Date: 201405
Local time of day: 1801-2400
Location: DEN.Airport, CO
Flight conditions: VMC
Light: Daylight
Aircraft: Regional Jet 200 ER/LR (CRJ200)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class E D01
ATC / advisory: TRACON D01
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Confusion; Other / Unknown
Anomaly: ATC Issue All Types
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Became Reoriented; Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Human Factors; Aircraft; Procedure
Primary problem: Human Factors

Narrative: While approaching DEN; we were on the WAHUU arrival. We were somewhere prior to SAYGE waypoint; when I received a confusing clearance from ATC; 'Callsign; descend via the WAHUU arrival except maintain 1-1-thousand.' As there are some intervening step-down altitudes published; I was unsure exactly what ATC wanted us to do; and so I asked for clarification. The response from ATC was exactly what had been previously said; verbatim. So; I asked; 'am I cleared down to 1-1-thousand at this time?' Then another voice (I assume a Supervisor) came on the frequency and clarified that they wanted us to meet any intervening step-downs; but once reaching 11;000 feet; to maintain that altitude. I feel that the new RNAV arrivals and departures in DEN and other stations are overly complex and require a very high workload at a phase of flight in which there are many other tasks we need to accomplish. There are too many fixes; they are too close together; and the descent rate needed when told to 'descend via...' is highly variable from one fix to another. These arrivals require significantly more attention and 'heads-down' time in the cockpit than traditional arrivals. In addition; the new use of 'descend via' and 'climb via' phraseologies seem to be a work in progress; with constantly varying language used. In another example; just the other day I had some confusion with a 'climb via' clearance: Our Pre-Departure Clearance (PDC) said; 'climb via the SID; except maintain 10;000.' Well; as there are no intervening leveloffs prior to reaching 10;000 feet; this verbiage is totally superfluous. My flight path would be no different if that phrase wasn't in there. Then; after leveling at 10;000 feet; I was given the following clearance; 'Call sign; climb via the SID.' There was no altitude assigned other than the original 10;000 feet. So I have to ASSUME that I am to climb to the top altitude printed on the chart - but I will always ask for clarification if this is not spoken. First of all; I feel the need for such a quantity and such complexity of these RNAV arrivals and departures needs to be re-evaluated and decreased. But barring that result I feel these types of clearances need to be clarified and the language standardized and published. In the descent example; it would have been totally clear if ATC had said; 'Descend via the arrival; but upon reaching 11;000 feet; maintain 11;000 feet.' Similarly; the climb clearance is perfectly clear if the altitude is included in the clearance; i.e.; 'Call sign; climb via the SID to maintain Flight Level 230.'




Synopsis: CRJ200 Captain laments the increasingly complex RNAV arrivals and departures with their associated descend via or climb via clearances with altitude modifications.