SR-0 (28)
e
Santa Monica, ~ifornia, July 8, 1977
-:f~tJ -- CJOy--- t::J-r'
TO:
Mayor and CIty Councll
FRO~1.
City Staff
SUBJECT:
Reduction of ~oise Limits at Santa ~onica Airport
Introduction
This report reviews the eliMination of night flIght operations and reduction of
current nOlse 1im2t restrictions at Santa ~onica Airport. It recommends the elImination
of night fllght operatIons at the alrport.
Background
Pursuant to the joint meetIng wlth the Alrport COmIDlSSIOn durIng December 1976,
the CIty Council requested that the Staff complete an analysls of:
1. The effects of reducing the current 100 db SENEL (Single Event NOIse
Exposure Level) limit to 90 db SENEL for all flights; and
2. Prohibiting all take off and landing operatIons between the hours
of 11:00 p.m. and 7:00 a.m.
Reduction of SE~cL limits frOM 100 db to 90 db
In order to accurately assess the impact of redUCIng the SENEL lImit from 100 db
to 90 db, Staff Isolated all flIghts that registered over 85 db on the ~irport
NOlse Monltorlng System for a period of four months, and placed them In 5 db
Intervals ranging from 85 db to 90 db, 90 db to 95 db, and 95 db to 100 db. The
summatIon of thls data as depicted in Table I Indicates that a reduction of nOIse
levels to the 90 db level would result in the ellmlnatlon of an average of 2.72% of
all flight operations at Santa Monica AIrport.
) I D
To: Mayor and City COu~
-2-
~
July 8, 1977
TA.BLE I
85-90 90-95 % 95-100 % 90-100 !Io Total
.
db db db db Operatlons
August ' 76 12 518 1.9 140 .5 658 2.44 26,965
February '77 18 424 2.1 101 .5 425 2.58 20 , 343
4.pnl '77 1370 676 2.76 138 .56 814 3.33 24,428
May '77 49 528 2.0 119 .46 647 2.52 25,645
I
Average percentage of total operatlons for fllghts
between 90 - 100 db = 2 72%
The Communlty ~Olse Level Effect of Ellmlnatlng Fllght Operatlons Over 90 db
In general, If nOlse events such as alrcraft flyovers are infrequent, the peak nOlse
level of indlvldual events wlll in most cases determlne individual reactlons to that
noise. However, If the nOlse events are relatlvely contlnuous, the cumulatlve noise
exposure becomes the more lmportant factor in gauglng community or resldents'
reactions to alrcraft nOlse. In reviewing the data In Table I for perceptible
CNEL (Cumulatlve NOlse Exposure Level) effect, Bolt, Beranek and ~ewman (nolse
consultants), projected that by reduclng the CNEL limlt to 90 db, a 1 to 3 db effect
could be achleved. In terms of communlty noise level (CNEL) reductlon. it lS Bolt.
Beranek and ~ewman's oplnlon that a 1 to 3 db CXEL decrease would be of marginal
consequence in lowerlng the percelved nOlse levels for residents in the 1mmedlate
vlclnity of the Alrport.
Bolt, Beranek and ~ewman substantlated th1S analyslS by Cltlng the example of
an experlment conducted in lnglewood
In this experlment, even though the movlng
and adjusting of nlght fllght patterns reslllted lTI a 2 db C~EL effect, the documented
To. ~Iayor and Cl ty coun.
-3-
-
July 8, 1977
resident response showed that the great rna]Orlty of resIdents had not noticed
any change. Further, during dlscussions wlth Staff, UCLA Professor Blll Meech am ,
Acoustical Engineer, also expressed doubt that eliminatIon of 2.72% of operatlons
consisting of fhghts in the 90 db to 100 db range would be substantIal.
Reaction to alrcraft nOlse is a comblnatlon of frequency as well as level. It is
Staff's bellef since total operatlons between 90 and 100 db amounts to 2.72% of
total fllght operatIons, any nOlse level reduction accompllshed by ellminating
those operatlons will provlde limited rellef to residents in terms of perceived
communlty nOlse level. The extent of relief will depend on the indivldual's
location to the alrport ~nd psychologlcal response to varlOUS levels of noise.
Financial Effect of Eliminating Flight Operations Over 90 db
Of the 440 a1rplanes currently tled down at Santa Monlca Airport, a 90 db
restr1ctIon could exclude up to approxImately 50 tWIn engine and 25 SIngle engine
aircraft (comblned estimated value -- ~1,000,000). In additlon, two Grumman I
turbo-prop aircraft (comblned estimated value -- $4,000,000), owned by Lear-Siegler,
Inc. and Hllton, Inc. would also be elimlnated. The resultant fInancial loss to
the Clty IS estlmated as follows:
Aircraft Petroleum Sales (net profIt)
~ircraft Tiedmi11 Rentals
Hangar T-201 Rental to Lear SIegler, Inc.
Aircraft Tax (property)
$20,000 per year
15.000 per year
18,000 per year
25,000 per year
$78,000
TOTAL:
It should be noted that the loss attributed to tiedown rental revenue would be
minlmized as vacancies are filled by replacement from new customers.
To:
Mayor and City coun~
-4-
~
July 8, 1977
The above figures represent direct estImated alrport revenue losses to the City,
and do not include losses that may be suffered by airport fIxed base operators.
The projected losses for the fixed base operators was not made avaIlable to the
Clty Staff, however, all operators were contacted and several Indicated that
losses would be substantlal.
RevIew of Lowering SENEL (Single Event Noise Exposure Level) LImits at Santa
MonIca Airport
The prImary conslderatlons in determlning the feaslbillty of reducing the SE~EL
limIts are communlty beneflt (C~EL effect) In terms of perceived noise level
reductIon, and financial impact on AIrport operatlons. Bolt, Beranek and Newman
suggest that a mln1mum CNEL effect of 5 dbs is required to achleve a perceptIble
Improvement in communlty n01se levels. Both SENEL and C~EL (Community ~oise Exposure
Level) are measures of A-weighted sound levels, a scale that suppresses low
frequency noises much lIke the human ear. The db(a) scale is used to assess noise
power or pressure levels, either as a slngle event in the case of SENEL or as a daily
community nOlse equivalent level, CNEL. The accumulation for C~EL lS adjusted to
glve more weIght to the noise occurrIng between 1900 and 2200 hours and most weight
occurrIng between 2200 and 0700 hours. Consequently, mere reductIon In SENEL does
not necessarlly guarantee an overall perceptible C~EL affect. A primary example is
the data gathered by Staff In explor1ng the possIbillty of redUC1ng the db level from
100 to 90.
The fact that the perceptible annoyance level of individuals is related to both
frequency of events and perceIved loudness of indIVIdual events suggests that a more
positlve C~EL effect may be achieved in Santa MonIca from combllllng levels of SENEL
reductIon wlth other Airport operatlng limitatlons, such as restricted pattern flying
and/or touch-and-go hours; the C~EL effect would exceed 5 dbs.
To'
Mayor and Clty coun~
-5-
4J
July 8, 1977
.:-
Therefore, In view of the above and the determlnation that a fully percept1ble
CNEL effect cannot be attalned by reduclng the SE~EL limits by 10 db, Staff
believe~ that a more complete study 15 necessary to determ1ne the necessary
comblnatlon of nOlse restrlctions to accompllsh a percept1ble effect. The
analysis would lnvolve the followlng research actlvity:
1. Programming of current n01se monitoring system to prlnt out all
flights over 70 dbs for a four month period. Th1S would allow
Staff to determine spec1f1cally what level db reduction would
generate a pOSltive CNEL effect.
2. Programming of current nOlse monitorlng system to compute
CNEL effect on a daily basls. ThlS would ass1st Staff in
projectlng the effect of pattern flying restrictlons, touch-
and-go restr1ctions and conversion of SENEL reduction to CNEL
effects.
3. Analysls of costs to C1ty and fixed base operators of any
nOlse reductlon program incorportating further SENEL restrictions
and/or other airport operation llmitations.
Prohibltion of Take-Off and Landing Operatlons Between 11'00 r.m. and 7:00 a.m
Evaluation of the data pertainlng to nlght flights as dlsplayed In T~~le II below
lndlcate that whlle nlght operat1ons conslst on the average of only .68% of total
monthly Airport operatlons, almost 80% of all nlght flights fall lnto the 90 to
100 db range.
To.
Mayor and City counc~
-6-
~
July 8, 1977
TABLE II
Total 90-100 db mght flights
85-90 90-95 95-100 Nigh t as % of as % of total
db db db Operations total night operatlon
operations
August t 76 58 16 74 100% .27%
February I 77 10 59 15 84 88% .41%
I
April '77 120 97 52 366 40,7% 1.5%
May t 77 13 103 26 142 90.8% .55%
Average percentage - total night operation for flights between 90 db - 100 db
79.8T
Average percentage - night fllghts as % of total alrport operatIons .68%
On the basis of thIS data, the effect of restricting night flights to the 90 db
SENEL lImit would be to drop the average SEXEL db per night fllght from approximately
92,2 dbs (weighted average) to a projected weIghted average of 86 to 88 dbs SENEL.
In db(a) weighted measurement a 5 db reduction lS equivalent to 40% reduction in
perceived noise. Consequently, Staff believes that a substantial nOlse level lmprove-
ment would be achIeved by reduclng SENEL limits for night flights from 100 db to
90 db.
Enforcement
Currently the City has no enforcement of 100 db SEKEL violations committed at night
when the flight tower is closed although the data IS recorded by n01se monitor1ng
equlpment. If a 90 db restriction is imposed for night fllghts, violat1ons would
~
To:
~myor and CIty counc~
-7-
~
July 8, 1977
be more prevalent and enforcement Kould require sophlsticated nOIse monltoring
equipment and attendant personnel. ~Iinlmum costs for equipment and personnel
would exceed $30,000 for the first year and $20,000 for subsequent years. In order
to clrcumvent costs related to enforcement of noise vlolatlons, Staff recommends that
all nIght flIght operatlons at Santa Monica Alrport be eliminated durIng the hours
of 11 00 p.m and 7'00 a.m. Enforcement would be carried out by eXIstIng guard
personnel unless thls proved to be insufficlent in practIce.
Flnanclal Effect of Restricting all FlIghts Between 11:00 p m. and 7:00 a.m.
h~lle several aircraft operators have Indlcated a preference for 24 hour access to
the Airport, it is Staff's opInion that ellmlnation of fllghts between 11.00 p.m.
and 7:00 a.m. would not cause an undue burden for most operators. Potential losses
in gasolIne sales should not exceed $5,000 annually.
AlternatIves
I. Reductlon of SE~EL lImIts from 100 db to 90 db
1. Do not approve any change in the current 100 db lImit until
further staff analysis lS completed -- This alternative recognIzes
that In addltlon to further data breakdown of all fllghts over 70 db
for the purpose of determlnlng a reduced SENcL lImit that would produce
a more beneflclal CNEL effect, lmprovement in the CNEL level may also
be achieved by combinIng lower SENEL restrlctions with other operatIonal
lImitatIons such as restrIcted pattern flying. thIS analysIs would also
have to include the flnancial effect of such action.
2 Impose restriction of 90 db -- ;nalysis of data collected by staff indicates
that a 10 db reduction in SF~EL would elIminate 2.72% of the total
airport flIght operations, wIthout providIng substantlal C~FL reductions.
;'
To:
d ~
Mayor an Clty Councll
-8-
~
July 8, 1977
II. Prohlbitlon of Take-Off and LandIng OperatIons Between 11:00 p.m.
and 7:00 a.m,
1. Prohlblt all nlght flights between 11:00 p.m. and 7:00 a.m -- This
alternatlve lS most acceptible in that It would allevlate the noise
problem for Airport residents durlng the nIght hours and should not
requlre addItional expendlture for enforcement.
2. RestrIct night flying to 90 db SE~~L -- ThIS alternatIve lS less
deslrable due to the difficulty and expense ($30,000) that would be
incurred as a result of attempting to enforce this ordInance.
3. Maintain current night fllght operations with no restrictions
thIS alternatlve would, of course, result in no change in the noise
level of the airport.
Recommendations
1. Staff recommends that the City Councll approve alternative number 1 in relatIon
to reductIon of SENEL lImIts from 100 db to 90 db. thIS would authorize the
Clty Staff to complete analysIs of fllght data over the next four months with
the objectlve of outllnIng to Councll a method of nOlse reductlon wIth speCIfic
costs to the AIrport and Airport operators. This report would be provlded to
Councll by December 1977.
2 Staff recommends that Council approve alternative 1 relating to prohibItion of
take-off and landing operations between 11.00 p.m. and 7'00 a.m. This alternatlve
would eliminate all night flights at Santa MonIca Alrport durlng those hours
and request that the City Councll authorize the City ~ttorney to draft an
ordInance for fIrst readIng.
Prepared by. Larry J. Kosrnont
AdmInIstrative Asslstant
LJK:pp