The avionics box had passed MIL-STD-810 temperature and vibration testing. The programme manager was satisfied. Then the customer — a commercial aircraft OEM — asked for the DO-160 test report.
There wasn't one. The DO-160 testing was "planned for a future phase."
The product was not qualified for commercial aviation. MIL-STD-810 and DO-160 are not interchangeable standards. They were written by different organisations, for different regulatory authorities, covering different test philosophies — and for anyone building hardware for both military and commercial aviation, or moving a product from one market to the other, the differences between them determine whether a completed test campaign is worth anything in the new context.
What DO-160 actually is and who it governs
DO-160 — full title "Environmental Conditions and Test Procedures for Airborne Equipment" — is published by the Radio Technical Commission for Aeronautics (RTCA) and has been the primary standard for commercial avionics environmental qualification since its first publication in 1975. The current version is DO-160G, published in December 2010 and referenced by FAA Advisory Circular AC 21-16G as the acceptable means of compliance for airworthiness requirements. In Europe, the technically identical standard is EUROCAE ED-14G; test data generated to DO-160G is accepted by EASA as compliant with ED-14G, making a single test campaign sufficient for both US and European market certification.
DO-160 covers 26 sections, each dedicated to a category of environmental stress that airborne equipment may encounter. The breadth is wider than most engineers expect from a "temperature and vibration" framing. Sections cover temperature and altitude (Section 4), temperature variation (Section 5), humidity (Section 6), operational and crash safety shock (Sections 7 and 8), vibration (Section 8), explosion proofness (Section 9), waterproofness (Section 10), fluids susceptibility (Section 11 — which explicitly includes carbonated beverages and aviation cleaning solvents), sand and dust (Section 12), fungus resistance (Section 13), salt spray (Section 14), and electromagnetic compatibility across fifteen additional sections covering magnetic effect, power input, voltage spikes, audio susceptibility, and lightning induction, among others.
Not every section applies to every product. A typical avionics electronic box is tested against 12 to 18 sections depending on its installation location and function. A complete test campaign covering all applicable sections typically requires four to eight weeks of laboratory time. The sections that require environmental chambers — primarily temperature and altitude (Section 4), temperature variation (Section 5), and humidity (Section 6) — are where the thermal and climatic test equipment described elsewhere on this site becomes relevant.
Section 4: the most technically demanding section and why
Section 4 of DO-160 is described by chamber manufacturers who specialise in avionics testing as the most technically demanding of the climatic sections, for a reason that is easy to miss on first reading: it doesn't test temperature and altitude independently. It tests them simultaneously.
Aircraft cabin equipment experiences pressure changes during flight, and avionics equipment in unpressurised bays, wheel wells, or engine nacelles experiences even more extreme pressure variation. Section 4 test categories combine specific temperature ranges with specific altitude (reduced pressure) conditions, because the combination produces failure modes that neither test alone would find — dielectric breakdown at reduced pressure, cooling degradation as convective heat transfer drops with air density, and condensation on cold structures when pressure and temperature both change rapidly after descent.
This means the chamber needs both thermal control capability and an integrated vacuum system. A standard climatic chamber with no pressure capability cannot run DO-160 Section 4 compliance testing. Manufacturers who build combined temperature-altitude chambers specifically for DO-160 — FDM Environment Makers in France covers both the climatic and reduced-pressure requirements, and Thermotron has historically served the aerospace qualification market — are addressing a niche that general-purpose chamber manufacturers don't cover by default.
DO-160 vs. MIL-STD-810: the differences that matter operationally
Both standards cover thermal, vibration, humidity, and mechanical shock testing of hardware expected to operate in demanding environments. That is where the similarity ends.
MIL-STD-810 is a tailoring methodology — it tells you how to derive test conditions from measured or estimated field data, and explicitly describes its default conditions as guidance, not mandatory requirements. The result is that two test campaigns both labelled "MIL-STD-810" can use significantly different temperature ranges, ramp rates, and cycle counts if the tailoring was done differently. The standard's default values are a starting point for engineers who haven't measured the actual deployment environment, not a fixed specification.
DO-160 defines fixed test categories. Section 4's category A1 specifies equipment tested to −55°C ground survival and −55°C low operating; category B1 goes to −55°C low operating and adds high-altitude low-pressure conditions. These are not adjustable by tailoring — they are the test, and a product either passes the applicable category or it doesn't. The comparability this produces is the point: a DO-160G category B1 result from one laboratory means the same thing as a DO-160G category B1 result from another, which is why airframe OEMs can include it directly in their equipment qualification requirements without additional translation.
In practice, many military avionics components are required to satisfy both standards — DO-160 for the commercial aspects of certification and MIL-STD-810 for the military tailoring requirements. The test campaigns are not interchangeable, but they can be sequenced efficiently, and some test conditions overlap enough to avoid full repetition when the test plan is written with both standards in mind from the start.
The drone and UAV market: DO-160 expanding beyond manned aircraft
DO-160 was written for manned aircraft. Its category structure — from light general aviation through jumbo jets and supersonic transport — doesn't obviously include unmanned aerial vehicles. But the FAA and EASA have moved toward referencing DO-160 for drone avionics qualification as part of their Specific and Certified categories under EASA Regulation 2019/947, and as the UAV market has matured, commercial drone manufacturers designing hardware for regulated airspace operations have adopted DO-160 as the environmental qualification baseline regardless of whether their specific application formally requires it.
The practical reason: DO-160 is the environmental qualification language commercial aviation customers understand. A drone manufacturer selling a navigation system to an aerospace OEM for integration into a larger platform benefits from DO-160 test data the way any other avionics supplier does — it's the format the customer expects and can directly evaluate.
What the test campaign requires from your chamber facility
For the climatic sections of DO-160, the chamber requirements are specific. Section 4 requires simultaneous temperature and altitude control — either an integrated temperature-altitude chamber, or a standard climatic chamber with a separately controlled altitude bell jar or vacuum enclosure. Section 5 (temperature variation) requires the chamber to achieve the rate of temperature change specified by the applicable test category, which for some categories reaches 10°C per minute — achievable with smaller chambers but challenging at larger workspace volumes. Section 6 (humidity) requires a calibrated humidity source and continuous monitoring.
The precision requirements for DO-160 temperature testing are similar to those of automotive standards like AEC-Q100 but differ in the altitude simulation requirement, which is specific to aerospace. For a lab configuring equipment specifically for DO-160, the combination of temperature range, ramp rate, and altitude capability narrows the chamber selection significantly compared to a general-purpose IEC 60068 test laboratory. The chamber selection guide covers the specification-to-chamber-type mapping in detail, and the altitude test chamber overview addresses the specific pressure and temperature requirements for aerospace environmental testing.
For laboratories that run both DO-160 commercial and MIL-STD-810 military programmes, the overlap in equipment requirements is significant enough that a single well-specified thermal chamber can serve both — though the altitude simulation requirement for Section 4 typically requires either a dedicated chamber or a chamber with an optional altitude module that standard MIL-STD-810 thermal testing doesn't need.
The Environmental Qualification Form: the document that ties everything together
One of the most practical features of DO-160 is the Environmental Qualification Form (EQF), provided in Appendix A of the standard. The EQF is a structured summary of all DO-160 testing conducted on a specific product — every section tested, the category applicable to each section, and any limitations or installation restrictions that affect where the equipment can be installed on an aircraft.
Airframe OEMs and system integrators use the EQF as the first document they review when evaluating a piece of equipment for aircraft integration. A complete, accurate EQF allows an engineer unfamiliar with the component to assess its environmental qualification in minutes, because the format is standardised across all DO-160 equipment. An incomplete EQF, or one that doesn't accurately reflect the actual test categories used, creates downstream problems in the aircraft certification process that are expensive to resolve after the fact.
Writing an accurate EQF from incomplete or incorrectly documented test records is not possible without repeating the tests. This is why the documentation requirements for DO-160 testing — keeping the actual test conditions, chamber calibration data, and test sequence records alongside the pass/fail results — matter as much as the test results themselves.
Starting a DO-160 programme: the three questions that determine your test plan scope
Before a DO-160 test plan can be written, three questions need answers that only the product's intended installation determines. First, where will the equipment be installed on the aircraft? The installation location drives the applicable category for temperature (Section 4) and vibration (Section 8) — equipment in a pressurised cabin, an unpressurised equipment bay, an engine nacelle, and a wheel well face categorically different environmental conditions, and the DO-160 category structure reflects this. Second, what is the equipment's function? Safety-critical equipment has different performance requirements during environmental exposure than non-essential equipment, and this affects what constitutes a pass during testing. Third, what aircraft types will the equipment be installed on? The spectrum from light general aviation to supersonic transport covers a wide range of vibration profiles, altitude conditions, and temperature extremes, and selecting the right category requires knowing where in that spectrum the target platform sits.