B757-200
Situational Awareness; Human-Machine Interface; Communication Breakdown
Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Human Factors
We were on pre-final vectors. We were [then cleared direct JENFR;] 'cross JENFR at 4;100.' Both PF and PM confirmed that restriction was in the MCDU. PF switched to FLCH to expedite descent. Subsequently given 'cleared for the ILS Runway 30.' The PF put 2;500 in the MCP. Just prior to JENFR; we noticed aircraft descending through 4;100. Autopilot was disconnected by PF. Aircraft was leveled off at 3;850. We crossed JENFR a few seconds later; and continued our descent and approach. Nothing said by ATC. Switching out of VNAV with its inherent increased protection; and then subsequently setting a new altitude in the MCP...Obviously FLCH will not honor the restriction in the MCDU. Not catching the FLCH mode by the PM was also a cause.[To avoid this in the future:] Don't set the MCP window lower or higher than a restriction when operating in FLCH. Quicker/More Accurate cross checking by the PM.
A B757-200 flight crew; cleared to cross JENFR at 4;100 FT and; shortly after; cleared for the ILS 30 at OAK descended below the restriction when the PF entered the glideslope intercept altitude in the altitude alert window while operating in FLCH mode vice VNAV as intended.