MD-11
Flight Crew Last 90 Days 60; Flight Crew Total 7500; Flight Crew Type 2500
Situational Awareness; Human-Machine Interface; Confusion; Communication Breakdown; Distraction
Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Flight Crew FLC complied w / Automation / Advisory; Flight Crew Became Reoriented
Human Factors
Setting up for the approach we were cleared to descend to 2;000 feet and given a right turn of 270 degrees heading to intercept the course for RNAV 30R and cleared for the approach. Approach gave us a vector and cut the final corner.  We were given an intercept heading of 270 degrees that would have put us established between Fix X and Fix Y on the RNAV 30R.  The Captain called for direct Fix X and asked the Fist Officer (FO) to clear the turn point since we were on radar vectors to final well inside of Fix X.FixY was set in the FMS AS +2;000 feet. The Captain was established on the intercept heading of 270 degrees inbound between Fix X and Fix Y; he then armed NAV. While still descending to 2;000 feet in V/S mode; the Captain asked the FO to set min alt of 461 feet in the altitude window.  Prof was not re-engaged at that point; so the aircraft did not level off at 2;000 feet as was required to cross Fix Y.  The aircraft continued down. When the Enhanced Ground Proximity Warning System (EGPWS) went off for the gear; 'To low Gear' we realized that the aircraft had not leveled off as programed because we were not in Prof Mode; we climbed back up to 2;000 feet. At this point we were approximately 16 miles from the end of the runway. We reset the altitude; verified the box and continued the approach to a normal RNAV to 30R and landing without further incident.
I was established on the intercept heading inbound between Fix X and Fix Y; armed NAV; and then made my mistake. While still descending to 2;000 feet in V/S mode I asked the First Officer (FO) to set min alt of 461feet in the altitude window without selecting prof or verifying that prof was selected.So the aircraft did not level off at 2;000 feet to cross Fix Y as was programed in the box. The aircraft continued down. When I realized that we had not leveled off at 2;000 feet I asked for 2000 feet in the altitude window and rolled the vertical speed wheel up for a climb back up to 2000'; the Enhanced Ground Proximity Reporting System (EGPWS) went off for the gear; 'TOO LOW GEAR'.My mistakes were not verifying on the PFD that we were in prof. setting minimum altitude of 461 feet prior to leveling off at 2;000 feet. Not disconnecting the autopilot and aggressively climbing back to 2;000 feet. If I had I don't believe the EGPWS would have gone off.
An MD-11F air crew descended below the published altitude for an intermediate fix on final approach and received the 'TOO LOW GEAR' warning.  They climbed back to the appropriate altitude; continued the approach and landed.