FAT - user presence

Is user required to be present during system FAT execution (FAT - supplier site)?

GAMP does not mention such case.


Absolutely, how will you know that the system is working correctly otherwise.

Formal testing does not end on FATs. You have SAT, OQ, PQ, all kinds of ‘pre’ tests and Integration tests on users site.

User is not present during UTs and Component Tests, that are also executed on suppliers site. I can’t get my head around why during FAT and not Component Test (CT is very similar to FAT) user has to be present? What is the difference in value that FAT makes user presence vital? One more - SAT is most of the times reflection of FATs, then I understand user presence is required.


It is useful to have the User present at the FAT stage in case the vendor design does not meet all of the User Requirements. If this is the case, then the risk of a “system” ending up on the clients/user site not meeting all of the requirements is reduced, and can be rectified before despatch!

However I don’t believe there is any ‘rule of thumb’ on this issue, and it tends to depend on the clients own ‘ways of working’ i.e. if the end-User trusts the FAT team / Validation Lead doing the FAT, then he/she may not attend the FAT.

One of the main reasons would be to ensure you are getting what you expected. There is typically a progress payment upon shipping a system. You may want to know what you are getting before it hits your loading dock! If there are issues or problems, the FAT will usually find them and they can be addressed before the system is shipped.