Narrative:

We were assigned the SHEAD7 departure from las. We briefed a departure from 1R and the shead routing; including the altitude restrictions at mddog; tarrk; shead; and dbige. We also briefed a company field and facilities notice regarding complying with altitude restrictions on the SHEAD7. In addition; we referenced an fdc NOTAM usd 01/242 for the SHEAD7 that reads; 'cross mddog at 9;000 (ATC)/at or above 9;000. Cross tarrk at 11;000 (ATC)/at or above 11;000.' we interpreted this NOTAM as clarifying a minimum altitude at or above mddog and tarrk; since the chart only references an altitude for each intersection. The meaning of 'ATC' in the NOTAM was unknown to us. On departure from las climbing through 9;000; the las departure controller queried us about our altitude and told us to stop our climb and maintain 10;000. He stated that we should have leveled at 9;000 until mddog. We responded that we were planning to cross mddog at or above 9;000; referring to the fdc NOTAM 01/242. There was no traffic conflict in this instance. However; inbound arrivals to las from the south and west arrive in this area between 9;000 and 11;000 ft; so it had the potential for conflict. Cause; the wording in this fdc NOTAM is not clear. There is no explanation for the letters 'ATC' in the NOTAM. The company field and facilities does not refer specifically to the NOTAM; so there is confusion which directive applies. The previous day on a departure from las runway 25R; upon check-in with departure control we immediately received an unrestricted climb to FL190. This is the clearance I have received in most of my departures from las. This clearance may have conditioned us to believe the hold down altitude of 9;000 at mddog was rarely used (or unnecessary). The 'at or above' wording in the NOTAM seems appropriate considering the rising terrain to the west of the airport. I believe that notams need to be written in plain english. Abbreviations and condensed wording can be misinterpreted and lead to mistakes. In this instance; the NOTAM is unnecessary; as the altitude crossing restrictions on the chart need to be applied; and if the altitude restrictions were unnecessary; ATC can offer an unrestricted climb.

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Original NASA ASRS Text

Title: Air Carrier departure from LAS noted confusion regarding the altitude restrictions listed on the SHEAD7 SID; indicating uncertainty between crossing restriction/s ATC vs. conventional.

Narrative: We were assigned the SHEAD7 departure from LAS. We briefed a departure from 1R and the SHEAD routing; including the altitude restrictions at MDDOG; TARRK; SHEAD; and DBIGE. We also briefed a company field and facilities notice regarding complying with altitude restrictions on the SHEAD7. In addition; we referenced an FDC NOTAM USD 01/242 for the SHEAD7 that reads; 'CROSS MDDOG AT 9;000 (ATC)/AT OR ABOVE 9;000. CROSS TARRK AT 11;000 (ATC)/AT OR ABOVE 11;000.' We interpreted this NOTAM as clarifying a minimum altitude at or above MDDOG and TARRK; since the chart only references an altitude for each intersection. The meaning of 'ATC' in the NOTAM was unknown to us. On departure from LAS climbing through 9;000; the LAS Departure Controller queried us about our altitude and told us to stop our climb and maintain 10;000. He stated that we should have leveled at 9;000 until MDDOG. We responded that we were planning to cross MDDOG at or above 9;000; referring to the FDC NOTAM 01/242. There was no traffic conflict in this instance. However; inbound arrivals to LAS from the south and west arrive in this area between 9;000 and 11;000 FT; so it had the potential for conflict. Cause; the wording in this FDC NOTAM is not clear. There is no explanation for the letters 'ATC' in the NOTAM. The company field and facilities does not refer specifically to the NOTAM; so there is confusion which directive applies. The previous day on a departure from LAS Runway 25R; upon check-in with Departure Control we immediately received an unrestricted climb to FL190. This is the clearance I have received in most of my departures from LAS. This clearance may have conditioned us to believe the hold down altitude of 9;000 at MDDOG was rarely used (or unnecessary). The 'at or above' wording in the NOTAM seems appropriate considering the rising terrain to the west of the airport. I believe that NOTAMs need to be written in plain English. Abbreviations and condensed wording can be misinterpreted and lead to mistakes. In this instance; the NOTAM is unnecessary; as the altitude crossing restrictions on the chart need to be applied; and if the altitude restrictions were unnecessary; ATC can offer an unrestricted climb.

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.