Why FAT Should Confirm Alignment, Not Reveal Its Absence

By Juergen Metzger, Pharma-Technology-Consulting LLC

In many aseptic fill/finish projects, the factory acceptance test (FAT) has unintentionally become the first true integration test of the entire project.

That is a problem. FAT should confirm alignment, not reveal its absence.

And yet, this is exactly what happens in many projects. Critical interventions are discussed for the first time, airflow concerns suddenly become visible, automation limitations appear unexpectedly, material transfer concepts prove impractical, and operators realize that the process may look good on paper but not necessarily in reality.

The uncomfortable truth is that many of the most expensive problems in aseptic manufacturing projects are not created during FAT. They are created much earlier. FAT simply becomes the first moment when the project can no longer hide its inconsistencies.

The URS Often Defines Technology, Instead Of Defining The Problem

One of the most common root causes appears very early in the project phase: the user requirement specification (URS).

In theory, the URS should define process needs, contamination risks, operational expectations, production philosophy, intervention strategies, maintenance concepts, and long-term life cycle considerations. In reality, many URSs already prescribe technology before the actual problem is fully understood.

Projects often begin with statements such as “We need an isolator,” “We need robotics,” or “We need a turnkey line” long before the organization has fully aligned internally on process flow, operator interaction, cleaning concepts, environmental monitoring strategy, or operational reality. As a result, technology decisions are frequently made before the operational strategy itself is mature. The project then starts building around assumptions that were never fully challenged in the first place.

Those gaps rarely remain hidden forever. They simply surface later, usually during FAT, when schedules tighten, engineering changes become expensive, and flexibility is already limited.

Vendors Often Develop In Parallel — But Not Together

Modern aseptic fill/finish projects involve a growing number of highly specialized suppliers. Fillers, isolators, lyophilizers, automation platforms, transport systems, environmental monitoring, vision inspection, MES, and SCADA systems are frequently developed by different organizations working within their own scope boundaries.

Each supplier may optimize its own area extremely well. The problem is that nobody fully owns the interfaces. And in aseptic processing, interfaces are often exactly where the biggest operational and contamination control risks exist.

Airflow interaction between filler and isolator, transfer timing between modules, environmental monitoring locations, glove access, software communication, line clearance concepts, or intervention recovery strategies often remain insufficiently challenged until the system is physically integrated. At that point, the project begins discovering that individually optimized systems do not automatically result in an operationally optimized process.

Automation Is Frequently Defined Too Late

Another recurring issue appears around automation philosophy. Early project discussions often focus heavily on mechanical layouts, throughput expectations, equipment footprints, and utilities. Automation logic, operator workflow, audit trails, recipe handling, MES integration, and recovery concepts are frequently addressed later in the project life cycle.

Then FAT arrives.

Suddenly, teams realize that alarm handling does not fully match operational expectations, electronic batch recording concepts remain unclear, intervention recovery logic becomes complicated, or user access structures were never fully aligned with production reality.

In many projects, operators only truly understand the automation philosophy once the system is already operational during FAT. That is far too late.

Automation should not simply control equipment. It should support operational reality.

Smoke Studies And Airflow Concepts Are Still Underestimated

Airflow visualization and intervention assessment continue to be underestimated in many projects, particularly in highly automated systems.

Computational fluid dynamics (CFD) simulations are valuable tools, but they do not fully replace realistic airflow testing under operational conditions. This becomes increasingly important in systems involving robotics, gloveless concepts, rapid transfer port (RTP) interaction, high-speed filling, nested syringes, or complex intervention scenarios.

In reality, airflow disturbances often become visible only when operators interact with the system, when robots move dynamically, when doors open and close, or when realistic maintenance and intervention situations are simulated properly.

This is exactly why integrated mockups, practical smoke studies, and early operational testing remain critical long before formal FAT execution begins.

Too often, smoke studies are still treated primarily as a regulatory deliverable instead of a true engineering and contamination control tool.

Operational Reality Is Often Missing From Early Project Decisions

One recurring pattern in aseptic projects is that systems are frequently designed around ideal production conditions. Real manufacturing environments rarely operate that way.

Especially in small molecule fill/finish manufacturing, operations involve constant variability: Format changes, manual interventions, maintenance access, troubleshooting, environmental monitoring activities, cleaning procedures, and operator interaction are all part of normal daily operations. If those realities are not integrated early into the project strategy, even technically advanced systems can become operationally fragile.

This becomes particularly visible in highly automated systems. A technically impressive solution that is difficult to maintain, difficult to recover after faults, or difficult to operate consistently may ultimately introduce additional operational risk instead of reducing it.

In many cases, the issue is not the technology itself. The issue is that the operational reality was never fully integrated into the design philosophy from the beginning.

FAT Often Becomes The First Honest Conversation

One of the most revealing moments in many projects is the first fully integrated FAT. For the first time, engineering, automation, QA, operators, maintenance, validation teams, and suppliers are all standing in front of the same operational system.

And suddenly, the questions become very practical. How exactly will this intervention work? Can this area actually be cleaned properly? Why is this glove position unreachable? What happens during a line fault? How realistic is this recovery procedure? Can operators execute this process consistently during daily production?

This is often the moment when organizations recognize that true alignment never fully existed. The FAT did not create the problem. It simply exposed it.

So, What Does This Mean In Practice?

Strong aseptic projects rarely succeed because of one specific technology alone. They succeed because alignment happens early. That includes realistic URSs, early cross-functional involvement, integrated contamination control strategies, practical intervention assessments, early involvement of operators and quality teams during design reviews, realistic smoke studies, integrated mockups, and honest discussions about operational reality long before qualification activities begin.

FAT should not become the first moment when the project truly behaves like a complete operational system. It should simply confirm that the alignment already exists. Because once major gaps appear during FAT, the project is no longer optimizing. It is recovering.

About The Author:

Juergen M. Metzger is founder and principal of Pharma-Technology-Consulting, LLC, specializing in aseptic fill/finish, containment systems, and Annex 1 compliance. He has nearly 30 years of experience in the pharmaceutical manufacturing industry, with a focus on isolator technology, aseptic processing, and contamination control strategies. He began his career with Bosch Packaging Technology in 1999 and has held technical and leadership roles across engineering, product management, business development, and global project coordination. He has worked extensively on aseptic fill/finish systems worldwide, supporting the design, implementation, and optimization of complex manufacturing environments. Over the course of his career, he has also served in director-level and strategic advisory roles focused on new technologies, market development, turnkey projects, and aseptic manufacturing strategy across the Americas and international markets.