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B737 captain reported the aircraft climbed 400 feet while on altitude hold while they were looking for traffic; a repeat gripe for this aircraft.
| Attributes | |
| ACN | 1399685 |
| Time | |
| Date | 201610 |
| Local Time Of Day | 0601-1200 |
| Place | |
| Locale Reference | ZZZ.ARTCC |
| State Reference | US |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | B737 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Route In Use | Vectors |
| Flight Plan | IFR |
| Aircraft 2 | |
| Make Model Name | Medium Large Transport |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Route In Use | Vectors |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Altitude Hold/Capture |
| Person 1 | |
| Function | Captain |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 99 Flight Crew Total 21000 Flight Crew Type 4000 |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Conflict Airborne Conflict Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance |
Narrative:
While in cruise flight we were being given vectors at FL200; center called traffic at our 11 o'clock position at FL190. For about 90 seconds the first officer and I scanned the horizon for the [aircraft]. Then the altitude alert system chimed indicating we were (+400 feet) off altitude set in our cruise panel window. I gently lowered the nose so as not to cause the other aircraft TCAS to go off based on our descent rate. I then re-engaged the altitude hold.after speaking with our mechanics on the ground this is not the first or second time this aircraft has been written up for such an event. Maintenance always writes up our aircraft as unable to duplicate. It is my fault for not having monitored our altitude while looking for traffic.
Original NASA ASRS Text
Title: B737 Captain reported the aircraft climbed 400 feet while on altitude hold while they were looking for traffic; a repeat gripe for this aircraft.
Narrative: While in cruise flight we were being given vectors at FL200; Center called traffic at our 11 o'clock position at FL190. For about 90 seconds the First Officer and I scanned the horizon for the [aircraft]. Then the altitude alert system chimed indicating we were (+400 feet) off altitude set in our cruise panel window. I gently lowered the nose so as not to cause the other aircraft TCAS to go off based on our descent rate. I then re-engaged the altitude hold.After speaking with our mechanics on the ground this is not the first or second time this aircraft has been written up for such an event. Maintenance always writes up our aircraft as unable to duplicate. It is my fault for not having monitored our altitude while looking for traffic.
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.