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Flight crew of A320 encounter turbulence and over-reactive autothrottles input on approach to iad. Possible breach of unstabilized approach criteria ensued.
| Attributes | |
| ACN | 602083 |
| Time | |
| Date | 200312 |
| Day | Wed |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | airport : iad.airport |
| State Reference | VA |
| Altitude | msl single value : 1900 |
| Environment | |
| Flight Conditions | IMC |
| Weather Elements | Rain |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | tower : iad.tower |
| Operator | common carrier : air carrier |
| Make Model Name | A320 |
| Operating Under FAR Part | Part 121 |
| Flight Plan | IFR |
| Aircraft 2 | |
| Navigation In Use | ils localizer & glide slope : 19l |
| Flight Phase | descent : approach |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 220 flight time total : 7300 flight time type : 3900 |
| ASRS Report | 602083 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 260 flight time total : 10000 flight time type : 2500 |
| ASRS Report | 602086 |
| Events | |
| Anomaly | inflight encounter : turbulence inflight encounter : weather non adherence : company policies other anomaly |
| Independent Detector | other flight crewa |
| Resolutory Action | flight crew : overrode automation flight crew : exited adverse environment |
| Supplementary | |
| Problem Areas | Weather Environmental Factor Aircraft Flight Crew Human Performance |
| Primary Problem | Weather |
Narrative:
Moderate turbulence from doccs intersection through landing. Intercepting GS on the ILS to runway 19L at iad. Outside the OM we selected managed speed, after verifying activated and confirmed. Autothrottles surged causing indicated airspeed to increase although magenta managed speed indicator showed slower. I believe that aircraft sensed a loss of energy due to turbulence and decided to increase power. Captain disconnected autothrottles and hand-flew aircraft to a safe landing on runway 19L at iad. Very heavy rain on final with gusty winds at 3000 ft from 220 degrees/65 KTS diminishing to about 210 degrees/10 KTS at 20 ft. We felt the approach was conducted in a safe manner (it took a few moments to get back on GS after power surge), but it may not have met stabilized criteria at 500 ft due to the gusty WX conditions. From OM inbound conditions were officially VFR although heavy rain caused diminished visibility through windshield even with wipers on fast. Our focus for the last 800 ft or so was outside to maintain visual alignment with runway. Landing was uneventful and within touchdown zone.
Original NASA ASRS Text
Title: FLT CREW OF A320 ENCOUNTER TURB AND OVER-REACTIVE AUTOTHROTTLES INPUT ON APCH TO IAD. POSSIBLE BREACH OF UNSTABILIZED APCH CRITERIA ENSUED.
Narrative: MODERATE TURB FROM DOCCS INTXN THROUGH LNDG. INTERCEPTING GS ON THE ILS TO RWY 19L AT IAD. OUTSIDE THE OM WE SELECTED MANAGED SPD, AFTER VERIFYING ACTIVATED AND CONFIRMED. AUTOTHROTTLES SURGED CAUSING INDICATED AIRSPD TO INCREASE ALTHOUGH MAGENTA MANAGED SPD INDICATOR SHOWED SLOWER. I BELIEVE THAT ACFT SENSED A LOSS OF ENERGY DUE TO TURB AND DECIDED TO INCREASE PWR. CAPT DISCONNECTED AUTOTHROTTLES AND HAND-FLEW ACFT TO A SAFE LNDG ON RWY 19L AT IAD. VERY HVY RAIN ON FINAL WITH GUSTY WINDS AT 3000 FT FROM 220 DEGS/65 KTS DIMINISHING TO ABOUT 210 DEGS/10 KTS AT 20 FT. WE FELT THE APCH WAS CONDUCTED IN A SAFE MANNER (IT TOOK A FEW MOMENTS TO GET BACK ON GS AFTER PWR SURGE), BUT IT MAY NOT HAVE MET STABILIZED CRITERIA AT 500 FT DUE TO THE GUSTY WX CONDITIONS. FROM OM INBOUND CONDITIONS WERE OFFICIALLY VFR ALTHOUGH HVY RAIN CAUSED DIMINISHED VISIBILITY THROUGH WINDSHIELD EVEN WITH WIPERS ON FAST. OUR FOCUS FOR THE LAST 800 FT OR SO WAS OUTSIDE TO MAINTAIN VISUAL ALIGNMENT WITH RWY. LNDG WAS UNEVENTFUL AND WITHIN TOUCHDOWN ZONE.
Data retrieved from NASA's ASRS site as of July 2007 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.