Medium Large Transport; Low Wing; 2 Turbojet Eng
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 166; Flight Crew Total 19629; Flight Crew Type 1543
Confusion; Situational Awareness
Deviation - Altitude Overshoot; Deviation - Altitude Crossing Restriction Not Met; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance; Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Chart Or Publication; Human Factors
Our original clearance from DEN was to climb via COORZ THREE RNAV departure except maintain 10;000 feet. On departure climb; ATC cleared us to 'climb via COORZ THREE' I had to think for a moment as to whether that terminology meant we could climb to published top altitude of FL230. After brief discussion with First Officer (FO) I remembered that yes that is what that means and he agreed. FO reset MCP altitude to FL230 and I confirmed it by pointing at it. I remembered from our pre-departure crew briefing that there was a small print note on the departure chart that said we needed to accelerate to at or above 250 knots above 10;000 feet. I looked at altimeter and saw we were climbing through about 9;600 feet so I called for ECON CLIMB. Speed bug on speed tape advanced to about 305 knots and I lowered the pitch to begin accelerating from approximately 225 knots with a plan to be just under 250 knots as aircraft climbed through 10;000 feet with further acceleration above 10;000 feet to ECON CLIMB speed. Climb rate was now about 500 FPM and continuing to decrease. Aircraft pitch was just slightly above flight director pitch bar. That seemed normal to me as I assumed the pitch bar was directing me to accelerate which I was doing just not quite at as aggressively as the flight director was indicating. Speed was about 240 knots as the aircraft slowly climbed through 10;000 feet. At about 10;300 feet ATC said something about our crossing restriction being 10;000 feet but he said 'no problem' you're cleared to cross the next restriction at or below 11;000 feet. That was CRONA. It was here that I realized that the aircraft had climbed through 10;000 feet just before we had crossed the LINGR departure fix with the at or below 10;000 feet restriction. I was immediately angry with myself for not catching it; for focusing on our new top altitude and speed requirements to the exclusion of the altitude restriction at LINGR. I realized then that the flight director wasn't so much pitching down because of the commanded speed but because we needed to level off at 10;000 feet before crossing LINGR. I also realized; that once again we as a crew are struggling with climb via procedures. When the controller cleared us to 'via...' my mind set became about continuing the climb to the CORRECT top altitude. I didn't forget that we had crossing restrictions in between but by the time I could process the new clearance that eliminated the original 10;000 feet restriction as the top altitude the aircraft was just about through the LINGR 10;000 feet restriction so I missed it.
Flying in VNAV/LNAV; Just before reaching 10;000 feet at LINGR on the COORZ3 departure Den dept control cleared us to climb via the SID. As we reset the altitude on the MCP to the top altitude; we reached 10;000 feet. The Captain called for ECON CLIMB. I selected ECON on the FMC and executed it. LINGR is restricted to at or below 10;000. The flight director should have commanded a level off; but it did not seem to do so. Prior to reaching LINGR; ATC advised us about the restriction and instructed us to remain at or below 11;000 until he next fix on the SID (CRONA). We speculate that VNAV was attempting to recalculate the PATH and did not command level off at 10;000. We were at 10;200 when ATC called us. We had some distraction concerning what was top altitude that caused me not to monitor the current altitude closely at LINGR. Also; I haven't had many flights departing west from KDEN. Most times I have gone east. Going east; it is typical for ATC to give clearance to final altitude; canceling the CLIMB VIA restrictions. I may have had some expectation bias that today's clearance would be the same.
Air carrier flight crew reported an altitude deviation due to a misinterpretation of ATC instructions in regard to the published instrument departure.