Runway and Taxiway Safety Areas

In my research, I came across a brief and unexpected history lesson in the Airport Design FAA Advisory Circular (AC). Pilots used to land what they called, "landing strips." With the advancement in airplanes, the landing strips needed to be improved or paved and thereafter became known as runways. The term landing strip was still used, but now referred to the graded area surrounding the runway. Since this area was no longer used for landing, the term was eventually changed to the more applicable term we know today -  runway safety area.

Photo credit: Bill Liao via Foter.com / CC BY-NC-SA
Bill Liao via Foter.com / CC BY-NC-SA


Safety areas surround taxiways and runways and are suitable for reducing the risk of damage to an airplane when it unintentionally leaves the pavement proper. Safety areas are cleared and graded with no hazardous surface variations. The grading also includes planned out drainage to prevent ponding water. Only necessary objects are allowed to be in a safety area, and every object present must be frangible, or break off, at no higher than three inches. Under dry conditions, the surface must be capable of of supporting snow removal and aircraft rescue and firefighting equipment as well as the an aircraft without causing major damage to that aircraft.

Taxiway Safety Area
Taxiway Safety Area (AC 150/5300-13A)


Dimensions of safety areas are determined based on the Airport Design AC (150/5300-13A). Taxiway safety areas are only located on the sides of the taxiway and vary in width from 49 feet to 262 feet. Runway safety areas surround the entire runway including the ends. The dimensions range from 120 feet to 500 feet in width and 240 feet to 1000 feet in length beyond the departure end of the runway. Most large commercial airports have safety areas 500 feet in width and 1000 feet at each end of the runway. When it is not possible to have a full safety area at the end of the runway, an EMAS system (Engineered Materials Arresting System) may be installed. EMAS systems are made from a lightweight cement  designed to stop airplanes by slowing them down quickly in the event of an overrun. The aircraft actually sinks down into the material. It's really neat, look it up!

Courtesy of Key West Int'l Airport and Zodiac Aerospace (Source)


Construction is not permitted within a runway or taxiway safety area. If construction needs to be done, the safety area can be restricted to a smaller group of aircraft. This is done often at large airports where many construction projects are done each year. A Notice to Airman (NOTAM) is issued by the airport operator and larger aircraft are not permitted into the restricted taxiway area.

 

Runway Safety Area (AC 150/5300-13A)




Okay, let's get to the whole reason for safety areas: runway excursions. According to a Skybrary article about runway end safety areas,  minor overruns occur on average once per week and worldwide are the fourth overall cause of airline fatalities. If excursions are really happening this often, it is very important to ensure that safety areas area kept cleared, graded, and within all FAA and ICAO guidelines that apply. According to the Canada transportation safety board, at least one airplane per month runs off the runway (and interestingly in Canada, that number is double).

Here are a few links to YouTube video runway excursions:

St. Barts Runway Overrun (quite the safety area)

Plane slides off runway at LaGuardia

Airphile Express Overrun

Boeing 727 Overrun

EMAS System Promo








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