Narrative:

Our flight plan had us dispatched in payload. Our dispatcher was trying to give us more fuel for forecast thunderstorms at destination. I understood this because the week before several flights; including this one; had to divert due to insufficient fuel. My first officer and I had not operated in this configuration in a long time; and felt something was not correct. My first officer stated that he thought the center tank should be empty. I looked it up in the systems manual; and it read that the center tank could not be fueled; but any fuel in the tank could be burned normally. It did not say the center tank had to be empty. I also checked in the aom limitations and normal chapters; but found nothing about this mode. We operated the flight with fuel in the center tank and payload selected. We did not need to be in payload because the weight was within range mode limits so no limitations were exceeded. When I discussed the situation later with another crew member; he referred me to the aom supplemental section where it clearly states that the trim tank should be empty. I was still concerned about the situation so I talked to an acp. I felt the dispatcher should be aware of our mutual mistake so that we could trap the error in the future. I also think the systems manual should be changed because the way it is written is misleading. Now that the crew and dispatcher are aware of the mistake; it might be helpful to brief maintenance; as they rarely use this mode.

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Original NASA ASRS Text

Title: A300 flight crew experienced confusion when being dispatched in the 'payload' mode and could not determine if fueling the center tank was allowed. The center tank was fueled; but not permitted by FOM supplemental procedures.

Narrative: Our flight plan had us dispatched in Payload. Our dispatcher was trying to give us more fuel for forecast thunderstorms at destination. I understood this because the week before several flights; including this one; had to divert due to insufficient fuel. My FO and I had not operated in this configuration in a long time; and felt something was not correct. My FO stated that he thought the center tank should be empty. I looked it up in the systems manual; and it read that the center tank could not be fueled; but any fuel in the tank could be burned normally. It did not say the center tank had to be empty. I also checked in the AOM Limitations and Normal chapters; but found nothing about this Mode. We operated the flight with fuel in the center tank and Payload selected. We did not need to be in Payload because the weight was within Range Mode limits so no limitations were exceeded. When I discussed the situation later with another crew member; he referred me to the AOM supplemental section where it clearly states that the trim tank should be empty. I was still concerned about the situation so I talked to an ACP. I felt the dispatcher should be aware of our mutual mistake so that we could trap the error in the future. I also think the Systems manual should be changed because the way it is written is misleading. Now that the crew and dispatcher are aware of the mistake; it might be helpful to brief maintenance; as they rarely use this Mode.

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.