EMB ERJ 170/175 ER/LR
Communication Breakdown; Situational Awareness
ATC Issue All Types
General None Reported / Taken
Human Factors; Procedure
Enroute to RDU; Washington Center changed our arrival to the ALDAN1 from the SBV4. Approaching the SBV VOR we were instructed to 'DESCEND VIA THE ALDAN 1 ARRIVAL'. My student placed 8;000 FT into the altitude pre-selected and enabled VNAV. Shortly after passing the SBV VOR; ATC instructed us to perform a left hand 360 and descend via the ALDAN 1; to 12;000 FT. At this point we were no longer on an arrival; and we were in HDG mode and FPA. The instructions to 'DESCEND VIA' the arrival were contradictory to the other instructions given. Approximately 30 degrees into our left 360; Washington Center cleared us to RDU VIA THE ALDAN 1; DESCEND VIA THE ALDAN1 TO 12;000 FT. They then immediately switched us to RDU Approach. Checking on with RDU Approach I informed them that we had been turned off the arrival; requested direct to any fix on the arrival; and told them that we were descending to 12;000 FT. RDU Approach sent us direct to ALDAN; to cross ALDAN at 10;000 FT. From this point; everything was fairly normal; except that ATC continued to use the phraseology to DESCEND VIA; but continued to issue intermediate altitude constraints. Suggestions; in my professional opinion; ATC controllers need some basic knowledge of avionics and how we as pilots interact with the system and instructions that they are tasked with managing. Using the phraseology DESCEND VIA on an arrival such as the ALDAN 1 is not the same as saying COMPLY with altitudes on the arrival. The former suggests a clearance to the bottom of the arrival; the latter suggests intermediate altitude restrictions. A pilot cannot descend via anything while in heading mode; spinning in space; and again in this case descend via was the improper terminology. After turning an aircraft off an arrival; you cannot simply state 'cleared to RDU VIA the ALDAN 1 arrival'; the crew requires an instruction to proceed back to the RNAV arrival; either direct to a waypoint or a heading to rejoin; in one word; more training.
Air Carrier being handled by ZDC described a confused descent clearance involving the 'descend via' phraseology but with an intermediate vector off the procedure; the reporter suggesting additional training is needed for ATC.