Flight Crew Last 90 Days 200; Flight Crew Total 12000; Flight Crew Type 5000
Distraction; Human-Machine Interface
Deviation - Altitude Crossing Restriction Not Met; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification
Human Factors
Captain requested our one and only restroom break prior to starting our descent into Denver which was delayed because of passenger use of the forward lavatory. The Captain left the cockpit followed by myself. I came back to cockpit from restroom break and while I was gone we had received a clearance to cross TOMSN Intersection at FL190 and speed 250 KTS. I believe we had previously received a clearance to descend to FL250 and the autopilot was in ALT HOLD so VNAV was not engaged. [Neither] the Captain nor I noticed this condition and so the descent did not occur with the autoflight. Scheduling had sent an ACARS message right at the time of my bathroom break and the Captain was involved in the reassignment from Crew Scheduling that turned our scheduled one leg day into a multi leg 8 hour flying time day with approximately 13 hours of duty. I had started my day very early to make a commute; so the reassignment was unacceptable and created stress and tension in the cockpit where our focus on flying the plane was compromised as we reviewed the ACARS message from Crew Scheduling. The Captain then realized that he had not started the descent in time to make the assigned altitude and speed crossing restriction. I asked the Controller if we could get relief on the altitude crossing restriction and he said to do the best we can and that we could delete the speed. We missed the crossing altitude by approximately 2;000 FT. No apparent traffic conflict. The timing of the message from Crew Scheduling coincided with our descent into Denver and the assigned crossing assignment which was the triggering factor. Also; the delayed restroom break contributed to my being out of the cockpit during the initial descent from cruise altitude and then the assigned crossing at TOMSN.
The flight crew did not begin the descent at the appropriate point due to distraction. The distraction occurred due to a late lavatory visit and an untimely ACARS message in regard to crew schedule change.