Most of the world’s airports’ infrastructure is outdated, because it was built several decades ago, based on the aircraft fleet, traffic intensity and safety measures suited to the time when the airport was built. Since the aircrafts have increased, the last decades, in both weight and speed, the safety margins have therefore consequently decreased.
Example of development from 1950 to 2020:
- Demands on airports has gradually increased over time
- In 1950 a DC 3 had a weight of 11.000 kg carrying 30 passengers landing in 90 knots
- Today a A330 has a weight of 230.000 kg carrying 300 passengers landing in 140 knots
- Despite modern systems the need for runway safety requirements have increased with a factor of x3+
Basic facts – runway safety
Runway excursions are the most common type of aviation accidents worldwide representing 22% of all accidents. The reasons behind many of these accidents are either pilot errors (not following SOP, landing late or landing at high speed), mechanical failures (brake malfunction), weather (wind, contamination of pavement), sabotage or other examples of human errors.
Runway Excursions – what is it?
According to ICAO, a runway excursion is a veer off or overrun off the runway surface. This means when the wheels of an aircraft on the runway surface depart the end (overrun) or the side (veer-off) of the runway surface, which can occur at take-off or landing.
Statistics of Runway Excursions:
- Runway excursions costs exceed $900 million per year
- Runway overruns account for more than 50% of runway excursions
- Non-compliance RESA’s create risk to passengers, airports, airlines and the general Public
- EMAS is the safest option for meeting ICAO RESA requirements when there is a non-compliant RESA
In case of a runway overrun, there could be severe consequences depending on when and where the aircraft get to a stop. Some runways are built dangerously close to the sea, rivers, cliffs, roads or other obstacles and in these cases an overrun can lead to catastrophic consequences such as fatalities or severe injuries to passengers and crew. And not to mention damage to the aircraft and to the airfield installations, leading to costly delays and damaged airline and airport reputation.
Passive Safety is important
No matter which active systems the aircrafts have installed and what procedures the pilots shall follow, passive safety systems are still necessary. When comparing driving a top modern car, with active safety systems, on a mountain road close to a cliff without any safety precautions, or choosing to drive the same car on a road with safety railings, the choice is rather clear.
Mitigate the severity of runway excursions
The surface surrounding the runway prepared or suitable for reducing the risk of damage to airplanes in the event of an undershoot, overshoot, or excursion from the runway is called Runway Safety Area. A good and reliable area at the end of runways, a Runway End Safety Area (RESA), is the best way of mitigating impact in case of an excursion of an aircraft. Most runways have enough area for a sufficient RESA, stopping an aircraft at 70 knots within 300 meters from the end of the runway (ICAO recommendation). If there are space limitations and reduction of the runway’s declared distances or a geographical extension is not possible, an EMAS (Engineered Material Arresting System) is the option.