RTCA DO 160 G is the official standard for EMC and Environmental compliance for aerospace industry. The standard covers various equipment (electronic, electrical, avionics, landing gear, actuators, etc.) over different categories to ensure airborne equipment complies with a minimum set of requirements.

Equipment categories are determined based on installation location of the equipment, input power requirements (constant or variable primary AC power system, constant frequency system, narrow variable frequency system or wide variable frequency system, DC power - Engine driven alternators/rectifiers) and various other factors.

Methods for measuring emissions as per DO-160 standards.

Limits for emissions testing for RTCA DO 160G are in Section 21.0. It covers Conducted and Radiated Emissions testing and spans 150 kHz – 6 GHz range.

Installation categories for RTCA DO 160 Section 21 emissions are B, L, M, H and Q. Applicable category is typically defined in the EMC/EMI test plan and is based on installation location of the end equipment. For example, Category M equipment will be equipment installed in the passenger cabin or cockpit of an aircraft where electromagnetic apertures are significant but located away from receiving antennas.

Some of the main differences between RTCA and commercial EMC testing are as follows. Test distance is 1m vs 3m in commercial setup, LISNs used are 5 μH instead of 50 μH and the equipment is setup on a metallic table vs non-metallic table for commercial testing.

Figure 1 – Typical Conducted Emissions setup (RTCA DO 160G Section 21)

Given these physical differences in measurement setup test data is not easily transposable between the aerospace and commercial standards. Apart from the above-mentioned differences there are test specific differences also, like frequency ranges scanned, measurement bandwidths used, and measurement detectors used. 

Given the fact more and more RF equipment is used in aerospace industry RTCA DO160 emissions testing is referenced in various commercial equipment standards. For example, medical equipment EMC standard IEC 60601-1-2 references RTCA DO 160G emissions testing for medical devices that can be carried on board an aircraft.

Key equipment and setups for emissions testing

Section 21 of RTCA DO 160G allows for two measurement methods for Radiated Emissions testing, semi anechoic chamber or reverb chamber method. While both are accepted, most labs had a semi anechoic chamber setup and it is the more common used test method. Test limits are same between the two measurements however chamber verification/calibration requirements differ.

Radiated Emissions testing is also setup on a metallic table and measurement antennas are 1m from the EUT. Below is a typical test setup for emissions testing. 

Figure 2 – Radiated Emissions setup (RTCA DO 160G Section 21)

A notable emission limit for aerospace testing are the notches in the emission limits. Usually, these notches exist to minimize RF interference between ATC frequencies, or other known frequencies that are used in the aircraft communication systems. Below is an example of an emission limit for Category M equipment 3 different notches in 108-132 MHz, 960 – 1215 MHz and 1525 – 1680 MHz band.

Figure 3 – Cat M limit for Radiated Emissions and notches in the scanning range. (RTCA DO 160G Section 21)

Addressing common compliance issues during testing.

Conducted and Radiated Emission test non-compliance is an often-discussed topic in EMC labs and among electronic engineers. There are various reasons a product is non-compliant with the standard. There could be an offending cable which is not shielded correctly, an impedance mismatch on PCB board or something much more drastic as PCB layouts didn’t take certain high frequency signals and terminations into account correctly. Some of the EMC patches can be applied in a test lab, ferrites, shields, board level filters. However more persistent problems in the design can lead to expensive board re spins and delays. To combat last minute failures test labs recommend performing prescan for RF emissions testing in an accredited test facility with calibrated test equipment. Identifying issues at an earlier stage can help reduce test timelines and keep cost overruns in check.

Available DO‑160 tests

In addition to emissions, DO‑160 defines a comprehensive suite of environmental and electromagnetic tests that may apply depending on the equipment’s function and location. These tests include:

• Temperature and altitude: Verifies performance across temperature extremes and reduced pressure conditions.
• Temperature variation: Subjects equipment to rapid temperature changes to assess thermal shock.
• Humidity: Exposes devices to high moisture levels to check for condensation effects.
• Operational shocks and crash safety: Ensures equipment continues to function after mechanical shocks.
• Vibration: Evaluates resistance to continuous vibration from engines and airframe.
• Explosion‑proofness: Confirms that equipment will not ignite flammable atmospheres.
• Waterproofness: Tests sealing against dripping or sprayed water.
• Fluids susceptibility: Assesses tolerance to aviation fluids such as hydraulic oils and fuels.
• Sand and dust: Checks that airborne particulates do not impair operation.
• Fungus resistance: Determines whether materials support fungal growth.
• Salt fog: Evaluates corrosion resistance in saline environments.
• Icing: Tests operation after exposure to icing and freezing rain.
• Fire and flammability: Measures resistance to ignition and flame spread.
• Magnetic effect: Assesses interference with onboard compasses
• Power input: Checks resilience to voltage variations
• Voltage spike: Subjects equipment to transient over‑voltages
• Audio‑frequency conducted susceptibility: Looks at low‑frequency conducted disturbances on power lines
• Induced signal susceptibility: Evaluates coupling of RF energy onto wiring
• Radio‑frequency susceptibility (radiated and conducted): Examines immunity to RF fields and currents
• Emission of radio‑frequency energy: Measures conducted and radiated emissions from the equipment.
• Lightning‑induced transient susceptibility: Tests ability to withstand lightning‑generated transients.
• Lightning direct effect: Examines damage due to direct lightning strikes.
• Electrostatic discharge (ESD): Assesses tolerance to human‑body and machine‑model discharges.

These tests provide a framework for demonstrating that airborne electronics can endure the harsh conditions encountered in flight. By understanding the DO‑160 requirements early and integrating EMC and environmental considerations throughout development, designers can avoid costly delays and produce safer, more reliable equipment.