Air Carrier Flight Crew reported when ATC canceled their RNAV approach and assigned a heading for an ILS Approach they failed to set a new hard altitude in the autopilot.
Synopsis
Air Carrier Flight Crew reported when ATC canceled their RNAV approach and assigned a heading for an ILS Approach they failed to set a new hard altitude in the autopilot.
Narrative
We were descending via the OHSEA 2 into SNA in VFR conditions. We were cleared for the RNAV Z approach for Runway 20R. We set the MCP to field elevation and were descending via VNAV. Prior to KLEVR; ATC canceled the RNAV approach and told us to expect the ILS and gave us a vector. We switched the approach to the ILS in the FMC and ran the change triangle checklist items. After our second vector we noticed that the ALT selector was still set to field elevation for the previously assigned RNAV approach. We asked ATC what altitude he wanted us at which he replied 3000 ft. (the altitude we were currently at) and that we were cleared the ILS approach. We flew the ILS approach and landed with no further incident.When we were given the approach change last minute; our task saturation increased dramatically. We did verify the MCP was set for the ILS; but initially missed the ALT selector. The lesson learned here was that when you are vectored off an RNAV approach; to make sure the new hard altitude is set and verified in the MCP. This was a good example of CRM that trapped and mitigated and error. In the future; I plan to 'walk the panel' in its entirety anytime an approach change occurs.
Second reporter narrative
We were on the OHSEA 2 RNAV arrival; level at 5000. ATC cleared us for the RNAV Z 20R so we linked the arrival and the approach at KLEVR and set the field elevation in the MCP. Just prior to KLEVR ATC canceled our approach clearance and gave us a heading for vectors to the ILS 20R. After our second vector we realized we were descending towards the mountains; when we looked at the MCP and the field elevation was still set. We leveled off and called ATC to see what altitude we were cleared to which he replied; 3000ft. We had originally leveled off at 3200ft. so we continued down to 3000ft. The rest of the approach went well; but we were not sure if we were cleared originally from 5000 ft. on the arrival to 3000ft. This flight was the perfect example of how a crew can do everything right and still have issues work their way through the Swiss cheese. The big lesson learned was that when you are vectored off of an RNP approach you have to reset a hard altitude in the MCP. If it wasn't for the great CRM in the flight deck this flight could have ended much worse.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.