What is a Clearance Bar?
A clearance bar is a row of three yellow taxiway lights that marks a holding point or an intersecting taxiway.
Definition
Clearance bar is the FAA name. ICAO and EASA call the lights intermediate holding position lights. The two systems use the same pattern of three yellow lights across the taxiway, and they differ in detail. The sections below give both.
ICAO defines an intermediate holding position as a designated position for traffic control. Taxiing aircraft and vehicles stop there and hold until the aerodrome control tower clears them to proceed. It is not a runway holding position. The holding position page covers holding positions in general.
The taxiway light page lists every type of taxiway light and its colour. This page covers the clearance bar alone.
What a clearance bar tells the crew
The FAA gives a clearance bar two jobs (AC 150/5340-30J, 4.1.4):
- At a hold point. In low visibility, the bar warns pilots and drivers of a hold point that is not a runway holding position. The FAA installs these bars at designated hold points for operations below 600 ft (183 m) runway visual range.
- At an intersection. At night and in bad weather, the bar tells them that they are approaching an intersecting taxiway. The FAA generally installs these bars where the centerline lights do not follow the curve and no edge lights stand.
The AIM gives the same two jobs. A clearance bar makes a holding position easier to see in low visibility. It may also show where an intersecting taxiway is at night (AIM 2-1-10).
ICAO and EASA describe one job. The lights mark an intermediate holding position. Both recommend the lights where the crew does not need the stop-and-go signal of a stop bar (ICAO 5.3.21.2, CS ADR-DSN.M.735(a)(2)).
What the standards require
| Item | ICAO Annex 14, 5.3.21 | EASA CS ADR-DSN.M.735 | FAA AC 150/5340-30J, 4.1.4 and 4.7 |
|---|---|---|---|
| Name | Intermediate holding position lights | The same | Clearance bar |
| When provided | Required below 300 m runway visual range, unless a stop bar stands there. Recommended where a stop bar signal is not needed | Recommended below 350 m, with the same two conditions | At designated hold points below 600 ft (183 m) runway visual range. At intersections as listed below |
| Number | Three | Three | Three |
| Colour and mode | Fixed yellow, unidirectional, toward the approach | The same | Steady yellow, in-pavement. Normally unidirectional. Bidirectional if the hold point serves both directions |
| Spacing across the taxiway | 1.5 m, symmetrical about the centre line and at right angles to it | The same | Centre light in line with the centerline lights, the others at 5 ft (1.5 m) intervals. The outer lights may move 1 ft (305 mm) sideways |
| Distance from the marking | Along the marking, 0.3 m before it | The same | On a line 2 ft (0.6 m) from the holding side of the marking, with a tolerance of 2 in (50 mm) |
| Beam | Distribution similar to centre line lights, if provided | The same | Axis parallel to the taxiway path centerline, with a tolerance of 1 degree |
ICAO writes a Standard (“shall”) and gives 300 m. EASA writes “should” and gives 350 m. EASA leaves GM1 ADR-DSN.M.735 blank.
When the FAA installs a clearance bar at an intersection
AC 150/5340-30J, 4.7.1.2 says to install clearance bars, without regard to visibility, at a taxiway intersection with non-standard fillets. It says the same where the taxiway centerline lights do not follow the curves at the intersection. These bars are unidirectional.
The FAA allows three exceptions:
- It may omit the bar where taxiway edge lights stand at the intersection (4.7.1.3).
- At a T or plus-shaped intersection, it may replace the bar, or add to it, with an omnidirectional yellow taxiway intersection light. The angle between any two adjacent centre lines must be 90 degrees, plus or minus 10 degrees (4.7.1.4).
- It may omit the bar on an exit taxiway. This applies if the bar would stand before a runway holding position, or within 200 ft (61 m) beyond it (4.7.1.5).
Clearance bar, stop bar and runway guard lights
Three kinds of light near a holding position have different jobs. The colour and the mode show which is which.
| Light | Colour and mode | Where | Job |
|---|---|---|---|
| Clearance bar | Three steady yellow lights | A hold point or an intersecting taxiway | Marks the point |
| Stop bar | Row of steady red unidirectional lights, and an elevated red light on each side | Across the taxiway at a runway holding position | Shows the ATC clearance to enter or cross the runway in low visibility |
| Runway guard light | Flashing yellow | At a taxiway and runway intersection | Makes the taxiway and runway intersection easier to see |
Source: AIM 2-1-10. A clearance bar gives no stop-and-go signal. By the ICAO definition, a crew holds at an intermediate holding position until the tower clears it to proceed.
The AIM adds one warning. Some airports have a row of three or five in-pavement yellow lights at taxiway and runway intersections. These are not clearance bars (AIM 2-1-10).
When the lights are on
AC 150/5340-30J, 4.8.5.4.1 gives two rules:
- A clearance bar at a low visibility hold point may be switched off above 1,200 ft (365 m) runway visual range. The FAA recommends that local controls or circuit selector switches do this.
- Any other clearance bar stays on whenever the taxiway centerline lights are on. This includes a bar that does both jobs.
ICAO 5.3.21 and CS ADR-DSN.M.735 give no switching rule for these lights.
Maintenance
For taxiway lights, EASA sets numeric maintenance objectives only for centre line lights and for stop bars at a runway holding position. Both apply to use below 550 m runway visual range. ADR.OPS.C.015(b) gives no numeric objective for intermediate holding position lights.
The test for an unserviceable light still applies to each one. A light is unserviceable if its main beam average intensity is below 50 percent of the specified value. It is also unserviceable if its filter is missing or damaged, or if the beam has the wrong colour (ADR.OPS.C.015(c)).
What an inspection checks
An inspection of a clearance bar covers these items:
- Each of the three lights is lit and shows yellow.
- The three lights stand 1.5 m apart, in line across the taxiway.
- The bar stands at the holding position marking, at the distance that the applicable rule sets.
- The lights face the approaching traffic.
- Where a stop bar stands at the same holding position, the clearance bar is not needed there under ICAO and EASA.
A drone flight can record whether each light is lit, its colour and its position. TarmacView’s taxiway lights inspection does this for the taxiway network. It does not measure intensity in candela.
Frequently Asked Questions
- What is a clearance bar on a taxiway?
- A clearance bar is a row of three yellow taxiway lights that marks a holding point or an intersecting taxiway. The FAA uses the name. ICAO and EASA call the same pattern intermediate holding position lights. A clearance bar does not protect a runway. Stop bars and runway guard lights do that.
- What colour are clearance bar lights?
- Clearance bar lights are yellow and steady. ICAO and EASA specify three fixed unidirectional lights that show yellow toward the approaching traffic. The FAA AIM describes three in-pavement steady-burning yellow lights.
- How many lights are in a clearance bar, and how far apart are they?
- A clearance bar has three lights. ICAO and EASA space them 1.5 m apart, symmetrically about the taxiway centre line. The FAA puts the centre light in line with the taxiway centre line lights and the other two outboard at 5 ft (1.5 m) intervals.
- What is the difference between a clearance bar and a stop bar?
- A stop bar shows red and gives a stop signal at a runway holding position. A clearance bar shows yellow and marks a holding point that is not a runway holding position, or an intersecting taxiway. ICAO calls for intermediate holding position lights where a stop bar signal is not needed.
- When must a taxiway have clearance bars?
- ICAO requires intermediate holding position lights at a position for use in runway visual range below 300 m, unless a stop bar stands there. EASA recommends them below 350 m. The FAA installs clearance bars at designated hold points for operations below 600 ft (183 m) runway visual range.
- Where does a clearance bar stand?
- ICAO and EASA place the lights along the intermediate holding position marking, 0.3 m before it. The FAA puts the centre lights on a line parallel to the holding side of the marking and 2 ft (0.6 m) from it. At an intersection without a marking, the FAA locates the bar as if the marking were there.
- Can a clearance bar be switched off?
- In the FAA system, yes, in one case. A clearance bar at a low visibility hold point can be switched off above 1,200 ft (365 m) runway visual range. A clearance bar at an intersection stays on whenever the taxiway centerline lights are on.
References
- icao-annex-14-vol1
- Annex 14 to the Convention on International Civil Aviation, Aerodromes, Volume I, Aerodrome Design and Operations, Ninth Edition (July 2022, consolidated with later amendments) ICAO
- easa-ear-aerodromes
- Easy Access Rules for Aerodromes (Regulation (EU) No 139/2014), including CS-ADR-DSN Issue 7 EASA
- faa-ac-150-5340-30j
- AC 150/5340-30J, Design and Installation Details for Airport Visual Aids FAA
This is a reference entry. TarmacView provides drone inspection services and doesn't sell the equipment or materials described in this glossary.
