Feasibility analyses for paired approach procedures for closely spaced parallel runways

Abstract

In current air traffic operations in the U.S., closely spaced parallel runways (CSPRs) separated by less than 2500 feet (ft) can be used to conduct simultaneous parallel operations using visual separation. Once below visual approach minima, such dual runway operations are no longer possible. To address this loss of throughput, several concepts are currently under consideration. This paper discusses a “paired approach” concept which enables use of CSPRs down to Category I and II approach minima. The paper documents Monte Carlo analyses on the feasibility and trade-offs of paired approach procedure variants with and without an escape maneuver. It concludes that both procedure variations require echelon staggering for most airports with runway centerline (RCL) separations below 2500 ft and provides window parameters required for an acceptable Target Level of Safety (TLS). It shows that a value of up to 4000 ft for this echelon spacing is adequate for most CSPRs for an adverse wind threshold of 10 knots; the specific value depending on the concept variation and geometry. Other findings include the ability to achieve abeam positioning with an escape procedure for several runway configurations. Many procedural combinations examined are capable of pairing 95% to 100% of aircraft. Additionally, this paper presents an analysis of wake encounter risk during blunders. The analysis results suggest the non-escape procedure variant has a high probability of wake vortex encounter during blunder. On the other hand, the escape procedure variant with a delay in breakout of 8 seconds or less appears to provide protection from wake encounters even during a blunder. Preliminary considerations for surveillance requirements are presented, including optional 1090 MHz Extended Squitter (1090ES) Automatic Dependent Surveillance-Broadcast (ADS-B) messages and fields that may support the escape procedure variation.