Narrative:

In mia we were starting our first leg. We received our clearance from clearance delivery. The clearance for departure was the winco 1 RNAV departure. We briefed this departure as the RNAV that it is and the first officer who was flying also included 'nav at 400 ft'; meaning we would be selecting that for the climb out. The push and taxi was normal and un-rushed. The taxi check was done and the brief was again done stating 'winco one departure.' we received our takeoff clearance which was 'cleared for take off; fly heading 270 winco one' (paraphrasing). This confused me. I asked for clarification and the reply was partially blocked but I thought I heard tower tell us to fly heading 270 to join the winco one. By this time the first officer had the controls and power was being applied. I turned my attention to the take off roll. At 400 ft the first officer called for FMS navigation and I complied and we started the turn that is in the winco one. We switched over to departure frequency and I made a point checking in to tell them that we were flying the winco one departure. After a few seconds the controller came back stating we should have been on a heading of 270. He/she issued direct to another fix further up on the winco one and stated that it wasn't a problem. I asked for more clarification and the controller said that headings were given for takeoff. I did not pursue it further. Suggestions; this clearance was at the point of being intentionally confusing from our point of view and coupled with the clarification on the take off roll that didn't clarify anything at all; I am upset that this event happened. An RNAV departure is an RNAV departure; not vectors. There is nothing on the winco one about getting vectors. We briefed it twice and were ready for that. We were given a heading but also the RNAV departure as we briefed. That is not an RNAV departure. That is confusing. There was absolutely no reason for tower to issue a heading but in the same breath also issue the RNAV departure clearance. If they just wanted a heading and said only the heading; the point would be clear and this would not have happened. I think that the clearance was an improper one that resulted in us not doing what ATC wanted; however; I was given 'fly heading 270; winco one' I complied with the last instruction from ATC; which was 'winco one.' in the case of altitude clearances for example; if you were given a crossing restriction and then later another crossing restriction while still in the same descent; the last crossing restriction must be met but the first does not unless explicitly told to comply with both. This is sort of the same situation here. I was given two clearances and I complied with the last one issued. There is no reason for this to have happened. ATC needed to be clearer on what they wanted.

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Original NASA ASRS Text

Title: Air Carrier departure from MIA; assigned an RNAV departure was also given an assigned heading contrary to the RNAV SID; the reporter indicating the clearances were in conflict with one another.

Narrative: In MIA we were starting our first leg. We received our clearance from Clearance Delivery. The clearance for departure was the WINCO 1 RNAV departure. We briefed this departure as the RNAV that it is and the First Officer who was flying also included 'Nav at 400 FT'; meaning we would be selecting that for the climb out. The push and taxi was normal and un-rushed. The taxi check was done and the brief was again done stating 'WINCO ONE departure.' We received our takeoff clearance which was 'Cleared for take off; fly heading 270 WINCO ONE' (paraphrasing). This confused me. I asked for clarification and the reply was partially blocked but I thought I heard Tower tell us to fly heading 270 to join the WINCO ONE. By this time the First Officer had the controls and power was being applied. I turned my attention to the take off roll. At 400 FT the First Officer called for FMS NAV and I complied and we started the turn that is in the WINCO ONE. We switched over to Departure frequency and I made a point checking in to tell them that we were flying the WINCO ONE departure. After a few seconds the Controller came back stating we should have been on a heading of 270. He/She issued direct to another fix further up on the WINCO ONE and stated that it wasn't a problem. I asked for more clarification and the Controller said that headings were given for takeoff. I did not pursue it further. Suggestions; this clearance was at the point of being intentionally confusing from our point of view and coupled with the clarification on the take off roll that didn't clarify anything at all; I am upset that this event happened. An RNAV departure is an RNAV departure; not vectors. There is nothing on the WINCO ONE about getting vectors. We briefed it twice and were ready for that. We were given a heading but ALSO the RNAV departure as we briefed. That is not an RNAV departure. That is confusing. There was absolutely no reason for Tower to issue a heading but in the same breath also issue the RNAV departure clearance. If they just wanted a heading and said only the heading; the point would be clear and this would not have happened. I think that the clearance was an improper one that resulted in us not doing what ATC wanted; however; I was given 'Fly heading 270; WINCO ONE' I complied with the last instruction from ATC; which was 'WINCO ONE.' In the case of altitude clearances for example; if you were given a crossing restriction and then later another crossing restriction while still in the same descent; the last crossing restriction must be met but the first does not unless explicitly told to comply with both. This is sort of the same situation here. I was given two clearances and I complied with the last one issued. There is no reason for this to have happened. ATC needed to be clearer on what they wanted.

Data retrieved from NASA's ASRS site as of April 2012 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.