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

2. 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

3. 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

4. AIRCRAFT NOISE SOURCES
Source:
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

5. 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

6. 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)

7. 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

8. 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

9. LOW NOISE DEPARTURE PROCEDURESVY 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

10. 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“

11. 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

12. 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

13. 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

14. 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)

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

16. 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

17. 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

18. 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

19. 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

20. 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 ° FPA 2
APPROACH FLAPS
GEAR DOWN
LANDING FLAPS
Deceleration segment with configuration phase at ° 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

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

22. 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)

23. 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

24. THANK YOU VERY MUCH FOR YOUR ATTENTION!
Dr. Reinhard König
Tel.:
Fax:
German Aerospace Center
Institute of Flight Systems
Lilienthalplatz 7
D Braunschweig
Roman-Georg Huemer
Tel.:
Fax:
German Aerospace Center
Flight Department
Lilienthalplatz 7
D Braunschweig