Good riddance to LDA-Z

In low visibility conditions, when the clouds are below 3,500’ and/or visibility is less than three miles, aircraft without modern avionics are guided by land-based radio beams called Localizer Type Directional Aid (LDA).  As illustrated above, the “Notorious LDA-Z” beam is straight-line flight path guidance from Glen Echo, MD to DCA.  These aircraft fly directly over our neighborhoods. The FAA is adopting a recommendation from the CWG to implement a GPS guided flight path that will move these planes over the river. 

Press on Palisades airplane noise and move from LDA-Z to RNAV GPS

• D.C. catches break from airplane noise - AXIOS  

• New FAA guidance attempts to decrease noise for residents living near Reagan Airport Fox DC New

• It’s taken a long time’: How some neighborhoods got relief from plane noise WTOP 

• New flight path reduces noise for residents near Reagan National Airport DC NEWS NOW 

• Some DC Neighborhoods Will Experience Quieter Skies Thanks to an FAA Rule Change Washingtonian 

<Evidence of Success Provided by MWAA>

Visible increased concentration of flight density over the river between October 2023 (before RNAV GPS) and October 2024 (after RNAV GPS)

The FAA implemented RNAV GPS in mid-July.  One communter carrier has not converted all of its operations, but the FAA expects them to be completed by the end of August.  Palisades residents should notice that, during low visibility conditions, more planes adhere to the river path.

Attached are 2 graphics from October 2023 and 2024 from Mike Jeck (and comments).  These track density plots used a full month of south flow arrivals to Runways 19 and 15 in October 2023 and 2024 to generate the graphics. If you zoom in, you can see a significant reduction in LDA overflights of Palisades associated with the new GPS Runway 19 procedure.

In late October I attended the AAAE/ACI-NA Airport Noise Conference where I presented on land use and "noise office nuts and bolts". While there I interacted with other airports, FAA and consultants who were in awe of what the DCA CWG has accomplished regarding flight path changes. My phone has not stopped ringing with questions from airports and consultants about how these results can be achieved elsewhere.  (Jim, I most certainly mentioned you and Vianair) I am not aware of another airport in the US where cooperation between communities and FAA exists at this level or produces results like we see in the graphics.   

Thank you all for all the hard work over the past 9 years that has driven these changes, and I look forward to seeing the south of the airport notional designs. 

[Web Editor Note - MWAA neglects to  mention that it did not fund the effort to develop the RNAV GPS  flight path but shamelessly asserts credit]

Michael Jeck

Airport Noise Information Manager

703.417.1204

The LDA-Z equipment has been taken down for repair and renovation.  The FAA expects that the LDA-Z beam will be operational again in October.  At that point, however, LDA-Z will only be used as a safety fallback in the event that an aircraft can not use RNAV over-the-river paths (such as avionic equipment failure).

LDA-Z Background Information