Excerpt from AS9100C - 8.2.1
:Information to be monitored and used for the evaluation of customer satisfaction shall include, but is not limited to, product conformity, on-time delivery performance, customer complaints and corrective action requests. Organizations shall develop and implement plans for customer satisfaction improvement that address deficiencies identified by these evaluations, and assess the effectiveness of the results.
NOTE Monitoring customer perception can include obtaining input from sources such as customer satisfaction surveys, customer data on delivered product quality, user opinion surveys, lost business analysis, compliments, warranty claims and dealer reports."
First: Why do people rely on the bias and perception of customers that will provide incomplete, inaccurate, misleading and erroneous information>
Second: You should know if your customer is satisfy by looking at your internal metrics and meet the customer requirement - Quality and on time (plus an effective system that will allow you to maintain competition).
Third - If you go to the top of the page and click "Post Attachment Files" and do a search for Customer - you will find formulas to calculate customer satisfaction which does not depend on the mis - representation of a customer that had a bad day.