostic Procedure

1. ObservationMap the full extent of the water-affected area — which base cans, pull boxes, or vault areas — before beginning individual fault investigation, and identify and address the water source.
2. MeasurementWith all affected circuits confirmed isolated, systematically megger each affected circuit segment before attempting to re-energise anything.
3. MeasurementAssess whether water reached the equipment vault/CCR room and inspect that equipment separately and thoroughly before considering system-wide re-energisation.
4. DecisionCircuit-level ingress only, vault unaffected → proceed with systematic pump-out, drying, and insulation verification circuit by circuit. Vault/CCR affected → treat as a higher-priority, system-wide event requiring full equipment assessment before any re-energisation.
5. Fault LocationPrioritise fault investigation and restoration by circuit criticality given the scale of the event.
6. Root CauseConfirm every affected circuit passes insulation testing before re-energising, and monitor for a secondary fault wave as residual moisture continues to affect components over subsequent days.

Test Points

Root Cause Verification

Systematically re-verify insulation resistance for every affected circuit before and after re-energising, and continue monitoring for a secondary fault wave over the following days.

Corrective Action

• Stop the water source in coordination with the responsible utility or civil team.
• Pump out and dry all affected base cans, pull boxes, and vault areas.
• Replace components confirmed damaged by water exposure rather than only drying and re-testing marginal readings.
• Prioritise restoration by circuit criticality.

Preventive Action

• Maintain a water-event emergency response procedure specific to the AGL system, including coordination steps with utility/civil teams to address the source.
• Identify water-vulnerable base cans and vault areas in advance and consider protective measures proactively.
• Coordinate with facility utility management to reduce the risk and response time for burst-main-type events near AGL infrastructure.

Related References

SOP: SOP-EMR-08 (Major Water Ingress Emergency Response Procedure)

Standards: FAA AC 150/5340-30

Diagram: Emergency Water Event Response Checklist

Case Study: Division 21 — Operational & Maintenance Problems (flood-related failure pattern)

Equipment / System

AGL system components across potentially multiple circuits, CCRs, surge protection devices, and control system equipment, assessed collectively for lightning-induced damage.

Possible Causes

Required Tools

Safety Precautions

• Confirm no ongoing lightning risk before sending personnel to survey outdoor equipment; follow site lightning safety procedures for timing of the response.
• LOTO all circuits before internal inspection of CCRs, surge protection devices, or control equipment suspected of strike damage.

Diagnostic Procedure

1. ObservationEstablish the approximate strike location/time from available lightning detection data or reports, and identify which circuits/equipment are within the likely affected radius.
2. MeasurementSystematically survey CCRs, surge protection devices, and control equipment across the likely affected area for damage indicators (blown surge devices, tripped protection, control card faults) rather than waiting for each to be individually reported.
3. MeasurementMegger circuits within the affected area systematically to catch induced insulation damage that may not have caused an immediate trip.
4. DecisionDamage pattern is widespread across the affected area → proceed with a full systematic replacement/repair campaign rather than treating each as an isolated fault. Damage is isolated to one or two points → handle as standard single-fault troubleshooting but keep the wider area on watch.
5. Fault LocationPrioritise the systematic survey over reactive one-at-a-time troubleshooting, since lightning damage often presents as multiple simultaneous minor faults rather than one obvious major fault.
6. Root CauseConfirm all systematically surveyed equipment within the affected area is tested and restored or replaced before considering the event closed out.

Test Points

Root Cause Verification

Conduct a follow-up functional and photometric check across the full affected area over the following days, since some lightning-induced degradation can manifest as delayed rather than immediate failure.

Corrective Action

• Replace sacrificed surge protection devices across all affected locations.
• Repair or replace CCR control cards or other equipment confirmed damaged by the surge.
• Repair localised severe cable damage at the direct or near-direct strike point using the major cable fault procedure.
• Restore ALCMS/communication equipment if affected.

Preventive Action

• Ensure surge protection devices are installed and rated appropriately at all CCRs and vulnerable equipment locations given the site's lightning exposure.
• Maintain a lightning-event response procedure that defaults to a systematic area survey rather than isolated fault response.
• Monitor local lightning detection data to trigger a proactive survey promptly after a confirmed nearby strike.

Related References

SOP: SOP-EMR-09 (Lightning Damage Survey and Response Procedure)

Standards: FAA AC 150/5340-30, IEEE surge protection guidance

Diagram: Lightning-Affected Area Survey Checklist

Case Study: Division 01 — CCR Troubleshooting

Equipment / System

AGL infrastructure across a significant portion of the airfield — multiple base cans, cable routes, vaults, and potentially above-ground equipment — assessed collectively during and after a broad flooding event.

Possible Causes

Required Tools

Safety Precautions

• Follow the airport's overall emergency management plan for a flooding event; AGL response is one component of a broader coordinated response involving airport operations, emergency services, and possibly civil authorities.
• Treat all flood-affected AGL infrastructure as an electrical hazard until systematically isolated and confirmed safe, given the scale and potential for vault-level impact.

Diagnostic Procedure

1. ObservationCoordinate with the airport emergency management structure to understand the full scope of the flooding event and its impact on operational areas before beginning AGL-specific assessment.
2. MeasurementSystematically isolate and assess all AGL circuits within the flood-affected area, prioritising by operational criticality (active runway circuits first) rather than by convenience of access.
3. MeasurementAssess vault/equipment room impact separately and thoroughly, since this can pose a broader system risk beyond any single circuit.
4. DecisionFlooding is receding and localised → proceed with systematic circuit-by-circuit recovery per the major water ingress procedure, prioritised by criticality. Flooding is extensive or ongoing → focus on safety isolation and coordinate a phased recovery plan with airport emergency management rather than attempting simultaneous full restoration.
5. Fault LocationPrioritise safety and operational criticality over completeness of individual fault diagnosis during the acute phase of the event.
6. Root CauseConfirm systematic insulation testing and restoration of every affected circuit as flood water recedes, coordinating the sequence with airport emergency management and ATC.

Test Points

Root Cause Verification

As flood water recedes, systematically re-verify insulation resistance and functional/photometric performance for every affected circuit, coordinating the restoration sequence and any required NOTAM actions with airport emergency management and ATC.

Corrective Action

• Execute a phased, criticality-prioritised recovery of AGL circuits as conditions allow.
• Pump out and dry affected vaults, base cans, and pull boxes systematically across the affected area.
• Replace components confirmed damaged by flood exposure.
• Coordinate all restoration milestones with airport emergency management and ATC.

Preventive Action

• Maintain an AGL-specific annex within the airport's overall emergency management plan for major flooding events.
• Identify flood-vulnerable AGL infrastructure across the site in advance for prioritised protective measures where practical.
• Participate in airport-wide flood emergency exercises to ensure the AGL response is integrated with the broader emergency management structure.

Related References

SOP: SOP-EMR-08 (Major Water Ingress Emergency Response Procedure), Airport Emergency Management Plan (AGL Annex)

Standards: FAA AC 150/5340-30, local emergency management coordination requirements

Diagram: Airfield Flood Impact and Recovery Priority Map

Case Study: Division 21 — Operational & Maintenance Problems (flood-related failure pattern)

Equipment / System

ALCMS-to-CCR communication network (fibre, copper, or wireless link and associated network equipment) across the site, assessed for a widespread or total communication loss distinct from a lighting-circuit fault.

Possible Causes

Required Tools

Safety Precautions

• Confirm the actual lighting status at the field level directly (via CCR local panels or visual check) rather than relying solely on ALCMS, since lighting may still be functioning correctly despite the communication loss.
• Coordinate with ATC to clarify that this is a monitoring/control communication issue and confirm whether operational lighting status can still be managed via local CCR control if needed.

Diagnostic Procedure

1. ObservationConfirm the scope of the communication loss — all CCRs, a specific zone, or intermittent — and cross-check whether the underlying lighting circuits are still functioning normally at the field level.
2. MeasurementCheck the central ALCMS server and network equipment status first, since a widespread loss usually traces to a central point rather than many simultaneous field-level link failures.
3. MeasurementIf the central equipment appears healthy, use network diagnostic tools to trace the communication path toward the affected CCRs to isolate a backbone break.
4. DecisionCentral ALCMS/server or network equipment fault confirmed → escalate to IT/network support for restoration while confirming lighting itself remains locally controllable. Backbone break confirmed → proceed to physical fault location on the communication cable/network path.
5. Fault LocationDistinguish between a central-equipment cause and a distributed backbone/cable cause before committing resources to physical fault-finding.
6. Root CauseConfirm ALCMS visibility and control is restored to all previously affected CCRs and cross-check reported status against local panel status before closing out.

Test Points

Root Cause Verification

After restoration, cross-check ALCMS-reported status against local CCR panel status for every previously affected unit to confirm accurate communication has been restored, not just that the link is technically up.

Corrective Action

• Restore or repair the central ALCMS server/network equipment fault.
• Repair a physically damaged communication backbone/cable.
• Escalate to IT/network support for a software/firmware or configuration fault.
• Maintain local CCR control and manual status reporting to ATC throughout the outage as a contingency.

Preventive Action

• Maintain a documented contingency procedure for continuing safe lighting operations via local CCR control during an ALCMS communication outage.
• Ensure redundant communication paths exist for critical CCRs where practical to reduce single-point-of-failure risk.
• Coordinate with IT/network support on a rapid-response protocol specific to ALCMS communication given its operational criticality.

Related References

SOP: SOP-EMR-10 (ALCMS Communication Failure Contingency Procedure)

Standards: FAA AC 150/5340-30, site IT/network support procedures

Diagram: ALCMS Communication Network Diagram

Case Study: Division 01 — CCR Troubleshooting

Equipment / System

ALCMS server, application software, and its central hardware, assessed for a system-level failure affecting monitoring/control capability across the airport.

Possible Causes

Required Tools

Safety Precautions

• Immediately confirm and communicate to ATC that lighting circuits should be verified via local CCR control/manual observation, since ALCMS status cannot be trusted during a confirmed system failure.
• Follow manufacturer-specified safe shutdown/restart procedures for the ALCMS server rather than attempting an uncontrolled restart, which risks further data corruption.

Diagnostic Procedure

1. ObservationConfirm the nature of the failure — fully offline, unresponsive but powered, or providing erroneous data — through direct observation of the server and application.
2. MeasurementCheck server hardware status/diagnostics first to rule in or out a hardware-level cause before assuming a software fault.
3. MeasurementIf hardware appears healthy, review recent update/patch history and application logs for the point of failure.
4. DecisionHardware fault confirmed → escalate for hardware repair/replacement or failover to a backup/redundant server if available. Software/application fault confirmed → follow manufacturer-specified recovery procedure, restoring from backup if database corruption is involved.
5. Fault LocationPrioritise restoring basic monitoring/control capability, even in a degraded form, over pursuing a complete root-cause diagnosis during the acute outage.
6. Root CauseConfirm ALCMS status accurately reflects verified local CCR status for every circuit before returning to normal ALCMS-based operation, given the risk of residual data corruption after a major failure.

Test Points

Root Cause Verification

After recovery, cross-check ALCMS status against local CCR panel status for every circuit airport-wide before fully trusting ALCMS-based operation again, and monitor system stability over the following operating period.

Corrective Action

• Fail over to a backup/redundant ALCMS server if available.
• Restore the ALCMS application/database from a verified backup following manufacturer procedure.
• Escalate to the manufacturer for hardware or software support where in-house recovery is not possible.
• Maintain manual/local CCR control and status reporting to ATC throughout the outage.

Preventive Action

• Maintain a tested backup/redundant ALCMS server configuration for critical airports.
• Verify ALCMS backup integrity on a defined schedule so a recovery can be trusted when needed.
• Maintain a current manufacturer support contract and escalation contact for rapid response to a major ALCMS failure.

Related References

SOP: SOP-EMR-11 (ALCMS System Failure Recovery Procedure)

Standards: FAA AC 150/5340-30, ALCMS manufacturer documentation

Diagram: ALCMS Server and Backup Architecture Diagram

Case Study: Division 21 — Operational & Maintenance Problems (false alarms, unexpected shutdown)

Equipment / System

Backup/emergency lighting provision — standby generator, battery backup, or secondary CCR/feed configuration — assessed specifically for its failure to perform its intended role during a primary system outage.

Possible Causes

Required Tools

Safety Precautions

• Notify ATC immediately that backup lighting has failed to activate, since this compounds the operational impact of the original primary failure and may require additional restrictions.
• Follow manufacturer safety procedures for generator and transfer switch inspection, particularly if a failed start or transfer is suspected to involve a fuel, mechanical, or electrical fault.

Diagnostic Procedure

1. ObservationConfirm exactly what backup element failed — generator start, transfer switch operation, battery capacity, or the backup circuit itself — rather than treating the whole backup system as a single fault.
2. MeasurementCheck the generator start sequence and transfer switch operation logs (if available) for the specific point of failure during the attempted activation.
3. MeasurementIf the power source and transfer functioned correctly, test the backup lighting circuits themselves for an independent fault.
4. DecisionGenerator/transfer switch fault confirmed → escalate to the responsible mechanical/electrical backup power team for repair. Backup circuit-specific fault confirmed → treat as a standard lighting circuit fault per the relevant division, noting it went undetected due to infrequent energisation.
5. Fault LocationIsolate whether the failure is in the power source, the transfer mechanism, or the lighting circuit itself, since each requires a different responsible team and repair approach.
6. Root CauseConfirm a full functional test of the backup system — start, transfer, and lighting circuit operation together — before considering it restored to service, not just a fix of the single component that failed.

Test Points

Root Cause Verification

Conduct a full end-to-end functional test of the backup system (start, transfer, and lighting operation together) and confirm it performs correctly before considering the backup provision restored.

Corrective Action

• Repair or service the standby generator if it failed to start or reach stable output.
• Repair or replace a failed automatic transfer switch.
• Recharge, service, or replace a depleted/failed battery backup system.
• Repair the independent backup circuit fault per the relevant division procedure.

Preventive Action

• Conduct full-load, end-to-end backup system tests (not just a generator start test) on a defined regular schedule so latent faults are caught before an actual emergency.
• Include backup lighting circuits in the routine PM cycle despite their infrequent energisation, to catch independent faults proactively.
• Verify backup system sizing/configuration against actual required load periodically, particularly after any system expansion.

Related References

SOP: SOP-EMR-12 (Backup Lighting System Verification and Recovery Procedure)

Standards: FAA AC 150/5340-30, NFPA 110 (standby power systems)

Diagram: Backup Power and Lighting System Diagram

Case Study: Division 01 — CCR Troubleshooting