An A320 Captain reported that dispatch cannot supply a flight crew with Spoiler Inoperative landing runway corrections because once airborne there is no method of displaying what factors were used to determine the landing corrections. The flight crew must manually calculate the corrections.

Narrative

The flight was dispatched with MEL Spoiler 3 inoperative. The MEL requires takeoff and landing data be manually computed; due to the numerous variables affecting Allowable Takeoff Gross Weight (ATOG) and allowable landing weight (i.e. flaps setting; aircraft weight; runway length; runway conditions; weather conditions). The Captain from the inbound flight left us: 1) A copy of the MEL 2) Notes he used to determine max landing weight 3) Printed takeoff data from the Dispatcher for the current airport/runway and Flaps 2The takeoff data included a remark showing the MEL weight penalty (2.7R) used for the current conditions. Once in cruise flight; we requested Dispatch send us landing data for the 3 runways in use at our destination; using flaps full. We received the landing data approximately 15 minutes later. The landing data did not contain any information indicating that the MEL/Flight Manual restrictions were applied. We then requested; VIA ACARS that the Dispatcher verifies that the landing distance and allowable landing weights were adjusted; per the MEL and Flight Manual. We also calculated our landing data using the MEL restrictions and our Flight Manual and determined all runways in use at our airport were legal to use. We did not receive a reply from the Dispatcher; verifying what factors and restrictions from the MEL and Flight Manual were used. At the end of the duty day; I contacted the Dispatch Supervisor to discuss the landing data message received; and lack of reply from the Dispatcher to clarify the landing data we did receive. He stated that with this MEL; there was no way to indicate on the landing data printout what factors were used to determine the landing distance data; and that the weight penalty could not be manually entered at all. This all highlights a limitation to our current system regarding MELs that require manual input for accurate takeoff and landing data.