FAA Prepares Infrared Lighting Specifications
The FAA released a draft of Engineering Brief No. 98 in October titled Infrared Specifications for Aviation Obstruction Light Compatibility with Night Vision Imaging Systems (NVIS).
According to contacts at the FAA, both the AC 150/5345-43 and 70/7460-1 will be revised at some point in 2018 to incorporate the specifications detailed in the brief and to make them a required standard for newly filed installs. Flash Technology provides an option for infrared emitters with the Vanguard product line that meets the proposed specifications summarized below.
This brief provides information about the interaction of light-emitting diodes (LEDs) used in obstruction lighting fixtures with Night Vision Imaging Systems (NVIS) on board both rotary and fixed-wing aircraft. In addition, this engineering brief proposes performance specifications for infrared emitters to be added to LED L-810 and L-864 obstruction light fixtures to ensure compatibility with NVIS. These changes are necessary in order to address the concern that certain LED obstruction lighting systems fall outside the combined visible and near-infrared spectrum of NVGs (Night Vision Goggles).
Proposed Infrared Specifications for LED Obstruction Lights with IR
A nominal IR output wavelength of 800-900 nm is proposed.
Flash Technology uses infrared 850 nm emitters.
For both the L-810 (L) and L-864 (L) IR fixtures, it is recommended that the vertical radiometric requirements of the IR radiation are identical to the existing FAA requirements in AC 150/5345-43 for the photometric beam width and distribution of the visible light.
Flash Technology places the infrared emitters in the optical focal point of the light and therefore provides an identical beam pattern for both visible and infrared LEDs.
Minimum IR Radiant Intensity
For wavelengths from 800 to 900 nm, a minimum radiant intensity of 4mW/sr (0.004 W/sr) is recommended for both L-810 (L) and L-864 (L) IR fixtures.
Flash Technology meets the minimum requirements for radiant intensity for both the L-810 and L-864. It is expected that the minimum requirements for an L-864 will be raised from 4mW/sr to 246mW/sr in the revisions next year to match the relative change in intensity between an L-810 and L-864 (32.5 candela to 2,000 candela). This increase will also be met by the current Flash Technology L-864 design.
IR must mimic both pulse width/duration of visible light so pilot does not ‘see’ two different light sources.
Flash Technology infrared emitters flash at the same duty cycle as the visible LEDs, flashing in sync and are not steady on.
The complete Engineering Brief can be found here: https://www.faa.gov/airports/engineering/engineering_briefs/media/draft-eb-98.pdf
Flash Technology will share any updates on these changes as they become available.