Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Flight Crew Landed in Emergency Condition; Flight Crew Diverted; Flight Crew Landed As Precaution; General Maintenance Action
Aircraft
We took off and the first indications of a problem were rather benign. We were advised to recycle our transponder and I lost my Air Data Computer; with corresponding loss of FD. No other ECAM warnings displayed at this time. Good weather was in front of us and bad weather back at departure airport; just on the very back edge of a large system. ATC advised us that FL230 would be the highest altitude available due to transponder being inop. We then noticed that we had a TAT (Total Air Temperature) issue along with all 3 pitots faulted. We were +7C at FL200 so elected to level there and sort things out. We coordinated with [Operations] to continue to [destination] at FL200 with fuel on board. I then started to look at enroute airports. About this time we started getting multiple ECAM warnings including 3 directing us to turn off all pitot heats due to overheat. This so much went against our instincts that we ended up have a long discussion which included current temps; VMC; enroute weather; divert possibilities etc. We ended up complying with the ECAM. Shortly thereafter we started losing various systems and having gyrations with the remaining yaw damper. Both N1 modes faulted; complete loss of airspeed etc. I [advised ATC] and read pitch and power settings to my F/O while we started a slow controlled descent and requesting immediate divert to [a nearby alternate]. We also immediately turned the pitot heats back on. Through FL180 things started to return and we were able to call ramp that were inbound. We decided to maintain a high speed through 10;000 ft to keep the TAT up since we still were not sure what we had as far as pitot heat. In the end we made flying the aircraft a priority; though it certainly was more difficult to ignore the wildly spinning speed tapes than I might have imagined. We slowed and configured well outside of the marker; probably ran the before landing checklist 3 times. Normal landing with very tentative braking because we were showing no anti-skid. Stopped midfield. Taxied in.After much discussion with Tech Pilot; duty officer; mechanics etc; the glaring question in our minds is: Why is the failure of the switch that dictates to the aircraft that it is on the ground or in flight not tied in to the ECAM? It (ECAM) warns us of all kinds of mundane; nice to know stuff; but this [is] a big ticket item that it completely ignores. We are left to play 'connect the dots' with ECAM guidance that could have possibly catastrophic results. The one glaring thing that kept repeating to us during our hours long debrief and Monday morning quarterbacking of ourselves is that we did exactly as we were trained. 'Do not try to out-think the ECAM. Comply with the ECAM.' Do not be a Sinatra and do it 'My Way' etc. etc. Complying with the ECAM got us into trouble in this case. What amazed us was how quickly things unraveled at that point. We thought we would have a bit more lead time; especially at such a high TAT with no visible moisture.
After landing and a long discussion with maintenance and a tech pilot; we figured out the failed systems were still in the ground mode. Some component had failed causing them to think they were still on the ground. No transponder (thought it was on the ground). Pitot heat didn't switch to 'air' mode; etc. When we did what the plane thought we should do (turning off pitot heat); it caused our loss of airspeed. Add a note (other than in the supplementary section of the QRH) to prevent someone from doing what we did. Just as our gut told us even in clear air turning off all pitot heat is a bad idea. But; that's the path the ECAM led us down. Even a warning or note in the expanded verbiage of the QRH procedure saying 'failure of all 3 pitot systems is extremely rare and caution should be exercised in turning them all off.'
A300-600 flight crew reported multiple anomalies during climb related to failure of the air-ground sensing switch. Flight crew was critical of the ECAM procedure that called for turning off power to all pitot heats; since that action resulted in more failures.