# SDR ASAA2020021423182

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: February 12, 2020
- Submitted: February 14, 2020
- Operation: Air carrier
- Aircraft: [N419AS](https://openairdocs.org/aircraft/N419AS), registered now
- Make and model: Boeing 737990ER
- Aircraft serial: 41734
- Aircraft time: 27,378 hours, 8,829 cycles
- System (JASC): [3400 · Navigation System](https://openairdocs.org/jasc/3400)
- Part: Unknown
- Condition: Unknown
- Stage of operation: DE
- How discovered: 9
- Nature of condition: O
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/ASAA2020021423182

## Discrepancy

ON A RNAV APP ANGEL 4 LNAV VNAV ENGAGED AT APPROX 13500 THE AIRCRAFT BEGAN A RAPID DESCENT NOSING OVER AND ACCELERATING TO 315. THE ALTITUDE ON THE APPROACH HAD A 12000 OR ABOVE THAT WOULD HAVE BEEN BROKEN UNLESS THE AP WASN'T DISENGAGED. GROUNDED - YES. PERFORMED FMC BITE TEST PER B737-900 FIM 34-61 TASK 801. NO FAULTS FOUND, GROUND VERIFICATION COMPLETE. NO HISTORY FOR 30 DAYS.

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