Information Sign
A yellow sign with black text and symbols that provides non‑regulatory operational information to pilots and vehicle drivers on the airfield — for example radio frequencies, areas not visible from the tower, and noise abatement procedures. It is distinct from the black‑background/yellow‑text Location Sign (which identifies the taxiway or runway you are on) and the black‑background/white‑numeral Runway Distance Remaining Sign, both separate sign categories.
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What Is It?
An Information Sign is a yellow rectangular sign with black text and symbols that gives pilots and vehicle operators operational information the airport operator determines they need at a given location — most commonly applicable radio frequencies, notice of areas not visible from the control tower, and noise abatement procedures. Unlike mandatory instruction signs (red/white), information signs are advisory rather than regulatory. They are a distinct FAA/ICAO sign category from Location Signs (black background, yellow text, used to confirm which taxiway or runway you are currently on) and Runway Distance Remaining Signs (black background, white numerals) — both of which happen to share elements of the same surface-movement guidance role but carry different information under different colour codes.
Purpose & Function
The information sign exists for the specific, narrower set of operational notices that don't fit any of the airfield's other sign categories: applicable radio frequencies, the location of areas not visible from the control tower, noise abatement procedures, and similar advisories the airport operator determines pilots or drivers need at a given point. Its yellow-on-black colour scheme signals that the content is advisory rather than regulatory, the same way a red mandatory instruction sign signals a binding obligation — but that colour is shared with several other non-mandatory sign types (location, direction, destination signs), so the legend itself, not just the colour, is what tells a pilot which of those categories they're reading.
Where Is It Used?
Installed wherever the airport operator determines pilots or vehicle drivers need an operational notice that isn't covered by a mandatory, location, direction, or destination sign — typically near an area not visible from the tower, at a point where a specific radio frequency applies, or where noise abatement procedures need to be flagged. They are placed at a height of 1.5 to 2 metres above the pavement, on frangible supports. Because their use is discretionary rather than mandated at every such location, information signs are more variable in number and placement between airports than the other sign categories.
Installation & Location
Posts are founded at the specific point the notice applies to — the edge of an area not visible from the tower, a taxiway segment with a distinct radio frequency, or a location affected by noise abatement procedures — set back clear of wingtip clearance for that location's design aircraft, with orientation set out so the panel is read squarely by traffic approaching from the intended direction. Because siting is driven by where the airport operator has identified a need rather than by a fixed geometric rule tied to every intersection, setout is agreed with airfield operations on a case-by-case basis. Illuminated panels are cabled from the nearest taxiway or runway lighting distribution point; retroreflective panels need only the foundation and fixing.
How Does It Work?
The sign displays black text (and occasionally a symbol) on a yellow background, following ICAO Annex 14 and FAA AIM 2-3-12 conventions. Unlike direction or destination signs, an information sign does not carry a directional arrow — it states a fact or notice rather than pointing somewhere. The sign is either non‑illuminated (using retroreflective sheeting) or internally illuminated (LED or fluorescent) for nighttime visibility. The information is presented in a clear, standardized format that is legible from a distance. The sign is mounted on a frangible or breakaway support to minimize aircraft damage in case of collision.
System Architecture & Control Logic
Information signs sit on one of two very different control models depending on their illumination type. An internally illuminated sign (LED or fluorescent panel) is wired onto the constant current series circuit for that section of taxiway: an ALCMS selects the required brightness step from RVR or ATC input, the CCR regulates the entire loop to a fixed current, and the sign's panel — fed through its own isolating transformer — burns at the same intensity as every other fixture sharing that loop. A fault is detected the same way as for any other AGL fixture: a voltage rise at constant current flags an open circuit or failed transformer as a loop-level fault, not a fault isolated to the sign itself. A non-illuminated sign using retroreflective sheeting has no electrical control path whatsoever — its legibility depends entirely on the sheeting reflecting an aircraft's or vehicle's landing lights back toward the source, so there is no ALCMS command, no CCR current, and nothing for the control system to monitor or fault-detect on that sign.
Illuminated variant: ALCMS → CCR → Loop → Sign Panel. Retroreflective variant: no electrical path at all.
What Kind of Information It Carries
Physical Construction
The panel is an extruded aluminium frame carrying a Class 1/2 retroreflective face with the legend cut in black on yellow, or a translucent acrylic panel with the legend as a perforated film backlit by an internal LED module where the site calls for illumination. Because the message here is advisory rather than mandatory, the frame and legend colours follow the yellow/black information format rather than the red/white treatment reserved for instruction signs, letting a pilot distinguish the two families at a glance before reading the text itself. The frame is gasket-sealed to an IP65 rating and mounted on a frangible coupling and below-grade base plate so it shears away cleanly on impact.
Technical Parameters
| Parameter | Typical Value |
|---|---|
| Colour | Yellow background, black text (ICAO / FAA) |
| Dimensions | 1.2 m × 0.6 m (typical) or as per site requirements |
| Text Height | 150–200 mm (depending on viewing distance) |
| Illumination | Non‑illuminated (retroreflective) or internally illuminated (LED) |
| Retroreflective Class | Class 1 or Class 2 (ASTM D4956) |
| Mounting Height | 1.5–2 m above pavement |
| Frangible Support | Breakaway coupling or frangible post |
| Protection Class | IP65 (weatherproof) |
| Operating Temperature | -40°C to +60°C |
Electrical Requirements
| Requirement | Typical Value |
|---|---|
| Circuit Type | Series circuit, constant current (CCR fed) — illuminated variant only |
| Rated Series Current | 6.6A (3 to 5-step: 2.8A / 3.4A / 4.1A / 5.2A / 6.6A) |
| Isolation | Via dedicated isolating transformer, not directly connected to series loop |
| Transformer Secondary | Matched to sign wattage; sized to series circuit rating |
| Cable Type | L-824 single-conductor, direct-burial rated, 5kV or 600V per circuit design |
| Connector | L-823 primary connector, submersible-rated splice |
| Insulation Resistance | ≥ 50 MΩ (megger test, cable-to-ground) |
| Earthing/Grounding | Sign body and base can bonded to airfield earth grid |
| Fault Protection | CCR-level ground fault and open-circuit detection |
| Non-Illuminated Variant | No electrical supply required — passive retroreflective panel only |
Photometric Requirements
| Parameter | Typical Value |
|---|---|
| Background Luminance (Yellow) | ≥ 30 cd/m² average (illuminated variant), uniformity ratio ≤ 10:1 (max:min) |
| Legend Contrast (Black) | Opaque legend masking against the illuminated yellow background; contrast ratio ≥ 5:1 |
| Retroreflective Coefficient (Non-Illuminated Variant) | RA ≥ 20 cd/lux/m² (yellow) per ASTM D4956 Class 1/2 |
| Chromaticity (Yellow Background) | Within ICAO Annex 14 aeronautical yellow boundary (CIE coordinates) |
| Viewing Angle | ± 5° horizontal, legible from typical cockpit eye height |
| Luminance Tolerance | ± 25% of rated value across the panel face |
| Maintenance Factor | ≥ 50% of new-panel luminance before lamp/LED or sheeting replacement is due |
| Test Method | Luminance meter/photometer at normal and oblique angles, or retroreflectometer for the non-illuminated variant |
Applicable Standards
ICAO Annex 14
Information sign colours, dimensions, and placement
FAA AC 150/5340-18
Standards for Airport Sign Systems — siting, design, and colour convention for this sign type
FAA AC 150/5345-44
Equipment/fixture specification for the sign unit itself (siting, design and colour are governed by AC 150/5340-18 above)
ASTM D4956
Retroreflective sheeting performance standards
IEC 60598
Luminaire requirements for illuminated signs
Installation Requirements
Setting-Out & Siting Survey
CivilSurvey and mark the sign position from the design/siting drawing before excavation, confirming clearance from the taxiway/runway edge safety area and any frangibility height limit.
Foundation / Base Plate Installation
CivilExcavate and set the base plate or footing to design depth, keeping the finished mount level and within the frangible height limit for the sign's location.
Frangible Mount Fitting
MechanicalFit the frangible post or breakaway coupling and torque to the specified value, confirming it shears as designed under lateral load and does not bind.
Cable Route & Connector Termination
ElectricalWhere the sign is internally illuminated, lay the duct/cable route to the panel and terminate the L-823 connector per manufacturer procedure, keeping the splice fully submersible-rated before backfill.
Isolating Transformer Matching
ElectricalWhere the sign is internally illuminated, confirm the isolating transformer wattage and ratio match the panel and the series circuit's rated current step before connection.
Panel Legend & Content Setting
QualityBefore the panel is fixed and the position closed out, confirm the frequency, notice, or advisory text on the panel matches the airfield signage schedule for that location.
Retroreflective Sheeting Application
MechanicalApply and inspect the retroreflective sheeting for correct grade, alignment, and freedom from bubbles or edge lifting before the panel is mounted.
Pre-Backfill Sign-off
DocumentationRecord base/footing position, frangible coupling torque, cable route, and panel content as-built before backfill, since these are not inspectable once the site is closed.
Testing & Commissioning
Insulation Resistance (Megger) Test
Pre-EnergisationWhere the sign is internally illuminated, megger-test the isolating transformer and internal wiring before the circuit is energised, confirming insulation resistance clears the acceptable minimum ahead of backfill.
Loop Continuity & Resistance Test
Pre-EnergisationFor an illuminated installation, verify series loop continuity through the sign and record loop resistance, ruling out open circuits or high-resistance splices before first energisation.
Primary/Secondary Voltage Verification
EnergisationWith the CCR energised, confirm secondary voltage at the illuminated sign's L-823 connector matches the transformer's rated ratio at the commissioned current step.
CCR Brightness Step Response
EnergisationCycle the CCR through every intensity step and confirm an illuminated panel responds correctly at each, ruling out a marginal transformer or a loose connection.
Retroreflectivity / Luminance Verification
Final AcceptanceMeasure sheeting retroreflectivity with a retroreflectometer against ICAO/FAA commissioning minimums; where the panel is internally illuminated, also verify luminance and colour uniformity with a luminance meter.
Legend & Content Verification
Final AcceptanceConfirm the frequency, notice, or advisory text on the panel matches the airfield signage schedule for that location.
Frangible Coupling & Mounting Verification
Pre-EnergisationConfirm the frangible coupling, base depth, and panel height meet as-built tolerances before the site is finally backfilled.
Documentation & As-Built Sign-off
Final AcceptanceRecord retroreflectivity/luminance readings, and (where illuminated) insulation, continuity, and voltage readings, alongside as-built position in the commissioning dossier for handover.
Inspection & Maintenance
Retroreflectivity Check
AnnualMeasure sheeting retroreflectivity with a retroreflectometer against ICAO / FAA minimums, and budget for sheeting replacement roughly every 5–7 years.
Illumination System Test
AnnualTest internal LED or fluorescent illumination for uniform, even lighting so the sign remains legible at night, especially ahead of low-visibility seasons.
Frangible Coupling Inspection
AnnualCheck the coupling or post for brittleness or corrosion and replace per manufacturer schedule to preserve breakaway performance on impact.
Seal & Cable Gland Check
AnnualInspect housing seals and cable glands for degradation, since moisture ingress through damaged seals is a leading cause of corrosion and electrical faults.
Sign Face Cleaning
QuarterlyClean dirt, de-icing fluid residue, and rubber deposits off the sign face to keep both reflectivity and legibility within spec.
Insulation Resistance Test
AnnualMegger-test internal wiring and any isolating transformer to confirm insulation resistance stays above minimum, catching moisture ingress early.
Common Field Issues
Retroreflective Sheeting Degradation
UV exposure, weathering, and abrasion can reduce reflectivity. Regular inspection and replacement (typically every 5–7 years) is recommended.
Internal Illumination Failure
LED or fluorescent lighting can fail, reducing nighttime legibility. Regular testing of the illumination system is essential.
Frangible Support Fatigue
Breakaway couplings can become brittle over time. Regular inspection and replacement as per manufacturer guidelines are required.
Moisture Ingress
Water ingress through seals can cause corrosion and electrical faults. Routine seal checks and use of desiccants are recommended.
Troubleshooting Guide
Legend Unreadable at Night, Fine by Day
Illuminated Sign Dark or Flickering
Moisture or Condensation Inside Housing
Sign Leaning, Loose, or Misaligned
Failure Modes & Root Causes
LED Panel / Internal Light Source Failure
Retroreflective Sheeting Degradation
Frangible Coupling Fatigue / Impact Damage
Power/Circuit Connector Degradation
Legend Mismatch After an Operational Change
Safety & Operational Notes
Circuit Isolation Before Access
Electrical SafetyDe-energise and lock out the feeder circuit at the CCR or panel, then verify zero energy at the base can before opening the housing or handling cable connectors.
Airside Work Coordination
OperationalAny work on or near the movement area requires ATC/airside coordination and a NOTAM where the sign will be dark, obscured, or out of tolerance, with vehicle and personnel movement kept clear of the taxiway or runway strip per the aerodrome's safety management procedures.
Frangibility Not to Be Defeated
MechanicalNever substitute the frangible coupling with a rigid fitting or over-torque it during installation or repair; the coupling must still shear cleanly on aircraft impact to limit damage under the frangibility requirement.
FOD Control at the Base
OperationalKeep tools, fasteners, and removed gaskets accounted for at all times when the base can or housing is open, and secure or remove any loose material before reinstating the sign, to prevent foreign object debris on the movement area.
Insulation Test Before Re-Energisation
Electrical SafetyAfter any cable, connector, or panel work, megger test the affected circuit before restoring power, since a residual fault at re-energisation can trip the feeder circuit or damage healthy units on the same loop.
PPE & Grounding
Personnel SafetyUse insulated tools and appropriate PPE when working on circuit connections, and confirm the sign housing and base can are bonded/grounded per the electrical design before reconnecting the circuit.
Legend Accuracy Verification
OperationalAfter any change to the operational notice it displays (frequency, noise abatement procedure, or similar), cross-check the sign's legend against the current airfield operational records before signing off the work as complete.
Engineering & Expert Notes
Confirm What Category of Information Before Setting Repair Priority
OperationalAn information sign's content — a frequency, a tower blind-spot warning, a noise abatement notice — varies by site; triage repair urgency by what the sign is actually displaying at that location, not by a blanket "information sign" label.
Schedule an Explicit Content Audit Rather Than Relying on Incidental Reports
MaintenanceBecause these signs serve varied, non-regulatory purposes, content drift is easy to miss — it's less likely to be caught the way a gate or stand-number mismatch gets reported. Put a periodic content audit on the schedule directly.
Follow the Same Fault-Diagnosis Chain Regardless of Message Type
TroubleshootingVoltage at the connector, then driver, then LED module — that diagnostic order applies regardless of what notice the sign displays. Don't skip steps just because the sign feels lower-stakes.
Environmental Exposure Doesn't Care About Regulatory Status
DurabilityUV and de-icing fluid degrade an information sign's face on the same physical timeline as a mandatory instruction sign. Track face condition on the same inspection schedule even if repair priority differs.
Confirm the Sign's Purpose Before Reprinting Its Legend
OperationalBefore altering text on an information sign, confirm with airfield operations exactly which notice it is displaying and why — a frequency, a tower blind-spot warning, or a noise abatement procedure each has a different update trigger and approving authority.
Frangibility and Setback Rules Don't Relax for “Just Information”
MechanicalApply the same frangible-coupling and clearance requirements as any other airfield sign — a non-regulatory message doesn't reduce the mechanical hazard the sign poses if struck.
Frequently Asked Questions
Short answers about the information sign: purpose, siting, power, standards, maintenance and common faults.
Q1What is an airfield information sign?
An information sign is a yellow rectangular sign with black text and symbols that gives pilots and vehicle operators operational information the airport operator determines they need at a location, most commonly applicable radio frequencies, areas not visible from the control tower, and noise abatement procedures.
Q2Is an information sign mandatory or advisory?
Advisory. Unlike red-and-white mandatory instruction signs, information signs are not regulatory, and their use is discretionary rather than mandated at every such location.
Q3How is an information sign different from a location sign or a distance remaining sign?
An information sign (black on yellow, no arrow) states a fact or notice. A location sign (yellow text on a black background) confirms which taxiway or runway you are on, and a distance remaining sign (white numeral on black) shows runway length left. They are separate FAA/ICAO sign categories.
Q4Where are information signs installed?
Wherever the airport operator decides an operational notice is needed that a mandatory, location, direction or destination sign does not cover, typically near an area not visible from the tower, where a specific radio frequency applies, or where noise abatement procedures need flagging. They stand 1.5 to 2 metres above the pavement on frangible supports.
Q5How is an illuminated information sign powered?
An illuminated information sign is wired onto the constant current series circuit for its section of the airfield and fed through its own isolating transformer rather than directly from the loop. The Constant Current Regulator (CCR) holds the loop at a fixed current (up to 6.6 A, with steps of 2.8, 3.4, 4.1, 5.2 and 6.6 A) and the ALCMS selects the brightness step, so the sign burns at the same intensity as the other fixtures on that loop. The non-illuminated variant is a passive retroreflective panel with no electrical supply.
Q6Which standards apply to information signs?
ICAO Annex 14 covers colours, dimensions and placement, with FAA AIM 2-3-12 conventions, and FAA AC 150/5340-18 covers siting, design and colour convention. FAA AC 150/5345-44 is the equipment specification for the sign unit, ASTM D4956 sets retroreflective sheeting performance, and IEC 60598 covers luminaires for illuminated signs.
Q7What are the photometric requirements for an information sign?
On the illuminated variant the yellow background should average at least 30 cd/m² (uniformity no worse than 10:1) with an opaque black legend giving a contrast ratio of at least 5:1. The non-illuminated variant needs a retroreflective coefficient of at least 20 cd/lux/m² for yellow per ASTM D4956 Class 1 or 2.
Q8Why is an information sign mounted on a frangible support?
The panel sits on a frangible post or breakaway coupling so that it breaks away if an aircraft strikes it, limiting damage to the aircraft. The coupling can turn brittle from weather and vibration, so it is inspected annually and replaced to the manufacturer's schedule to preserve its breakaway performance.
Q9How often should information signs be inspected and maintained?
Typical intervals are quarterly for cleaning dirt, de-icing fluid residue and rubber deposits off the sign face, and annual for retroreflectivity measurement, illumination testing, frangible coupling inspection, seal and cable gland checks, and insulation resistance (megger) testing. Retroreflective sheeting is usually budgeted for replacement every 5 to 7 years.
Q10What are the common field issues with information signs?
Four issues recur: retroreflective sheeting degradation from UV, weathering and abrasion (replacement is typically due every 5 to 7 years); failure of the internal LED illumination, which cuts night visibility; frangible support fatigue, as breakaway couplings turn brittle with weather and vibration; and moisture ingress through damaged seals or cable glands, which causes corrosion and electrical faults. Routine seal checks and desiccants are recommended. A legend that no longer matches after an operational change is also a listed failure mode.
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