Narrative:

Have a procedural complaint about new arrival into sfo. The PIRAT2 RNAV arrival is new and for a while was not being used by ATC. Old arrival procedure was direct pirat - cross pirat at 10;000 [feet]. New procedure has numerous step down fixes; altitudes; and speeds. Today we were filed PIRAT2 and when we got in radar contact with oakland; were given direct pirat; cross at 10;000 [feet]. RNAV procedure says pirat 15;000 [feet] or below. Fix prior to pirat has speed at 260 kts.; so we asked 'do you need a speed at pirat?'; ATC says no. So now I'm wondering are we on the arrival or not. ATC never said descend via; or cancel PIRAT2. From pirat on; there are two more fixes/speeds. Do we need to follow the path or not? Now a frequency change and a very busy controller; who say expect vectors for ILS. I was confused as what we should doing. All worked out; but this has happened to me before; and ATC needs to get verbiage correct; i.e. 'Cleared to descend via PIRAT2; except cross pirat at 10;000 [feet]' or something else. I know the fix is to just ask; but sometimes you don't have time to go into a whole dissertation as to what ATC expects.

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Original NASA ASRS Text

Title: B777 Captain reported unclear instructions from ATC.

Narrative: Have a procedural complaint about new arrival into SFO. The PIRAT2 RNAV arrival is new and for a while was not being used by ATC. Old arrival procedure was direct PIRAT - cross PIRAT at 10;000 [feet]. New procedure has numerous step down fixes; altitudes; and speeds. Today we were filed PIRAT2 and when we got in radar contact with Oakland; were given direct PIRAT; cross at 10;000 [feet]. RNAV procedure says PIRAT 15;000 [feet] or below. Fix prior to PIRAT has speed at 260 kts.; so we asked 'Do you need a speed at PIRAT?'; ATC says no. So now I'm wondering are we on the arrival or not. ATC never said descend via; or cancel PIRAT2. From PIRAT on; there are two more fixes/speeds. Do we need to follow the path or not? Now a frequency change and a very busy controller; who say expect vectors for ILS. I was confused as what we should doing. All worked out; but this has happened to me before; and ATC needs to get verbiage correct; i.e. 'cleared to descend via PIRAT2; except cross PIRAT at 10;000 [feet]' or something else. I know the fix is to just ask; but sometimes you don't have time to go into a whole dissertation as to what ATC expects.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.