Noise Per Seat

or

How to Increase Annoyance without really Trying

Bill Swan

Economist

BOEING

Commercial Airplane Group

Marketing

July 2000

Noise per Seat Lowest for Small Airplanes

this is PER SEAT, not per departure

Bigger airplanes make more noise PER SEAT

not only is per departure noise higher, but so is per passenger noise

If you drive airports to fewer airplane movements per day

air travel moves to larger airplanes

total noise increases

This result is revolutionary

counter-intuitive for many

means limiting departures will increase noise

reducing noise will mean using smaller airplanes & more departures

Now, can we really explain how we got these numbers?

Movement Mix at Airports

Take 1% of the world’s scheduled passenger jet departures

Think of it as Amsterdam’s Schiphol airport in size

Departures per Day
Seats / Short Haul / Long Haul / Night Short / Night Long / Total
75 / 31 / 0 / 1 / 0 / 31
100 / 83 / 0 / 2 / 0 / 85
125 / 103 / 1 / 2 / 0 / 106
150 / 115 / 2 / 4 / 0 / 121
175 / 18 / 3 / 1 / 0 / 22
200 / 23 / 6 / 1 / 1 / 30
250 / 12 / 4 / 1 / 1 / 18
300 / 10 / 5 / 0 / 1 / 15
350 / 1 / 1 / 0 / 0 / 2
400 / 7 / 7 / 0 / 1 / 16
TOTAL / 402 / 29 / 11 / 4 / 446

short haul under 1600 kilometers; 3200 for widebodies.

night defined as after 2300 and before 0600

Apply Stage 3 Departure Loudness


Total Noise Combines Loudness and Frequency

Noise is measure of Annoyance at one spot on the ground -- one person listening

Day-Night Level (DNL) is total noise estimate

one of several in common use

imperfect but as sensible as any

DNL makes sense:

louder is worse

more frequent it worse

moving from 50 to 60 per hour not as bad as from 10 to 20

adds 10 dB for night operations

Nsis Number of departures of airplane size s

epnl is the single-event noise level (with 10 added for night)

Noise Per Departure is Change in Total

noise reduction for removing one departure

DNL value at start was 70.7 total for all movements on list

How much does total noise change for one departure?

Requires two DNL calculations and taking the difference

Added Noise Per Departure
Seats / event
epnl / DNL Noise
75 / 89.4 / 0.64
100 / 90.3 / 0.80
125 / 91.3 / 1.00
150 / 92.2 / 1.25
175 / 93.2 / 1.55
200 / 94.1 / 1.94
250 / 96.1 / 3.01
300 / 98.0 / 4.68
350 / 99.9 / 7.28
400 / 101.8 / 11.34

Noise Per Seat Divides by Seats

per-seat measure is noise per passenger

Noise Per Seat, Index
Seats / Noise / Noise/seat
75 / 0.64 / 1.07
100 / 0.80 / 1.00
125 / 1.00 / 1.00
150 / 1.25 / 1.04
175 / 1.55 / 1.11
200 / 1.94 / 1.21
250 / 3.01 / 1.50
300 / 4.68 / 1.95
350 / 7.28 / 2.60
400 / 11.34 / 3.54

These are the values plotted on the original graph:

Normalized Against their own Lowest Available,

Actuals Show the Same Pattern


Consequences Are Surprising

intuitions about departure frequency are misleading

Example: replace 2 departures at 125 seats with one at 250 seats

total noise goes up 50%

5-days-a-week at 250 seats makes same noise as twice-daily at 125

large airplane/constant noise reduces air travel by 30%

Limits on departures will increase total noise

if air travel is anywhere near original total seats

Noise reductions can be achieved by adding departures

accompanied with reductions in airplane sizes used

Reducing noise at airports will require

more departures

smaller airplanes

Frequency caps will increase total noise

unless air travel is curtailed dramatically

Simple Measurements Do Not Reduce Noise

but simple things will

83% of departures are narrow-body short-haul daytime

they contribute only 28% of the departure noise

based on being 3dB quieter than long-haul levels

these will be eliminated first with departure limits

1% of departures are wide-body long-haul nighttime

they contribute 26% of the noise

these will not be the first to be eliminated

Drasticdeparture-reduction plan:

reduce departures from 446 to 266

eliminates all below 125 seats, plus 60% of 125-seaters

OR

Reduce the wide-body sizes by one step (50 seats)

requires 6 more operations per day for same seat total

reduces noise the same as drastic departure-reduction plan

Can Institutions Work to Reduce Noise?

Political constraints can limit travel while increasing noise

Noise per seat higher for larger aircraft.

Noise certification levels miss big short-haul noise savings.

Measures that miss these two effects will not limit noise effectively.

Can institutions develop measures that will?

Airline Industry Analysis Page 1 c:\user\projects\noise\NoiseView.doc 11/02/2018 3:06 PM