B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 100; Flight Crew Total 15000; Flight Crew Type 1130
Confusion; Communication Breakdown
Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Human Factors
Vnav descent into ZZZ.  Cleared approach after ZZZ intersection for 16L.  Passing ZZZ intersection; level change was set.  Altitude was set to 1;900 feet.  App mode armed.  Speed set to 180 and flaps 5 selected. Called for gear;  flaps 10 and landing checklist. Captain set 100 feet for touchdown thinking we were still in VNAV.  I did not verify that setting.  I realized we were going further below glide path and cross checked the altitude. Realizing we were low I disconnected autopilot added power and climbed gently to intercept glide path.
Inbound to outer marker ILS 16L ZZZ; plane descended 900 feet below crossing altitude. Pilot Flying took plane out of VNAV into LVL CHG; airplane did not level at FMC altitude of 1;900 feet. MCP altitude was touchdown zone at time of incident.
A B737 air crew got low on the glide slope on final approach. There seem to have been inputs made to the mode control panel; which were unverified. This led the Pilot Flying to think the aircraft was in VNAV when; in fact; it was in level change; resulting in flight below the glide path.