AMA rules state "<span style="font-family: "Times New Roman","serif"; font-size: 10pt; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA">4.3: Weight and Size:<span style="mso-spacerun: yes"> </span></span><span style="font-family: "Times New Roman","serif"; font-size: 10pt; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA">No model may weigh more than 5000 grams gross, excluding fuel, ready for takeoff.<span style="mso-spacerun: yes"> </span><span style="mso-spacerun: yes"></span>Electric models are weighed with batteries.<span style="mso-spacerun: yes"> </span>In Sportsman, Intermediate and Advanced an allowance of 115 grams is permitted."
Does this mean if you are flying in Intermediate at the Nats, you are legal and allowed to fly up to 5115grams? I would assume the 50 g allowance would not apply since they should have calibration weights on location at the Nats.
However if calibration weights were not on site, would the 50 gram allowance add to that weight so that a 5165 gram would be allowed to fly, in Intermediate or advanced? "<span style="font-family: "Times New Roman","serif"; font-size: 10pt; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA">If no calibration system is available for the scales, a tolerance of 50 grams will be allowed for possible inaccuracies in the measurement instrument.</span></span>

Correct. The additional does NOT include the extra 50 grams as the scales will be calibrated. In FAI this isn't the case as they get the 50g regardless of scale calibration, but this does not apply to intermediate and advanced. All scales will be calibrated at the NATS and have the ability to be re-calibrated as needed. You are correct though. If the calibration weights were not available then you would get the extra 50g.

Archie
2012 NATS ED

Thanks Archie. As a CD I wanted to be sure I have the proper understanding. There has been some discussion in our area about this, and opinions varied.