A data logger is the only evidence you will have about what happened to a shipment between two warehouses. Choose it badly and you get an alarm with no context. Handle an excursion badly and you turn a recoverable event into a written-off consignment or, worse, an out-of-specification product delivered to a patient.
Types of logger
- Single use, usually a card or strip with a USB connector or a PDF generated on plug-in. Cheap, no return logistics, fine for one way lanes. The data is only available once someone at destination downloads it.
- Reusable, programmed and returned. Lower cost per trip at volume, but you need a return process that actually works, and calibration has to be maintained.
- Bluetooth, read by phone at any handover point without opening the shipper. Good for checkpoints along a route.
- Real time cellular, reporting continuously with configurable alarms, and often GPS location too. The only type that lets you intervene while the shipment is still moving, which is the whole point.
Real time is the meaningful upgrade. A single use logger tells you, after the fact, that your product spent nine hours at 31C in a transit warehouse. A real time logger tells you while there is still time to send someone.
Getting the setup right
- Place the logger with the product, not on the outside of the box. Outside surface temperature is not product temperature. For pallet shipments, place loggers where the mapping says the risk is, usually the outer edges and the top.
- Set a sensible logging interval. Every 5 to 15 minutes is typical. Too coarse and you miss short excursions; too fine and the memory fills before arrival.
- Start it at the right moment, after packing and just before despatch, so you are not recording the packing room.
- Use calibrated devices and keep the certificates. An uncalibrated logger is not evidence.
- Agree in advance who downloads it and where the file goes. Data that sits unread on a device in a warehouse has bought you nothing.
Mean kinetic temperature
MKT is a single calculated temperature that expresses the cumulative thermal stress of a variable temperature history. It weights higher temperatures more heavily than a simple average, because degradation accelerates non-linearly with heat.
It is genuinely useful for assessing whether a product's overall exposure was acceptable across a long journey. It is not a way of averaging away a spike: a short excursion far outside the range can be product-critical even where the MKT looks comfortable, and some products have hard limits that MKT does not address at all.
When an excursion happens
This is the part that gets handled wrong under time pressure. The sequence is:
- Quarantine the product. Physically segregate it and mark it as not for release. Do not put it into stock and do not deliver it.
- Do not destroy anything. This is the most important line here. An excursion is not automatically a loss, and destroying product removes the option of assessing it.
- Keep it at the correct storage condition while the assessment happens. Further exposure makes a recoverable situation unrecoverable.
- Notify quality immediately, with the full temperature trace, not a summary.
- Record the event as a deviation: what happened, when, how long, how far out of range, and the suspected cause.
- Wait for the decision.
Who actually decides
The critical governance point: the decision on whether excursed product may be released belongs to the marketing authorisation holder or the manufacturer's qualified person, assessed against the product's stability data. It does not belong to the freight forwarder, the driver, the warehouse supervisor or the buyer.
Many products have stability data supporting defined excursions, and are released routinely after assessment. Others have none and are rejected on a small breach. The forwarder cannot know which, so the forwarder must never make the call. Their job is to preserve the product and report accurately and fast.
Making the data useful afterwards
Traces are worth more in aggregate than one at a time. Reviewed across a quarter they show which lane, which station and which season produce the excursions, which is what lets you fix a route rather than argue about a shipment. That analysis is also what qualifies a lane under GDP.
General guidance. Excursion handling must follow your own quality system and the product's marketing authorisation. Nothing here overrides your standard operating procedures.
