Last month, I talked about the RTCA and who they are. This month, let us look at the history and development of DO-160.
The RTCA document titled “Environmental Conditions and Test Procedures for Airborne Equipment” is better known as DO-160 and as EUROCAE ED-14 in Europe and elsewhere. It is based on a history of documents and test procedures to establish equipment performance standards for avionics in a wide range of environmental conditions.
The roots of this document go back to April 13, 1954, and a publication called DO-60 (Note 60, not 160), titled “Environmental Test Procedures Airborne Radio Equipment” – based on earlier works such as DO-44. The document includes just 15 pages for temperature, altitude, humidity, vibration and shock tests, and two tests one would consider EMI Tests. These two tests were a “Susceptibility Test,” which injected a 1000 µV signal through a capacitor onto various lines, and a “Low Voltage Test.”
By June 1968, DO-138 “Environmental Conditions and Test Procedures for Airborne Electronic/Electrical Equipment and Instruments,” was created. It appears to be based on DO-108, but that document is unavailable to verify that basis. DO-138 has much in common with early editions of DO-160, including setup drawings and test equipment. However, for EMI testing, the emissions section is included as Appendix A, not part of the body of the test procedure.
For the release of DO-160 in February of 1975 and DO-160A (July 1980), all current sections from 1-21 are in place. The use of document revisions (DO-160A, DO-160B, etc.) and of Change Notices (ex., DO-160A has Notice 1 replacing Section 9 Explosion Test) locked DO-160 into the Environmental Test Procedure it is now known as.
With DO-160C, December 1989, and its three Change Notices, the EMI section of the document took a radical turn. Before this, conducted and radiated susceptibility test levels were typically benign, often performed using a signal generator and no amplifier – the highest level was Category Z in DO-160B at 2 V/m from 118-135 MHz. However, Section 20 was updated to include test amplitudes of no less than 5 V/m (Category T) and as high as 200 V/m (Category Y), with testing performed up to 18 GHz. Previously, no testing was performed above 1.215 GHz. In addition, Section 22 Indirect Lightning was introduced, and Section 23 for Direct Lightning.
In DO-160D, Section 18 through Section 21 mandated sweep rates for testing, and for emissions, the bandwidths to be used were fixed, with broadband testing removed. Section 25, ESD, was included. In Notice 2, Sections 16 and 18 were updated, and in Notice 3, Indirect Lightning was reworked to include Multiple Burst and Multiple Stroke effects.
Currently, the special committee, SC-135, along with EUROCAE working group WG-14, is laboring to complete DO-160H along with EUROCAE’s ED-14H, with plans to have it available in December 2025. A great deal of work is being done to clean up the document, correct misunderstandings and misinterpretations, and hopefully arrange the information in a more logical manner. When completed, the committee hopes to start work on the update to DO-357, the user guide and supplement for DO-160. It is hoped that providing more information in DO-357 will help the user understand the intent and goal of the test, perform proper measurements, and obtain quality data for the compliance of the avionic system.
In the EMC world of aeronautics, the RTCA has other documents which may be of interest. These include:
- DO-199 – Potential Interference to Aircraft Electronic Equipment from Devices Carried Aboard (Volumes 1 and 2)
- DO-233 – Portable Electronic Devices Carried on Board Aircraft
- DO-294C – Guidance on Allowing Transmitting Portable Electronic Devices (PED) Tolerance
- DO-307B – Aircraft Design and Certification for Portable Electronic Device (PED) Tolerance
- DO-363 – Guidance for the Development of Portable Electronic Devices (PED) Tolerance for Civil Aircraft
- DO-380 – Environmental Conditions and Test Procedures for Ground Based Equipment
It should be noted that DO-199 is a 1988 document and report based on an earlier DO-119 document from 1963. Portable electronics in the 1960s were limited to portable radios and the like. It was not found to be a significant concern until 1983 when some aircraft carriers would not allow the use of personal computers by passengers on the aircraft. In the next blog, we will look at the use of portable electronics on aircraft and the documents above, which address them.
