EMB ERJ 190/195 ER/LR
Flight Crew Air Transport Pilot (ATP)
ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Incursion Taxiway
Flight Crew FLC Overrode Automation
Aircraft; Company Policy; Procedure
Aircraft had MEL requiring an autoland [function check]. We set up and attempted to perform the autoland [function check]. Weather was VMC; we informed tower that we would be conducting an autoland and he said; 'okay'. When we were about to flare; the controller (or more likely the ground controller) taxied an aircraft through the critical area on taxiway Yankee. This caused the localizer to become erratic and we had to disconnect the autopilot before it put us in the dirt. I called tower on the phone to advise them of their mistake; I am not sure action will be taken on their end.This situation was caused by ATC error. ATC should have advised us that they were 'unable to protect the ILS critical area.' We should not have to do [function checks] exactly because of these types of situations. Controllers are not familiar with our procedures and because of [a new pilot training] program; we have significantly increased the amount of [function checks] required in VMC conditions. I suggest trying to get rid of this [function check] requirement for the airline.
An EMB-190 Captain reported requesting an autoland from the Tower in VMC in order to return the system to service after maintenance. The response is OK. During the flare; Ground Control taxis an aircraft through the localizer requiring the Captain to take over manually.