Date: 201203
Local time of day: 0601-1200
Location: CYYZ.Airport, ON
Light: Daylight
Aircraft: Medium Transport; Low Wing; 2 Turboprop Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
ATC / advisory: TRACON CYYZ
Reporter organization: Air Carrier
Reporter function: Pilot Flying; First Officer
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Workload; Situational Awareness; Confusion; Communication Breakdown; Distraction
Anomaly: ATC Issue All Types; Deviation - Altitude Crossing Restriction Not Met; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew; Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented
Contributing factors: Environment - Non Weather Related; Procedure; Manuals
Primary problem: Ambiguous

Narrative: Flying the Waterloo Four Arrival into Toronto. Both pilots reviewed the new 'Canadian Airspace and ATC Phraseology Changes' and thought we understood the procedure. Upon approaching ROKTO at an altitude above 14;000 FT I queried ATC (pilot not flying was off frequency) if we were cleared for the STAR and should we maintain the associated altitudes on our own. The Controller replied confusedly; 'you haven't been cleared for the arrival?' We had not been given specific clearance. He then cleared us for the Waterloo Four Arrival and told us to slow to 250 and maintain 11;000 FT I think. We may not have crossed ROKTO at exactly 250 KTS and possibly were between 14;000 and 12;000 FT; maybe lower. With each fix and a lower crossing altitude ahead we both thought we had to descend on our own to meet those restrictions. Reluctant to do this automatically on our own the Captain asked ATC if we should clear the next fix at its assigned altitude. Each time the Controller did not answer our question but instead cleared us to an altitude lower than the restriction. We were finally cleared to 4;000 FT before NOXER. ALORU has a crossing altitude of 3;000 FT. The Captain thinks we were given a heading before we reached ALORU. I can't remember if we crossed ALORU or not. Either way we were cleared for our approach and told to intercept the glide slope at 4;000 FT. After the flight I mentioned that I thought we had made several errors on the arrival and that we should have started down to 3;000 FT to cross ALORU on our own. We reviewed the memo on this and became even more confused. For instance the Company's memo states; 'The new phraseology requires aircraft to comply with SID/STAR altitude and speed restrictions unless specifically canceled by ATC.' We were never told to NOT comply with the restrictions so we think we should have kept descending on our own to meet them. It then goes on to say; 'Descend Via the (STAR)' does not exist in Canada. When you hear 'Cleared for the (STAR)' or 'Via (STAR); descend to 12;000 FT' you are expected to descend via the STAR and meet all altitude and speed restrictions contained therein. So descend (meeting altitude requirements) to 12;000 FT but because ATC did not specifically cancel the other restrictions I wasn't sure whether we should stay at 12;000 FT or continue down per the STAR. The point I was missing; does ATC have to clear you for the arrival and then clear you to descend to the lowest altitude on the STAR to meet every restriction or should you just meet them on your own since you are cleared for the STAR and restrictions were not canceled? Looking at a Canadian publication; it reads; 'Without delay the pilot will commence a normal descent to FL240 and when convenient continue descent in order to meet the altitude and speed restrictions coded in the STAR. The pilot will level at 12;000 FT unless further descent is received from ATC.' I interpret this to mean one should only comply with restrictions on the STAR within the altitude block given unless canceled by ATC; NOT to comply with ALL restrictions unless canceled. In our case; approaching ROKTO we were told to descend to 11;000 FT. I wasn't sure if we should we have stayed at 11;000 FT or descended on our own to meet NOXER at or below 4;500 FT. Now I believe we should have stayed at 11;000 FT until cleared to a lower altitude as happened. Similarly; we were cleared to 4;000 FT before NOXER; I didn't know if that meant we should have stayed at 4;000 FT after NOXER or descended via the rest of the arrival to be at 3;000 FT by ALORU. ATC never said anything to us about an improper altitude. I found the Company's memo to be somewhat misleading in that it is telling us if we are cleared for the STAR we should comply with all published altitudes unless specifically canceled. The operative word is 'therein' obviously restrictions 'therein' but what about the next lower altitude? Nowhere did it say to stay at the assigned altitude. More emphasis was place on; if cleared for the STAR; we should meet ALL restrictions. Now that I have read over the Canadian memo I think I understand the procedure. I think I would have been better off reading ONLY the Canadian memo. The Company's memo only confused me as it was someone's interpretation of the official Canadian explanation yet only addressed 1 or 2 scenarios and put emphasis on the main point as if it were the only condition. In future; perhaps the Company memo should simply state there have been changes to phraseology and reference the official documents instead of providing their own version of an explanation.




Synopsis: An Air Carrier crew descending into CYYZ was confused; as are many US based crews; about the descent STAR procedure after the clearance statement 'DESCEND to XX;000 FT' and the aircraft is on the arrival routing.