The Persistent CLIFY

This weekend I sat down with the newly released KML and way-point data from the FAA. The new authoritative “TARGET” way-point data allowed me to confirm my coordinates and there were no surprises there. Once I loaded up the new flight track KML on top of my authenticated flight tracks I got a bit of a surprise:


Upper flight tracks from the FAA KML are on Clover Park CLIFY, lower flight tracks are on SMO CLIFY. White is IRNMN STAR, Red is BIGBR STAR

When we first met CLIFY in June it was crossing a tree in Santa Monica’s Clover Park, but since July 1st CLIFY has been closely aligned with the SMO radio beacon [ see CLIFY got Moved ]. Somehow, withe the KML release it’s back in Clover Park again. I assume that the coordinates released in the <8/25>TARGETS Distribution package last week are authoritative- they do match the “corrected” coordinates given out July 1st. Browsing around the released Google Earth KML I noticed other anomalies in the KML.
–UPDATE*1 the 9/22/15 TARGETS package has moved CLIFY back over Clover Park. The KML was right. This EA comment was written before the 9/22 adjustment. Some of this discussion is only relevant for the 8/25 —

–UPDATE*2 The 9/2/16 Final EA moves CLIFY back next to the SMO VOR.
But why is this CLIFY position persistent and how far back does it go?

CLIFY is a satellite way-point used by IRNMN, CRSHR, HUULL & BIGBR STARs to replace the SMO VOR. The SMO CLIFY is on the same latitude as SMO whereas the Clover Park CLIFY shifts the arrival paths .47 miles north. Currently conventional flights cross over SMO.

A brief timeline:

  • June 18th, 2015- Initial way-points from presentation boards: 34° 1’1.35″N 118°27’23.94″W
  • July 1st, 2015- Presentation board “correction”: 34° 0’36.64″N 118°27’25.58″W
  • August 25th, 2015- TARGET Distribution package: 34° 0’36.64″N 118°27’25.58″W
  • September 3rd, 2015-Google Earth KML Data:  34° 1’1.35″N 118°27’23.94″W
  • *–September 22nd, 2015- TARGET Distribution package: 34° 1’1.35″N 118°27’23.94″W *UPDATE–
  • *–September 2nd, 2016- Final EA: 34° 0’36.64″N 118°27’25.58″W *UPDATE–

Prior to the June 18th presentation board releases the only comparative mapping of the flight paths was in the Noise Technical Report, released as part of the EA. A layered pdf shows  current conditions and proposed changes. Fortunately, I had already disassembled the pdf so I can readily isolate and identify the flight tracks. The images below show the vector outlines of the flight paths, the green and orange color are the superimposed flight tracks.

Comparing current to proposed demonstrates a shift to the north of the flight tracks at SMO. That flight tracks are at 2 different latitudes. Supporting analysis of the density of the paths relative to I-10 support that the Clover Park CLIFY was being used while the noise analysis was being created.

Was the noise analysis performed with the Clover Park CLIFY?

There is enough separation between the daytime flight paths to compare noise effects. The (SMO)IRNMN enters Culver City at Overland and Venice and is .21 nm north of the Conventional SADDE STAR and .2 nm south of the (CP)IRNMN.

A misplaced CLIFY waypoint affects both flight paths over Culver City

A moved CLIFY waypoint effects both daytime IRNMN, CRSHR, HUULL(white) and late-night BIGBR(red) flight paths over Culver City. The current SADDE conventional path is in yellow.

The SADDE/IRNMN flight tracks from CLIFY to DAHJR are effectively the same altitude and descent angle under IFR so one would expect the same noise impacts. I loaded the newly released US Census Block Population Centroids Noise Grid data. (Hooray and thanks FAA.)

The expected behavior should be a decrease in noise south of and along SADDE, an increase along the new SMO IRNMN, and an increase along the Clover Park(CP) IRNMN by a small amount as it picks up additional flights. Increases .2 nm North of the OP IRNMN should be less than the either of the IRNMNs.

[Edit: it may be easier to use my new Change in Noise map than this table to trace the dB DNL change]

Census Centroid dB
1.8 nm44.2-.444.1-0.344.1-0.243.8-
2.5 nm44.5-.444.3-0.344.1-0.243.8043.30.1
2.9 nm44.5-.444.4-0.344.2-0.143.8043.40.2
3.2 nm44.6-.544.5-0.444.3-0.244.1043.80.1
3.6 nm44.8-.544.7*-0.3*44.4-0.144.2043.80.2
DAHJR (5nm)45.2-.645.1-0.444.

Immediately the CP IRNMN is behaving oddly with a net change of “0”. This is not an appropriate response to being within the outer boundary of a new flight path- especially when considering the north path’s noise is increasing at a faster rate. SADDE and South of SADDE are decreasing- and they even seem to be decreasing as if they are moving outside the RNAV outer boundary. From these result it appears that the noise modeling flight track may be going over the CP IRNMN.

An alternate interpretation is that an erroneous Optimized Profile Descent(OPD) calculation of -.1 or more is being added. It is expected an OPD will decrease the noise from a aircraft with a high throttle setting but it hasn’t been proven that high throttle planes is dominat noise producer for this descent. Correcting that assumption lets the SMO IRNMN fall in line but it still leaves the CP IRNMN suspect and the North requiring a further examination.


The noise modeling under the IRNMN flight path is suspect.

  • Was CLIFY misplaced in Clover Park during the noise analysis?
  • Is an OPD benefit being misapplied?
  • Is the RNAV -> RNP narrowing being properly represented?

The noise analysis around the IRNMN/CRSHR/HUULL RNAV requires further investigation. BIGBR also uses CLIFY and should be investigated as well particularly since it has been lowered 1000ft at CLIFY.

The KML data does not reflect final waypoints but it gives an interesting glimpse in the earlier stages of the project. I believe we need to have an auditor look at the noise analysis, or this should proceed to an EIS as the integrity of the analysis is in question.

–These instructions were relevant 9/7 and may be different based on the 9/22 change- refer to your data package before updating–
To replace CLIFY in your dataset with the “official” TARGET coordinates search the KML for all instances of -118.4566494689281,34.01704041074508 and replace with -118.4571055555556,34.01017777777778. There will be 41 replacements. This will only patch the Proposed Action Procedure Routes. Flight tracks and Corridors will still be incorrect.
Other errors:
1.) LAX BIGBR STAR has at least 5 extra waypoints Between CLIFY and TOMYS over Baldwin Hills that should be deleted.
2.) KLIPR (in LAX ORKA SID) should be -118.4323611,33.9329444 not -118.4131911521656,33.95149537535652

Waypoints are available in the TARGETS Distribution Package from the EA website. Google Earth stores them as -Longitude(Deg),Latitude(Deg).