Approach noise measurements

Fact Check: Measured outdoor noise level
Complaints generally report "loud" or "bad" noise from jet freighters. So far contacts with homeowners who live at or near points that should have the maximum possible exposure to freighter overflight noise indicate that no noise problem exists. What do measurements of the noise show?

The table below is gradually accumulating new noise level measurements made by the author of this web site, using a meter with calibrated accurracy of ± 1.5 dB. All measurements are in dBA, A-weighted decibels. All measurements reported on this page are for L_max, the maximum sound level observed during an overflight, using the meter's max-hold feature to capture L_max.

Freighter noise measurement summary (L_max, maximum sound level)

	West ridge site	EDH CSD site	Bay Area comparison: Foster City at San Mateo Bridge Outer Marker for SFO approaches
Number of measurements:	28	26	70
Minimum L_max:	58.2 dBA	58.7 dBA	62.3 dBA
Average L_max:	66.8 dBA	63.8 dBA	71.2 dBA
Maximum L_max:	77.1 dBA	68.9 dBA	84.3 dBA

NNI noise index:	11.7	7.3	46.2
Noise complaints per thousand approaches:	1,919		2
The noise complaint rates were checked for the first seven months of year 2008. For flights over EDH complaints originating from both EDH and Folsom are counted. In most months this accounts for about 97% of all noise complaints correlated with flights to and from Mather. If reports from a single complainer in Rescue are discounted, Folsom and EDH account for about 98% to 99% of all Mather noise complaints. The NNI noise index models noise annoyance, based on average noise level per flight and average number of flights per day. A value of 0 represents no noise annoyance, values less than 35 represent insignificant annoyance.

This is based on all measurements to date. "West ridge site" is directly below the ILS approach to Mather Runway 22L at the highest point on the west ridge of El Dorado Hills. "EDH CSD site" is also directly below the same ILS approach path, but is near the CSD Pavillion, at a lower elevation.

Basic unweighted sound measurements in decibels (dB) measure sound pressure levels without regard to frequency. A-weighted decibels are the most common derived measurement, using a frequency-dependent weighting function to produce dBA values more nearly representing the sound level perceived by human hearing.

Sound level measurements
Measured noise histograms

Photo gallery of notable extremes

Quietest freighter approach at west ridge: 58.0 dBA, Boeing 757-200
Loudest freighter approach at west ridge: 77.1 dBA, Airbus A300-600
Second loudest approach at west ridge: 74.9 dBA, Boeing 767-300 while extending landing gear
Loudest aircraft of any type at west ridge: 81.1 dBA, V-22 Ospcey (military)
Sound level at Mather, just off the end of the runway: 94.2 dBA, Airbus A300-600

Quietest freighter sound level measured to date in EDH: 58.0 dBA
Overflight at 16:23, 2/4/2009
757-200 over EDH west ridge
3,875 feet above mean sea level, ~2,175 feet above ground level, on standard ILS glide slope
High approaches, well above the glide slope, have been observed
but their sound level could not be measured reliably due to ambient noise

Highest civilian freighter sound level measured to date in EDH: 77.1 dBA
Overflight at 17:28, 11/13/2008

Not much to see in the dark.
These lights belong to the inbound Airbus A300-600 on the ILS glide slope. With nothing unusual in its flight path, first guesses for factors producing higher noise than usual would be relatively higher airspeed, atmospheric factors, and possibly aircraft configuration. If airspeed was high the crew may have had spoilers extended in order to track the glideslope while slowing; Spoiler extension also adds noise..

Second highest civilian freighter sound level measured to date in EDH: 74.9 dBA,
Overflight at 17:11, 10/24/2008
767-300 with landing gear transiting, wheel wells open, when directly overhead
loudest approach, aircraft view

Loudest noise measured to date in El Dorado Hills
for all types of aircraft: V-22 Osprey, 81.1 dBA
Overflight at 17:19, 10/9/2008
Military aircraft such as the V-22 are exempt from FAR 36 noise limits.
A noise level similar to this measurement but not measured occurred on an overflight of this author's home by an Air Force C-17 cargo jet (4 engines).

How to find a loud approach: Stand in front of the runway!
94.2 dBA measured for an Airbus ~ 150 feet overhead
Overflight at 17:26, 2/12/2009
Click on any of the images below for photos at full resolution. Download may be slow due to large image size

Freighter Noise Measurement Log

This table records all measurements of jet freighter approach noise since starting these acquisition of a sound level meter at the beginning of October, 2008. The second section of a table includes a sparse sample of aircraft noise measurements which do not involve air carrier cargo operations at Mather Airport..

Codes used to designate the measurement site in the Site column are: "WR" for EDH west ridge, directly below ILS approach; "CSD" for El Dorado Hills Community Services District, near the Pavilion building, within about 200 feet of a position directly below the ILS approah; OTH for "other", location described in notes.

Date	Time	Flight	AC Type	L_{max (dBA)}	Site	Notes
10/2/2008	16:03	UPS2960	757-200	66.3	WR
10/2/2008	17:24	UPS2958	767-300	65.5	WR
10/3/2008	16:55	UPS2958	A300-600 or 767	inaudible	OTH	Sighted aircraft while driving, 1 to 2 miles short of reaching the observation point on Ridgeview: Pulled over onto the shoulder of EDH Blvd, about 500 feet north of the power lines, to attempt measuring noise. Jet noise was inaudible, covered by road traffic noise. Traffic noise was steady, measured between about 80 to 83 dBA.
10/3/2008	18:01	ABX406	767-200	66.1	WR	Meter was reset just before registering L_max. A car passing on the street just before that time produced a noise reading just over 72 dBA.
10/10/2008	17:00	UPS2958	767-200	63 - 66 (estimated)	WR	Sound level is estimated by audible comparison to samples above. Wind at this time was too high for a valid reading from the meter: Peak sound measured 80+ dBA due only to wind at the meter's microphone. The apparent jet sound level seemed slightly quieter than other approaches, probably due to sound dispersion caused by air turbulence in the windy conditions. This estimate is not used in in statistics for average L_max.
10/12/2008	18:08	ABX1755	767-200	67.4	WR	Initial approach south of ILS due to conflicting traffic (Cessna 210). The 767 joined turned onto the ILS approach path slightly west of LDORR and several hundred feet above the glide slope. Photos show early flap extension to flaps 15 and use of spoilers to capture the glide slope from above. Altitude at EDH west ridge was still about 300 to 400 feet above the glide slope.
10/14/2008	16:01	UPS2960	757-200	60.7	CSD
	16:59	UPS2958	A300-600	68.5	CSD
	17:59	ABX1755	767-200	66.5	WR
	18:03	ABX406	767-200	59.4	WR
10/16/2008	16:51	UPS2958	A300-600 or 767-300	63.8	CSD
10/16/2008	17:28	UPS2798	757-200	61.2	WR
10/17/2008	16:55	UPS2958	767-300	63.1	CSD
10/21/2008	16:22	UPS2960	757-200	64.8	WR
	17:09	UPS2958	A300-600	68.0	CSD	ear down, flaps 15. Flight track shows the aircraft entered the area high and fast, well above the ILS glide slope and fast enough to level briefly near Garden Valley at 10,500 feet to reduce speed. Descent rate suggests the crew dropped the gear and went to flaps 15 at that point. The aircraft dropped through the glide slope approximately at LDORR and continued descending. below the glide slope. It appears to have added throttle when crossing Serrano about 500 feet below the glide slope, then crossed the EDH western ridgeabout 300 to 400 feet below the glide slope.
	17:56	ABX406	767-200	58.7	CSD	Quiet approach, very close to ambient noise, L_max reading could possibly be a spike in ambient.. This was a high overflight. The approach began exactly like the preceding UPS 2958 approach, but the aircraft didn't dirty up after slowing. It crossed the IAF (CAMRR) ~2,000 feet above the glide slope and crossed CSD about 1,500 feet above the glide slope.
10/23/2008	17:30	UPS2798	757-200	inaudible	OTH	Sighted from Lakehills Drive near Salmon Falls, estimating slightly less than 2 miles from ILS/Locator approach path.
10/23/2008	17:58	ABX406	767-200	65.0	CSD
10/24/2008	17:11	UPS2958	767-300	74.9	WR	Several dB louder than loudest prior approach. This is an outlying data point: The loudest prior measurement at this site (EDH west ridge) was 67.4 dB. L_max = 74.9 dBA probably is correct, but a component of this sound level measurement may have been from passage of a car on the street with maximum car noise preceding maximum aircraft noise by about 3 seconds. Landing gear were being extended while the aircraft was directly overhead. Photo shows wheel wells open, gear in transit, flaps 15. The temporary condition of having wheel wells open probably contributed to aerodynamic noise. The aircraft passed the IAF (CAMRR) about 500 feet above the glide slope. Its sink rate increased soon after passing LDORR. The flight track suggests that it captured the glide slope roughly over Serrano, where decreased sink rate suggests possibly having added some power.
10/24/2008	18:02	ABX406	767-200	61.1	CSD
10/28/2008	16:11	UPS2960	757-200	63.0	CSD
10/28/2008	17:35	UPS2836	757-200	inaudible	OTH	While driving on EDH Blvd near CSD with convertible top down the aircraft passed directly overhead. No jet noise was discernable, its level was below that of ambient noise (road noise + traffic noise).
10/30/2008	16:18	UPS2960	757-200	63.1	WR
10/30/2008	16:56	UPS2958	A300-600	71.1	WR
10/31/2008	16:47	UPS2958	767-300	67.8	WR
11/4/2008	16:39	UPS2960	757-200	60.6	CSD
11/4/2008	16:52	UPS2958	A300-600	68.9	CSD
11/10/2008	17:55	ABX406	767-200	inaudible	OTH	Observation while driving on EDH Blvd with convertible top up and windows closed, passing CSD while the aircraft crossed directly overhead.
11/11/2008	16:09	UPS2960	757-200	71.4	WR	Approach may have been a few degrees louder than usual due to weather conditions. A solid stratus overcast probably resulted from a fairly strong temperature inversion.
	17:20	UPS2958	A300-600	72.1	WR	Loudness may have been affected by same weather conditions as for UPS2960 as well as by VNAV. The aircraft flew ~500 feet below the ILS glide slope from first appearance on WebTrak, probably ~ 15 miles northeast of CAMRR, until reaching the EDH eastern ridge. At that point it added throttle to reduce sink rate to about half normal. It intercepted the glide slope just west of the EDH western ridge.
	17:32	UPS2836	757-200	inaudible	OTH	Approach path found on WebTrak passed almost directly over my house, with house about 1/10 mile offline at ~4,300 feet msl (~ 3,500 msl). House windows were closed.
11/13/2008	17:28	UPS2958	A300-600	77.1	WR	Unusually loud. WebTrak showed a normal approach, on the glide slope, at all points west of LDORR. Conjectures for possible factors producing atypically high noise are (1) atmospheric conditions, and (2) relatively heavy cargo load.
11/14/2008	17:19	UPS2958	767-300	barely audible	OTH	Approach was south of ILS as it crossed EDH Blvd, was observed from Olson Lane, a few hundred feet from EDH Blvd, about a mile from where the aircraft crossed EDH Blvd. Sound was barely audible amid ambient background noise, mainly EDH Blvd traffic. The jet's sound level was too low to register on the meter,which was showing ambient noise about 65 dBA.
11/14/2008	18:01	ABX406	767-200	62.9	CSD
11/17/2008	18:04	ABX406	767-200	66.2	WR
11/18/2008	16:10	UPS2960	757-200	64.5	CSD
	17:00	UPS2958	A300-600	71.3	WR
	17:44	UPS2836	757-200	59.7	CSD
11/20/2008	17:22	UPS2958	A300-600	72.2	WR
11/20/2008	17:31	UPS2798	757-200	58.2	WR
11/21/2008	17:03	UPS2958	767-300	barely audible	CSD	Approach was converging on the ILS locator course from the south, passed about 1 1/2 mile south of CSD. Jet sound was too low to distinguish on the meter, barely possible to pick out from ambient background by ear.
11/25/2008	16:25	UPS2960	757-200	64.5	WR
	17:19	UPS2958	A300-600	68.7	WR
	17:56	ABX406	767-200	66.4	CSD
12/2/2008	16:21	UPS2960	757-200	63.9	WR	Analysis of flight track data indicates that the louder of these two flights flew about 20 knots faster over EDH than the quieter flight. These were both 757-200's on virtually identical approach paths, including glide slope, only a few minutes apart.~1,000
12/2/2008	16:29	UPS2962	757-200	68.3	WR
12/3/2008	17:09	UPS2958	A300-600	66.7	CSD	Level and low, ~3,000 feet. ATC altitude direction was for clearance from a Beech Baron holding at 5,500 feet.
	18:04	ABX406	767-200	63.8	CSD
	18:18	UPS2964	757-200	61.0	CSD
12/4/2008	17:00	UPS2958	A300-600	63.3	CSD	Approach was about 2,300 feet above glide slope at CSD.
12/10/2008	16:08	UPS2960	757-200	~60 - 65	WR	A few dB quieter than 2958 (next in table); lost L_max on meter by personally making a louder sound.
12/10/2008	16:55	UPS2958	A300-600	66.8	WR
12/11/2008	17:18	UPS2968	A300-600	66.9	CSD
12/16/2008	11:38	UPS2603	DC-8-70	72.9	WR	Dirty configuratione: Gear extended, flaps appeared to be fully extended. Aircraft was converging on the glide slope from above, had been ~2,000 feet above glide slope at CAMRR, down to ~300 feet above glide slope at EDH west ridge.Sound level is partly due to this being a 4-engine transport.
	12:51	UPS2583	A300-600	70.5	WR	~200 feet above glide slope but appeared to be carrying more than 15 degrees of flaps.
	16.15	UPS2860	757-200	70.1	WR
	17:54	UPS2962	757-200	61.5	WR
	18:34	UPS2960	757-200	61.9	WR
	19:00	UPS2958	A300-600	~69	WR	Couldn't identify exact L_max, a car passed by exactly at the time of L_max.
	19:11	UPS2964	757-200	60.7	WR
12/23/2008	18:00	UPS2964	757-200	63.7	CSD
	18:07	ABX406?	767-200?	59.9	CSD
	18:11	UPS2958	A300-600	64.4	CSD	Not yet on ILS, probably passed about 1/4 to 1/2 mile south of CSD.
12/31/2008	17:54	ABX406	767-200	66.5	CSD
1/7/2009	16:14	UPS2960	757-200	59.1	CSD
	17:32	UPS2958	A300-600	67.6	CSD
	18:02	UPS2836	757-200	totally inaudible	OTH	Attempted measurement from inside CSD Pavilion. This 757 passed ~ 1 hour after departing Boise, was on the glide slope as it overflew CSD at 4,203 feet. Its entire approach was nominal.
Other noise measurement samples of interest (not freighters or not from El Dorado Hills)
Date	Time	Flight	AC Type	L_max	Site	Notes
10/9/2008	17:19	--	V-22	81.1	WR	USAF V-22 Osprey (twin engine tilt-rotor VTOL) crossing the ILS, generally north to south. Flight path was directly overhead in a shallow cruise-descent. WebTrak showed a crossing altitude of about 5,400 feet msl, ~4,300 feet agl.
11/6/2008	16:52	--	UPS delivery truck	82.1	WR	Surface traffic: UPS delivery truck passing tthe west ridge observation point on Ridgeview. Most cars and SUVs record L_max in a range of about 60 to 75 dBA, most around 65 to71.
2/12/2009	17:26	UPS2958	A300-600	94.2	OTH	Observed from Mather Blvd, within about 15 feet from the extended runway centerline, as the aircraft passed about 150 feet overhead.

Measurements above are by personal use of a hand-held meter, with calibrated accuracy ± 1.5%. Unless otherwise noted the observation point is on Ridgeview (top of EDH western ridge) directly below the ILS approach path. Ground level at this point is about 1,100 feet MSL, possibly as high as 1,110 feet. The glide slope crossing altitude at this point appears to be between about 3,700 feet and 3,900 fees MSL. This is the point in El Dorado Hills with minimum slant distance to the ILS glide path.

References

Also see additional references cited in Fact Check: Indoor noise level

Mather Airport Continuous Descent Approach (CDA) Noise Analysis Report, Sacramento County Airport System, Novmenber, 2006.
Summary: Use of CDA procedures reduced approach noise by approximately 4 dB relative to non-CDA approach procedures. Average maximum noise (L_max) at a measurement site on EDH's west ridge was 61.2 dB for CDA approaches, 64 dB for non-CDA approaches.
Original source on web: http://www.sacairports.org/noise/CDA/CDA%20ESA%20Report_110806.pdf
Technical Memorandum, Noise Measurements and Analysis of Nighttime (10 pm - 7 am) UPS Flights Along the ILS Approach Corridor to Mather Airport, Harris Miller Miller & Hanson, Inc., June 24, 2004
Summary: Measured noise (Lmax) at the west ridge of El Dorado Hills averaged 65 dB for nighttime approaches flown by UPS flights.
Original source on web: This document appears to no longer be on the web site of its original source, the Sacramento County Airport System.

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