B737-700 first officer reported that while on final approach the aircraft pitched over and started a...

Attributes
ACN	1717390
Time
Date	202001
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Light	Daylight
Aircraft 1
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Flight Plan	IFR
Component
Aircraft Component	Autopilot
Person 1
Function	Pilot Flying First Officer
Experience	Flight Crew Last 90 Days 140 Flight Crew Type 2312
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Altitude Excursion From Assigned Altitude Inflight Event / Encounter CFTT / CFIT Inflight Event / Encounter Unstabilized Approach

Narrative:

We were doing the RNAV west to xxr from zzzzz. Aircraft was doing fine as we configured. Approaching 1;300 feet AGL; just as the flaps were set to 30; the aircraft pitched over and started a dive. I said; 'what's it doing?' a few times quickly then clicked off the autopilot and recovered the aircraft below 1;000 feet. Tower gave us a low altitude alert. I had the ILS in as backup; and I climbed back to a normal glidepath and landed uneventfully. The captain and I discussed the situation and we agreed that the aircraft (for some reason) went to 'speed' and was chasing the airspeed. We all have the aircraft go into speed during arrivals with no indication; but this was a first for me on approach. Had this been night/IMC; it could have resulted in something very bad.

Original NASA ASRS Text

Title: B737-700 First Officer reported that while on final approach the aircraft pitched over and started a dive. After disengaging the autopilot; the flight crew recovered and made an uneventful landing.

Narrative: We were doing the RNAV W to XXR from ZZZZZ. Aircraft was doing fine as we configured. Approaching 1;300 feet AGL; just as the flaps were set to 30; the aircraft pitched over and started a dive. I said; 'what's it doing?' a few times quickly then clicked off the autopilot and recovered the aircraft below 1;000 feet. Tower gave us a low altitude alert. I had the ILS in as backup; and I climbed back to a normal glidepath and landed uneventfully. The Captain and I discussed the situation and we agreed that the aircraft (for some reason) went to 'Speed' and was chasing the airspeed. We all have the aircraft go into speed during arrivals with no indication; but this was a first for me on approach. Had this been night/IMC; it could have resulted in something very bad.

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.

B737-700 first officer reported that while on final approach the aircraft pitched over and started a dive. After disengaging the autopilot; the flight crew recovered and made an uneventful landing.