A reefer booking with the correct temperature setpoint is not, by itself, proof that the shipment was maintained correctly. Cold-chain performance depends on the actual product temperature at loading, supply and return air, relative humidity, fresh-air ventilation, gas composition, airflow through the cargo, power continuity, door-opening time, equipment status and the quality of data recorded throughout the journey. Frozen cargo, chilled food, fresh produce, flowers, pharmaceuticals and biologics can require very different — sometimes opposite — humidity and ventilation settings. This article provides an operational control framework from product specification and booking through loading, in-transit monitoring, delivery and deviation assessment, helping businesses avoid the familiar outcome of “the setpoint was correct, but the cargo still deteriorated.”

Prepared by TGIMEX · Updated: 21 July 2026 · Scope: Temperature-controlled ocean, road and air transport

QUICK FACTS

The product specification is the source of truth

There is no universal temperature, humidity or ventilation setting. Instructions must come from the manufacturer, cargo owner, quality dossier and applicable product rules.

Setpoint is not product core temperature

Separate the controller setpoint, supply air, return air and actual cargo temperature. Each value answers a different operational question.

Airflow and stowage determine temperature distribution

Blocking T-bar floors, exceeding load lines or using non-ventilated packaging may create hot spots while the refrigeration unit appears normal.

Power gaps and uncontrolled time must be recorded

Power-off events, delayed plug-in, long door openings, ramp exposure and transfer delays belong in the cold-chain timeline.

Data needs thresholds and a response process

Loggers and remote monitoring are useful only when linked to approved limits, escalation owners, response times and an excursion assessment process.

Illustration for Which Parameters Must Be Controlled in Cold-Chain Transportation? — Illustration of the logistics topic, document or operation discussed in the article.

SCOPE OF APPLICATION

This framework applies to ocean reefer containers, refrigerated trucks, cold-storage transfers and air shipments using active or passive temperature-control packaging. It covers frozen and chilled foods, fresh produce, flowers, temperature-sensitive ingredients, pharmaceuticals, vaccines and biologics.

The article does not prescribe commodity-specific temperatures. Transport limits must be confirmed against the product specification, storage label, stability data, shipper instructions, sector regulations, destination-market requirements and the applicable quality/transport agreement.

Do not rely on a generic cargo name: “cold cargo,” “chilled,” “frozen” or “pharma” is not enough for booking. The file should state the transport range, tolerance, permitted time outside range, humidity, ventilation, controlled atmosphere, sanitation, packaging and excursion response requirements.

KEY TERMS

Term	Operational meaning	Control role
Cold chain	The storage, transport and handover chain used to maintain specified environmental conditions.	Continuity must be demonstrated across every transfer point, not only the main carriage.
Setpoint	The temperature value programmed into the refrigeration controller.	An operating instruction; it does not prove the product core temperature.
Supply air temperature	The temperature of air delivered by the unit into the cargo space, commonly through the floor area in a reefer container.	Shows how the unit is supplying conditioned air against the setpoint.
Return air temperature	The temperature of air returning to the unit after circulating through the load.	Indicates the thermal load returning to the refrigeration system.
Cargo/core/pulp temperature	The actual temperature measured in the product, package core or fruit pulp.	Important for pre-cooling verification and delivery quality assessment.
Relative humidity – RH	The relative moisture content of the air in the cargo space.	Affects dehydration, condensation, mould, packaging strength and product stability.
Fresh-air ventilation	The amount of outside air exchanged, often expressed in m³/h or air changes per hour.	Used for respiring produce; incorrect settings may accelerate ripening or moisture loss.
Controlled atmosphere – CA	Control of O₂, CO₂ and sometimes N₂ in the container.	Can reduce respiration and ripening for approved commodities.
Cargo pre-cooling / equipment preparation	Bringing the product to its approved loading temperature before stuffing. Pre-cooling an empty container is a separate operation and should only be used with a temperature-controlled loading interface and carrier/commodity instructions.	Transport refrigeration mainly maintains condition. Pre-cooling an empty container and then opening it in hot, humid ambient air may cause condensation and does not replace cargo pre-cooling.
Temperature excursion	An event in which temperature or another condition exceeds the approved limit.	Must be assessed by severity, duration, measurement location and product stability data.
Data logger	A device recording temperature, humidity or other parameters at defined intervals.	Provides independent or supplementary evidence alongside controller and remote-monitoring data.

HOW THE CONTROL SYSTEM WORKS

1. Refrigeration maintains conditions; it does not correct every upstream error

A reefer unit or refrigerated vehicle has finite capacity. If the cargo has not reached the required loading temperature, produces significant field heat, is stowed too tightly or is exposed during a long door-open period, stabilization may be slow and temperature distribution may be uneven. Transport refrigeration primarily maintains prepared cargo rather than rapidly removing the full heat load. Cargo should be pre-cooled to specification; an empty container should only be pre-cooled when the loading process preserves a suitable cold environment, because opening a cold box to hot, humid ambient air can create condensation.

2. The controller measures air while quality resides in the product

Setpoint, supply air and return air are refrigeration-system data. Core or pulp temperature is product data. A stable air-temperature graph does not rule out a warm pallet inside the load, particularly where airflow is restricted.

3. Frozen cargo and respiring produce follow different logic

Frozen cargo generally prioritizes temperature stability and protection from heat and moisture ingress. Fresh produce may require ventilation, high RH or controlled atmosphere. Pharmaceuticals depend on stability data, qualified packaging, route profiles and approved excursion limits. Settings must not be copied across commodities.

4. Cold chain is a continuous timeline

Risk exists during pickup, loading, port gates, terminal dwell, transshipment, power interruptions, inspection, sampling, unloading and final handover. The record should identify custody, location, equipment status and supporting evidence for every critical interval.

PARAMETER CONTROL MATRIX

Parameter	What to confirm	Evidence source	Risk if omitted
Setpoint and acceptable range	Programmed value, °C/°F unit, tolerance, chilled/frozen mode and continuous/cyclic operation.	Product spec, booking instruction, controller record.	Wrong setting or confusion between a single value and an approved range.
Product temperature at loading/delivery	Measurement location, method, sample size, time and core/pulp temperature.	Pre-cooling, loading and receiving reports.	Warm cargo is loaded and later blamed on the refrigeration unit.
Supply air	Trend, deviation from setpoint and expected defrost-related fluctuations.	Controller and remote-monitoring data.	Abnormal cooling output or probe faults are missed.
Return air	Trend and supply–return differential after stabilization.	Controller/data report.	High thermal load, airflow restriction or door-opening effects are missed.
RH and dehumidification	Target RH, dehumidification status and condensation limits.	Commodity guide, booking and sensor log.	Dehydration, mould, wet cartons or label/packaging damage.
Fresh-air ventilation	m³/h or air-changes/hour, open/closed status and any planned changes.	Commodity instruction, booking and controller setting.	Gas accumulation, accelerated ripening, dehydration or heat/moisture ingress.
O₂/CO₂ and CA	Targets, tolerances, pull-down time and commodity compatibility.	CA service specification and gas-sensor report.	Physiological injury or ineffective atmosphere control.
Airflow and stowage	Open T-bar floor, load line, clearances and package vent orientation.	Stow plan, loading photos and survey report.	Hot spots, local freezing or poor cooling at the door end.
Equipment status	PTI, alarms, probes, defrost, fans, door gasket, cleanliness and odour.	PTI report, EIR and controller alarms.	Insufficient equipment performance, probe error or contamination.
Power/fuel continuity	Plug-in/out time, power-off duration, genset fuel and backup power.	Terminal events, telematics and driver log.	Undetected loss of refrigeration during dwell or transfer.
Door openings and dwell	Frequency, duration, ambient conditions and time outside cold storage.	Door sensor, GPS event, warehouse log and EIR.	Heat/moisture ingress, condensation and shelf-life loss.
Location, route and transit	Routing, ETA, transshipment, delays and inspection/cold-store dwell.	Tracking and milestone events.	Passive packaging duration is exceeded or fuel/cold-treatment plans fail.
Logger/probe and calibration	Device ID, placement, interval, time zone, calibration and alarm thresholds.	Configuration file, calibration certificate and placement map.	Unreliable, untraceable or non-representative data.
Seal, hygiene and integrity	Seal number, walls/floor/doors, moisture, odour and signs of entry or pests.	EIR, loading/receiving photos and sanitation records.	Contamination, loss disputes and poor incident attribution.

DOCUMENTS AND DATA TO REVIEW

Document/data	Prepared or issued by	Fields that must match	When used
Product specification / storage label / stability data	Manufacturer, QA or cargo owner	Temperature range, excursion allowance, RH, ventilation/CA and shelf life.	Before quotation and booking.
Transport order / shipper instruction / SLA-QTA	Cargo owner and logistics provider	Settings, alarm thresholds, 24/7 contacts, escalation and handover evidence.	Before pickup.
Reefer booking confirmation	Carrier/forwarder	Equipment type, setpoint, ventilation, humidity, CA, cold treatment and monitoring.	Before equipment release/loading.
PTI/EIR and sanitation record	Depot, carrier, driver or warehouse	Container number, unit status, alarms, gasket, clean/dry/odour-free condition.	At equipment handover.
Pre-cooling and loading report	Plant, cold store or surveyor	Product temperature, time, measurement location, stowage and load-line photos.	During loading.
Logger plan and calibration	QA, cargo owner or logger provider	Logger ID, placement, interval, time zone, serial number and calibration validity.	Before sealing.
In-transit monitoring report	Carrier, telematics platform, airline or 3PL	Setpoint, supply/return, RH, O₂/CO₂, power, alarms, GPS and event time.	During transport and alerts.
Handover/receiving record	Receiving warehouse, consignee or surveyor	Seal, product temperature, package condition, door time and logger custody.	At delivery.
Excursion/deviation assessment	QA/product owner and relevant parties	Magnitude, duration, location, root cause, quality impact and disposition.	Immediately after a deviation.
Claim file	Cargo owner, insurer, carrier and surveyor	Timely notice, logs, survey, photos, value documents and chain of custody.	After loss or dispute.

CONTROL PROCESS FROM BOOKING TO DELIVERY

Classify the cargo and lock the specification

Confirm whether the product is frozen, chilled, fresh produce, pharmaceutical or biologic and obtain an approved written instruction.

Assess the route and equipment

Review total transit, transfers, climate, intermediate storage, power availability, equipment/packaging capability and contingency plans.

Transmit exact settings in the booking

State temperature, ventilation, RH/dehumidification, CA/O₂/CO₂, cold treatment and monitoring service using unambiguous units.

Receive and inspect equipment

Verify alarms, sensors, door gasket, cleanliness, odour, airflow floor, equipment number and power connection.

Confirm product temperature before loading

Measure under the agreed method; do not use one surface reading as evidence for the entire shipment.

Load according to an airflow plan

Keep air channels open, respect the load line, place loggers/probes as mapped, photograph the load and seal the unit.

Monitor power milestones and excursions

Track plug-in/out, supply/return air, alarms, door events, ETA and delays; escalate under the SLA rather than waiting for destination.

Prepare a controlled cold delivery

Book the receiving dock, minimize door-open time and prepare unloading space, logger readers and quarantine/rejection criteria.

Review data and close the shipment file

Reconcile controller data, independent loggers, receipt temperature and milestones. QA/product owner should assess every material excursion before product disposition.

COMMON RISKS AND ERRORS

Error	Cause	Impact	Control
Checking only the setpoint	System data is confused with product temperature.	Warm loading or hot spots remain undetected.	Require cargo temperature, supply/return data and loggers.
Using “standard practice” settings	No approved product specification.	Quality loss or non-compliant storage conditions.	Issue written transport instructions before booking.
Confusing cargo pre-cooling with container pre-cooling	The empty box is cooled while the cargo remains warm, followed by long door opening in hot/humid ambient conditions.	Condensation, wet cartons, high heat load and prolonged stabilization.	Pre-cool cargo to specification; pre-cool the container only with a suitable cold loading interface and carrier confirmation.
Blocking airflow or exceeding load line	No stow plan or unsuitable pallets/packaging.	Uneven temperature distribution.	Use loading photos and a stuffing standard.
Confusing ventilation units	m³/h and air changes/hour are mixed.	Incorrect fresh-air rate.	State the unit in booking and verify the controller.
Ignoring power-off events	No plug-in milestone or genset contingency.	Temperature rises during terminal or warehouse dwell.	Monitor power events, fuel and response deadlines.
Placing one logger next to the air outlet	No risk-based placement map.	Data does not represent the load.	Set quantity and placement through QA risk assessment.
Automatically destroying cargo after an excursion	No review of duration, severity or stability.	Unnecessary commercial loss.	Perform a documented QA/product-owner assessment.
Automatically accepting cargo because the graph looks normal	Seal, odour, moisture, packaging and core temperature are ignored.	Local damage or contamination is missed.	Use combined data and physical receipt checks.
No chain of custody	Handover times and logger custody are not recorded.	Claims and responsibility become difficult to establish.	Sign each transfer and synchronize time zones.

OFFICIAL AND OPERATIONAL SOURCES

Source / standard	Role in this article
IATA – Temperature Control Regulations, 2026 Edition	Air-transport requirements and standards for temperature-sensitive pharmaceutical, vaccine and healthcare/life-science cargo.
IATA – Perishable Cargo Regulations, 2026 Edition	Requirements and best practices for food, flowers, produce and other perishable cargo transported by air.
IATA – Pharma & Healthcare	Time and Temperature Sensitive Label and shipper responsibility for healthcare cargo.
WHO TRS 1025 Annex 7 – Good storage and distribution practices	GDP principles for storage, distribution, environmental conditions, records and quality controls for medical products.
WHO TRS 961 Annex 9 – TTSPP guidance	Framework for time- and temperature-sensitive pharmaceutical storage and transport.
WHO – Cold chain equipment and dry store temperature mapping tool	The page was published on 22 January 2026; WHO identifies tool version 9.2 as updated in June 2024 for mapping and monitoring three-dimensional cold spaces.
UNECE – ATP Agreement 2024	Temperature and equipment conditions within ATP scope: international carriage involving at least two Contracting States and the modes covered by ATP; it is not a universal mandatory setting guide for every shipment in Vietnam.
FAO – Refrigerated road transport	Why equipment cannot compensate for poor pre-cooling, packaging, stowage or handling.
Hapag-Lloyd – Reefer Cargo Handling	Setpoint, humidity, ventilation, stuffing and airflow practices.
Carrier Transicold – Controller/Data Tools	Supply/return air, alarms, defrost, probes and pre-trip inspection functions.
CMA CGM – Reefer solutions	Temperature, humidity, ventilation and atmosphere control by cargo type.

Source note: ATP, IATA, WHO, FAO and carrier guidance have different scopes. Mandatory rules in the export/import country, the approved product specification and the actual contracts take priority.

FAQ

Is the correct setpoint enough?

No. At minimum, review loading product temperature, supply/return air, airflow, power events and receipt data; RH, ventilation or CA may also be essential.

What is the difference between supply and return air?

Supply air leaves the refrigeration unit for the cargo space; return air comes back after passing through the load. Their trend and differential help explain thermal load but do not replace product-core measurements.

Can a reefer rapidly cool warm cargo?

Do not plan on that assumption. Transport refrigeration mainly maintains prepared cargo; pull-down capability depends on equipment, product, packaging, field heat and stowage.

Should frozen cargo ventilation always be closed?

Follow the commodity instruction and carrier confirmation. Many frozen loads use closed fresh-air ventilation, but this must not be treated as a universal rule.

How many data loggers are required?

There is no universal number. Quantity and placement depend on load size, value, expected hot spots, regulatory/QA requirements, mapping and route risk.

Does remote monitoring replace independent loggers?

Not automatically. Controller data describes equipment conditions; independent loggers may be located near the product. The evidence model should be defined in the SLA/QTA and claim protocol.

Who decides whether product remains usable after an excursion?

Normally QA, the product owner or another authorized quality decision-maker should assess stability/product data. A carrier or forwarder supplies evidence but should not make the product-quality decision alone.

APPLICATION NOTE: This is a control map, not a commodity setting sheet. Each shipment should use a version-controlled transport instruction with an approver, alarm thresholds, escalation contacts and excursion rules. When controller, independent logger and receipt measurements conflict, preserve all evidence and investigate before assigning responsibility.

TGIMEX IMPLEMENTATION SUPPORT

TGIMEX helps businesses turn the article into a shipment-ready checklist, covering input-data review, dossier preparation, milestone control, and coordination with the relevant parties.

Convert guidance into checks

Assign an owner and deadline to every operational control point.

Reconcile shipment data

Compare booking, transport, commercial, customs, and delivery evidence.

Manage operational risk

Record discrepancies, actions, and decision evidence to prevent recurrence.

Discuss your shipment dossier

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