FAT VS SAT
Factory Acceptance Test vs Site Acceptance Test — two distinct stages in the quality-assurance and commissioning lifecycle of AGL equipment and systems. FAT proves the equipment is ready for the site. SAT proves the installed equipment and system are ready for operation at the airport.
At a Glance
| Parameter | FAT | SAT |
|---|---|---|
| Full form | Factory Acceptance Test | Site Acceptance Test |
| Location | Manufacturer's factory | Project / airport site |
| Timing | Before shipment | After installation |
| Main purpose | Verify equipment manufacture & functionality | Verify installed system & site integration |
| Environment | Controlled factory environment | Actual project environment |
| Installation status | Factory assembled | Installed and commissioned |
| Witnesses | Client / consultant / manufacturer | Client / consultant / contractor |
| Documentation | FAT report | SAT report |
| Site interfaces | Limited / simulated | Fully checked |
| Handover relevance | Pre-shipment acceptance | Final site acceptance |
What Is FAT & SAT?
FAT — Factory Acceptance Test
FAT is performed at the manufacturer's facility before dispatch. The test verifies that the equipment has been manufactured in accordance with the approved design and project specification, and that it performs its intended functions correctly.
Typical AGL equipment that may undergo FAT
- Constant Current Regulators (CCR)
- AGL control panels
- Remote-control / monitoring panels
- Lighting control systems
- Transformers
- Other packaged electrical equipment
Main objective: Prove that the manufactured equipment complies with the approved design and specification before shipment.
SAT — Site Acceptance Test
SAT is performed at the project site after installation. The test verifies that the installed equipment and system function correctly under actual site conditions, with all site interfaces, cabling, fixtures and supporting infrastructure in place.
SAT verifies
- Correct installation
- Cable connections and polarity
- Insulation resistance
- CCR output and regulation
- Lighting operation and brightness steps
- Control and remote operation
- Monitoring and alarms
- Integration with other installed equipment
Main objective: Prove that the installed equipment/system is ready for operation at the airport.
FAT & SAT in the Project Lifecycle
Equipment designed to approved specification.
Equipment manufactured and assembled at factory.
Factory Acceptance Test — verify equipment before dispatch.
Equipment cleared for shipment to site.
Equipment arrives at airport project site.
Equipment installed, cabled and connected.
Site Acceptance Test — verify installed system.
System accepted for operational use.
FAT vs SAT — Test Scope
| Test Area | FAT | SAT |
|---|---|---|
| Visual inspection | Yes — equipment condition | Yes — installed condition |
| Wiring verification | Yes — internal wiring | Yes — site cabling & terminations |
| Insulation tests | Yes — equipment | Yes — complete circuit |
| Output current / regulation | Yes — test load | Yes — actual installed load |
| Step / brightness control | Yes — functional check | Yes — with actual fixtures |
| Protection functions | Yes | Yes — with site conditions |
| Alarm / monitoring | Yes | Yes — with site interfaces |
| Control interface | Simulated | Actual site control system |
| Fixture operation | Not applicable | Yes — all installed fixtures |
| Cable continuity / polarity | Not applicable | Yes |
| System integration | Limited | Full site integration |
| Emergency / failure functions | Simulated | Actual site conditions |
FAT vs SAT — CCR Example
Suppose a 6.6 A Constant Current Regulator (CCR) is supplied for an airport project.
FAT — At the Factory
│
▼
TEST LOAD
│
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MEASURE
CURRENT / VOLTAGE /
PROTECTION / CONTROL
The manufacturer verifies that the CCR performs correctly against the approved test procedure and specification.
SAT — At the Airport
│
▼
6.6 A SERIES CIRCUIT
│
▼
ISOLATION TRANSFORMERS
│
▼
RUNWAY / TAXIWAY LIGHTS
The installed system is tested as a complete site installation — verifying that the CCR operates correctly with the actual installed circuit and equipment.
Key insight: The CCR may pass FAT perfectly, but SAT is still required to verify that the entire installed system — CCR, series circuit, isolation transformers and fixtures — operates together correctly at the airport.
Controlled Environment vs Actual Site Conditions
FAT — Controlled Factory Environment
- Controlled temperature and conditions
- Test load instead of actual fixtures
- Simulated control signals
- No site cable runs
- No site interference
- No site installation variables
SAT — Actual Airport Site
- Actual site environment
- Actual cables and cable runs
- Actual fixtures and loads
- Actual control system
- Actual monitoring interfaces
- Actual site installation conditions
SAT therefore provides information that cannot always be obtained during FAT — site cabling, actual fixture loads, control-system integration and the influence of the installed environment.
What Happens When a Test Fails?
FAT Failure
│
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FAIL
│
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CORRECTIVE ACTION
│
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RETEST
│
▼
PASS
│
▼
DISPATCH
A failed item should generally be resolved before shipment.
SAT Failure
│
▼
FAIL
│
▼
SITE RECTIFICATION
│
▼
RETEST
│
▼
PASS
│
▼
ACCEPTANCE
SAT failures may involve either equipment issues or installation/interface issues.
Example: CCR OK + Control Panel OK + Cable Installation ✕ → SAT Failure
FAT vs SAT Documentation
FAT Documentation
- Approved FAT procedure
- Inspection checklist
- Test results
- Calibration certificates
- Equipment test records
- Non-conformance records (if applicable)
- FAT report
- Certificate of acceptance / release
SAT Documentation
- Approved SAT procedure
- Site test records
- Commissioning records
- Cable test results
- Functional test results
- Alarm / monitoring test results
- As-built verification
- Punch-list / NCR records
- SAT report
- Site acceptance certificate
Who Is Involved?
FAT — Typical Participants
- Manufacturer — conducts the test
- Client / Consultant — may witness FAT
- Inspection / QA Team — verification
The client or consultant may witness FAT according to the approved inspection and test plan (ITP).
SAT — Typical Participants
- Contractor — installation and testing
- Manufacturer / Commissioning Team — support
- Client / Consultant — witnessing and approval
- Site Operations — operational verification
The exact responsibilities are project-specific and defined in the contract and ITP.
Full Engineering Parameters
| Parameter | FAT | SAT |
|---|---|---|
| Primary focus | Equipment | Installed system |
| Location | Factory | Site |
| Timing | Pre-dispatch | Post-installation |
| Environment | Controlled | Actual |
| Equipment test | Yes | Yes |
| Installation test | Limited | Yes |
| System integration | Limited | Yes |
| Site cabling | Usually simulated / test setup | Actual |
| Field interfaces | Limited | Fully tested |
| Main acceptance | Equipment acceptance | Site / system acceptance |
| Witnessing | Client optional | Client required |
| Remedial action | Factory rectification | Site rectification |
Myths vs Facts
No. A successful FAT does not automatically mean that the installed system will pass SAT. Site installation, cabling and integration issues can cause SAT failure even when the equipment is perfectly manufactured.
No. SAT does not replace FAT. Manufacturing defects should be identified during FAT, not discovered at site. Relying on SAT to catch equipment defects is not an acceptable quality-assurance strategy.
They are fundamentally different tests with different objectives, scopes and environments. FAT tests the equipment; SAT tests the installed system.
SAT involves comprehensive testing of installation, cabling, insulation, control, monitoring, alarm functions, intensity steps, system integration and operational performance — not just "power on."
Type testing and FAT serve different purposes. Type testing validates the design; FAT verifies that the specific manufactured unit meets the specification and is free from manufacturing defects.
Easy Memory
FAT
│
▼
EQUIPMENT
│
▼
TEST
│
▼
PASS
│
▼
SHIP
FAT proves the equipment is ready for the site.
SAT
│
▼
INSTALL
│
▼
CONNECT
│
▼
TEST
│
▼
PASS
│
▼
ACCEPT
SAT proves the installed system is ready for operation.
FAT vs SAT — The Engineering Perspective
FAT and SAT are not interchangeable — they are complementary stages in the quality-assurance and commissioning lifecycle.
FAT provides confidence that the manufactured equipment meets the specification before it leaves the factory. SAT provides confidence that the installed system operates correctly at the airport, with all site interfaces, cabling and fixtures in place.
For an AGL project, FAT is primarily equipment-level verification before dispatch, while SAT is installation, functional and system-integration verification at the airport.
Critical engineering point: A successful FAT does not guarantee a successful SAT, and SAT should not be relied upon to catch manufacturing defects. Both tests are necessary and serve different purposes in the project quality-assurance framework.
Engineering & Expert Notes
Do Not Assume SAT Repeats FAT
ScopeFAT proves the equipment; SAT proves the installed system. Plan both and avoid gaps.
Use FAT Records as the Baseline for SAT
BaselineCompare site results with factory data to spot transit or installation damage.
Test Interfaces on Site
IntegrationMany problems appear only where equipment connects. Include those tests.
Close Punch Items Before Handover
ClosureTrack defects to completion and retest as needed.
Frequently Asked Questions
FAT is performed at the factory before shipment to verify equipment manufacture and functionality. SAT is performed at the site after installation to verify the installed system and site integration.
No. SAT can fail due to site installation issues — cabling errors, incorrect terminations, damaged cables, site environment, control-system integration problems — even when the equipment itself is perfectly manufactured.
No. SAT does not replace FAT. Manufacturing defects should be identified during FAT, not discovered at site. Relying on SAT to catch equipment defects is not an acceptable quality-assurance approach.
The client or consultant may witness FAT according to the approved inspection and test plan. The manufacturer conducts the test; the client/consultant provides verification.
Corrective action is taken at the factory, followed by retesting. The equipment should generally not be dispatched until FAT is passed.
Site rectification is carried out — this may involve rework, repair, replacement or adjustment. After rectification, the affected portion is retested. The system is accepted only after SAT is passed.
The requirement for FAT depends on the project specification, contract requirements and the inspection and test plan. Critical equipment such as CCRs, control panels and packaged systems typically require FAT.
Governing Documents
For an actual project, always verify the current applicable editions of the relevant documents and the approved inspection and test plan (ITP).
Project-Specific ITP
The approved Inspection and Test Plan defines the specific FAT and SAT requirements, scope, witness points and hold points for each project.
Contract Technical Specifications
The contract documents define the technical requirements, equipment specifications and acceptance criteria that FAT and SAT must verify.
Manufacturer's FAT/SAT Procedures
Approved test procedures from the manufacturer or commissioning team, detailing the test sequence, acceptance criteria and test records.
Final Engineering Note
FAT and SAT requirements are project-specific. Always verify the approved ITP, contract requirements and applicable standards for the specific project — do not rely on a generic comparison page for project execution.
FAT proves the equipment is ready for the site. SAT proves the installed system is ready for operation. Both are essential, complementary stages in the AGL project quality-assurance and commissioning lifecycle.
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