EMB ERJ 145 ER/LR
Situational Awareness; Distraction; Workload; Communication Breakdown
Aircraft Equipment Problem Critical; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Returned To Clearance; Flight Crew Became Reoriented
Human Factors; Aircraft; Procedure
We were on the YWT4 RNAV arrival to Runway 23 at CYYZ. It was our first time with this arrival/runway combination. This was one of those OPD arrivals; which is complicated by itself; and we were given a late runway change to 23; which is an unusual runway for us. We also were dealing with low bleed air temperature while in moderate ice; having to slow down for an ATC speed assignment requiring speed brakes; all while complying with turns as assigned by ATC and changes to the aircraft configuration. We had to quickly re-brief the approach while trying to get the speed under control. We were descending when the Captain selected 'SPEED HOLD' too close to our cleared altitude of 4;000 FT MSL and the Autopilot blew through it and continued descending. We caught it too late (3;600 FT or so) and started climbing back up to 4;000 FT. ATC asked about our altitude and we said 'climbing back to 4;000 FT.' No further deviations occurred and we landed normally.We need to be careful using speed mode or when changing modes close to assigned altitude. Also; we needed better monitoring and crosschecking. The Captain said he was changing the mode; which was good CRM; but I did not confirm what he did; and that was poor monitor/crosscheck. I will be more vigilant from now on; even with a familiar crew.
While descending on the WATERLOO RNAV STAR TO CYYZ AN E145 flight crew; distracted by other duties and; perhaps failing to insure altitude capture was active; failed to level at 4;000 FT as cleared.