The flight is the cheap part. The report is what the client pays for and what an auditor examines, and most of the reports we see fail on the same three things: missing measurement conditions, findings without severity classification, and thermal images with no visible counterpart.
Key takeaways
- The flight is the cheap part — the report is what the client pays for and what an auditor examines.
- Reports fail on the same three things: missing measurement conditions, findings without severity classification, and thermal images with no visual pair.
- Every thermal image needs its visual counterpart shot from the same position; the pair is what makes a finding defensible.
- Classify severity against stated criteria instead of describing what you saw — description is not actionable, classification is.
On this page
Why reports get rejected
A thermal finding is an assertion about equipment condition that may trigger an outage, a repair or a warranty claim. For it to survive scrutiny it has to be reproducible: another thermographer, given your report, should be able to return to the same asset under similar conditions and reach the same conclusion.
That is the standard the structure below is designed to meet. It is not bureaucracy; it is the minimum information needed for the finding to mean anything six months later.
Required fields, by section
| Section | Field | Why it is required |
|---|---|---|
| Header | Site, asset ID, date, time | Reproducibility |
| Header | Operator name and certification level | Accountability |
| Header | Equipment: payload model, serial, last calibration | Traceability of the measurement |
| Conditions | Ambient temperature, wind speed, cloud cover | Affects every thermal reading |
| Conditions | Equipment load at time of survey | Electrical findings are meaningless without it |
| Conditions | Emissivity and reflected temperature used | The two largest operator-controlled errors |
| Conditions | Measurement distance and viewing angle | Determines validity of the reading |
| Finding | Thermal image with temperature scale visible | The evidence itself |
| Finding | Paired visible image, same framing | Confirms what is being looked at |
| Finding | Reference temperature and delta | Findings are comparative, not absolute |
| Finding | Severity classification against a stated criterion | Turns an observation into an action |
| Finding | Recommended action and timeframe | What the client actually buys |
| Closing | Exclusions and limitations | What was not inspected, and why |
The paired-image rule
Every thermal finding needs a visible-light image of the same subject, framed the same way, captured in the same pass. Without it, the reader has a warm blob and your word for what it is.
This is a strong argument for dual-sensor payloads on inspection work. A single-sensor thermal payload forces a second pass, and second passes drift — different framing, different time, sometimes different day. Dual-sensor pods such as OP-90A capture both channels simultaneously with a known alignment, which makes the pairing automatic rather than an editing task.
Annotate on the visible image, not only on the thermal. Clients and engineers read the visible one.
Classifying severity instead of describing it
A report that says “connection appears hot” gives the client nothing to act on. A report that says “22 K above reference phase at 68 % load — Class 3, repair at earliest opportunity, re-inspect within one month” is actionable and auditable.
Use a published criterion and state which one. For electrical work, temperature-rise bands against a reference phase are standard; see substation drone inspection for the bands. For building and roof work, moisture area and pattern classification serve the same purpose.
Where a finding cannot be classified — insufficient load, poor viewing angle, unknown emissivity — say so explicitly and mark it for re-survey. An honest “inconclusive” protects the report far better than a confident guess.
Practical structure that clients accept
- Executive summary — count of findings by severity, and the one thing to do first.
- Scope and method — what was inspected, equipment used, conditions.
- Findings — one per page, thermal and visible paired, classified, with recommended action.
- Asset register — everything inspected with no finding, so absence is documented rather than implied.
- Exclusions — what could not be inspected and why.
- Appendix — flight log, calibration certificate, criteria reference.
Related reading
Operations: emissivity in drone thermography, thermal reflections and false positives and data management.
Technology: radiometric temperature measurement and the calibration chain.
Making the report reproducible six months later
The real test of a report is whether a different thermographer can repeat it. That requires three things the average report omits: the exact position the image was taken from, the equipment state at the time, and the criterion used to classify.
Position is the easiest to fix and the most often missed. A payload with laser ranging and geolocation can stamp each finding with a coordinate and an accuracy radius, which turns “north-east corner of building 3” into something a follow-up crew can fly directly to. Where that is unavailable, a marked-up site plan with numbered capture positions serves the same purpose.
Equipment state means payload serial, firmware version and last verification date. It sounds excessive until a client disputes a finding and the question becomes whether the instrument was in calibration on that date.
The criterion means naming the standard or policy used for severity classification, in the report, with the bands reproduced. A classification that references an unnamed criterion cannot be checked and will not survive a dispute.
- Capture position for every finding: coordinate with accuracy radius, or a numbered site plan.
- Equipment state: model, serial, firmware version, last verification date.
- Named classification criterion with its bands reproduced in the appendix.
- Conditions block completed for every survey, not once per report.
- Version the report itself — findings get revised, and revisions need a trail.
FAQ
What is the most commonly missing section in thermal reports?
The measurement conditions block — ambient temperature, equipment load, emissivity, reflected temperature, distance and viewing angle. Without it, findings cannot be reproduced or defended, and electrical findings in particular are meaningless because severity scales with load.
Do I need a visible image for every thermal finding?
Yes. A thermal image alone shows a warm region; the paired visible image establishes what the region is. Dual-sensor payloads capture both simultaneously, which removes the framing drift that a second pass introduces.
What if a finding cannot be classified?
Record it as inconclusive with the reason — insufficient load, unfavourable angle, unknown emissivity — and schedule a re-survey. An explicit inconclusive is far more defensible than a confident classification made on inadequate data.