New landing requirement considered

 - December 27, 2007, 9:44 AM

Still concerned about landing overrun accidents, the FAA published a new Advisory Circular (91-79) on November 6 to advise pilots and operators about how to avoid such mishaps. While the circular is not mandatory, the FAA recommends that commercial and Part 91 business jet operators incorporate the material into their operations manuals or appropriate documents such as standard operating procedures (SOPs). The agency is also planning to form an aviation rulemaking committee that will make recommendations for a requirement that pilots assess landing-distance performance before landing.

Overruns account for about 10 incidents and accidents per year, according to FAA and NTSB numbers. Yet the FAA’s recent focus on the subject stems from one particular overrun–the accident involving a Southwest Airlines Boeing 737-700 on Dec. 8, 2005, at Chicago Midway International Airport. The probable cause, according to the NTSB, “was the pilots’ failure to use available reverse thrust in a timely manner to safely slow or stop the airplane after landing, which resulted in a runway overrun. This failure occurred because the pilots’ first experience and lack of familiarity with the airplane’s autobrake system distracted them from thrust reverser usage during the challenging landing.”

The Safety Board also highlighted Southwest Airlines’ “failure to provide its pilots with clear and consistent guidance and training regarding company policies and procedures related to arrival landing distance calculations; programming and design of its onboard performance computer, which did not present inherent assumptions in the program critical to pilot decision-making; plan to implement new autobrake procedures without a familiarization period; and failure to include a margin of safety in the arrival assessment to account for operational uncertainties.”

While business jet landing-performance graphs don’t usually take reverse thrust into account, Southwest Airlines incorporates a credit for reverse thrust when calculating landing distances in the 737-700.

Despite the circumstances of the Southwest accident, about a year later the FAA tried to require all Part 121, 125, 135 and 91K (fractional) operators to add a 15-percent margin to landing-distance assessments via a policy order. Under the proposed policy, pilots would have had to assess landing distance and add the 15-percent margin before every landing. According to the National Air Transportation Association, “as a mandatory new requirement, it constituted rulemaking and could not be implemented via a policy order.”

The FAA subsequently backed down on the mandatory policy and issued a Safety Alert for Operators ( airline_safety/safo/all_safos/media/2006/safo06012.pdf) that reiterated the 15-percent margin concept and suggested that operators employ the margin voluntarily. At the time, the FAA said it planned to explore rulemaking to make the landing-distance assessment and the 15-percent margin mandatory, and that appears to be the focus of the planned rulemaking committee.

Meanwhile, AC 91-79 is the most current information available on overrun prevention.

Not all pilots agree that new rules or procedures are needed because of one accident. But it is clear that the FAA wants to do something about overruns besides issue advisory material, and any further overrun accidents will likely entrench the agency more deeply in its chosen course of action.  

'Landing_Reqs_Tables' PDF