Date: 201405
Local time of day: 0001-0600
Location: ZZZ.ARTCC, US
Flight conditions: IMC
Light: Night
Aircraft: A300
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Cargo / Freight / Delivery
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Airspeed Indicator
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Confusion; Situational Awareness
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Aircraft Equipment Problem Critical; Deviation - Altitude Excursion From Assigned Altitude; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Clearance
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Flight Crew Diverted; Flight Crew Landed As Precaution; General Declared Emergency; General Maintenance Action
Contributing factors: Aircraft; Human Factors; Weather
Primary problem: Aircraft

Narrative: I was the Captain and the pilot flying. The aircraft was in level cruise at FL330; .79 mach with AP1 engaged in ALT HLD and autothrottles in mach mode. Flying in IMC conditions with a SAT of approximately -52. We were flying a route coordinated with Dispatch to avoid weather. We were well clear of any convective activity and the ride was slightly choppy. The First Officer said that he needed to take a biological break and exited the cockpit. Suddenly the aircraft started descending and accelerating. The ECAM started producing audible and visual alerts. The Captain's airspeed indicator read about 80 knots and the First Officer's 300 to 320. I immediately disconnected the autopilot and autothrottles; transitioned to the standby ADI and airspeed indicator; and then hollered for the First Officer to return. He immediately returned. I leveled the aircraft between FL300 and FL310. ECAM indicated an IAS/ADC disagreement. It also indicated NAV ADC failure. I selected Captain's ADC INST to number 2 per the ECAM procedures. Instrument readings were improved after instrument switching and I engaged AP 2 and autothrottles. Overall the First Officer and I both felt like the aircraft was under control; then we received a heading change from ATC. Using the heading select turn knob we selected the new heading. The aircraft started banking for the turn and I felt what I believe was initial buffet. I disconnected the autopilot autothrottles and leveled the aircraft at 280 knots on the standby instruments. We declared an emergency with ATC and ask them to inform the Company. I observed that the SAT was reading -27; I felt the reading was erroneous but turned on the engine and wing anti ice to be safe. The First Officer informed me that ZZZ was the closest airport. I asked him to obtain the METAR using ACARS; weather was 10 miles visibility and 9;500 foot ceiling. We told ATC that we were diverting to ZZZ and started descending. I elected to descend at 280 knots and about 1;500 to 2;000 FPM to keep the aircraft stable and avoid large changes in pitch; attitude and thrust settings. We set up the FMC and nav radios for the ILS; briefed the approach; ran the approach and landing checklists. After landing we taxied to parking and secured the aircraft. I completed a through logbook write up and extensively debriefed the mechanic.


Second narrative: We were well clear of any convective activity and the ride was slightly choppy. I decided it was a good time to use the bathroom before our turn and descent for landing; and asked the Captain if he agreed due to the slight IMC chop and weather on our left flank. He agreed and I exited the cockpit. As soon as I had closed the door of the head I felt a sudden descent begin and had to grab for something to hold on to. I heard the autopilot kick off and the Captain yelled for me to return to the cockpit; which I immediately did. ECAM was producing various audible and visual alerts. The Captain's Primary Flight Display Attitude Indicator was blank and the speed tape was all red showing approximately 80 knots and the First Officer's showed approximately wings level; nose level; 320 knots; 20 knots into the barber pole. The Captain had disconnected the autopilot and autothrottles and transitioned to the standby ADI and airspeed indicator; and was attempting to fly level at approximately FL320. He immediately instructed me to declare an emergency as I strapped in and put on my headset. ECAM had a full page of malfunctions and procedures displayed with the primary one being an airspeed and ADC disagreement. It also indicated NAV ADC failure. The Captain had me pull the tab and activate the Emergency Warning Cancellation button to clear the noise. I utilized this button several times during the next few minutes. The Captain was concerned about airspeed and we agreed that 280 KIAS on the standby ASI's and my PFD speed tape was a good target so we began slowing to that. I believe that both my speed displays were close to each other. The Captain observed that the SAT was reading -27; and had me turn on the engine and wing anti ice to be safe. The focus was then back to ECAM which instructed us to confirm airspeed and then switch the Captain's ADC INST to number 2. The Captains PFD then mostly matched (FD's did not seem to match exactly) the First Officer's and we engaged AP 2 and autothrottles. We communicated with ATC and stabilized on a heading and altitude. We were given a left turn and selected the new heading with the heading select knob. As the aircraft reached about 20 degrees AOB we felt what the Captain announced as initial stall buffet. This was very disconcerting because now we weren't sure if we could trust the airspeed indications we had. The Captain disconnected the autopilot; autothrottles and leveled the aircraft at 280 knots on the standby instruments. We confirmed our emergency with ATC; asked them to inform the company; and told them we would need to divert to an adequate landing field immediately. I noticed that ZZZ was the closest airport on my NAV display and announced that it would be a good choice. The ATIS weather was 10 miles visibility and 9;500 foot ceiling. We told ATC that we were diverting to ZZZ and started descending. All descents were at 280 knots and about 1;500 to 2;000 FPM to keep the aircraft stable and avoid large changes in pitch; attitude and thrust settings. I set up the FMC and nav radios for the ILS; briefed the approach; ran the approach and landing checklists. Aircraft appeared to fly normally on approach and First Officer FD tracked the ILS properly. After landing we taxied to parking and secured the aircraft.


Synopsis: A300 Captain experiences an ADC failure at FL330 with the First Officer on a bathroom break. The autopilot pitches over; attempting to maintain Mach number which is decaying on the Captain's instruments. The First Officer returns to find the airspeed 20 knots into the barber pole on his side. The airspeed is stabilized at 280; an emergency is declared and the flight diverts to a suitable airport.