A319
Flight Crew Air Transport Pilot (ATP)
Situational Awareness; Confusion; Communication Breakdown; Human-Machine Interface
ATC Issue All Types
General None Reported / Taken
Procedure; Chart Or Publication; Human Factors
Folks; pilots should not accept a change of altitude clearance without being given an altitude to climb or descend to. Put differently: a change of altitude clearance should not be given to a pilot to 'climb or descend now'...and ATC will tell you later what altitude to level off at. This is; however; exactly what happens when Washington Center clears a pilot to 'Descend Via the TRUPS Arrival' without designating whether it is a north or south landing in DCA due to the fact there are different [runway] transition [bottom] altitudes established (6;000 landing north vice 8;000 landing south) on the TRUPS RNAV arrival. I received this 'Descend Via' clearance far enough from DCA that ATIS was not available--although ACARS was. Regardless; not being assigned a transition is the same thing as not being assigned an altitude when different transition [bottom] altitudes exist. In this case; I did not accept the 'Descend Via Clearance' until Potomac Approach issued the transition; therefore designating the 'Cleared to Altitude.'  In contrast; when an aircraft landing Charlotte is given a 'Descend Via the Ivane' by Atlanta Center; if the pilot does not state the landing runway to Charlotte Approach on initial call they will not accept the initial call and will require the pilot to repeat the Descend Via Clearance stating the transition (runway). This in fact makes good sense.  Pilots are trained to select a (cleared to/hard) altitude on their associated flight computers; and that altitude represents their clearance. Although I am not a human factors expert; if the role of the 'Altitude Select Window' on a transport category aircraft is altered; a large spike in altitude deviations in all phases of flight is likely. Bottom line: Descend or Climb Via Clearances should [identify the runway of intended landing] when different transition altitudes are specified in the procedure.
An A319 Captain took exception to 'descend via' clearances that do not specify a specific altitude and/or landing runway/direction when a procedure--such as the TRUPS RNAV STAR to DCA--has different 'bottom' altitudes depending on landing direction or runway.