Warning for Low-Flying Aircraft
The sign warns of low-flying aircraft in the area.
When You See This Sign
When you see sign A23 you should immediately increase your attention, reduce your speed if necessary and avoid abrupt maneuvers. Keep an eye on the sky and on other road users' behavior, but do not stop in the lane unless absolutely necessary.
Rules & Regulations
- Sign A23 (triangular with a red border) is a warning sign and indicates the risk of low-flying aircraft in the marked area.
- The sign does not impose an automatic duty to yield or stop; drivers should adjust speed and attention according to actual conditions.
- The sign is often placed near airfields, helicopter pads, or other locations where air traffic regularly passes at low altitude, and can be supplemented with information plates about distance or specific regulations.
- Any supplementary signs (e.g., distance indicators) or local regulations must be followed — note that A23 only warns, while supplementary signs may contain additional rules.
Tips for Drivers
- Reduce your speed slightly and be extra attentive to both the sky and other road users who may be disturbed or distracted by low-flying aircraft.
- Avoid sudden braking — signal in good time and slow down gradually if you need to adjust your driving because of aircraft activity or other road users' reactions.
- Be prepared for sudden noise or light disturbances (especially from helicopters). Hold the steering wheel firmly in windy conditions and secure loose items if you are riding a motorcycle or driving an open-top vehicle.
- Watch for supplementary signs indicating distance or specific instructions, and observe pedestrians and cyclists who may stop to look up at aircraft.
Common Mistakes
- Thinking the sign requires you to stop or that it imposes a duty to yield — A23 is only a warning.
- Confusing A23 with signage that indicates airport rules or landing prohibitions; A23 only warns that aircraft may pass at low altitude.
- Underestimating the effects of helicopter downdrafts or sudden noises and therefore not adjusting speed or driving attention.
Test Yourself
Road Sign: Warning for Low-Flying Aircraft
What should you keep in mind here?
- A Low-flying aircraft may occur in the area — be alert for unexpected noises and flashes.
- B Airport nearby with a marked approach — vehicles are prohibited from starting.
- C Helicopter landing site where vehicles must stop and keep the area clear.
- D Warning for flying objects that may fall onto the road — stop immediately.
Exam Tip
On the theory test, questions about this sign often try to make you believe it implies a stop or right-of-way duty. The correct answer is that it is a warning — you should adjust speed and attention, not automatically stop.
Did You Know?
A23 is relatively uncommon and is mainly used near smaller airfields, helicopter pads, or military/training airfields where aircraft regularly pass at low altitude; the sign belongs to the A-series of warning signs in the Swedish road sign system.
Frequently Asked Questions
Do I have to stop when I see the low-flying aircraft sign?
No, the sign does not require you to stop. However, you should adjust your speed and attention to the situation and only stop if it is necessary and safe.
Is overtaking prohibited when the sign is posted?
No, the sign does not prohibit overtaking per se. Overtaking is allowed only if it is safe and not regulated otherwise by a supplementary sign or local regulations.
Where is the sign usually placed and what does a supplementary plate below it mean?
The sign is most often placed at entrances to areas near airfields or helicopter sites. A supplementary plate can indicate distance or specific times when low flying occurs and must be observed.
Practice more in the app
Study Swedish road signs and driving theory in English. 314 signs with rules, tips and quizzes.