NOISE ABATEMENT PROCEDURE DESIGN R. Koenig, Institute of Flight Systems R.-G. Huemer, Flight Department German Aerospace Center (DLR) Lilienthalplatz 7, D-38108 Braunschweig, Germany MIT-DLR-DLH Workshop Seeheim, Germany 17 August - 19 August, 2004

CONTENTS 1) INTRODUCTION 2) AIRCRAFT NOISE SOURCES 3) OPERATIONAL OBJECTIVES and REQUIREMENTS 4) LOW NOISE DEPARTURE PROCEDURES 5) LOW NOISE APPROACH PROCEDURES 6) SHORT-TERM SOLUTIONS FOR APPROACH PROCEDURES 7) CONCLUSIONS

INTRODUCTION Noise abatement procedures (NAPs) have already been designed in the past But today the full noise reduction potential is not exploited due to the fact that engine noise becomes lower than airframe noise, especially in the approach phase additional possibilities for aircraft guidance and control exist advanced noise calculation tools allows a new optimization of noise abatement procedures A prerequisite for any new flight procedure design is to maintain safety standards and economical demands Short term solution could only be realized if extensive hard- and software changes are avoided

AIRCRAFT NOISE SOURCES Source: www.airliners.net HIGH-LIFT DEVICES LANDING GEAR ENGINES A direct reduction of noise emission from engines, high lift devices and landing gear can be realized only medium term or long term Engine noise emission depends mainly on thrust level Airframe noise emission depends on airspeed powered by approx. 5 (~V5) A duplication of the distance to the noise source reduces the immission between 6 and 10 dB

AIRCRAFT NOISE SOURCES Consequently a reduction of noise immission can be obtained by the following short term measures decreased thrust level increased flight path height decreased airspeed delayed slats and flaps extension delayed landing gear extension Unfortunately these measures are partly contradictory at take-off a decreased thrust level combined with an increased flight path height is impossible at approach the airspeed can not decrease without appropriate flap setting

OBJECTIVES and REQUIREMENTS FUTURE NOISE ABATEMENT PROCEDURES (NAPs) OPERATIONAL OBJECTIVES and REQUIREMENTS FUTURE NOISE ABATEMENT PROCEDURES (NAPs) Legal Requirements (e.g. National Regulations, ICAO PANS-OPS Safety (e.g. Airline Standard Operating Procedures) Air Traffic Management & Capacity Issues (e.g. Aircraft Movements per Hour during Peak-Time) Economical & Ecological Feasibility (e.g. Time & Fuel Consumption)

LOW NOISE DEPARTURE PROCEDURES Conventional ATA Modified ATA ICAO-A Current Departure Procedures ICAO-A Procedure: 1) Take-off thrust and V2 until 1500 ft 2) Thrust cut back and V2 until 3000 ft 3) Acceleration to 250 kts and flap retraction 4) Climb using 250 kts 1 2 3 4 Conventional ATA Procedure: 1) Take-off thrust and V2 until 1000 ft 2) Thrust cut back, acceleration to 250 kts and flap retraction 3) Climb using 250 kts 1 2 3 Modified ATA Procedure: 1) Take-off thrust and V2 until 1500 ft 2) Thrust cut back, acceleration to 250 kts and flap retraction 3) Climb using 250 kts 1 2 3

LOW NOISE DEPARTURE PROCEDURES Flight mechanics basics True Arspeed (TAS) The question is to gain height steep or fast? Rate of Climb (R/C) VX: Best angle of climb (noise optimal) VX VY: Best rate of climb (time and fuel optimal) VY

LOW NOISE DEPARTURE PROCEDURES VY VX Vmod. ATA Optimization with respect to Best Angle of Climb (VX): reduced noise, ecological Optimization with respect to Best Rate of Climb (VY): time - and fuel saving, economical

LOW NOISE DEPARTURE PROCEDURES IAH = 3000 ft Modern Noise Abatement (MoNA) Departure Procedure MONA Modified ATA ICAO-A 4) Climb with 250 kts 4 3) Final acceleration until 250 kts is reached 3 2) Thrust cut back, intermediate acceleration until 3000 ft and flap retraction 2 1) Take-off thrust and V2 until 1000 ft 1 Noise reduction related to „Modified ATA“

LOW NOISE DEPARTURE PROCEDURES Noise immision and fuel consumption up to 6000 ft height and 250 kts speed related to the MOD-ATA Procedure Intermediate Acceleration Height [ ft ] Fuel-Consumption [ % ] Additional FUEL CONSUMPTION MONA ICAO-A NOISE IMMISSION MONA ICAO-A Additional Noise

LOW NOISE APPROACH PROCEDURES Low Drag Low Power Approach (LDLP) Introduced in the 1970s by Lufthansa German Airlines, known as „Frankfurt Procedure“ 1 Constant speed descent from cruise level or initial approach altitude at max. 250kts below flight level 100 2 Transition to level flight and deceleration to clean manoeuvring speed ”” Level flight at ””, followed configuration to approach flaps and deceleration to ”S” speed 3 4 Stabilization on glide path, final configuration and deceleration to final approach target speed ”VTGT” Standard approach procedure of many major aircarriers

LOW NOISE APPROACH PROCEDURES Noise metrics of LDLP-Approaches with different intermediate approach altitudes (3000 ft and 4000 ft) Noise reduction only in the intermediate approach altitudes area of up to -5 dB

LOW NOISE APPROACH PROCEDURES Vertical flight path of different approach procedures Low Drag Low Power Approach (LDLP) Two Segment Approach (TSEG) Steep Approach (STEEP) Continuous Descent Approach & Low Drag Low Power Approach (CDA-LDLP) Continuous Descent Approach & Two Segment Approach (CDA-TSEG) Continuous Descent Approach & Steep Approach (CDA-STEEP)

LOW NOISE APPROACH PROCEDURES Flight mechanics basics Stationary descent on a free path: Required thrust for a specified path:

LOW NOISE APPROACH PROCEDURES Combined CDA / STEEP APPROACH Maximizing the distance between noise source and observers 1 Constant speed descent from cruise level or initial approach altitude at max. 250kts below flight level 100 Deceleration phase, accompanied by configuration changes at minimum allowable speed for respective configuration 2 3 stabilization on steep 4° glide path, constant speed descent with final approach target speed „VTGT“ Minimizing required thrust levels, by continuous descent and steep final approach Configuration changes as late and as slow as possible, at minimum allowable speed for respective configuration

LOW NOISE APPROACH PROCEDURES Noise metrics of a combined CDA / STEEP Approach compared to LDLP - Approach Noise reduction within the complete approach area of up to -8 dB

SHORT-TERM SOLUTIONS Short-term realizability requires Observance of the given operational objectives and requirements Procedures, that get along with today’s equipment Modern noise simulation tools for accurate noise immission predictions Simulator- and flight test demonstration of suggested procedural solutions Segmented Continuous Descent Approach (SCDA) Developed by modern means of Noise-Simulation like the DLR SIMUL-Program Considers “Lessons Learned” of the optimization process of modified CDA-Procedures Observes operational objectives and requirements as far as possible

SHORT-TERM SOLUTIONS Segmented Continuous Descent Approach (SCDA) VFW-614 ATTAS Fixed-Base Simulator Advanced Technologies Testing Aircraft System (ATTAS) VFW-614 Simulator & flight-test demonstration conducted 2003 by German Aerospace Center Test-Pilots using the VFW-614 fixed base simulator and the Inflight Simulator ATTAS Extensive survey on pilot workload issues and pilot-acceptance performed on Lufthansa German Airlines Airbus A320 and A330 Full-Flight Simulators, together with airline-pilots of Lufthansa Lufthansa Flight Training Full-Flight Simulator

Reference 3° ILS Glide Path SHORT-TERM SOLUTIONS Segmented Continuous Descent Approach (SCDA) Maximum use of automation including autothrottle and autopilot in “Selected Guidance” mode Whole approach conducted in “Track/Flight Path Angle” mode Trajectory-guidance via target-flight path angles - selected at three pre-defined waypoints Pre-flight calculation of point of descent according to forecast-weather-data Glide path intercept and stabilization of aircraft performed by the autopilot Level flight at initial approach altitude at max. 250 kts 1 POINT OF DESCENT Constant speed descent at max. 250kts and - 2.8 ° FPA 2 APPROACH FLAPS GEAR DOWN LANDING FLAPS Deceleration segment with configuration phase at - 1.0 ° FPA 3 GLIDE PATH INTERCEPT FPA -2.8° DECELERATION FPA -1.0° Steep approach segment with - 5,4° FPA at VTGT+10kts and final configuration 4 Outer Marker SCDA Procedure Reference-LDLP Reference 3° ILS Glide Path FPA -5.4° Glide path intercept, deceleration to VTGT and stabilization for final approach on - 3° FPA ILS-glide path at VTGT 5

SHORT-TERM SOLUTIONS Noise metrics of SCDA compared to LDLP Noise reduction within the approach area until nominal glide path intercept from above

SHORT-TERM SOLUTIONS ATTAS flight test at Braunschweig Research Airport Braunschweig airport has some local peculiarities, such as 3.5° glide slope and 2200 ft AGL intermediate approach altitude Operational feasibility was achieved using existing functionality of auto-pilot / auto- thrust systems The used “Selected Flight Path Angle Mode“ requires a timely turn in of appropriate FPA values Maximum allowable sink-rates (from SOPs) were adhered Compensation of outer disturbances, like horizontal wind changes, was not possible A reduction of up to -8 dB maximum A-weighted sound level was metered at a distance of 8 nm to the runway threshold Low Drag Low Power / Segmented Continuous Descent (1) / Segmented Continuous Descent (2)

CONCLUSIONS Noise saving potential of future approach and departure procedures could be demonstrated Safety standards are maintained Ecological and economical demands are taken into account Operational feasibility using todays on board equipment could be demonstrated More precise and safe flight path control can come up only using advanced on board and on ground equipment Further developments of flight management and flight control systems are necessary

THANK YOU VERY MUCH FOR YOUR ATTENTION! Dr. Reinhard König Email: reinhard.koenig@dlr.de Tel.: +49 531 295 2668 Fax: +49 531 295 2845 German Aerospace Center Institute of Flight Systems Lilienthalplatz 7 D-38108 Braunschweig Roman-Georg Huemer Email: roman-georg.huemer@dlr.de Tel.: +49 531 295 3213 Fax: +49 531 295 2220 German Aerospace Center Flight Department Lilienthalplatz 7 D-38108 Braunschweig