Date: 201208
Local time of day: 0001-0600
Location: CZYZ.ARTCC, ON
Light: Daylight
Aircraft: Regional Jet 700 ER/LR (CRJ700)
Operator: Air Carrier
Operating under: Part 121
Flight phase: Descent
ATC / advisory: Center CZYZ
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown
Second reporter function: First Officer; Pilot Flying
Anomaly: ATC Issue All Types
Detector: Person Air Traffic Control
Result: General None Reported / Taken
Contributing factors: Procedure; Human Factors
Primary problem: Procedure

Narrative: [I] cleared DTW - PISNT Intersection - Waterloo 4 Arrival into Toronto. In cruise at FL190 between PISTN Intersection and Waterloo on the Waterloo 263 radial. First Officer was flying and fully briefed the arrival with crossing restrictions and speeds. ATC cleared us to descend to 11;000 FT. We were NOT given any 'descend via' instructions. We took this as a routine descent clearance and began a descent from FL190 to 11;000 at a normal rate of descent (probably around 1;500 FPM). 11;000 is NOT a published altitude anywhere on the Waterloo arrival into Toronto. ATC later contacted us and said 'don't worry about it now' and pointed out a requirement to cross Waterloo between 14;000 and 16;000 FT. We were later given a descent to 8;000. On the way to 8;000; the ATC Controller told us to stop the descent at 8;000 due to departing traffic climbing to 7;000. The next published altitude on the chart was 6;000; but we had not been given a 'descend via' clearance or an altitude below 8;000. I firmly believe ATC was confused or mistaken as to whether we had been given a 'descend via' clearance; we had NOT. It appears that the Arrival controllers at CYYZ were expecting a 'descend via' - but we were never cleared that way. Cause; the threat was an altitude deviation; but I don't believe we had an altitude deviation. We complied with all clearances. I believe the Controller made a mistake and didn't give us the clearance that the later controllers were expecting. Suggestions; I am concerned over the confusion this has caused. We were NOT given a 'descend via' clearance. The First Officer and I were concerned that we now must query ATC on ANY new altitude to see if they really want us to descend to that altitude. Mistrust of routine ATC clearances greatly increases pilot workload. I think the Controller made a mistake on his clearance.


Second narrative: We are in cruise heading from DTW to Toronto. Center told us to descend and maintain 11;000 FT. We were at FL190 and approximately 40 miles from Waterloo (a fix on the Waterloo 4 arrival). There was NO mention of 'in accordance with' in that transmission. We descend to 11;000 FT about the time we reach Waterloo. We are given a change of frequencies; to Arrival/Approach. At this time; Approach stated (paraphrase); 'it's okay for today; but want you to know that even if given an altitude to descend to; you still have to comply with the altitude restrictions on the arrival.' There was a restriction; an altitude block; for a point 8 miles beyond Waterloo that is above 11;000. Based on this comment; we became focused on not 'missing' any further restrictions and did not ask further questions of ATC. Cause; It is our belief that either ATC made a mistake (did not say; 'IAW the Waterloo 4 arrival restrictions').  There was NO way we could have thought that we needed to follow the arrival altitude restrictions based upon the ATC instructions.  We were not even on the Waterloo arrival yet! Our flight plan had us go to a nav point direct to Waterloo and that nav point was not an arrival transition. Bottom line; without being given a 'descend via' or language similar; there is no reason to believe that we need to do anything other than what was directed by ATC. If that were the case; ANY TIME ATC gives an altitude; we would have to query to ensure they don't mean anything other than what they commanded. Suggestions; we need to ensure that 'descend via' language is a requirement if ATC expects us to descend IAW an arrival procedure. ATC needs to ensure clarity of their directions. I do not believe the flight crew should change any of their procedures.  There was NO evidence based on this situation (outside of the arrival geographically; and no verbiage about descend IAW) to suggest we should have asked a question--there was no reason to do so.


Synopsis: Air Carrier on descent to Toronto was questioned by ATC with regard to crossing altitudes; the flight crew expressing concern reference the phrase 'descend VIA' and it's application/use in this event.