Date: 202104
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: B737 MAX Series Undifferentiated
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class B ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: Autopilot
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; Captain
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Time Pressure; Human-Machine Interface; Troubleshooting
Second reporter function: Pilot Flying; First Officer
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Flight Crew Overcame Equipment Problem; Flight Crew Overrode Automation; Flight Crew Regained Aircraft Control; Flight Crew Returned To Clearance; Flight Crew Took Evasive Action; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: We were cleared for the visual approach to Runway XXR. The First Officer was flying. We had intercepted the final approach course with Flaps 10 and assigned a speed of 170 or less. The airplane intercepted the final approach course with VOR/LOC armed. The autopilot intercepted the final at 2;200 feet; just outside of ZZZZZ; and at that time APP mode was selected. Upon intercepting the Glide Slope; the First Officer called for 'Flaps 15; Landing Gear down.' The aircraft captured the glideslope uneventfully. Shortly after passing ZZZZZ; the First Officer called for 'Flaps 30.' I selected Flaps 30 and as the flaps were moving to Flaps 30 the aircraft abruptly pushed the nose over approximately 8 to 10 degrees down. The First Officer and I were startled by the pushover; and both of us did a rapid assessment of what was happening. Approximately three or four seconds into the push over event and a full dot low on the G/S; the GPWS issued a 'Caution Obstacle.' The First Officer responded by disengaging the autothrottle and the autopilot. He corrected the flight path and landed the aircraft uneventfully.

Callback: Reporter stated that further data analysis showed the pitch down event was due to a glide slope drop out that was caused by another aircraft on the runway ready for departure. Reporter also stated that these types of glide slope losses were known to occasionally occur with this runway.

Second narrative: We were cleared for the visual approach to Runway XXR. [I] was flying. We had intercepted the final approach course with Flaps 10 and assigned a speed of 170 or less.  The autopilot intercepted the final approach course with VOR/LOC armed. Approach mode was then selected. The autopilot intercepted the glide slope at 2;200 feet just outside of ZZZZZ. Upon intercepting the G/S; [I] called for 'Flaps 15; Landing Gear down.'  The aircraft captured the glideslope uneventfully. Shortly after passing ZZZZZ; [I] called for 'Flaps 30.'  [Captain] selected Flaps 30; and as the flaps were moving to Flaps 30; the aircraft abruptly pushed the nose over approximately 8 to 10 degrees down. [We] were startled by the push over; and both of us did a rapid assessment of what was happening.  Approximately 3 or 4 seconds into the push over event and a full dot low on the G/S; the GPWS issued a 'Caution Obstacle.'  [I] responded by disengaging the autothrottle and the autopilot. [I] corrected the flight path and landed the aircraft uneventfully.


Synopsis: B737 MAX flight crew reported the aircraft abruptly pitched down during flap extension while on a visual approach with automation engaged. Pilot flying disconnected automation and executed an uneventful landing.