What is an engineered materials arresting system (EMAS)?
Learn what an engineered materials arresting system (EMAS) is, how airport EMAS stops runway overruns, where it sits and what pilots should do.
An engineered materials arresting system (EMAS) is a purpose-built bed of crushable, energy-absorbing material beyond a runway end. During an overrun, the aircraft’s wheels sink into and crush the bed, producing controlled resistance that slows the aircraft when the airport cannot provide a full-length runway safety area.
In our Aviation & Real-World Flying reference, we use the formal expansion Engineered Materials Arresting System. “Engineered material arresting system” is a common singular variant, while “EMAS system” is understood but technically repeats the word “system”.
EMAS is passive: neither the pilot nor air traffic control switches it on. It is a last layer of protection after braking, runway design, operating procedures and overrun prevention have failed.
How does airport EMAS work?
Airport EMAS works by absorbing kinetic energy through the controlled crushing of calibrated, low-strength material beneath the landing gear.
As the wheels enter the bed, they break through its protective surface and sink into the crushable material. Resistance builds around the tyres and landing gear, progressively decelerating the aircraft. The effect comes mainly from crushing and displacing the engineered material, not simply from tyre friction.
Many installations use manufactured cellular cementitious blocks covered by a weather-resistant surface. Other accepted designs can use different crushable media. This is not ordinary soft ground, loose gravel or a layer of foam: the material strength, bed dimensions, foundation, drainage and surface protection form one engineered installation.
Design calculations account for the selected aircraft or fleet mix, aircraft mass, landing-gear layout, tyre loading, likely runway-exit speed, available length and width, site slope, climate and obstacles beyond the bed. The bed may become deeper along its length so that resistance increases as the aircraft moves through it, although construction details vary by approved system.
In United States FAA design practice, a runway-exit speed of 70 knots is the familiar reference for a standard installation. A constrained site may have an approved system with lower stopping capability. That figure is an engineering criterion, not an operating limit, a guaranteed stopping speed or performance credit that pilots may use in their calculations.
What can an EMAS arresting system not do?
EMAS cannot guarantee a safe stop in every runway excursion.
- An aircraft can miss the bed during a lateral excursion or enter it at a large angle.
- An aircraft that remains airborne can pass over part or all of the crushable section.
- Entry above the installation’s design assumptions can leave insufficient bed length.
- Collapsed or missing landing gear changes how loads reach the material; the bed may still help, but its predicted wheel-arresting performance no longer applies directly.
- EMAS does not prevent the original rejected take-off, unstable landing, brake failure, fire or structural damage that caused the overrun.
Where is EMAS installed at an airport?
An EMAS bed is installed beyond the physical runway end, usually centred on the extended centreline and within the runway-end safety area.
An airport may have EMAS at one end, both ends or only on selected runways. A bed at one physical end protects aircraft travelling towards that end, including landing overruns and rejected take-offs in that direction. Roads, railways, water, steep ground, buildings and airport boundaries are common reasons there is not enough space for a conventional safety area.
A setback or blast-resistant lead-in may separate the usable runway from the crushable bed. The setback protects the material from routine jet blast and is not necessarily part of the energy-absorbing section. Our explanation of how runways and their surrounding safety margins function provides the wider layout context.
EMAS is not extra runway. It does not increase take-off run available or landing distance available. It must not be included in aircraft performance calculations, and pilots should not assume that it increases accelerate-stop distance available; only an officially declared stopway can receive that treatment.
How can pilots identify an EMAS runway installation?
Airport diagrams and operational remarks are more reliable than colour or surface appearance when identifying EMAS.
Depending on the authority and chart format, the bed may be labelled, outlined or described with its dimensions in airport remarks. Yellow chevrons can indicate unusable pavement or appear over an EMAS area in some jurisdictions, but chevrons alone do not prove that a crushable arresting bed is present.
Real-world examples can be examined through our KJFK runway-end charts and approach plates and the KINT airport chart collection. For operational use, confirm the latest effective airport diagram, aerodrome information, remarks and notices rather than measuring an unscaled diagram or relying on scenery appearance.
How is EMAS different from a stopway, blast pad or arresting cable?
EMAS is a sacrificial wheel-arresting bed; a runway safety area, stopway, blast pad and cable arresting system each perform a different job.
| Installation | Primary purpose | How it interacts with an aircraft |
|---|---|---|
| EMAS | Reduce the consequences of a straight-ahead runway overrun | Crushes around the wheels to produce controlled resistance |
| Runway safety area | Provide a cleared and graded area around the runway | Reduces hazards and supports emergency access but does not necessarily stop the aircraft |
| Stopway | Provide a prepared area for stopping after an abandoned take-off | Uses normal aircraft braking and may be included in declared accelerate-stop distance when officially designated |
| Blast pad | Prevent jet blast from eroding the ground beyond the runway | Is not intended for take-off, landing or routine taxiing and provides no landing-distance credit |
| Arresting cable | Stop a suitably equipped aircraft, principally in military operations | A tailhook engages the arresting cable; the wheels do not need to crush a material bed |
A mistake we see regularly is calling every marked area beyond a runway a stopway. The markings, declared distances and published airport data determine its status; appearance alone does not.
When do airports choose an engineered materials arresting system?
Airports choose EMAS when straight-ahead overrun protection is required but a compliant conventional runway safety area cannot reasonably be built.
A full cleared and graded safety area is normally the first solution because it can accommodate more excursion paths and allows simpler emergency access. At a constrained airport, however, extending that area may require land acquisition, road or railway relocation, major earthworks or construction over water.
Airport planners and regulators compare several options:
- Extend or regrade the safety area when suitable land and obstacle clearance are available.
- Relocate the runway end or reduce declared distances when the resulting aircraft-performance and capacity penalties are acceptable.
- Install EMAS when limited ground remains beyond the runway and a compact, predictable wheel-arresting system provides the best practical mitigation.
The decision also considers the critical aircraft, fleet changes, rescue access, drainage, snow and ice procedures, jet-blast exposure, inspection requirements and the cost of restoring the bed after an engagement. EMAS does not remove every runway safety-area requirement and is not an effective substitute for protection against lateral excursions.
What does the engineered material arresting system market include?
The engineered material arresting system market is a specialised airport-infrastructure market covering design, approved energy-absorbing materials, site preparation, installation, inspection, maintenance and post-engagement repair.
It is not a commodity market in which airports buy generic crushable blocks by area. Procurement is based on regulator acceptance, modelled stopping performance for the airport’s aircraft, civil-engineering requirements, climate suitability, maintainability and replacement support.
Published market estimates require careful reading. Some combine civil EMAS with military cables, barriers and other runway arresting equipment; others count only new beds while excluding replacement modules and maintenance. A meaningful estimate should define the product scope, geography, base year and whether refurbishment is included. The formal aviation term generally uses “materials” in the plural even though commercial searches often use “engineered material arresting system market”.
What should a pilot do if an overrun into EMAS is unavoidable?
If entry into EMAS becomes unavoidable, the crew should remain aligned and follow the aircraft’s approved rejected-take-off or landing-overrun procedure.
- Continue the approved stopping actions. Apply wheel braking, aerodynamic braking and permitted reverse thrust as specified by the aircraft and operator procedures.
- Maintain directional control. Aim to enter the bed straight and near its centre rather than swerving towards obstacles or unsuitable ground.
- Avoid unnecessary steering in the bed. Uneven penetration can increase asymmetric loads and complicate recovery.
- After stopping, assess the emergency. Notify air traffic control and complete the appropriate shutdown or evacuation checklist. Fire, smoke or another immediate hazard takes priority.
- Do not attempt to taxi out. Engine thrust and wheel movement can embed the landing gear further, disturb debris and increase damage.
EMAS should never be treated as planned stopping distance. Its presence does not justify accepting an unstable approach, continuing a take-off outside limits or reducing normal performance margins.
Does EMAS damage the aircraft?
EMAS is designed to reduce injury and aircraft damage, but an engagement is not expected to be damage-free.
The bed is deliberately sacrificial. Individual blocks or sections crush and must be inspected, removed and replaced. The supporting base, joints, drainage and protective surface also require examination before the installation can return to full service.
The aircraft normally needs inspection of its tyres, wheels, brakes, landing gear, lower fuselage and engines. Debris ingestion is possible, particularly if thrust is applied after stopping. Recovery may require temporary ramps, lifting equipment and specialised towing rather than ordinary taxi power.
Weathering, water ingress, damaged surface seals, jet blast and unauthorised vehicle entry can also degrade a bed without an aircraft overrun. Airports therefore inspect and maintain EMAS as a safety system, not merely as pavement at the end of a runway.
Is EMAS modelled in flight simulators?
In most flight simulators, visible EMAS is scenery rather than a fully modelled energy-absorbing system.
Microsoft Flight Simulator 2024 and 2020, FSX, Prepar3D and X-Plane can display the bed, blocks and markings while assigning the area a generic concrete, rough-ground or collision surface. Some detailed airport add-ons implement custom drag or stopping behaviour, but that capability is package-specific rather than guaranteed by the platform.
A mistake we see constantly is assuming that a convincing yellow-chevron rectangle must function. An abrupt stop against an invisible collision box is not EMAS behaviour; nor is a generic soft surface that flips the aircraft or instantly collapses the landing gear.
- Confirm from airport data that the object represents EMAS rather than a blast pad or stopway.
- Check the scenery documentation for an explicit statement about custom arresting behaviour.
- If testing it in a simulator, keep aircraft mass, entry speed, braking and weather constant. Treat the result only as a test of that scenery package, never as evidence of real-world stopping performance.