[BC] Re: Long Wave

[Patrick Griffith, N0NNK / WPE9HVW]

The NDBs that are co-located with a marker beacon are usually called an
LOM (locator outer marker). Generally you use the NDB to fly to the
marker beacon from any direction. If you arrive over the marker beacon
at the specified altitude you are in position to intercept the
glideslope to guide you to the end of the runway. LOMs usually are not
displayed on general navigation charts. They appear only on approach
charts for the particular airport that they serve. There are some photos
of an LOM (FN on 400 kHz) on my web site at
http://community.webtv.net/N0NNK/FN400. This particular beacon also
emits a 2nd harmonic on 800 kHz that is audible on my car radio for a
distance of about 2 miles from the transmitter. The Y shaped double yagi
for the 75 MHz marker beacon emits a very low power inverted tear drop
pattern that can only be received as you pass directly overhead. 

There is only one true stand alone NDB left here in the Denver area.
That is CASSE (AP on 260 kHz) located about 5 miles south of Centennial
Airport. It uses an approximately 120 foot series fed guyed tower with
no paint and no lights. In the past CASSE also transmitted aviation
weather information for the Denver area. But that service has been
discontinued. Now it only sends AP in Morse Code. AP was derived from
Arapahoe County Airport - the former name of Centennial Airport.

There use to be several more NDBs and LOMs around the Denver area
associated with approaches to Stapleton Airport. These were
decommissioned when Stapleton was replaced by Denver International
Airport.

The FAA has been in the process of decommissioning NDBs that are no
longer needed for primary navigation. They shut down a large number of
them nationwide in the past year. The Aircraft Owners and Pilots
Association successfully lobbied against the shutdown of a small number
of these that they considered as essential to general aviation
navigation.

Patrick Griffith
Westminster, CO
http://community.webtv.net/N0NNK/
http://community.webtv.net/AM-DXer/