Air Carrier Cargo (Freighter) Approaches
Logs were compiled for one week of each month for 4 months

Logs

080301:  March 1 through March 7, 2008
080401:  April 1 through April 7, 2008
080508:  May 8 through May 14, 2008
080608: June 8 through June 14, 2008
081201: December 1 through December 7, 2008

Special case:  The week before Christmas week,with increased UPS traffic
Approaches: 081215: December 15 through December 22
Departures:  081215: December 15 through December 22

Excel spreadsheet listing all ABX and UPS operations, 4/1/2008 through 5/21/2008
Excel spreadsheet listing all ABX and UPS operations, 5/15/2008 through 6/20/2008


Summary of all air carrier cargo approach activity
from logs covering 4 weeks, early 2008
Type Count % of Total Average approaches per day
All approaches: 196 100% 7.00
ILS approaches over EDH: 126 64% 4.50
ILS over EDH in early a.m.: 56 29% 2.00

Potential noise exposure in El Dorado Hills, from all logs*
estimates for maximum sound level (Lmax) based on flight tracks,
*totals for noise exposure summaries exclude the portion of the first week of April for which WebTrak data was purged before the entire week's flight tracks could be captured.
Total Flights / % of total approaches
(116 total approaches with track data saved)
None
0 dB,
no overflight		 Low
65-70 dB,
~65 db average		 Low to
Moderate
~75 dB		 Moderate
~80 dB		 High
~ 85 dB
or more
 Approaches not over EDH: 58 flights 58
ILS approaches over EDH: 110 flights 94 13
 3 0
ILS over EDH in early a.m.: 49 flights 45 3 1 0

Capture and publication on SierraFoot of additional approach flight track data has been suspended because of the substantial personal time burden for doing this and the general consistency of flight track data seen so far. At the time of this update more than 1,000 freighter approaches have been checked on web tracks over a period now in excess of 6 months. So far no approaches have been seen that would be expected to produce noise over 80 dB and the percentage of approaches that may have produced noise between 75 dB and 80 dB is in the range of 1% to 4% of all approaches.

This author estimates the loudest noise observed personally during this time to have been about 77 to 80 dB for an overflight by an Air Force C-17 (four-engine freighter) in level flight at about 2,200 feet above local ground level. The loudest prior approach was in approximately 1994, estimated to be about 85 dB for an Air Force B-52H (8-engine bomber) in level flight about 1,500 feet above ground level.

Notes for noise estimates:

See the comparison with environmental noise to compare these noise levels with other environmental sources of noise.
   Noise chart 1, annotated    Noise chart 1, annotated

The basis for estimates of noise exposure is measured data from noise tests performed in 2003, 2004, and 2006, which provide a documented basis for correlating noise levels with flight tracks. The estimates here for 2008 flight track data are deliberately biased somewhat toward slightly overestimating actual sound levels. This serves to provide a reasonable margin of error to avoid underestimating noise levels.

Notes on logs:

Each log summarizes approaches in a table covering one week of data..

Each log entry for an ILS approach overflying El Dorado Hills and part of Folsom links to two captured images of the flight track:
One image shows the aircraft at the Initial Approach Fix,  a second image shows the aircraft as it overflies the western ridge in El Dorado Hills.
Each log entry for an approach which does not overfly El Dorado Hills links to one captured image of the flight track.

The most important content in the data boxes attached to each aircraft icon in the flight track images is the aircraft's altitude. When viewing complete flight tracks with WebTrak watching altitude in consecutive updates allows identifying approximate rate of descent. The two most common cases are descent on the 3-degree glide slope and holding altitude. These correspond, respectively, to a throttle setting almost at flight idle and to throttles advanced far enough for level flight. When the Constant Descent Approach procedure is used and is executed correctly the throttles are always retarded and the aircraft is on the glide slope after passing the Initial Approach Fix  at CAMRR. CAMRR is about a mile southwest of the intersection of Lotus Road and Gold Hill Road:  33.5 nautical miles DME from the SAC VOR, 18.9 nautical miles from the approach end of Runway 22L at Mather. (1 nautical mile, 6,076 feet = 1.15 statute miles, 5,280 feet)


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