Notes for presentation slides

These are summary notes to accompany the PowerPoint presentation titled "Noise or Annoyance?". In some places where common journalistic convention is to use the term "this writer", this text instead uses the personal pronoun "I", recognizing that thes parts refer to first-person testimony as a witness.

The slides were designed to be used with verbal narration to fill in information that would tend to be cumbersome if included in the slides. This set of notes is intended to provide a minimal replacement for that narration in order to allow distributing the presentation by web posting, by email, or by printed copy.

Slide 1:  Title slide ("Noise or Annoyance?")
The title introduces the basic concept that objectively measurable noise and public annoyance are not necessarily directly coupled. Seminal research into the question of annoyance is primarily from England and Europe, where historic patterns of development around major airports produced generally higher levels of noise exposure than have existed at major U.S. airports.

The photo shows a Boeing 757-200 freighter operated by UPS approaching the west ridge of El Dorado Hills. Perspective makes both the treetops in the foreground and the freighter appear closer than they would in unaided human vision: This photography used a zoom lens at 200 mm focal length, and the resulting image was cropped in digital postprocessing.

The 757-200 has an authorized Constant Descent Approach procedure and has logged the lowest Lmax sound measurement measured to date by this writer on the EDH west ridge:  58.0 dBA.  The 757 CDA procedure calls for throttles at idle, flaps 1 at this point, going to flaps 15 after passing the ridge. ("Flaps 1" is the setting for leading edge slats extended to their intermediate position, trailing edge flaps unlatched.)


Slide 2:  Approaches as portrayed by critics...

This uses one photo to convey a sense of the impression given by noise critics in comments at local public meetings. The classic example was testimony at an EDH CSD meeting by an EDH complainer who said that early morning jet noise wakes him up even when he is using earplugs while sleeping. This individual lives about 1.6 miles offline from the ILS course. My experience has been that this distance is at the limit of audibility for freighter approach noise while listening from a quiet area, with ambient noise around 35-40 dBA. Published research indicates that noise level is reduced by about 15 dB inside a house with windows open and about 35 dB by typical earplugs.

The actual photo is an Airbus A-300-600F about to land at Mather in late afternoon twilight. Photography was from Mather Blvd, just off the approach end of Runway 22L, with the freighter at about 150 feet above ground level. Its configuration is with landing gear down, flaps and slats fully deployed for landing, spoilers retracted, and throttles slightly above flight idle. Actual measured noise for this overflight was 94.1 dBA.  Actual A300 approaches at the EDH west ridge have tended to average about 68 dBA.


Slide 3:  Sanity Checks...

This slide is reasonably self-evident.  In not quite these words, it suggests questioning to what extent our situation is consistent with others versus being anomalous with respect to (a) noise and (b) annoyance.


Slide 4:  Locations of frequent complainers

Despite the title referring only to complainers (needed for brevity) this is about the geographic scope of  potential exposure to noise from the ILS approach and how significant complainers' home locations correlate with potential noise exposure.

Slide 5:  Homeowners reporting no jet noise problem

This is similar to Slide 4 except that it plots home locations and one office location of people who report no freighter noise problem. I have not sought out such reports but have heard them in incidental personal contact with the people in question, usually while I've been "on station" under the ILS at either the EDH west ridge observation point or the EDH CSD observation point.

I've talked with three of the four homeowners on Ridgeview whose property is directly below the ILS approach. One person encountered at that location is a contractor who formerly lived in Folsom at a location he reported to be under the approach path. One person encountered while he was walking among CSD facilities indicated his home's approximate location nearby. One person with a CSD office stated that he did not hear approaches from his office.

Two significant individuals are not noted on this slide because I do not know their exact locations. One said this at a Community Countice meeting: "I don't know about jet freighter noise, but my quality of life is in the toilet because of traffic noise from El Dorado Hills Blvd." The other submitted a letter to the editor which was published in Village Life saying that he lived on the EDH easern ridge, which is mainly in Serrano property, and experienced no problem with jet noise, although about once every other year one would pass over with more noise than would be desirable.


Slide 6:  Interwoven Issues

This summarizes questions in need of answers. The slide is substantially self-sufficient.


Slide 7:  Radar or DME Required

An image clipped from the IFR approach plate for the Mather ILS to Runway 22L.

The key points highlighted in yellow are the approach fixes:  CAMRR, LDOOR, YOSHE, and GADBE. These are based on tracking the localizer and receiving DME information from SAC VOR.

The spot highlighted in orange is the highest obstacle near the ILS approach. This is at 1,126 feet, at the EDH west ridge. Maximum elevation is slightly higher on the east ridge,about 100 feet, but the ILS glide sope is about 600 feet higher than at the west ridge.


Slide 8:  Mather ILS Vertical Profile

This shows crossing altitudes for the ILS 3-degree glide slope:  6,500 feet msl at CAMRR, the Initial Approach Fix; 5,000 at LDORR; 3,000 at YOSHE; and 1,800 at GADBE, the Final Approach Fix. Altitude at each fix determines its location:  Given a specific altitude, such as 6,500 feet MSL, the fix is located by identifying the DME distance from SAC VOR that corresponds to the point on the Mather 22L locator course that crosses that altitude on a 3-degree glide slope.


Slide 9:  Nominal ILS Approach, at Initial Approach Fix

A captured screen image of a WebTrak rendition of a typical early morning ILS approach shows UPS 956 passing CAMRR, the Initial Approach Fix, at a crossing altitude of 6,509 feet. Annotations added to the image mark the locations and crossing altitudes of three of the four ILS fixes: CAMRR, LDORR, and YOSHE.

This particular approach involves a 757-200 at 4:15 a.m. It's flight track is typical of early morning arrivals from the east, two of which occur in early morning hours, normally 5 days per week. Many of these arrivals are Constand Descent Approaches, with the approach's flight path actually being established over Squaw Valley VOR. Non-CDA approaches sometimes involve descents which reach 6,500 feet early and use level flight at 6,500 feet until they intercept the glide slope at CAMRR.


Slide 10:  Nominal ILS Approach, at El Dorado Hills west ridge

A second captured screen image shows the WebTrak rendition of the same approach as the aircraft reaches the west ridge of El Dorado Hills, the point of maximum measured noise in El Dorado Hills.  This flight track sampled ATC data a few seconds before the 757 overflew Ridgeview Drive. The reported altitude is 4,058 feet msl, typical crossing altitudes on the glide slope directly above Ridgeview are around 3,900 feet.

Annotations added to the image mark the points at which the ILS approach crosses the east and west ridges of El Dorado Hills and show the typical crossing altitudes at both points. Ground elevation is about 1,100 feet at the west ridge crossing, about 1,040 feet at the east ridge crossing.

The highest point on the east ridge is to the south/southeast at about 1,260 feet msl but is offline from the ILS approach by about 1.1 mile. Minimum terrain clearance in El Dorado Hills is at the west ridge point marked on the ILS approach plate at an elevation of  1,126 feet.


Slide 11:  ILS intercept @ LDORR with sample other traffic examples

This is a flight track from an afternoon arrival, captured at 5:28 p.m. Unlike early morning arrivals, afternoon arrivals are often permitted to take direct routes to intercept the ILS instead of diverting through Reno and the Squaw Valley VOR waypoint. Such direct clearances would be expected to be issued by Oakland Center (enroute ATC) while the aircraft is over Nevada rather than by Northern California Approach Control while it is nearing the Sacramento area.

Most such direct arrivals turn onto the Mather ILS locator course at or near the Initial Approach Fix at CAMRR. Some, such as the one in this flight track, intercept the locator course closer in, near LDORR, north of Green Valley Road. My personal impression was that approach discipline increased in the fall of 2008, especially in terms of both altitude and course in what probably was final ATC guidance by Oakland Center for better coordination with approach control.

This flight track image illustrats two other examples of traffic in the area. One is the Lear 45 on approach to Mather -- not necessarily carrying cargo, but an example of business jets that are capable of causing noise annoyance.

The other flight illustrated with a data block is an Ameriflight Swearingen Metro 4, one of the types used in regional cargo service. Ameriflight also flies Beech 99 Airliners and Cessna 208 Caravans. The other major regional freight carrier operating at Mather is Redding Aero Enterprises, with Cessna 402's as the mainstay of its fleet. During the busy month of December, 2008, Redding Aero Enterprises appeared to synchronize arrivals and departures at Mather, as in hub scheduling. It is reasonable to consider the combination of these two commuter lines to be the constituents of regional hub operations at Mather, even though both use different airports for their base facilities.

The two small icons near Francisco Drive and Green Valley Road probably represent either one or two T-38s. These often cruise between Beale AFB and Mather, often at 3,000 feet msl, and have variously been observed to range from quite to louder than expected (about 75 dB) while level at 3,000. The small icon headed northeast over Folsom indicates an aircraft whose type is unknown in the ATC data. Its course and location are typical of air carrier departures from San Francisco and Oakland at altitudes usually over 30,000 feet.  The aircraft headed northeast in the Granite Bay area is on a route most often used by departures from Sacramento International,which usally are near 20,000 feet by this point.


Slide 12:  VFR approach south of US 50

This shows an afternoon arrival of UPS 2958, from Louisville, Kentucky, on a direct inbound route for a VFR approach. Westbound UPS flights from Louisville and Des Moine often deviate by 100 to 200 miles from a direct route in order to avoid jetstream headwinds and to minimize time needed to cross a jetstream when it flows toward the south or southeast on part of their route.  (Incidental note for the general public -- this involves computerized flight planning to minimize fuel use and delay.)

When one of these flights has deviated to the south it is common for it to obtain clearance for an arrival entirely south of US 50, instead of detouring northward to the Squaw Valley VOR waypoint.  These are VFR approaches, most overflying El Dorado County south of El Dorado Hills but sometimes crossing as far north as the Town Center area.  Most have straight tracks until they intercept the runway heading south of Folsom or Rancho Cordova.  This approach is unusual in that it includes a deviation to the south followed by an S turn to join the runway heading. This would be expected if necessary to maintain traffic clearance from another aircraft at a conflicting altitude in an area near US 50 and East Bidwell. A personal guess is that this shows exactly that but that the aircraft was not recorded on WebTrak. WebTrak uses certain filters for certain flights that may be security-sensitive. Something in the nature of a National Guard helicopter flight from Mather could possibly be in this category.


Slide 13:  Loudest 2008 freighter approach recorded in WebTrak: Probably about 85 dBA

This Evergreen Airways flight, not part of the regularly scheduled air carrier cargo service to Mather, used an anomalous VFR approach. The flight originated in Seoul, South Korea and made a stop at Travis Air Force Base before the short hop to Mather. This in combination with the flight track suggest that the flight crew probably was unfamiliar with Mather noise abatement procedures.

The aircraft was a 747-100, larger than all freighters in scheduled service to Mather, with a maximum takeoff weight of about 735,000 pounds and power supplied by 4 engines instead of 2. It overflew El Dorado Hills in level flight at approximately 3,000 feet agl in a wide arc before turning onto final approach, instead of joining the final approach course over rural land. Its altitude over the EDH western ridge was about 1,900 feet above ground level.

By comparison with the SFO approach used by 747 aircraft over Foster City and with noise measurements at that point for 747-400 aircraft, a reasonable estimate of EDH west-ridge noise for this particular flight would be around 85 dBA. The actual noise level could be either higher or lower by a few decibels.


Slide 14:  Approach from south by UPS 954 plus other traffic (week before Christmas)

The track of UPS 954 illustrates its normal arrival from a south/southeast direction, turning onto final approuch south of US 50 and not overflying either El Dorado Hills or Folsom.

This slide also illustrates an exceptional coincidence, with two ILS approaches in progress simultaneously. UPS 896 and UPS 554 are additional flights added to handle pre-holiday shipping demand in the week before Christmas. The regularly scheduled early morning arrivals that overfly El Dorado Hills and Folsom, USP 956 and UPS 958, normally arrive about an hour apart.


Slide 15:  Approach Usage

Approach noise exposure in El Dorado Hills and Folsom is mainly limited to noise from overflights on the ILS approach.

This pie chart is based on flight track data for the week before Christmas, 2008. It shows that nearly 3/4 of all freighter arrivals used the ILS approach, which overflies El Dorado Hills and Folsom. Data for other weeks in 2008 shows a somewhat lower percentage of arrivals on the ILS, generally in the range of 62% to 65%. The remaining quarter of arrivals used VFR approaches from several directions, with most flying the entire approach south of US 50, mainly over rural land. Arrivals from the north normally pass west of Folsom before turning onto final approach.
The week before Christmas produced a few unusual variations in approaches due to weather, mainly ground fog at the airport. Two arrivals from the north overflew parts of Folsom, rather than the Orangevale/Citrus Heights area, in order to use the ILS for final approach in the presence of insufficient visibility for a VFR approach. At least one flight arriving from the east entered a high holding pattern, at about 23,000 feet, white the field apparently was below IFR minimums. That flight left the holding pattern after about 10 minutes and diverted to Oakland.


Slide 16:  Approach Noise Exposure Potential

A related pie chart covering the week before Christmas breaks down freater approaches into three categories:
Not quite half of these freighter arrivals occurrend in early morning, when sleep disturbance could be an issue.


Slide 17:  Overflight Noise Measurement

A graphic based on one published on the Oakland Airport's web site shows sample renditions of typical noise levels as a function of time during an overflight. The original noise envelope, in purple, is directly from the Oakland graphic: It portrays background noise and overflight noise that probably is derived from data saved at one of Oakland's permanent noise monitors.

Personal noise measurements of the SFO approach at Foster City are substantially consistent with those reported by Oakland, except that the ambient background noise is higher. Those measurements were made at the Outer Marker radio beacon, which still has transmitter hardware in place at the shoreline. Ambient noise at that site is mainly from Highway 92 at the west end of the San Mateo Bridge.

The noise envelope colored gold instead of purple is the same envelope copied downward to suggest typical overflights of the El Dorado Hills west ridge. The apex of this triangular envelope correspends to the average Lmax values measured on freighter approaches over this site. Ambient background noise level is slightly off the bottom of the chart, at about 40 to 50 dBA at most times and lowering to about 35 dBA in late night/early morning hours.

Text annotations label key measurement points for Lmax (maximum sound level) and SEL/SENEL (single event) sound level. The "one second" annotation refers to visualization of SEL/SENEL measurements, which normalize the time domain to 1 second. A rough nontechnical description is that SEL/SENEL measurements preserve the area under the sound level curve but squash it laterally into a one-second duration. This produces a single number that corresponds to total sound energy, basically the area below the sound level plot.

Almost all documentation in this presentation and on the corresponding section of SierraFoot.org uses Lmax measurements. This is because:


Slide 18:  Actual Crossing Altitudes on ILS at Initial Approach Fix

A histogram plots actual altitude at CAMRR (Initial approach fix, labeled Shingle Springs) for all freighter ILS approaches recorded in the five one-week samples posted on SierraFoot.org. This was plotted with one '*' for each overflight. The location in question is in the northern part of Rescue, which is north of Shingle Springs.

The plot shows a large spike at the designated altitude of the initial approach fix, 6,500 feet msl. Altitude scatter at this point probably involves  details of air traffic control handoff of arrivals from enroute air traffic control by Oakland Center to Northern California Approach Control. 

This plot provides a fact check for comments published in the local press and made by a Shingle Springs resident who lives about 4 miles away from the ILS approach course, at an elevation of about 1,500 feet. The specific comment in Sacramento-area press was:

"Our houses are at 1,500 to 2,000 feet and those planes are at 3,000 feet." 

The commentor's home is at about 1,500 feet. The highest ground level in this portion of Shingle Springs is about 1,600 feet, but most of this area (mapped in El Dorado County Parcel Book 70) lies in the range of about 1,200 to 1,500 feet.

The data from recorded flight tracks shows no freighter approaches below 3,900 feet in Rescue or Shingle Springs. 95% of arrivals were at altitudes above 5,000 feet, 90% above 5,800 feet.


Slide 19:  Actual Crossing Altitudes on ILS at El Dorado Hills west ridge

A histogram plots actual altitude at altitude at the El Dorado Hills west ridge, on Ridgeview Drive, for all freighter ILS approaches recorded in the five one-week samples posted on SierraFoot.org. This was plotted with one '*' for each overflight.

The plot shows crossing altitudes closely clustered around a modal peak at 3,900 feet msl. 11 approaches clustered into a small secondary mode covering the range of 3,000 to 3,200 feet. One isolated approach was the lowest, at about 2,700 feet.


Slide 20:  For comparison: SFO Approach at Foster City, Bay Area view

This flight track image captures a reasonably typical moment in a weekday afternoon, with five air carrier aircraft in various stages of approach to land at SFO.  The flight track image illustrates arrivals from the general directions of east, south and west. Two approach tracks pass Foster City -- one inshore for landing on Runway 28L, one offshore for landing on 28R. The offshore approach converges on the final approach course for 28R and joins it approximately off Coyote Point or slightly to the east/southeast.

Total daily traffic for both approach tracks is approximately 400 arrivals.


Slide 21:  For comparison: SFO Approach at Foster City

A smaller-scale view of the approach paths shows their spatial relationship to Foster City. The 28L track crosses directly over homes on the inshore side of Beach Park Blvd. at a crossing altitude usually in the range of 1,800 to 2,200 feet. Crossing altitude is highly inconsistent among different approaches in comparison with Mather approaches from CAMRR to Mather Airport, and especially from LDORR to Mather.

Lateral alignment of the 28R flight track also varies substantially at Foster City. Although most approaches on this track pass about a mile offshore, some are closer in and have been observed as little as 1/4 mile offshore. Noise from the offshore track is a few dB lower than from the inshore track, at a level similar to that measured on the Mather approach at the EDH west ridge. The loudest approaches measured at Foster City are inshore approaches by Boeing 747-400 aircraft.


Slide 22:  Measured Noise

A bar graph compares measured values at the EDH CSD site and the EDH west ridge site, both directly under the ILS approach path, and at the Foster City (SFO outer marker) site. Separate clusters of bars compare the minimum, average, and maximum noise levels observed. All measurements are for Lmax, the maximum sound level on in dbA (A-weighted decibels).

Each cluster of bars shows noise levels to be minimal at the EDH CSD , intermediate at the EDH west ridge, and maximal at Foster City. The largest difference is in the maximum sound level, with a Foster City measurement being approximately twice as loud (near 10 dBA) as the maximum at the EDH CSD site.


Slide 23:  Measured Noise

Histograms show the distributions of measured noise at each site. EDH measurements were taken over an extended period in 2008, due to the low frequency of freighter arrivals. Foster City measurements were taken in two separate sessions, one about 40 minutes in duration and one about an hour in duration.


Slide 24:  Ranges of measured noise compared with other sources

Bars are superimposed on a published chart illustrating sound levels typical for automobiles, trucks, and trains ate distances of either 50 feet or 100 feet. Each bar uses color density to suggest the frequency of sound levels within the length of the bar.

Not shown in this graph are sound levels from many other sources. Talk in conversations and at meetings usually produces an Lmax range around 70 dBA plus or minus about 3 to 4 dBA. A UPS delivery truck has been measured at 82 dBA from beside Ridgeview Drive. Harley Davidson motorcycles have recorded Lmax up to 99 dBA.


Slide 25:  Approaches per day and Noise-Number Index for Annoyance

This graph compares two measures related to noise exposure for each of the three measurement sites: EDH CSD, EDH west ridge, and Foster City.

Approaches per day is self-evident. Foster City dominates this measure, with about 400 air carrier aircraft approaches per day. During 2008 the average number of approaches per day over El Dorado Hills and Folsom by freighters was about 7. This rate decreased at the start of 2009, when Airborne Express ceased all operations into Mather except one flight per day. That flight arrives from SFO around 8 a.m. in the morning.

The second comparison is the NNI Noise-Number Index. This is a quantitative estimate of noise annoyance based on average noise per flight and number of flights per day.


Slide 26:  NNI Annoyance & Complaint Rate

A table compares the numeric NNI index values for each measurement site with the number of noise complaints logged per 1,000 approaches, as reported by the noise offices for the Sacramento County Airport System and for San Francisco/Oakland International Airport.

NNI values for the EDH measurement sites are 7.3 and 11.7, Foster City is 46.2. The published literature identifies NNI less than 35 corresponds to substantially no noise annoyance and values such as Foster City's being in a range that can be expected to produce sporadic noise complaints. Actual complaint rates from Folsom and El Dorado Hills are nearly a factor of 1,000 higher than that for Foster City. Web reports from a selection of airports in the U.S. and around the world generally show that even those with serial complainers tend to log about as many complaints per year as Folsom and El Dorado Hills produce per month. Later slides show that Folsom and EDH are atypical for the Sacramento region.


Slide 27:  Can a single serial complainer dominate complaint statistics?

This slide answers "yes" by reproducing a pie chart captured from the Los Angeles International Airport's web site, summarizing sources of noeise reports from July, 2008. 84% of all LAX noise reports in that month came from one household in Monterey Park. Monterey Park is about 20 miles east/northeast of LAX. The center of that community lies about 3 miles north/northwest of the tracks for straight-in approaches from the east to Runways 25L and 25R. It lies a similar distance south/southeast of a parallel track used for departures to the east. A sample of departures observed on LAX flight tracks passed Monterey Park at altitudes of at least 17,000 feet. Approaches appeared to usually be around 5,000 feet when closest to Monterey Park.
Sacramento region.

From 1959 through 1963 I lived in El Segundo, on a hill overlooking LAX, 0.23 mile from Runway 25L. At that time noise from commercial airliners was from 707s and DC-8s using first-generation turbojet engines, normally using water injection for increased takeoff thrust. My estimate of sideline noise from such takeoffs is about 105 to 110 decibels: When a jet takeoff occurred it was necessary to suspend conversation for about 20 to 30 seconds. LAX still received more noise complaints from El Segundo than from other areas in the July 2008 sample, with the exception of the one household in Monterey Park.


Slide 28:  Serial Complainers & MHR

A pie chart shows the areas of origin of all noise complaints made in 2008 that correlated with flights to or from Mather (MHR). The graphed results were for 7,448 complaints from Folsom, El Dorade Hills, Rescue, and Shingle Springs; 22 complaints from areas near Mather; and 146 complaints from all other areas.


Slide 29:  Serial Complainers & MHR

A similar pie chart shows the areas of origin of all noise complaints made in 2008 that correlated with flights to or from Sacramento International (SMF). The total was 2,461 from Folsom/EDH/Shingle Springs complainers, 191 from complainers in all other areas.

This illustrates that Folsom/EDH complaints are also extremely disproportionate for SMF flights.


Slide 30:  MHR serial complaints by community

This pie chart breaks down subtotals by community for the complaints generated by the apparent serial-complainer areas. Results were 6,024 for Folsom, 1,686 for El Dorado Hills, and 155 for Rescue & Shingle Springs.


Slide 31:  SMF serial complaints by community

A pie chart in the same form as that on Slide 30 shows 1,579 complaints from Folsom, 622 from El Dorado Hills, and 34 from Rescue and Shingle Springs.


Slide 31:  Populace in general

This slide delivers a message, noting the disparity between overall public perception ("we have a freighter noise problem") and homeowners living directly below the ILS approach ("there is no problem"). It follows by noting that public opinion is formed by public dialog and news coverage, unless direct personal experience differs.


Slide 32:  Final message

Public discourse and public policy determine public perception.

If public agencies treat something as a problem the public perceives it as a problem.


Slide 32:  Final message

Ending screen: A treighter viewed from behind flies toward Mather, with a treetop in the foreground.