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A B737-700 flight crew on vectors to intercept and ILS was surprised when the autopilot commanded a right turn and pitched up while the autothrottles failed to advance to maintain programmed airspeed.
| Attributes | |
| ACN | 881125 |
| Time | |
| Date | 201003 |
| Local Time Of Day | 1801-2400 |
| Place | |
| Locale Reference | P80.TRACON |
| State Reference | OR |
| Environment | |
| Flight Conditions | Mixed |
| Light | Night |
| Aircraft 1 | |
| Make Model Name | B737-700 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Initial Approach |
| Route In Use | Vectors |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Autopilot |
| Person 1 | |
| Function | Pilot Not Flying First Officer |
| Experience | Flight Crew Last 90 Days 181 |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Deviation - Track / Heading All Types Inflight Event / Encounter Loss Of Aircraft Control |
Narrative:
ATC had issued the following clearance; 'company fly heading 080; maintain 2;500 until established on the localizer; cleared ILS runway 10R approach.' the captain had the aircraft in heading select; with approach mode armed. The correct frequency was tuned and identified. We were level at 2;500 MSL and configuring for the approach. Autopilot and autothrottles were engaged. Captain called for flaps 15. I responded with flaps 15; and moved the flap handle to the 15 detent. Captain then selected flaps 15 maneuvering speed on the MCP. As he did so; the autopilot pitched the aircraft up; and started a climbing right turn. The airspeed bled off rapidly.we had a company captain in the jumpseat. He was the first to call out airspeed. The captain then disconnected the autopilot and corrected the attitude. As his hand went down to the thrust levers; the autothrottles finally responded appropriately to the condition; they advanced toward max thrust. After captain had corrected the attitude; he then disconnected the autothrottles and hand flew the remainder of the approach. The maximum altitude I saw was 3;300 MSL; and the minimum airspeed I saw was 126 knots. Unfortunately; I am uncertain as to what the FMA annunciations were at that point; the masi (mach airspeed indicator) and ADI had my full attention at that time. After much discussion with captain and the captain in the jumpseat; we were unable to ascertain exactly why the autopilot and autothrottles responded the way they did.
Original NASA ASRS Text
Title: A B737-700 flight crew on vectors to intercept and ILS was surprised when the autopilot commanded a right turn and pitched up while the autothrottles failed to advance to maintain programmed airspeed.
Narrative: ATC had issued the following clearance; 'Company fly heading 080; maintain 2;500 until established on the localizer; cleared ILS Runway 10R Approach.' The Captain had the aircraft in heading select; with approach mode armed. The correct frequency was tuned and identified. We were level at 2;500 MSL and configuring for the approach. Autopilot and autothrottles were engaged. Captain called for flaps 15. I responded with flaps 15; and moved the flap handle to the 15 detent. Captain then selected flaps 15 maneuvering speed on the MCP. As he did so; the autopilot pitched the aircraft up; and started a climbing right turn. The airspeed bled off rapidly.We had a Company Captain in the jumpseat. He was the first to call out airspeed. The Captain then disconnected the autopilot and corrected the attitude. As his hand went down to the thrust levers; the autothrottles finally responded appropriately to the condition; they advanced toward max thrust. After Captain had corrected the attitude; he then disconnected the autothrottles and hand flew the remainder of the approach. The maximum altitude I saw was 3;300 MSL; and the minimum airspeed I saw was 126 knots. Unfortunately; I am uncertain as to what the FMA annunciations were at that point; the MASI (Mach Airspeed Indicator) and ADI had my full attention at that time. After much discussion with Captain and the Captain in the jumpseat; we were unable to ascertain exactly why the autopilot and autothrottles responded the way they did.
Data retrieved from NASA's ASRS site as of April 2012 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.