Runway safety: RESA, EMAS and protection against overruns

A jet touches down too late in heavy rain, the brakes grip poorly on the film of water, and suddenly the runway end is too close. Whether such a moment ends with a scare or a catastrophe is often decided by what lies beyond the runway. That’s what the runway end safety area (RESA) is for and, where space is tight, arresting beds like EMAS. This guide explains how the safety areas are built, why the rules differ in Europe and the US, and how you can recognize the technology as a spotter at the fence.

Runway safety areas: the short answer

Beyond each end of a commercial runway lie two protection zones. Directly adjoining the pavement is the runway strip, which surrounds the runway on all sides and extends at least 60 meters beyond the end on larger runways. Next comes the RESA, a level, obstacle-free area at least 90 meters long. Both areas are meant to let an aircraft that rolls too far or touches down too early come to a stop without impact. Where the terrain doesn’t suffice because a road, a river or an embankment is in the way, an EMAS bed stops the aircraft over a much shorter distance.

Experts call such events runway excursions. That means any departure from the runway, either beyond the end (overrun) or off the side (veer-off). In 2008, the pilots’ association IFALPA calculated that about a quarter of accidents and incidents in air traffic involve such excursions. Most end with minor damage. It becomes dangerous where there is no room left beyond the runway.

Runway strip and RESA under ICAO

The international rules are set out in ICAO Annex 14 (Aerodromes). Which values apply depends on the runway code, which is based mainly on the takeoff distance of the design aircraft. Code 4 stands for runways of about 1,800 meters and up, so the typical runways of large commercial airports such as Frankfurt or Munich. How to read runway numbers and suffixes like L, C and R is explained in the article on runway designations.

The runway strip is a leveled area around the runway on which no fixed obstacles may stand. For runways of codes 2 to 4 and for instrument runways, it extends at least 60 meters beyond the runway end. Laterally, on precision approach runways at large airports, it extends far beyond the pavement and is almost 300 meters wide in total.

The RESA begins where the strip ends. Until 1999 it was only a recommendation; since then it has been mandatory for runways of codes 3 and 4, as well as for instrument runways of codes 1 and 2. The requirements at a glance:

Criterion	ICAO standard (mandatory)	ICAO recommendation
Length beyond the strip, code 3 and 4	at least 90 m	at least 240 m, where practicable
Length beyond the strip, code 1 and 2	at least 90 m (instrument runways)	at least 120 m
Width	at least twice the runway width	width of the graded portion of the strip
With arresting system	length may be reduced according to the system’s design	–

If you add 60 meters of strip and 240 meters of recommended RESA, you end up with about 300 meters of run-out beyond the pavement. This is exactly the value the US uses as its standard. The RESA protects in both directions, by the way: it also lies before the start of the runway and catches aircraft that touch down too early.

The US model: 1,000 ft and a law

The US aviation authority FAA goes further than ICAO. For runways used by aircraft with approach speeds above 120 knots, it requires, where practicable, a runway safety area (RSA) of 1,000 ft beyond the runway end, about 300 meters, up to 500 ft wide. The basis was an analysis of overruns from 1975 to 1987: around 90 percent of the aircraft involved came to a stop within 1,000 ft beyond the runway end.

In November 2005, the US Congress legally obligated commercial airport operators to meet the RSA standards by the end of 2015. The FAA launched a large reconstruction program covering more than 1,000 runways. Where airports couldn’t extend, EMAS was often used. The FAA, on the other hand, rejects simply shortening runways if that would restrict operations of the aircraft using them.

Other countries have chosen their own paths as well. According to a 2008 Flight Safety Foundation report, Austria likewise required 300 meters at commercial airports, whereas Japan required only 40 meters. Some countries filed differences with ICAO at the time and pointed to the runway strips they already had.

Three accidents that shaped the debate

How important run-out is is shown by accidents where it was missing. Three cases come up again and again in the expert discussion:

• Air France 358, Toronto, August 2, 2005: An Airbus A340-300 of Air France touched down far beyond the threshold of wet runway 24L at Toronto Pearson during a thunderstorm, rolled past the end and came to rest in a ravine. All 309 occupants survived; the aircraft burned out. The Canadian Transportation Safety Board (TSB) subsequently recommended a 300-meter RESA or an equivalent arresting system at Canada’s runways.
• Southwest 1248, Chicago Midway, December 8, 2005: A Boeing 737-700 of Southwest Airlines rolled past the end of runway 31C in snowfall and with a tailwind, broke through the fence and hit several cars on the adjacent road. A six-year-old boy was killed. The US accident agency NTSB named the lack of EMAS as a contributing factor; from 2007, Midway received arresting beds.
• TACA, Tegucigalpa, May 30, 2008: An Airbus A320 overran the end of a short runway at Toncontín Airport, plunged down an embankment and came to rest on a road. Five people died. According to IFALPA, the safety area beyond the runway was only about 15 meters long.

What all three cases have in common is that the actual mistake happened on the runway, but the severity was determined by what came after.

EMAS: a gravel trap for jets

The Engineered Materials Arresting System works like a gravel trap in Formula 1, only designed specifically for aircraft. At the runway end lies a field of lightweight blocks that deliberately break under the weight of an aircraft. The wheels sink in, the material absorbs the kinetic energy, and the aircraft decelerates evenly. Ideally, the occupants stay unhurt and the aircraft is only slightly damaged.

Today there are essentially two types of construction for the beds:

• Cellular concrete blocks: lightweight, crushable concrete blocks with a protective layer against jet blast. The manufacturer ESCO developed this system in the 1990s together with the FAA; today it is known under the name EMASMAX.
• Foam glass bed: The Swedish company Runway Safe uses foamed glass from recycled material, held by a plastic grid and sealed with a top layer.

The origins lie in New York: in the mid-1990s, a first bed of cellular concrete blocks was built in cooperation with the FAA for runway 04R at New York JFK Airport. The first general FAA specification followed in 1998; the current one is Advisory Circular 150/5220-22B from 2012. According to FAA figures from 2024, EMAS beds were installed at 121 runway ends at 71 US airports.

When an EMAS counts as equivalent

An EMAS doesn’t replace the full safety area arbitrarily. The FAA ties equivalence to a clear performance:

Variant	Design	FAA assessment
Standard EMAS	stops the design aircraft at 70 knots overrun speed	equivalent to a full 1,000-ft RSA
Non-standard EMAS	stops the design aircraft at 40 knots	permitted when neither a full RSA nor a standard EMAS is possible

The design aircraft (critical aircraft) is usually the heaviest type that regularly uses the runway. For very light aircraft, an EMAS is less effective because they don’t crush the material sufficiently.

Well-known EMAS arrests

Since the first arrest in 1999 at JFK, EMAS has stopped numerous aircraft, from business jets to freighters. A few cases involving airliners:

• New York JFK, May 1999: A Saab 340 with 30 people on board rolled into the bed of runway 04R and was stopped.
• Chicago O’Hare, July 2008: An Airbus A320 with 145 people on board came to a stop in the EMAS.
• Charleston (West Virginia), January 2010: A Bombardier CRJ200 of PSA Airlines rejected its takeoff and was caught by the bed with 34 people on board.
• New York LaGuardia, October 2016: A Boeing 737 carrying the then vice-presidential candidate Mike Pence slid past the runway end into the EMAS in rain. You can see the airport well from Planeview Park in Queens.
• Hollywood Burbank, December 2018: A Southwest Boeing 737-700 landed in heavy rain and was stopped by the bed at the runway end.

How many lives EMAS has saved exactly cannot be reliably quantified. What is clear: at several of these runway ends, roads, water or slopes begin beyond the bed.

EMAS in Europe and worldwide

Outside the US, EMAS is the exception. Most airports meet the ICAO rules through sufficiently long safety areas. But there are installations that show when the technology pays off:

• London City: The airport in the Docklands has a single runway of a good 1,500 meters between two dock basins. EMAS beds lie at both runway ends here, and the adjusted usable runway lengths have applied since July 2023. More about the airport with its steep 5.5-degree approach can be found in the profile of London City.
• Other countries: Installations exist in Madrid, Norway, Switzerland, on Réunion and Mayotte, in China, at Taipei Songshan Airport and in New Zealand, among others.
• Boston Logan: According to a 2008 Flight Safety Foundation report, there was an EMAS bed about 58 meters long between the end of runway 04L and the harbor basin. From the Castle Island spot, you look across the water at the airport.

When space is lacking: an airport’s options

Not every airport can simply extend its safety areas. Annex 14 acknowledges that terrain and structures at some runway ends make this practically impossible. Typical solutions are:

Shortening the usable runway length is the last resort for many authorities because it costs aircraft range and payload. Especially at airports with little space such as Madeira, where the runway partly stands on stilts, or Gibraltar, every meter decides the economic viability of routes.

Preventing overruns, not just catching them

RESA and EMAS are the last safety net. The real work happens before that. According to experts, overruns arise mainly from misjudged speed, height or distance, from inadequate information on weather and runway condition, and from technical failures. The most important countermeasures:

• Stabilized approaches: Anyone who arrives too high, too fast or in the wrong configuration goes around. Why a go-around is no drama but a normal procedure is explained in its own guide.
• Correct landing distance: Before every landing, crews calculate how much runway they need at the current weight, wind and runway condition. Tailwind and wet surfaces noticeably lengthen the distance.
• Reporting runway condition: After the Midway accident, the FAA set up a working group that produced a numbers-based runway condition code in 2016. ICAO has also standardized runway condition reporting worldwide. How airports keep runways grippy in winter is shown in the article on winter operations at the airport.
• Mastering crosswinds: Strong crosswind is often partly responsible for lateral excursions. The technique behind it is explained in the guide to crosswind landings.

If an incident happens anyway, the airport fire service is at the runway end within minutes. How its equipment is tied to aircraft size is covered in the post on airport fire service categories.

What spotters see at the runway end

For you at the fence, the safety areas are a piece of airport geography that answers many questions:

• Why the spot is so far away: Between the runway end and the fence lie strip, RESA and often the approach lighting. Even at spots directly in line with the runway, you therefore usually stand a good distance from the pavement. Extreme exceptions like Maho Beach on Sint Maarten are famous precisely for that reason.
• Displaced thresholds: If the landing threshold is shifted inward, an obstacle or safety area question is often behind it. The stretch before it is used for taxiing and takeoff, but not landing.
• Yellow chevrons on the pavement: Areas before the runway end that may not be used as runway, such as blast pads, are marked with yellow chevrons. An EMAS bed is usually recognizable as a gray, slightly raised field of many equally sized blocks.
• Long rollouts in the wet: In rain, aircraft need more runway to slow down. That is worth watching for video, as the guide Spotting landings or takeoffs shows.

If an incident actually happens while you are standing at the fence, helping the emergency crews takes priority over any photo. How to behave is described in the article Witnessing an emergency landing or incident.

Conclusion

Beyond every commercial runway lies a safety buffer that most passengers never notice: first the runway strip, then the runway end safety area. ICAO requires at least 90 meters of RESA and recommends 240; the US relies on about 300 meters beyond the runway end. Where roads, water or slopes prevent that, EMAS beds stop aircraft over a short distance, from New York to Chicago to London City. These areas don’t prevent overruns. But they make sure a mistake on the runway doesn’t become a catastrophe.