NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.
Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.
An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Maximum Luminous Intensity of LED-lighted X signs for Airport Runways
Published
Author(s)
Yoshihiro Ohno, Maritoni Litorja, Carl Miller
Abstract
This is a report for Inter-agency agreement 693KA9-18-N-00023 "Maximum Luminous Intensity for LED Signaling in an Airport Environment" by Federal Aviation Administration (FAA) and National Institute of Standards and Technology (NIST). The LED-based lighted X signs recently introduced at many airports are perceived too bright by pilots, causing glare and making it difficult to recognize the X character. The objective of the study is to determine the acceptable level of maximum luminous intensity of LED-lighted X signs that maintains clear visibility of the lighted X sign. A theoretical study with literature review was first made (Part 1). Then vision experiments were conducted using pilots as subjects (Part 2). The methods and results of these studies are reported.
Ohno, Y.
, Litorja, M.
and Miller, C.
(2024),
Maximum Luminous Intensity of LED-lighted X signs for Airport Runways, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/NIST.IR.8321, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=930682
(Accessed October 2, 2025)