Many airports throughout the country have airfield separations not consistent with existing Federal Aviation Administration (FAA) design requirements.  This is largely because these airports were designed when aircraft were smaller and before current design standards were established.   Over time airports have become physically and operationally constrained for many reasons, including encroaching development, environmental restrictions, and the variety and size of aircraft operating today.  When these airports redesign portions of their airfields, FAA typically requires that airfields be modified to meet existing standards regardless of the airport’s operating history or the impact to airport operations.

At constrained airports, meeting the current design standards is not always practicable or feasible; as a result, a modification of standards is required.  However, a broadly applicable, risk-based method has not been available to airports for use in supporting requests for modifications of standards.   As a result, default standards are applied, impacting airport efficiency and capacity, and potentially preventing certain aircraft from utilization of an airfield.  In addition, these default standards can impact an airport’s limited capital funding.

Although the FAA is requiring more risk-based decision-making at airports, not all separation standards have been included.  Research is needed to develop a risk-based analysis that could be applied to allow for a more consistent application of requests for modification of standards.

The objective of this research is to develop a method for assessing the risks associated with non-standard separations at existing constrained airports where standards can not be practicably met and applied nationally. The risk assessment method should support, explain, and justify requests to modify standards for non-standard separations. At a minimum, this research should include separations standards between taxiways and runways; taxiways/taxilanes and taxiways/taxilanes; and taxiways/taxilanes and fixed or movable objects. 

Status:  The report has been published as Report 51: Risk Assessment Method to Support Modfication of Airfield Separation Standards.  Appendices that provide detail and information on the development of the methodology can be found online.