Originally published January 2021. Last updated September 2026 to reflect AC 70/7460-1N. This page is maintained as a running record of FAA obstruction marking and lighting Advisory Circular revisions, current information first, superseded editions kept below and dated.
AC 70/7460-1N is the FAA’s current Advisory Circular for obstruction marking and lighting, effective August 11, 2026. It replaces AC 70/7460-1M, which had been in effect since November 2020. Here is what actually changed between the two editions, and what tower owners still need to know from 1M that carries forward unchanged.
Current: What Changed From AC 70/7460-1M to AC 70/7460-1N
According to the FAA’s own summary of principal changes in AC 70/7460-1N, the update:
- Updates the notice threshold for meteorological towers to cover structures with a highest point between 50 and 200 feet AGL, aligning with the FAA’s final rule on notice for meteorological towers and other wind energy systems under 14 CFR Part 77
- Updates the form and manner in which notice is required for certain structures
- Clarifies that a sponsor must comply with the conditions and limitations in a Determination of No Hazard to Air Navigation, including any marking requirements it contains
- Clarifies how a sponsor may request a modification from the marking and lighting requirements in a determination
- Clarifies the definition of catenary to explicitly include lines, powerlines, slacklines, transmission lines, logging cables, and valley-spanning cables, following an NTSB safety recommendation, relevant to electric transmission structures as well as towers
- Updates terminology from Notice to Air Missions (NOTAM) to Notice to Airmen (NOTAM)
None of these changes require existing tower lighting equipment to be modified. They mostly affect notice procedures and how sponsors document compliance with their determination.
Current: The Infrared (IR) LED Requirement Still Applies
The change most relevant to existing towers did not come from 1N, it came from AC 70/7460-1M in 2020, and it carries forward unchanged. Manufacturers are required to meet FAA specifications, under AC 150/5345-43, for certified red LED obstruction lights so they remain visible to pilots using night vision goggles. Some NVG filters can make standard red LED lights effectively invisible, which is the safety problem the requirement addresses.
Tower owners under older circulars are grandfathered in and are not required to retrofit compliant equipment on their own. But if a legacy, non-IR intermediate-level light is replaced with one that meets the IR specification, the top light on that structure must also be updated to the new specification, so pilots using night vision goggles cannot misread the tower’s true height. More detail is in our IR LED compliance guide.
A Simpler Way to Stay Current
Keeping up with which AC edition applies, and which equipment specification your tower needs, is exactly the kind of thing Tower Lighting as a Service (TLaaS®) is built to handle. We install IR-compliant LED lighting at no upfront cost to you, then manage compliance and monitoring going forward, so a new AC revision is our problem to track, not yours.
Revision History
Everything below reflects the rules in force at the time it was written and is kept for reference. It has been superseded by the current information above.
AC 70/7460-1M (November 2020 to August 2026, superseded)
The FAA released AC 70/7460-1M, effective November 16, 2020, which detailed new rules for obstruction marking and tower lighting. It cancelled AC 70/7460-1L Change 2. Most of the changes in 1M were minor and did not affect most tower owners, the bulk involved new obstruction lighting rules for temporary structures like cranes.
One change did directly affect tower owners: the addition of new infrared specifications for red LED-based obstruction lights, then a new requirement for new LED lighting system installations. Night vision goggles (NVGs) are increasingly used by pilots to amplify visible light, and many NVGs have filters, notably a Class B filter, designed to reduce the adverse effects of cockpit lighting. Those filters could make standard red LED obstruction lights effectively invisible, which presented a risk to pilot safety.
AC 1M required all new LED lighting system installations to meet the new IR specification. Tower owners under older circulars were grandfathered in and were not required to meet the new specification on existing equipment. However, because of the risk of a pilot misjudging a tower’s height, the rule specified that if a legacy, non-IR intermediate-level LED light was replaced with one meeting the new IR specification, the top-level light or lights also had to meet the new IR specification. This is the same rule that still applies today, described above under the current section and in our IR LED compliance guide.
Our OEM partner, Dialight, launched its first IR-enabled LED product in 2011, nearly a decade before the FAA requirement took effect in 2020.
Frequently Asked Questions About AC 70/7460-1N
What is AC 70/7460-1N and when did it take effect?
AC 70/7460-1N is the FAA’s current Advisory Circular for obstruction marking and lighting. It took effect August 11, 2026, and replaced AC 70/7460-1M.
What changed between AC 70/7460-1M and AC 70/7460-1N?
The FAA updated the notice threshold for meteorological towers, clarified that sponsors must comply with the conditions in their Determination of No Hazard to Air Navigation, clarified how to request a modification, expanded the definition of catenary to explicitly include powerlines and transmission lines, and updated NOTAM terminology from Notice to Air Missions to Notice to Airmen.
Do I need to upgrade my tower lighting because of AC 70/7460-1N?
Not on its own. Most of the AC 1N changes affect notice procedures and meteorological towers, not existing lighting equipment. The infrared LED requirement that affects lighting equipment was introduced earlier, in AC 1M, and simply carries forward.
What is the infrared (IR) LED requirement and does it still apply?
Yes, it still applies. Manufacturers must meet FAA specifications so red LED obstruction lights remain visible to pilots using night vision goggles. If a legacy, non-IR intermediate-level light is replaced with an IR-compliant one, the top light on that structure must also meet the IR specification. See our IR LED compliance guide for the full breakdown.
Does AC 70/7460-1N apply to meteorological towers?
Yes, more explicitly than before. AC 1N updated the notice requirements to cover meteorological towers with a highest point between 50 and 200 feet AGL, aligning with the FAA’s final rule on notice for meteorological towers and other wind energy systems.
Where can tower owners find the current AC?
The current version is always available from the FAA at AC 70/7460-1N. Because the FAA sometimes posts changes as separate files without updating a stable link, it is worth confirming you are looking at the current edition rather than bookmarking a single URL.
Why does this article keep the older AC 70/7460-1M content below?
We keep a dated record of each AC revision as it happens, rather than deleting old coverage, so this page functions as a running history of obstruction marking and lighting rule changes. The current section above always reflects the current AC. Anything below the revision history heading is dated and marked superseded.
Book a Call
Book a Call to learn how LumenServe keeps your tower lighting current with the latest FAA requirements, or reach our team directly at (512) 580-4600 or info@LumenServe.com. For the full set of owner obligations under the current AC, see our FAA tower lighting requirements guide.
