Narrative:

After an aircraft change following an air return; passengers were boarded and we pushed off the gate. When we were number 1 for departure; we had not yet received final weights so we sent a miscellaneous lw message to load planning visa ACARS. The reply message said that they were still waiting for customer service to finalize the seat map. I decided for no real reason to ask the cabin crew to accomplish a manual head count; this is not a required or even a recommended procedure; since the passenger final count is based on the seat map from customer service. The head count result was 12/117. After waiting for another few minutes; I called the load planning desk on my cell phone to inquire about the delay in final weights; and I gave the supervisor the final count numbers. He took it down; and we hung up. A few minutes later; we received the final weights via ACARS; and the passenger count on it was 9/76; with a final gross weight change of over 10;000 pounds of reduction. I immediately informed load planning via ACARS of the discrepancy; and the reply was that customer service says that their count was accurate. I then replied that we are sure that there are 129 passengers on board; not 85.after 1.5 hours off the gate; we returned to a gate to refuel; and at that time customer service accomplished a manual 'roll call' and checked each passenger against their manifest. During this time; a deadheading pilot informed me that his boarding pass was not scanned when he boarded that second plane; and that customer service just let him through. This indicated an error that probably caused the gross passenger count error. A 10;000 pound discrepancy in the final weight calculations can result in a possible tail strike; or worse; on takeoff.

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Original NASA ASRS Text

Title: A320 Captain reported discovering during taxi a gross error in the number of passengers on board which resulted in a 10;000 lb difference between planned and actual weight.

Narrative: After an aircraft change following an air return; passengers were boarded and we pushed off the gate. When we were number 1 for departure; we had not yet received final weights so we sent a MISC LW message to load planning visa ACARS. The reply message said that they were still waiting for customer service to finalize the seat map. I decided for no real reason to ask the Cabin Crew to accomplish a manual head count; this is not a required or even a recommended procedure; since the passenger final count is based on the seat map from customer service. The head count result was 12/117. After waiting for another few minutes; I called the load planning desk on my cell phone to inquire about the delay in final weights; and I gave the supervisor the final count numbers. He took it down; and we hung up. A few minutes later; we received the final weights via ACARS; and the passenger count on it was 9/76; with a final gross weight change of over 10;000 pounds of reduction. I immediately informed load planning via ACARS of the discrepancy; and the reply was that customer service says that their count was accurate. I then replied that we are sure that there are 129 passengers on board; not 85.After 1.5 hours off the gate; we returned to a gate to refuel; and at that time customer service accomplished a manual 'roll call' and checked each passenger against their manifest. During this time; a deadheading pilot informed me that his boarding pass was not scanned when he boarded that second plane; and that customer service just let him through. This indicated an error that probably caused the gross passenger count error. A 10;000 pound discrepancy in the final weight calculations can result in a possible tail strike; or worse; on takeoff.

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.