A320
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 190; Flight Crew Total 20250; Flight Crew Type 2200
Aircraft Equipment Problem Critical
General Declared Emergency; General Maintenance Action
Aircraft
During cruise flight we had a fault light on IR Number 2. We complied with the ECAM and referred to the FM and completed the additional steps. We did switch the IR to ATT mode and entered our heading per the FM but the IR seemed to remain completely inoperative. The MRM code for the malfunction was entered into ACARS. Approximately 55 miles out during descent IR Number 3 faulted. This resulted in the loss of the A/T along with both autopilots and flight directors and the First Officer's flight displays and put us into alternate law. I became the PF and the First Officer completed the ECAM and referred to the FM. The ECAM kept repeating and was difficult to clear and step through. By this time we were with Approach Control and cleared direct to a fix on the ILS to intercept. Approach control advised us LLWAS was in effect with winds out the N-NW at 10-15 KTS and that there had been recent reports of W/S. We were less than 30 NM out and there were still more of the checklist to read through and also the Approach/Landing Corrections for Failures procedure to complete. Considering these factors and since I was hand flying on raw data and the First Officer was very busy we decided it was prudent to declare an emergency and request delay vectors. The First Officer completed the checklists; the landing procedure and landing distance calculations; and notified Dispatch. The flight attendants and the passengers were briefed. I did not ask for cabin prep or request ARFF equipment. We completed an extended 270 degree right turn and landed uneventfully on the slightly longer runway. The airplane was in direct law for landing and flaps 3 per the FM. The wind was reported I think 350/11 with no recent W/S. The ARFF trucks were out and followed us to the gate. We briefed Maintenance and the outbound flight crew. Had we been further out when the second IR failed we may not have declared an emergency. In that case we would have had plenty of time to do everything and this would have been more of a non-event. However this situation presented like it would have made a good traditional simulator training scenario happening so close to arrival. Over the years I have been advised that declaring an emergency helps buy time and reduce workload with the service ATC provides. We did not especially want to hold with raw data or be rushed in for landing. I also thought the risk of a pilot deviation was greater due to no autoflight at all and the workload as it was.
About 2 hours into the flight we lost our No. 2 IR. I was just returning from the bathroom so the Captain had complied with the ECAM. We reviewed the Flight Manual (FM) and sent in the maintenance code. About an hour and a half later; in VFR conditions; while on the arrival descending below 20;000 feet the autopilot kicked off and I; Pilot Flying; (PF); lost most of my Primary Flight Display; (PFD) and Navigation Display; (ND). We had lost the No. 3 IR and got the ECAM Nav IR 2 + 3 Fault. The Captain quickly finished the Approach Descent Checklist and then he became the PF. I went through the ECAM checklist and then to the FM. The checklists were somewhat long and I could not get them done as ATC was vectoring us now for landing. The Captain opted to declare an emergency at this time to give us more time to complete the checklists associated with the loss of IRs 2 + 3. ATC was great giving us vectors around while we completed the checklists and informed dispatch. After calculating the landing distances and going through the F/CTL Direct Law non-normal procedure we reviewed all we had lost and when the aircraft would go from ALTN LAW to Direct Law and Manual trimming of the aircraft. When we were ready we notified ATC and told them we would take the longer runway. We received vectors to final for an uneventful landing flown by the Captain and taxi-in was normal. We did leave the ADIR's on at the end of the shutdown checklist to facilitate Maintenance troubleshooting and talked to Maintenance and the Fire Rescue who came on board to check to make sure everything was alright.
A320 flight crew experiences the loss of two IRU's. The first in cruise and the second an hour and a half later during descent. This results in Alternate Law flight controls and Direct Law when the gear is extended for landing. The time required to accomplish all checklists is long and the crew elects to declare an emergency to accomplish them.