Date: 201202
Local time of day: 1201-1800
Location: CYYZ.Airport, ON
Flight conditions: VMC
Light: Daylight
Aircraft: B737 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class C CYYZ
ATC / advisory: TRACON CYYZ
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Flying
Human factors: Communication Breakdown; Confusion; Training / Qualification
Anomaly: Deviation - Altitude Crossing Restriction Not Met; Deviation / Discrepancy - Procedural Clearance
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert
Contributing factors: Human Factors; Procedure
Primary problem: Procedure

Narrative: We were on the Waterloo 03 arrival about 30 miles out. ATC vectored us off the arrival onto a heading. ATC then gave us three descents: First; FL390-360; second; from FL360-310; then from FL310-290. We were then cleared back direct to YWT. Then; we were cleared to descend to 11;000 FT. We set the MCP to 11;000 and used FLT LVL change and started down. There was a crossing restriction at ROKTO between 16;000-14;000 FT which we went below. The [descent clearance] phrase was not made clear that we were re-cleared on the arrival and the terminology was to descend to 11;000 FT. ATC was fine with it and asked us what arrival we were given. We told them. The rest of the approach and landing were fine. I did read the recent alert addressing this and got caught in the same trap. However; for years we have used the term 'comply with the restriction' when given an attitude that is not on the Arrival. This is confusing. I have flown into CYYZ many times in the past few months with no issues over this in the past. It seems an easy fix however. They are asking us to make effort when terminology is being used that we are not clear with. We should have verified that ourselves and from now on I will.

Callback: The Reporter stated that the misunderstanding and subsequent altitude crossing error was the result of several factors. The first was the vector off route and re-clearance to YTW but no statement about cleared onto the WATERLOO Three. The second was the clearance to 11;000 FT and the assumption that because they were not cleared on the arrival that the descent clearance was meant as a descend now for traffic or some other ATC requirement. After the fact when they realized that ATC had meant for them to be on the arrival; the crew thought it was odd that there was no comment to either comply with or cancel the ROKTO constraint when the 11;000 FT clearance was issued. The Reporter did not remember the exact phraseology but does remember that the clearance was issued was somewhat different terms from what he was used and not like the US ATC clearance which includes 'Descend Via....' He did this same trip for the entire month and it became clear as the month progressed that CYYZ TRACON terminology began to include a statement to comply with the altitude constraints.



Synopsis: A B737 crew did not comply with the WATERLOO THREE ROKTO 16;000 FT to 14;000 FT crossing constraint after being cleared to 11;000 FT because it was not clear to them that they were flying the WATERLOO Arrival and the clearance phraseology did not make it clear that there were descent constraints in their clearance routing.