Product Description

Low Flying Aircraft Ahead – W351 Road Sign

The W351 Low Flying Aircraft Ahead road sign is a South African warning sign used to alert drivers and other road users to the likelihood of low-flying aircraft in the vicinity of the roadway.

The official South African road traffic sign designation is W351 LOW FLYING AIRCRAFT AHEAD. The sign is particularly relevant in areas where aircraft may fly low enough for their presence or sudden noise to affect road users.

The SARTSM specifically notes that W351 may be displayed in the environs of airports to warn drivers about the possibility of sudden aircraft noise, which could result in a startled reaction from a driver.

What Does the W351 Road Sign Mean?

W351 means Low Flying Aircraft Ahead. It warns road users that low-flying aircraft are likely to be present in the vicinity of the roadway.

The sign does not mean that aircraft will cross the road or that vehicles are expected to stop for aircraft. Its purpose is to prepare road users for the possibility of aircraft flying at a low altitude nearby and, importantly, for the possibility of sudden aircraft noise.

W351 is a warning sign and does not itself impose a specific speed limit or create a stop requirement.

Why Is the W351 Low Flying Aircraft Sign Important?

Drivers normally concentrate on the roadway and surrounding traffic. A loud or unexpected aircraft passing overhead can attract attention suddenly and may cause a startled reaction.

W351 provides advance information that low-flying aircraft may be present so that drivers are aware of the unusual environment before reaching the affected area.

This is especially relevant near airports and other locations where aircraft operate at relatively low altitude in the vicinity of roads.

When Is W351 Used?

The SARTSM states that W351 is used to warn road users about the likelihood of low-flying aircraft in the vicinity of the roadway.

The sign may be displayed in the environs of airports to warn drivers about the possibility of sudden aircraft noise that could result in a startled reaction.

The decision to use the sign should therefore be based on the actual relationship between aircraft operations and the roadway.

Where Is W351 Used?

W351 is mainly associated with roadways located close to areas where low-flying aircraft operate.

Potential applications may include:

• Roads near airports
• Airport access roads
• Roads close to airfields
• Roads within areas affected by low aircraft approaches or departures
• Roads near aviation facilities where low-flying aircraft are regularly present
• Other road sections where local aviation activity creates the relevant warning condition

The SARTSM specifically identifies airport environments as an application for W351.

W351 and Airports

Airports can have approach and departure paths that pass close to roadways.

Aircraft may therefore be visible or audible to drivers at relatively low altitude, depending on the airport layout, runway orientation and aircraft operations.

W351 can provide advance warning of this unusual road environment.

W351 and Sudden Aircraft Noise

One of the specific reasons identified by the SARTSM for W351 is the possibility of sudden aircraft noise.

An unexpected loud aircraft sound can attract a driver's attention away from the road or result in a startled response.

The warning sign prepares road users for this possibility before they reach the relevant area.

W351 Is Not a Collision Warning Sign

It is important not to describe W351 as a sign specifically intended to warn motorists about a direct collision between road vehicles and aircraft.

The official purpose is to warn of the likelihood of low-flying aircraft in the vicinity of the roadway, with particular attention to the possibility of sudden aircraft noise startling drivers.

This distinction makes the description more accurate for South African road-sign applications.

How Should Drivers Respond to W351?

Drivers approaching a W351 sign should remain attentive to the road and be prepared for the possibility of low-flying aircraft and sudden aircraft noise.

Drivers should:

• Remain focused on the roadway.
• Expect possible aircraft activity overhead.
• Be prepared for sudden aircraft noise.
• Avoid sudden steering movements caused by surprise.
• Maintain proper control of the vehicle.
• Continue observing other road users and road signs.
• Adjust speed where the surrounding road conditions require it.

The warning is intended to improve awareness of the unusual environment rather than instruct drivers to watch the sky instead of the road.

Does W351 Set a Speed Limit?

No. W351 is a warning sign and does not itself establish a legal speed limit.

Drivers should continue to obey the applicable speed limit and adjust their driving to the prevailing traffic, visibility and roadway conditions.

Does W351 Require Drivers to Stop?

No. W351 does not itself require a driver to stop or yield to aircraft.

It provides a warning about the possibility of low-flying aircraft and associated sudden noise in the vicinity of the roadway.

Any separate traffic-control requirement, such as a STOP or YIELD instruction, would need to be provided by the appropriate regulatory or warning sign.

W351 and Driver Awareness

The main benefit of W351 is advance awareness.

A driver who knows that low-flying aircraft may be present is less likely to be surprised by aircraft appearing overhead or by sudden aircraft noise.

The sign is therefore concerned with the interaction between the aviation environment and normal road-user attention.

W351 and Aircraft Approaches

Roads near airport approach paths may be close to aircraft operating at relatively low altitude.

The actual height and frequency of aircraft will depend on the aviation operation and site layout.

Where local conditions create a relevant warning requirement, W351 can communicate the possibility to road users.

W351 and Aircraft Departures

Aircraft departing from airports can also be visible or audible from nearby roads.

Where aircraft noise or low aircraft presence can create the type of driver-awareness issue addressed by W351, the sign may be considered in accordance with the applicable requirements.

W351 and Airfields

Roads near airfields or other aviation facilities may also experience aircraft activity close to the roadway.

Whether W351 is appropriate depends on the nature of the aircraft operations and their relationship to the road.

W351 and Aviation Facilities

Aircraft operations can vary considerably from one location to another.

Factors such as runway orientation, aircraft type, flight paths, operating schedules and distance from the roadway can affect whether low-flying aircraft are likely to be noticeable to drivers.

Sign selection should therefore be based on the actual site conditions.

W351 Sign Placement

W351 should be displayed in advance of the area where low-flying aircraft are likely to be present.

The SARTSM states that the appropriate warning-sign location should be determined using Figure 3.1 and the applicable advance-warning requirements.

The final position should also provide adequate visibility to approaching traffic.

W351 and Warning Distance

The appropriate distance between W351 and the relevant area depends on the operating conditions of the road.

South African warning-sign guidance generally determines advance placement according to factors such as operating speed, visibility and road layout.

Where the sign is positioned further from the hazard because of site conditions, the applicable supplementary distance information should be considered where required.

W351 and Sign Visibility

The W351 sign should be clearly visible to approaching road users before they enter the affected area.

Potential visibility problems include:

• Road curves
• Hills and crests
• Vegetation
• Buildings
• Other roadside signs
• Advertising structures
• Roadside equipment
• Poor sign placement

The sign should remain unobstructed, clean and legible.

W351 at Night

Aircraft activity and aircraft noise may be more noticeable at night, depending on the location and operating conditions.

Permanent W351 signs use retroreflective materials so that the warning sign can remain visible when illuminated by vehicle headlights.

Drivers should continue to concentrate primarily on the roadway while being aware that aircraft may be operating nearby.

Permanent W351 Sign Design and Colours

The permanent W351 warning sign follows the standard South African warning-sign colour arrangement:

• Triangle: Red retroreflective
• Symbol: Black semi-matt
• Background: White retroreflective

The sign uses an aircraft symbol to represent the low-flying aircraft hazard.

Is W351 a Yellow Road Sign?

The permanent W351 sign should not be described as a yellow warning sign.

For a permanent warning sign, the SARTSM specifies a red retroreflective triangular border, black semi-matt symbol and white retroreflective background.

Yellow backgrounds are associated with temporary warning signs rather than the permanent W351 sign.

Retroreflective W351 Sign

Retroreflective material helps the permanent W351 sign remain visible when illuminated by vehicle headlights.

The official specification allows permanent warning signs to use retroreflective red and white areas, while black areas remain semi-matt.

For public-road applications, the sign should be manufactured according to the applicable South African road traffic sign specifications.

W351 Sign Size

The appropriate size of W351 depends on the road environment and the applicable warning-sign requirements.

Factors that may influence the selected size include:

• Operating speed
• Road classification
• Viewing distance
• Traffic volume
• Roadside environment
• Available installation space

The SARTSM provides standard triangular warning-sign sizes, including 900 mm, 1200 mm and 1500 mm nominal side lengths, with the appropriate selection depending on the circumstances.

W351 and Large Road Signs

A larger warning sign may be appropriate where greater visual impact or emphasis is required.

The SARTSM notes that traffic volume, speed, road conditions, background lighting and other factors can influence the choice of warning-sign size.

W351 and Road Traffic Signs Near Airports

Roads around airports can contain several different traffic conditions, including airport traffic, pedestrians, service vehicles and aviation activity.

W351 addresses the specific issue of low-flying aircraft and sudden aircraft noise. Other traffic signs should be selected separately for other hazards.

W351 and Driver Distraction

The SARTSM's reference to sudden aircraft noise is important because an unexpected sound can produce a startled response.

W351 gives drivers advance knowledge that aircraft noise may occur, helping them understand why they may suddenly hear or see an aircraft nearby.

W351 and Heavy Vehicles

Drivers of trucks, buses and other large vehicles should remain attentive to the roadway when travelling through areas covered by W351.

A sudden aircraft sound should not cause unnecessary steering or braking movements.

W351 and Motorcycles

Motorcyclists should also remain focused on the roadway when travelling in areas where W351 is displayed.

Sudden noise or an aircraft passing overhead may be unexpected, so riders should maintain proper control and avoid abrupt reactions.

W351 and Cyclists

Cyclists travelling near airports and aviation facilities may also encounter low-flying aircraft activity.

W351 provides general advance awareness of the environment, although the sign is primarily a roadway warning for drivers and other road users.

W351 and Pedestrians

Pedestrians near roads close to airports may also notice low-flying aircraft and aircraft noise.

The warning sign is part of the road traffic-sign environment and does not replace any separate pedestrian or airport safety controls that may be required.

W351 on Airport Access Roads

Airport access roads can place road users close to aircraft operating areas.

Where low-flying aircraft are likely to be present in the vicinity of the roadway, W351 may provide useful advance warning of the aviation environment.

W351 on Public Roads in South Africa

On public roads, W351 should be selected, positioned and installed according to the applicable South African road traffic sign requirements and the requirements of the responsible road authority.

The warning should reflect an actual local condition involving low-flying aircraft in the vicinity of the roadway.

W351 on Private Roads and Properties

Similar low-flying-aircraft warning signage may also be useful on private roads and controlled properties located close to airports or aviation facilities.

Potential applications include:

• Airport-related properties
• Private access roads near airfields
• Industrial properties near airports
• Logistics facilities near aviation facilities
• Private estates within areas affected by low-flying aircraft
• Roads serving aviation-related developments

On private property, the sign can form part of an internal traffic-management arrangement based on local conditions.

W351 and Airport Development Areas

New developments located near airports may experience aircraft operations close to internal roads and access routes.

Where low-flying aircraft are likely to be noticeable to road users, suitable warning signage may be considered as part of the overall traffic-management design.

W351 and Industrial Areas Near Airports

Warehouses, factories, logistics facilities and other industrial properties can be located close to airports.

Where aircraft routinely operate nearby and the conditions create the type of hazard addressed by W351, appropriate warning signage can be included in the site's traffic-management planning.

W351 and Aviation Noise

The warning is particularly relevant to sudden aircraft noise rather than simply the existence of aircraft somewhere in the sky.

The SARTSM specifically identifies startling aircraft noise as a reason for providing W351 in airport environments.

W351 and Flight Paths

Aircraft flight paths differ from one airport and aviation facility to another.

A road may be affected by low-flying aircraft depending on its position relative to runways, approaches, departures and other aircraft operations.

The need for W351 should therefore be assessed using the actual local aviation and road environment.

Temporary Low Flying Aircraft Sign – TW351

The temporary version of W351 is designated TW351.

However, the SARTSM states that a temporary version of W351 is unlikely to be used. If required, it should be numbered and referred to as TW351.

This means that permanent W351 is the principal sign in the standard South African warning-sign system for this hazard, while temporary use is uncommon.

TW351 for Temporary Applications

Where an unusual temporary aviation-related condition creates a need for this warning, the temporary form may be considered if the applicable requirements support its use.

Because the SARTSM describes TW351 as unlikely to be used, the sign should only be selected where the site conditions genuinely justify the temporary warning.

Temporary Warning Sign Colours

Where a temporary warning version is used, South African temporary warning signs generally use:

• Triangle: Red retroreflective
• Symbol: Black semi-matt
• Background: Yellow retroreflective

This is the standard temporary warning-sign colour arrangement described by the SARTSM.

W351 Maintenance

W351 signs should be inspected and maintained so that they remain visible and legible to approaching road users.

Maintenance checks can include:

• Cleaning the sign face
• Checking for fading
• Checking for physical damage
• Checking mounting hardware
• Removing vegetation or obstructions
• Checking the condition of retroreflective materials

Airport and aviation-related environments can also involve dust, vehicle activity and other conditions that may affect roadside signs, making regular inspection useful.

W351 and Supplementary Plates

A supplementary plate can be used with a warning sign where additional information is required, such as an advisory speed, distance or text message.

Any supplementary information used with W351 should be relevant to the actual conditions and comply with the applicable South African road traffic sign requirements.

W351 and Other Warning Signs

W351 should not be used to communicate hazards that have dedicated warning signs.

For example, if the same roadway also has a sharp curve, pedestrian crossing or roadworks hazard, the applicable warning sign for that condition should be considered separately.

The overall sign arrangement should communicate each relevant hazard clearly without unnecessary duplication.

W351 and Road Layout

The presence of an airport does not automatically mean that every nearby road requires W351.

The sign is intended for locations where low-flying aircraft are likely to be present in the vicinity of the roadway and where the conditions justify the warning.

W351 and Weather Conditions

Weather can affect visibility of aircraft, but W351 is not a general poor-weather warning sign.

Other warning signs should be considered separately where fog, rain, reduced visibility or other weather-related hazards create a road condition requiring advance warning.

Who May Need W351 Low Flying Aircraft Signs?

W351 signage may be relevant to:

• Road authorities
• Municipalities
• Airport operators
• Airport-area property developers
• Traffic-management contractors
• Road construction contractors
• Industrial property managers
• Logistics facilities near airports
• Private estate managers
• Operators of private roads near aviation facilities

Benefits of W351 Low Flying Aircraft Warning Signs

• Warns road users about the likelihood of low-flying aircraft nearby.
• Provides advance awareness of an unusual aviation environment.
• Alerts drivers to the possibility of sudden aircraft noise.
• Can help drivers understand unexpected aircraft activity before reaching the area.
• Uses a recognisable aircraft warning symbol.
• Permanent W351 uses retroreflective warning-sign materials.
• TW351 provides a temporary option where genuinely required, although its use is uncommon.
• Can form part of a broader traffic-management arrangement near airports and aviation facilities.

Frequently Asked Questions About W351 Road Signs

What does W351 mean?

W351 means Low Flying Aircraft Ahead. It warns about the likelihood of low-flying aircraft in the vicinity of the roadway.

What is the official name of W351?

The official South African designation is LOW FLYING AIRCRAFT AHEAD.

What is W351 used for?

It is used to warn road users about the likelihood of low-flying aircraft near the roadway.

Why is W351 used near airports?

The SARTSM states that W351 may be used in airport environments to warn drivers about possible sudden aircraft noise that could startle them.

Does W351 mean aircraft will cross the road?

No. It warns about low-flying aircraft in the vicinity of the roadway. It does not by itself indicate that aircraft will cross the road.

Does W351 warn about aircraft collisions?

Its official purpose is to warn of low-flying aircraft and possible sudden aircraft noise, rather than specifically warning of a vehicle-aircraft collision.

Does W351 require drivers to stop?

No. W351 is a warning sign and does not itself require drivers to stop.

Does W351 impose a speed limit?

No. W351 does not itself establish a legal speed limit.

What should drivers do when they see W351?

Drivers should remain alert, expect possible low-flying aircraft or sudden aircraft noise and maintain proper control of the vehicle.

Is W351 a warning sign?

Yes. W351 is part of the South African W-series warning signs.

What colours does permanent W351 use?

Permanent W351 uses a red retroreflective triangle, black semi-matt aircraft symbol and white retroreflective background.

Is the permanent W351 sign yellow?

No. The permanent W351 sign has a white background. Yellow backgrounds are associated with temporary warning signs.

What is TW351?

TW351 is the temporary version of the Low Flying Aircraft warning sign.

Is TW351 commonly used?

No. The SARTSM states that a temporary version of W351 is unlikely to be used.

Can W351 be used near an airport?

Yes. Airport environments are specifically identified by the SARTSM as an application for W351.

Can W351 be used near an airfield?

It may be considered where low-flying aircraft are likely to be present in the vicinity of the roadway and the applicable requirements are met.

Can W351 be used on airport access roads?

Yes, where the road environment is affected by low-flying aircraft and the warning is appropriate.

Can W351 be used on a private road?

Similar low-flying-aircraft warning signage may be used on private roads and controlled properties near aviation facilities as part of an appropriate traffic-management arrangement.

Can W351 be used at industrial properties?

Yes, where an industrial property is located in an area affected by low-flying aircraft and the site conditions justify the warning.

Can W351 be used near a logistics facility?

Yes, where the facility is located near an airport or aviation operation and low-flying aircraft are relevant to the surrounding roadway.

Can W351 be used permanently?

Yes. W351 is primarily a permanent warning sign, subject to the applicable assessment and requirements.

Can W351 be used temporarily?

A temporary version, TW351, exists, but the SARTSM states that it is unlikely to be used.

What causes the need for W351?

The sign is used where low-flying aircraft are likely to be present in the vicinity of the roadway, particularly where sudden aircraft noise may startle drivers.

Does W351 mean an airport is immediately ahead?

No. The sign warns about low-flying aircraft in the vicinity of the roadway; it does not necessarily mean an airport entrance or runway is immediately ahead.

Can W351 be used with other road signs?

Yes. Other signs may be used separately where the roadway has additional hazards or traffic-control requirements.

Where should W351 be placed?

It should be positioned in advance of the affected area according to the applicable SARTSM warning-sign placement requirements and site conditions.

What size should a W351 sign be?

The appropriate size depends on operating speed, road environment and other applicable factors. Standard triangular warning-sign sizes are provided in the SARTSM.

Is W351 retroreflective?

Yes. The permanent W351 specification uses red and white retroreflective areas, with a black semi-matt symbol.

Can aircraft noise affect drivers?

The SARTSM specifically notes that sudden aircraft noise could result in a startled reaction from a driver, which is one reason W351 may be used near airports.

Can W351 be used at night?

Yes. Permanent warning signs use retroreflective materials to support visibility when illuminated by vehicle headlights.

Can Signs4SA supply W351 signs?

Yes. Signs4SA can assist with W351 Low Flying Aircraft Ahead signs and, where applicable, temporary TW351 warning signage.

Order W351 Low Flying Aircraft Warning Signs

Need W351 Low Flying Aircraft Ahead signs for an airport access route, road near an airfield, industrial property, logistics facility, private road or traffic-management application?

Signs4SA can assist with the supply of warning signs for different public-road and private-property applications, subject to the applicable South African road traffic sign requirements.

Contact Signs4SA with the W351 or TW351 code, required quantity, sign size, material and installation requirements to request a quotation.

One important feature of Low flying aircraft ahead signs is their high visibility. These signs are designed to be easily seen by drivers, even from a distance and in adverse weather conditions. Many Low flying aircraft ahead signs are also designed with reflective materials that make them visible at night.

Another important feature of Low flying aircraft ahead signs is their durability. Road signs are exposed to a wide range of environmental factors, including wind, rain, and extreme temperatures. As such, they need to be made from materials that can withstand these conditions and remain in good condition for years to come.

More About Low flying aircraft ahead

Low Flying Aircraft Ahead – W351 Road Sign

The W351 Low Flying Aircraft Ahead road sign is a South African warning sign used to alert drivers and other road users to the likelihood of low-flying aircraft in the vicinity of the roadway.

The official South African road traffic sign designation is W351 LOW FLYING AIRCRAFT AHEAD. The sign is particularly relevant in areas where aircraft may fly low enough for their presence or sudden noise to affect road users.

The SARTSM specifically notes that W351 may be displayed in the environs of airports to warn drivers about the possibility of sudden aircraft noise, which could result in a startled reaction from a driver.

What Does the W351 Road Sign Mean?

W351 means Low Flying Aircraft Ahead. It warns road users that low-flying aircraft are likely to be present in the vicinity of the roadway.

The sign does not mean that aircraft will cross the road or that vehicles are expected to stop for aircraft. Its purpose is to prepare road users for the possibility of aircraft flying at a low altitude nearby and, importantly, for the possibility of sudden aircraft noise.

W351 is a warning sign and does not itself impose a specific speed limit or create a stop requirement.

Why Is the W351 Low Flying Aircraft Sign Important?

Drivers normally concentrate on the roadway and surrounding traffic. A loud or unexpected aircraft passing overhead can attract attention suddenly and may cause a startled reaction.

W351 provides advance information that low-flying aircraft may be present so that drivers are aware of the unusual environment before reaching the affected area.

This is especially relevant near airports and other locations where aircraft operate at relatively low altitude in the vicinity of roads.

When Is W351 Used?

The SARTSM states that W351 is used to warn road users about the likelihood of low-flying aircraft in the vicinity of the roadway.

The sign may be displayed in the environs of airports to warn drivers about the possibility of sudden aircraft noise that could result in a startled reaction.

The decision to use the sign should therefore be based on the actual relationship between aircraft operations and the roadway.

Where Is W351 Used?

W351 is mainly associated with roadways located close to areas where low-flying aircraft operate.

Potential applications may include:

• Roads near airports
• Airport access roads
• Roads close to airfields
• Roads within areas affected by low aircraft approaches or departures
• Roads near aviation facilities where low-flying aircraft are regularly present
• Other road sections where local aviation activity creates the relevant warning condition

The SARTSM specifically identifies airport environments as an application for W351.

W351 and Airports

Airports can have approach and departure paths that pass close to roadways.

Aircraft may therefore be visible or audible to drivers at relatively low altitude, depending on the airport layout, runway orientation and aircraft operations.

W351 can provide advance warning of this unusual road environment.

W351 and Sudden Aircraft Noise

One of the specific reasons identified by the SARTSM for W351 is the possibility of sudden aircraft noise.

An unexpected loud aircraft sound can attract a driver's attention away from the road or result in a startled response.

The warning sign prepares road users for this possibility before they reach the relevant area.

W351 Is Not a Collision Warning Sign

It is important not to describe W351 as a sign specifically intended to warn motorists about a direct collision between road vehicles and aircraft.

The official purpose is to warn of the likelihood of low-flying aircraft in the vicinity of the roadway, with particular attention to the possibility of sudden aircraft noise startling drivers.

This distinction makes the description more accurate for South African road-sign applications.

How Should Drivers Respond to W351?

Drivers approaching a W351 sign should remain attentive to the road and be prepared for the possibility of low-flying aircraft and sudden aircraft noise.

Drivers should:

• Remain focused on the roadway.
• Expect possible aircraft activity overhead.
• Be prepared for sudden aircraft noise.
• Avoid sudden steering movements caused by surprise.
• Maintain proper control of the vehicle.
• Continue observing other road users and road signs.
• Adjust speed where the surrounding road conditions require it.

The warning is intended to improve awareness of the unusual environment rather than instruct drivers to watch the sky instead of the road.

Does W351 Set a Speed Limit?

No. W351 is a warning sign and does not itself establish a legal speed limit.

Drivers should continue to obey the applicable speed limit and adjust their driving to the prevailing traffic, visibility and roadway conditions.

Does W351 Require Drivers to Stop?

No. W351 does not itself require a driver to stop or yield to aircraft.

It provides a warning about the possibility of low-flying aircraft and associated sudden noise in the vicinity of the roadway.

Any separate traffic-control requirement, such as a STOP or YIELD instruction, would need to be provided by the appropriate regulatory or warning sign.

W351 and Driver Awareness

The main benefit of W351 is advance awareness.

A driver who knows that low-flying aircraft may be present is less likely to be surprised by aircraft appearing overhead or by sudden aircraft noise.

The sign is therefore concerned with the interaction between the aviation environment and normal road-user attention.

W351 and Aircraft Approaches

Roads near airport approach paths may be close to aircraft operating at relatively low altitude.

The actual height and frequency of aircraft will depend on the aviation operation and site layout.

Where local conditions create a relevant warning requirement, W351 can communicate the possibility to road users.

W351 and Aircraft Departures

Aircraft departing from airports can also be visible or audible from nearby roads.

Where aircraft noise or low aircraft presence can create the type of driver-awareness issue addressed by W351, the sign may be considered in accordance with the applicable requirements.

W351 and Airfields

Roads near airfields or other aviation facilities may also experience aircraft activity close to the roadway.

Whether W351 is appropriate depends on the nature of the aircraft operations and their relationship to the road.

W351 and Aviation Facilities

Aircraft operations can vary considerably from one location to another.

Factors such as runway orientation, aircraft type, flight paths, operating schedules and distance from the roadway can affect whether low-flying aircraft are likely to be noticeable to drivers.

Sign selection should therefore be based on the actual site conditions.

W351 Sign Placement

W351 should be displayed in advance of the area where low-flying aircraft are likely to be present.

The SARTSM states that the appropriate warning-sign location should be determined using Figure 3.1 and the applicable advance-warning requirements.

The final position should also provide adequate visibility to approaching traffic.

W351 and Warning Distance

The appropriate distance between W351 and the relevant area depends on the operating conditions of the road.

South African warning-sign guidance generally determines advance placement according to factors such as operating speed, visibility and road layout.

Where the sign is positioned further from the hazard because of site conditions, the applicable supplementary distance information should be considered where required.

W351 and Sign Visibility

The W351 sign should be clearly visible to approaching road users before they enter the affected area.

Potential visibility problems include:

• Road curves
• Hills and crests
• Vegetation
• Buildings
• Other roadside signs
• Advertising structures
• Roadside equipment
• Poor sign placement

The sign should remain unobstructed, clean and legible.

W351 at Night

Aircraft activity and aircraft noise may be more noticeable at night, depending on the location and operating conditions.

Permanent W351 signs use retroreflective materials so that the warning sign can remain visible when illuminated by vehicle headlights.

Drivers should continue to concentrate primarily on the roadway while being aware that aircraft may be operating nearby.

Permanent W351 Sign Design and Colours

The permanent W351 warning sign follows the standard South African warning-sign colour arrangement:

• Triangle: Red retroreflective
• Symbol: Black semi-matt
• Background: White retroreflective

The sign uses an aircraft symbol to represent the low-flying aircraft hazard.

Is W351 a Yellow Road Sign?

The permanent W351 sign should not be described as a yellow warning sign.

For a permanent warning sign, the SARTSM specifies a red retroreflective triangular border, black semi-matt symbol and white retroreflective background.

Yellow backgrounds are associated with temporary warning signs rather than the permanent W351 sign.

Retroreflective W351 Sign

Retroreflective material helps the permanent W351 sign remain visible when illuminated by vehicle headlights.

The official specification allows permanent warning signs to use retroreflective red and white areas, while black areas remain semi-matt.

For public-road applications, the sign should be manufactured according to the applicable South African road traffic sign specifications.

W351 Sign Size

The appropriate size of W351 depends on the road environment and the applicable warning-sign requirements.

Factors that may influence the selected size include:

• Operating speed
• Road classification
• Viewing distance
• Traffic volume
• Roadside environment
• Available installation space

The SARTSM provides standard triangular warning-sign sizes, including 900 mm, 1200 mm and 1500 mm nominal side lengths, with the appropriate selection depending on the circumstances.

W351 and Large Road Signs

A larger warning sign may be appropriate where greater visual impact or emphasis is required.

The SARTSM notes that traffic volume, speed, road conditions, background lighting and other factors can influence the choice of warning-sign size.

W351 and Road Traffic Signs Near Airports

Roads around airports can contain several different traffic conditions, including airport traffic, pedestrians, service vehicles and aviation activity.

W351 addresses the specific issue of low-flying aircraft and sudden aircraft noise. Other traffic signs should be selected separately for other hazards.

W351 and Driver Distraction

The SARTSM's reference to sudden aircraft noise is important because an unexpected sound can produce a startled response.

W351 gives drivers advance knowledge that aircraft noise may occur, helping them understand why they may suddenly hear or see an aircraft nearby.

W351 and Heavy Vehicles

Drivers of trucks, buses and other large vehicles should remain attentive to the roadway when travelling through areas covered by W351.

A sudden aircraft sound should not cause unnecessary steering or braking movements.

W351 and Motorcycles

Motorcyclists should also remain focused on the roadway when travelling in areas where W351 is displayed.

Sudden noise or an aircraft passing overhead may be unexpected, so riders should maintain proper control and avoid abrupt reactions.

W351 and Cyclists

Cyclists travelling near airports and aviation facilities may also encounter low-flying aircraft activity.

W351 provides general advance awareness of the environment, although the sign is primarily a roadway warning for drivers and other road users.

W351 and Pedestrians

Pedestrians near roads close to airports may also notice low-flying aircraft and aircraft noise.

The warning sign is part of the road traffic-sign environment and does not replace any separate pedestrian or airport safety controls that may be required.

W351 on Airport Access Roads

Airport access roads can place road users close to aircraft operating areas.

Where low-flying aircraft are likely to be present in the vicinity of the roadway, W351 may provide useful advance warning of the aviation environment.

W351 on Public Roads in South Africa

On public roads, W351 should be selected, positioned and installed according to the applicable South African road traffic sign requirements and the requirements of the responsible road authority.

The warning should reflect an actual local condition involving low-flying aircraft in the vicinity of the roadway.

W351 on Private Roads and Properties

Similar low-flying-aircraft warning signage may also be useful on private roads and controlled properties located close to airports or aviation facilities.

Potential applications include:

• Airport-related properties
• Private access roads near airfields
• Industrial properties near airports
• Logistics facilities near aviation facilities
• Private estates within areas affected by low-flying aircraft
• Roads serving aviation-related developments

On private property, the sign can form part of an internal traffic-management arrangement based on local conditions.

W351 and Airport Development Areas

New developments located near airports may experience aircraft operations close to internal roads and access routes.

Where low-flying aircraft are likely to be noticeable to road users, suitable warning signage may be considered as part of the overall traffic-management design.

W351 and Industrial Areas Near Airports

Warehouses, factories, logistics facilities and other industrial properties can be located close to airports.

Where aircraft routinely operate nearby and the conditions create the type of hazard addressed by W351, appropriate warning signage can be included in the site's traffic-management planning.

W351 and Aviation Noise

The warning is particularly relevant to sudden aircraft noise rather than simply the existence of aircraft somewhere in the sky.

The SARTSM specifically identifies startling aircraft noise as a reason for providing W351 in airport environments.

W351 and Flight Paths

Aircraft flight paths differ from one airport and aviation facility to another.

A road may be affected by low-flying aircraft depending on its position relative to runways, approaches, departures and other aircraft operations.

The need for W351 should therefore be assessed using the actual local aviation and road environment.

Temporary Low Flying Aircraft Sign – TW351

The temporary version of W351 is designated TW351.

However, the SARTSM states that a temporary version of W351 is unlikely to be used. If required, it should be numbered and referred to as TW351.

This means that permanent W351 is the principal sign in the standard South African warning-sign system for this hazard, while temporary use is uncommon.

TW351 for Temporary Applications

Where an unusual temporary aviation-related condition creates a need for this warning, the temporary form may be considered if the applicable requirements support its use.

Because the SARTSM describes TW351 as unlikely to be used, the sign should only be selected where the site conditions genuinely justify the temporary warning.

Temporary Warning Sign Colours

Where a temporary warning version is used, South African temporary warning signs generally use:

• Triangle: Red retroreflective
• Symbol: Black semi-matt
• Background: Yellow retroreflective

This is the standard temporary warning-sign colour arrangement described by the SARTSM.

W351 Maintenance

W351 signs should be inspected and maintained so that they remain visible and legible to approaching road users.

Maintenance checks can include:

• Cleaning the sign face
• Checking for fading
• Checking for physical damage
• Checking mounting hardware
• Removing vegetation or obstructions
• Checking the condition of retroreflective materials

Airport and aviation-related environments can also involve dust, vehicle activity and other conditions that may affect roadside signs, making regular inspection useful.

W351 and Supplementary Plates

A supplementary plate can be used with a warning sign where additional information is required, such as an advisory speed, distance or text message.

Any supplementary information used with W351 should be relevant to the actual conditions and comply with the applicable South African road traffic sign requirements.

W351 and Other Warning Signs

W351 should not be used to communicate hazards that have dedicated warning signs.

For example, if the same roadway also has a sharp curve, pedestrian crossing or roadworks hazard, the applicable warning sign for that condition should be considered separately.

The overall sign arrangement should communicate each relevant hazard clearly without unnecessary duplication.

W351 and Road Layout

The presence of an airport does not automatically mean that every nearby road requires W351.

The sign is intended for locations where low-flying aircraft are likely to be present in the vicinity of the roadway and where the conditions justify the warning.

W351 and Weather Conditions

Weather can affect visibility of aircraft, but W351 is not a general poor-weather warning sign.

Other warning signs should be considered separately where fog, rain, reduced visibility or other weather-related hazards create a road condition requiring advance warning.

Who May Need W351 Low Flying Aircraft Signs?

W351 signage may be relevant to:

• Road authorities
• Municipalities
• Airport operators
• Airport-area property developers
• Traffic-management contractors
• Road construction contractors
• Industrial property managers
• Logistics facilities near airports
• Private estate managers
• Operators of private roads near aviation facilities

Benefits of W351 Low Flying Aircraft Warning Signs

• Warns road users about the likelihood of low-flying aircraft nearby.
• Provides advance awareness of an unusual aviation environment.
• Alerts drivers to the possibility of sudden aircraft noise.
• Can help drivers understand unexpected aircraft activity before reaching the area.
• Uses a recognisable aircraft warning symbol.
• Permanent W351 uses retroreflective warning-sign materials.
• TW351 provides a temporary option where genuinely required, although its use is uncommon.
• Can form part of a broader traffic-management arrangement near airports and aviation facilities.

Frequently Asked Questions About W351 Road Signs

What does W351 mean?

W351 means Low Flying Aircraft Ahead. It warns about the likelihood of low-flying aircraft in the vicinity of the roadway.

What is the official name of W351?

The official South African designation is LOW FLYING AIRCRAFT AHEAD.

What is W351 used for?

It is used to warn road users about the likelihood of low-flying aircraft near the roadway.

Why is W351 used near airports?

The SARTSM states that W351 may be used in airport environments to warn drivers about possible sudden aircraft noise that could startle them.

Does W351 mean aircraft will cross the road?

No. It warns about low-flying aircraft in the vicinity of the roadway. It does not by itself indicate that aircraft will cross the road.

Does W351 warn about aircraft collisions?

Its official purpose is to warn of low-flying aircraft and possible sudden aircraft noise, rather than specifically warning of a vehicle-aircraft collision.

Does W351 require drivers to stop?

No. W351 is a warning sign and does not itself require drivers to stop.

Does W351 impose a speed limit?

No. W351 does not itself establish a legal speed limit.

What should drivers do when they see W351?

Drivers should remain alert, expect possible low-flying aircraft or sudden aircraft noise and maintain proper control of the vehicle.

Is W351 a warning sign?

Yes. W351 is part of the South African W-series warning signs.

What colours does permanent W351 use?

Permanent W351 uses a red retroreflective triangle, black semi-matt aircraft symbol and white retroreflective background.

Is the permanent W351 sign yellow?

No. The permanent W351 sign has a white background. Yellow backgrounds are associated with temporary warning signs.

What is TW351?

TW351 is the temporary version of the Low Flying Aircraft warning sign.

Is TW351 commonly used?

No. The SARTSM states that a temporary version of W351 is unlikely to be used.

Can W351 be used near an airport?

Yes. Airport environments are specifically identified by the SARTSM as an application for W351.

Can W351 be used near an airfield?

It may be considered where low-flying aircraft are likely to be present in the vicinity of the roadway and the applicable requirements are met.

Can W351 be used on airport access roads?

Yes, where the road environment is affected by low-flying aircraft and the warning is appropriate.

Can W351 be used on a private road?

Similar low-flying-aircraft warning signage may be used on private roads and controlled properties near aviation facilities as part of an appropriate traffic-management arrangement.

Can W351 be used at industrial properties?

Yes, where an industrial property is located in an area affected by low-flying aircraft and the site conditions justify the warning.

Can W351 be used near a logistics facility?

Yes, where the facility is located near an airport or aviation operation and low-flying aircraft are relevant to the surrounding roadway.

Can W351 be used permanently?

Yes. W351 is primarily a permanent warning sign, subject to the applicable assessment and requirements.

Can W351 be used temporarily?

A temporary version, TW351, exists, but the SARTSM states that it is unlikely to be used.

What causes the need for W351?

The sign is used where low-flying aircraft are likely to be present in the vicinity of the roadway, particularly where sudden aircraft noise may startle drivers.

Does W351 mean an airport is immediately ahead?

No. The sign warns about low-flying aircraft in the vicinity of the roadway; it does not necessarily mean an airport entrance or runway is immediately ahead.

Can W351 be used with other road signs?

Yes. Other signs may be used separately where the roadway has additional hazards or traffic-control requirements.

Where should W351 be placed?

It should be positioned in advance of the affected area according to the applicable SARTSM warning-sign placement requirements and site conditions.

What size should a W351 sign be?

The appropriate size depends on operating speed, road environment and other applicable factors. Standard triangular warning-sign sizes are provided in the SARTSM.

Is W351 retroreflective?

Yes. The permanent W351 specification uses red and white retroreflective areas, with a black semi-matt symbol.

Can aircraft noise affect drivers?

The SARTSM specifically notes that sudden aircraft noise could result in a startled reaction from a driver, which is one reason W351 may be used near airports.

Can W351 be used at night?

Yes. Permanent warning signs use retroreflective materials to support visibility when illuminated by vehicle headlights.

Can Signs4SA supply W351 signs?

Yes. Signs4SA can assist with W351 Low Flying Aircraft Ahead signs and, where applicable, temporary TW351 warning signage.

Order W351 Low Flying Aircraft Warning Signs

Need W351 Low Flying Aircraft Ahead signs for an airport access route, road near an airfield, industrial property, logistics facility, private road or traffic-management application?

Signs4SA can assist with the supply of warning signs for different public-road and private-property applications, subject to the applicable South African road traffic sign requirements.

Contact Signs4SA with the W351 or TW351 code, required quantity, sign size, material and installation requirements to request a quotation.

One popular type of road sign is the Low flying aircraft ahead sign. This type of sign is used to provide drivers with important information about the road ahead, such as directions, speed limits, and potential hazards.

Low flying aircraft ahead_ signs come in a variety of shapes and sizes, and are made from a range of materials, including metal, plastic, and reflective materials. They can be customized to meet the specific needs of a particular roadway or location, including the addition of logos, graphics, and text.

One important feature of Low flying aircraft ahead signs is their high visibility. These signs are designed to be easily seen by drivers, even from a distance and in adverse weather conditions. Many Low flying aircraft ahead signs are also designed with reflective materials that make them visible at night.

Another important feature of Low flying aircraft ahead signs is their durability. Road signs are exposed to a wide range of environmental factors, including wind, rain, and extreme temperatures. As such, they need to be made from materials that can withstand these conditions and remain in good condition for years to come.

For businesses and organizations that need to create custom road signs, working with a reputable sign company can ensure that their signs are of high quality and meet all necessary standards and regulations. Signs4sa can provide expert advice on design, materials, and installation, and can help businesses ensure that their signs are installed safely and effectively.

Overall, Low flying aircraft ahead signs are an important tool for ensuring road safety and providing drivers with the information they need to navigate effectively. By working with a professional sign company to create and install these signs, businesses and organizations can help ensure that their messages are seen and understood by drivers, and help to improve safety on the road.

Customer Reviews