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as a running record of FAA obstruction marking and lighting Advisory Circular revisions, current information first, superseded editions kept below and dated.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 infrared (IR) change was not part of 1N. The IR specification is in the FAA equipment standard, AC 150/5345-43J, which took effect for FAA-certified equipment on September 11, 2020. AC 70/7460-1M added a note about it, and 1N carries that note forward unchanged. According to the FAA, manufacturers are required to meet the specification 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.
AC 70/7460-1N says that when a legacy intermediate-level LED light is replaced with one that meets the specification, the top light(s) must also be updated, so the whole structure is visible to pilots using night vision goggles. Whether lights are replaced is determined by the FAA and your tower’s determination. 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 earlier change involved infrared (IR) specifications for red LED-based obstruction lights. AC 70/7460-1L (Change 2) first referenced them in 2018, and the FAA’s equipment standard, AC 150/5345-43J, set them out. 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 70/7460-1M, effective November 16, 2020, added a note on the new IR specification, which took effect for FAA-certified equipment on September 11, 2020. Because of the risk of a pilot misjudging a tower’s height, the note says that if a legacy intermediate-level LED light is replaced with one meeting the new IR specification, the top-level light(s) must also meet it. AC 1N carries this same note forward, as described above and in our IR LED compliance guide. Whether and when lights are replaced is determined by the FAA and your tower’s determination.
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?
That is determined by the FAA and your tower’s FAA determination, which typically follows changes to the structure. It is not something this article can decide. We can go through your determination with you.
What is the infrared (IR) LED requirement and does it still apply?
Yes, it is still in the FAA’s current documents. According to the FAA, manufacturers must meet its specification (AC 150/5345-43J) so red LED obstruction lights remain visible to pilots using night vision goggles. AC 70/7460-1N says that if a legacy intermediate-level light is replaced with one that meets the specification, the top light(s) must also be updated. 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. To download AC 70/7460-1N or any earlier edition, use our FAA regulations library.
