Captain experiences an airspeed discrepancy during approach between aoa and IAS with the aoa indicat...

Narrative:

Fully configured; on a stable flaps 35 approach; tracking the localizer and glideslope; we had a pitch attitude of 7 degrees and the aoa in the HUD was well out of the 'approach band' to the slow side. The computed FMS approach speed for a 325k landing was 140 knots. We bugged the approach speed to 145-146 knots to bring the aoa to the middle of the approach band and pitch attitude to 4.5-5 degrees (tracking a 3 degree glideslope.) a normal safe landing followed. We had the same aircraft and issue the day before on approach. On taxi from this flight we had air data computer #1 and air data computer #2 fail. This was written up and signed off before our return flight. We had no other maintenance issues on the flight. The training we are doing to crosscheck the aoa with our current pitch and power setting is working. Our training kicked in and made this a non-event. Both; myself with the aoa; and the first officer without the aoa (but he has an aoa background form his past experience) were able to recognize our pitch attitude was too high and make the necessary adjustments and land the aircraft safely.

Original NASA ASRS Text

Title: Captain experiences an airspeed discrepancy during approach between AOA and IAS with the AOA indicating slow. Airspeed is increased five knots bring the the AOA into the proper range. ADC malfunctions had been reported the previous day and addressed by Maintenance.

Narrative: Fully configured; on a stable Flaps 35 approach; tracking the localizer and glideslope; we had a pitch attitude of 7 degrees and the AOA in the HUD was well out of the 'approach band' to the slow side. The computed FMS approach speed for a 325k landing was 140 knots. We bugged the approach speed to 145-146 knots to bring the AOA to the middle of the approach band and pitch attitude to 4.5-5 degrees (tracking a 3 degree glideslope.) A normal safe landing followed. We had the same aircraft and issue the day before on approach. On taxi from this flight we had ADC #1 and ADC #2 fail. This was written up and signed off before our return flight. We had no other maintenance issues on the flight. The training we are doing to crosscheck the AOA with our current pitch and power setting is working. Our training kicked in and made this a non-event. Both; myself with the AOA; and the First Officer without the AOA (but he has an AOA background form his past experience) were able to recognize our pitch attitude was too high and make the necessary adjustments and land the aircraft safely.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1163115
Time
Date	201404
Local Time Of Day	0001-0600
Place
Locale Reference	ZZZ.TRACON
State Reference	US
Aircraft 1
Make Model Name	Heavy Transport
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Flight Plan	IFR
Component
Aircraft Component	Air Data Computer
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Less Severe

Captain experiences an airspeed discrepancy during approach between aoa and IAS with the aoa indicating slow. Airspeed is increased five knots bring the the aoa into the proper range. Air data computer malfunctions had been reported the previous day and addressed by maintenance.