SAT VS COMMISSIONING
Site Acceptance Test (SAT) verifies that the installed equipment/system meets the agreed acceptance criteria at site. Commissioning verifies that the complete installed system has been correctly installed, adjusted, energized, integrated, and made ready for safe operation. In many AGL contracts the two activities overlap or are combined — always follow the project's approved test procedures.
At a Glance
| Feature | SAT | Commissioning Test |
|---|---|---|
| Full form | Site Acceptance Test | Commissioning Test |
| Main purpose | Formal site acceptance | Prepare and prove system for operation |
| Timing | After installation | During/after installation, before operation |
| Main focus | Contractual acceptance criteria | Installation, configuration, adjustment, operation |
| Equipment scope | Installed equipment/system | Complete installed system |
| Site interfaces | Tested | Fully integrated |
| Functional testing | Yes | Yes |
| Calibration/adjustment | As required | Important |
| Client witness | Common | May be required |
| Final handover | Often linked to acceptance | Supports readiness for operation |
SAT
SAT is the formal test performed at the project site, run against a predefined acceptance procedure.
INSTALLATION
│
▼
SITE PRE-CHECKS
│
▼
SAT
│
▼
PASS?
↙ ↘
NO YES
│ │
▼ ▼
RECTIFY ACCEPTANCE
The SAT procedure normally defines exactly what must be demonstrated for formal acceptance.
Commissioning Test
Commissioning is broader than a single acceptance test — it is the technical process of getting the system into a correctly operating condition.
INSTALL → INSPECT → TEST → ENERGIZE → CONFIGURE → ADJUST → INTEGRATE → FUNCTIONAL TEST → READY FOR OPERATION
The objective is to make the system operate correctly, not simply to demonstrate compliance.
Meet Acceptance vs Prove Readiness
APPROVED PROCEDURE
│
▼
DEMONSTRATE
│
▼
FORMAL ACCEPTANCE
INSTALLED SYSTEM
│
▼
CHECK / ADJUST / INTEGRATE
│
▼
READY FOR OPERATION
Easy memory: SAT asks "does it meet the requirements?" Commissioning asks "does it work correctly?"
What Each Activity Covers
SAT Scope
For an AGL system, this could include:
- CCR operation
- Current-step operation
- AGL lighting operation
- Control functions
- Remote control
- Monitoring
- Alarm functions
- Communication, interlocking and protection functions
Commissioning Scope
Commissioning may include:
- Installation verification & cable testing
- Equipment checks & energization
- Parameter configuration & protection setting verification
- Functional testing & control-system integration
- Monitoring & alarm testing
- Operational checks
- Rectification and retesting
New CCR Connected to a Runway Circuit
Consider a new AGL CCR connected to a runway circuit. Commissioning progressively verifies the chain, then SAT formally demonstrates the operating result.
Commissioning: Progressive Verification
CCR ├─ Installation ✓ ├─ Power supply ✓ ├─ Earthing ✓ ├─ Control wiring ✓ ├─ Settings ✓ └─ Protection ✓ │ ▼ SERIES CIRCUIT ├─ Continuity ✓ ├─ Insulation ✓ └─ Circuit checks ✓ │ ▼ ISOLATION TRANSFORMERS │ ▼ RUNWAY LIGHTS │ ▼ CONTROL + MONITORING
SAT: Formal Demonstration
CCR STEP 1 ✓ CCR STEP 2 ✓ CCR STEP 3 ✓ CCR STEP 4 ✓ REMOTE ON/OFF ✓ ALARM ✓ MONITORING ✓ LIGHT OPERATION ✓
Results are recorded against the approved SAT procedure.
Where Each Stage Sits
A typical sequence places commissioning before a final SAT — but this is not universal.
FAT → DELIVERY → INSTALLATION → PRE-COMMISSIONING → COMMISSIONING → SAT → FINAL ACCEPTANCE
Some project specifications combine the two into a single site testing stage instead:
INSTALLATION
│
▼
COMMISSIONING + SAT
│
▼
ACCEPTANCE
Always follow the project's approved ITP, commissioning procedure and SAT procedure — the contract specification controls the actual sequence, not general convention.
Pre-Commissioning vs Commissioning vs SAT
| Stage | Main Question |
|---|---|
| Pre-commissioning | Is everything installed and ready to energize? |
| Commissioning | Does the system operate correctly after energization/configuration? |
| SAT | Does the installed system satisfy the formal acceptance requirements? |
PRE-COMMISSIONING → "Cables and equipment are installed correctly." COMMISSIONING → "System operates correctly." SAT → "System meets the contractual acceptance criteria."
Iterative Adjustment vs Predefined Procedure
Commissioning
Can be detailed and iterative — the purpose is to make the system work correctly.
TEST → ADJUST → RETEST → CONFIGURE → RETEST
SAT
Normally follows a predefined acceptance procedure — the objective is to formally demonstrate compliance.
TEST ITEM → ACCEPTANCE CRITERION → RESULT → PASS / FAIL
How a Failed Test Is Treated
SAT │ ▼ FAIL │ ▼ NCR / PUNCH ITEM │ ▼ RECTIFICATION │ ▼ RETEST → ACCEPTANCE
TEST │ ▼ FAIL │ ▼ ADJUST / REPAIR │ ▼ RETEST → PASS
A commissioning failure is expected as part of getting the system operational. A failed SAT item, by contrast, can affect formal project acceptance.
Activity-by-Activity Breakdown
| AGL Activity | Commissioning | SAT |
|---|---|---|
| Verify installation | Yes | May be verified |
| Cable testing | Yes | As specified |
| CCR energization | Yes | Yes |
| CCR configuration | Yes | Verify |
| Current-step operation | Yes | Yes |
| Isolation transformer checks | Yes | As specified |
| Lighting operation | Yes | Yes |
| Remote control | Yes | Yes |
| Monitoring | Yes | Yes |
| Alarm simulation | Yes | Yes |
| System integration | Yes | Yes |
| Adjustment/optimization | Yes | Usually limited |
| Formal contractual acceptance | Not necessarily | Yes |
Myths vs Facts
SAT and commissioning are not universally defined as fully separate activities. Many project specifications combine them, or run SAT as an activity that includes commissioning tests — the contract specification and approved test procedures control the actual scope.
Commissioning is the technical process of installing, energizing, configuring, adjusting and integrating the system so it actually works. SAT then formally demonstrates that the working system meets the agreed acceptance criteria — the two have different objectives, not just different levels of formality.
Commissioning failures are expected and are resolved through adjustment and retest as part of getting the system operational. A failed SAT item is typically logged as an NCR or punch item and can affect formal project acceptance.
The two activities often test many of the same functions — CCR steps, lighting operation, remote control, monitoring and alarms. What differs is the purpose: commissioning proves the system works, SAT formally records that it meets the acceptance criteria.
How Projects Structure the Two Activities
OPTION A OPTION B OPTION C
COMMISSIONING COMMISSIONING SAT
│ + includes
▼ SAT COMMISSIONING TESTS
SAT │
▼
ACCEPTANCE
Therefore, don't define SAT and commissioning solely by terminology. The contract specification and approved test procedures control the actual scope on a given project.
SAT vs Commissioning Test
Commissioning is the technical process of checking, energizing, configuring, adjusting, integrating and proving the installed system is ready for operation.
SAT is the formal site acceptance test used to demonstrate that the installed equipment/system meets the project-specific acceptance requirements. There is project-specific overlap between the two, and in many AGL contracts commissioning activities are performed within or alongside SAT.
A typical AGL sequence runs FAT → Installation → Pre-commissioning → Commissioning → SAT → Handover. But if the project specification combines commissioning and SAT, they may be performed as one integrated site testing stage — always follow the governing procedure, not a general rule of thumb.
Engineering & Expert Notes
Do Not Merge the Two Records
RecordsKeep acceptance evidence and commissioning data separate and clear.
Agree Acceptance Criteria Before Starting
PreparationSettle the test list and values in advance.
Define Retest Rules
RetestsAgree what to repeat after rectification.
Hand Over a Complete Baseline
HandoverProvide settings, results and photographs.
Frequently Asked Questions
SAT formally verifies that the installed equipment/system meets the agreed acceptance criteria. Commissioning verifies that the complete system has been correctly installed, adjusted, energized, integrated and made ready for safe operation.
A typical sequence places commissioning before SAT, but this is not universal. Some project specifications combine commissioning and SAT into a single integrated stage, or run SAT as an activity that includes commissioning tests.
No. A commissioning failure is expected as part of getting the system operational and is resolved through adjustment and retest. A failed SAT item is typically raised as an NCR or punch item and can affect formal project acceptance.
Pre-commissioning asks whether everything is installed and ready to energize. Commissioning then asks whether the system operates correctly once it is energized and configured.
Client witness is common during SAT since it is the formal acceptance step. Commissioning may also require client presence, but its main purpose is technical readiness rather than formal sign-off.
Yes. Functions such as CCR step operation, lighting operation, remote control, monitoring and alarms are commonly checked in both — the difference lies in the purpose and formality of the test, not necessarily the function tested.
Governing Documents
For an actual project, always verify the current edition of the applicable documents and the project's own ITP, commissioning procedure and SAT procedure.
Project ITP
The Inspection and Test Plan defines which activities are classified as pre-commissioning, commissioning and SAT, and the hold/witness points for each.
ICAO Annex 14, Volume I
Aerodrome Design and Operations — general basis for AGL system performance that commissioning and SAT are ultimately verifying against.
DGCA / AAI Requirements
For Indian airport projects, also verify applicable DGCA requirements, AAI requirements, airport-specific technical specifications, and contract-specific commissioning/SAT procedures.
Final Engineering Note
Do not assume SAT and commissioning are always separate stages. The contract specification and approved test procedures — not general terminology — define the actual scope and sequence on a given project.
Commissioning proves the system works; SAT formally records that it meets the agreed acceptance requirements — on many AGL projects, the two are performed together.
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