Air Data Fault after Departure from Clark
An A320 departs Clark (RPLC) at 0612 UTC for Davao (RPMD) at FL340. In IMC at FL180, the crew reports: captain's PFD airspeed frozen at 180 kt; first officer's PFD shows 250 kt; standby ASI shows 245 kt; captain's altitude is 800 ft higher than the first officer's; ECAM shows ADR 1 FAULT; autopilot has disconnected; TCAS shows no traffic. The aircraft is 25 minutes from Manila and 70 minutes from Davao. Fuel is sufficient for either destination plus 45 minutes final reserve. Manila is VMC with runway 06 ILS available; Davao is reporting 2,000 m visibility, TSRA, and low cloud. The captain says, "It's just one faulty display; we'll continue and use the first officer's instruments." The dispatcher must support the decision and coordinate ATS.
1. What is the likely system fault, and why is the captain's plan questionable?
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The likely fault is an air data reference problem on the captain's side, consistent with ADR 1 FAULT. A frozen captain's airspeed at 180 kt while the first officer's PFD shows 250 kt and the standby ASI shows 245 kt indicates that the captain's airspeed is unreliable. The 800 ft altitude split also shows that at least one altitude source is wrong, so the crew cannot simply assume the first officer's display is correct without cross-checking the standby instruments and applying the unreliable airspeed procedure.
The first officer's airspeed and standby airspeed are close, which supports the first officer's source, but the altitude disagreement must still be resolved. More importantly, continuing to Davao in thunderstorm conditions with low visibility reduces the crew's options while working a non-normal condition. Returning to Manila, which is VMC with an ILS, gives a simpler approach and better support. The captain's statement treats the fault as a single display issue when it affects air data and altitude awareness.
2. What should the dispatcher do while the crew works the problem?
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The dispatcher should provide decision support, not troubleshoot the aircraft. Pass Manila weather, runway 06 ILS status, Davao weather, and the fuel/time comparison for each option. Recommend a return to Manila unless the crew has a clear reason to continue. Ask the crew whether they want to declare an urgency or emergency, and be ready to relay that to ATS. Request priority handling, level allocation and, if needed, radar vectors.
The dispatcher should also notify operations, maintenance and emergency services, and obtain souls on board and fuel endurance for the ground response. Confirm that the crew has completed the applicable checklist and cross-checked standby instruments. If the captain insists on Davao, the dispatcher should state the risk clearly, confirm the commander's decision, and document it. The dispatcher must not pressure the crew or suggest that the fault is unimportant.
3. If the fault is later confirmed as a blocked pitot tube, what post-flight safety actions are appropriate?
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The event should be reported through the safety management system and maintained as a non-punitive occurrence report. Maintenance should inspect the pitot system, confirm that covers and plugs were removed, check for blockage or contamination, and test the air data system before the aircraft returns to service. The flight data and cockpit voice data should be preserved under the operator's procedures, and the crew should file a detailed report.
The dispatcher's record should include the weather, the crew reports, the options offered, and the commander's decision. Operations should review whether dispatch or ground procedures contributed, such as pitot cover control or pre-flight inspection. If a systemic issue is found, a safety risk assessment and corrective action should follow, with feedback to crews and dispatchers.