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CE680 flight crew experiences failure of the autopilot to track the localizer after capturing. The autopilot is disconnected and a hand flown approach to landing ensues. The aircraft had a history of pitching down while coupled on ILS approaches.
| Attributes | |
| ACN | 983076 |
| Time | |
| Date | 201112 |
| Local Time Of Day | 1801-2400 |
| Place | |
| Locale Reference | BWI.Airport |
| State Reference | MD |
| Environment | |
| Flight Conditions | IMC |
| Aircraft 1 | |
| Make Model Name | Cessna Citation Sovereign (C680) |
| Operating Under FAR Part | Part 135 |
| Flight Phase | Initial Approach |
| Route In Use | Vectors |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Approach Coupler |
| Person 1 | |
| Function | Pilot Not Flying First Officer |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 290 Flight Crew Total 11300 Flight Crew Type 360 |
| Person 2 | |
| Function | Captain Pilot Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine |
| Experience | Flight Crew Last 90 Days 156 Flight Crew Total 8982.2 |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Deviation - Procedural Clearance Deviation - Track / Heading All Types |
Narrative:
Flying in heavy rain and light turbulence; we were at 4;000 ft being vectored on a wide right downwind for ILS 33L. Just inside of janns (if) we were given a heading of 300 and descend to 2;000 ft; cleared for ILS 33L. The autopilot was engaged in a heading mode and a vertical descent was initiated. The 'approach' was armed. At approximately 3;000 ft; still descending to 2;000 ft the localizer came alive on both sides and then captured. The landing gear was lowered. However; the turn back to 330 to center the CDI was very slow and we flew through the course. The aircraft continued to turn back to a heading of about 360 and again flew through the localizer. However; this time it was not turning back to track inbound. I notified the pilot flying to turn back to the left to recapture the inbound course. At the same time; I turned the heading bug back to a heading of 300 but the aircraft was not turning and the flight director was apparently not following the heading bug. The pilot flying then disconnected the autopilot and began an immediate left turn. As we were passing a heading of about 330 in our turn back to 300; ATC notified us to make a turn back to 300 and intercept the approach. While hand flying; the PIC was able to level off at 2;000 ft and then capture the ILS. He hand flew the aircraft and we broke out of the clouds at 800 ft and landed. Prior to this event; pilots flying this aircraft have reported; while captured on an ILS with the autopilot engaged; a sudden nose down pitch and have had to disconnect the autopilot to maintain control of the aircraft. A human factor might be that once we observed the localizer to be 'captured' and intercepting the inbound course we did not expect it to become un-captured and fly right back through the course without remaining captured.
Original NASA ASRS Text
Title: CE680 flight crew experiences failure of the autopilot to track the localizer after capturing. The autopilot is disconnected and a hand flown approach to landing ensues. The aircraft had a history of pitching down while coupled on ILS approaches.
Narrative: Flying in heavy rain and light turbulence; we were at 4;000 FT being vectored on a wide right downwind for ILS 33L. Just inside of JANNS (IF) we were given a heading of 300 and descend to 2;000 FT; cleared for ILS 33L. The autopilot was engaged in a heading mode and a vertical descent was initiated. The 'approach' was armed. At approximately 3;000 FT; still descending to 2;000 FT the localizer came alive on both sides and then captured. The landing gear was lowered. However; the turn back to 330 to center the CDI was very slow and we flew through the course. The aircraft continued to turn back to a heading of about 360 and again flew through the localizer. However; this time it was not turning back to track inbound. I notified the pilot flying to turn back to the left to recapture the inbound course. At the same time; I turned the heading bug back to a heading of 300 but the aircraft was not turning and the flight director was apparently not following the heading bug. The pilot flying then disconnected the autopilot and began an immediate left turn. As we were passing a heading of about 330 in our turn back to 300; ATC notified us to make a turn back to 300 and intercept the approach. While hand flying; the PIC was able to level off at 2;000 FT and then capture the ILS. He hand flew the aircraft and we broke out of the clouds at 800 FT and landed. Prior to this event; pilots flying this aircraft have reported; while captured on an ILS with the autopilot engaged; a sudden nose down pitch and have had to disconnect the autopilot to maintain control of the aircraft. A human factor might be that once we observed the localizer to be 'captured' and intercepting the inbound course we did not expect it to become un-captured and fly right back through the course without remaining captured.
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.