Models of Wake-Vortex Spreading Mechanisms and Their Estimated Uncertainties

One of the primary constraints on the capacity of the nation's air transportation system is the landing capacity at its busiest airports. Many airports with nearly-simultaneous operations on closely-spaced parallel runways (i.e., as close as 750 ft (246m)) suffer a severe decrease in runway acceptance rate when weather conditions do not allow full utilization. The objective of a research program at NASA Ames Research Center is to develop the technologies needed for traffic management in the airport environment so that operations now allowed on closely-spaced parallel runways under Visual Meteorological Conditions can also be carried out under Instrument Meteorological Conditions. As part of this overall research objective, the study reported here has developed improved models for the various aerodynamic mechanisms that spread and transport wake vortices. The purpose of the study is to continue the development of relationships that increase the accuracy of estimates for the along-trail separation distances available before the vortex wake of a leading aircraft intrudes into the airspace of a following aircraft. Details of the models used and their uncertainties are presented in the appendices to the paper. Suggestions are made as to the theoretical and experimental research needed to increase the accuracy of and confidence level in the models presented and instrumentation required or more precise estimates of the motion and spread of vortex wakes. The improved wake models indicate that, if the following aircraft is upwind of the leading aircraft, the vortex wakes of the leading aircraft will not intrude into the airspace of the following aircraft for about 7s (based on pessimistic assumptions) for most atmospheric conditions. The wake-spreading models also indicate that longer time intervals before wake intrusion are available when atmospheric turbulence levels are mild or moderate. However, if the estimates for those time intervals are to be reliable, further study is necessary to develop the instrumentation and procedures needed to accurately define when the more benign atmospheric conditions exist.

[1]  S. Crow.  Stability theory for a pair of trailing vortices , 1970 .

[2]  E. R. Bate,et al.  Lifespan of trailing vortices in a turbulent atmosphere , 1976 .

[3]  Vernon J. Rossow.  Prospects for destructive self-induced interactions in a vortex pair , 1987 .

[4]  Vernon J. Rossow,et al.  Research on aircraft/vortex-wake interactions to determine acceptable level of wake intensity , 1988 .

[5]  Peter T. Zell,et al.  Performance and test section flow characteristics of the National Full-Scale Aerodynamics Complex 80- by 120-Foot Wind Tunnel , 1989 .

[6]  Hugh W. Coleman,et al.  Experimentation and Uncertainty Analysis for Engineers , 1989 .

[7]  H.-T. Liu,et al.  Effects of ambient turbulence on the decay of a trailing vortex wake , 1992 .

[8]  V. J. Rossow,et al.  Measurements in 80- by 120-foot wind tunnel of hazard posed by lift-generated wakes , 1993 .

[9]  Vernon J. Rossow.  Validation of Vortex-Lattice Method for Loads on Wings in Lift-Generated Wakes , 1994 .

[10]  Ralph E. Bach,et al.  Severe turbulence and maneuvering from airline flight records , 1992 .

[11]  Katharine K. Lee,et al.  EFFECTS OF ATC AUTOMATION ON PRECISION APPROACHES TO CLOSELY SPACED PARALLEL RUNWAYS , 1995 .

[12]  V. J. Rossow,et al.  Wind-tunnel measurements of hazard posed by lift-generated wakes , 1995 .

[13]  Steve Koczo.  Coordinated Parallel Runway Approaches , 1996 .

[14]  V. J. Rossow,et al.  Vortex wakes of two transports measured in 80 by 120 foot wind tunnel , 1996 .

[15]  George C. Greene,et al.  Wake Vortex Research—A Retrospective Look , 1998 .

[16]  Andrew K. Barrows,et al.  Flight Testing WAAS for Use in Closely Spaced Parallel Approaches , 1999 .

[17]  Vernon J. Rossow,et al.  Lift-generated vortex wakes of subsonic transport aircraft , 1999 .

[18]  Zhongquan Charlie Zheng,et al.  N-S Simulations of Crow-Type Instabilities in Vortex Wake , 1999 .

[19]  V. J. Rossow,et al.  Overview of Wake-Vortex Hazards During Cruise , 1999 .

[20]  Jonathan Hammer.  Case Study of Paired Approach Procedure to Closely Spaced Parallel Runways , 2000 .

[21]  George C. Greene,et al.  Wake Turbulence Limits on Paired Approaches to Parallel Runways , 2000 .

[22]  Fred H. Proctor,et al.  Large Eddy Simulation of Aircraft Wake Vortices Within Homogeneous Turbulence: Crow Instability , 2000 .

[23]  George F. Switzer,et al.  Numerical Study of Wake Vortex Behavior in Turbulent Domains with Ambient Stratification , 2000 .

[24]  Vernon J. Rossow.  Reduction of Uncertainties in Prediction of Wake-Vortex Locations , 2000 .

[25]  Rodney Teo,et al.  Computing provably safe aircraft to aircraft spacing for closely spaced parallel approaches , 2000, 19th DASC. 19th Digital Avionics Systems Conference. Proceedings (Cat. No.00CH37126).

[26]  J. D. Powell,et al.  Flight deck display of airborne traffic wake vortices , 2001, 20th DASC. 20th Digital Avionics Systems Conference (Cat. No.01CH37219).

[27]  K Rutishauser David,et al.  Aircraft Wake Vortex Spacing System (AVOSS) Performance Update and Validation Study , 2001 .

[28]  Turgut Sarpkaya,et al.  Wake-Vortex Eddy-Dissipation Model Predictions Compared with Observations , 2000 .

[29]  George C. Greene,et al.  Increasing airport capacity with modified IFR approach procedures for close-spaced parallel runways , 2001 .

[30]  Vernon J. Rossow,et al.  Use of Individual Flight Corridors to Avoid Vortex Wakes , 2002 .

[31]  J. Konopka,et al.  Wake Vortex Effects on Parallel Runway Operations , 2003 .

[32]  Vernon Rossow.  Implementation of Individual Flight-Corridor Concept , 2003 .

[33]  Aircraft Scale Turbulence Isotropy Derived from Measurements and Simulations , 2003 .

[34]  Kenneth Arkind,et al.  Maximum Capacity Terminal Area Operations in 2022 , 2003 .

[35]  Robert E. Robins,et al.  COMPARISON OF NUMERICAL MODEL SIMULATIONS AND SFO WAKE VORTEX WINDLINE MEASUREMENTS , 2003 .

[36]  Wayne W. Cooper,et al.  Exploration of Terminal Procedures Enabled by NASA Wake VAS Technologies , 2004 .

[37]  Rachelle L. Ennis,et al.  A Formal Approach to the Analysis of Aircraft Protected Zone , 2004 .

[38]  William S. Hindson,et al.  In-Flight Assessment of a Pursuit Guidance Display Format for Manually Flown Precision Instrument Approaches , 2004 .

[39]  Gordon H. Hardy,et al.  Cockpit Display of Traffic and Wake Information for Closely Spaced Parallel Approaches , 2004 .

[40]  Steven Lang,et al.  FAA/NASA WAKE TURBULENCE RESEARCH PROGRAM , 2004 .

[41]  Steven Lang,et al.  WAKE TURBULENCE RESEARCH PROGRAM: PROGRAM STATUS AND CONOPS EVALUATION TEAM PROCESS , 2004 .

[42]  M.E. Miller,et al.  Communication and the future of air traffic management , 2004, 2004 IEEE Aerospace Conference Proceedings (IEEE Cat. No.04TH8720).

[43]  Heinz Erzberger,et al.  Airport Arrival Capacity Benefits Due to Improved Scheduling Accuracy , 2005 .

[44]  V. Rossow.  Classical Wing Theory and the Downward Velocity of Vortex Wakes , 2006 .