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    Re: Small craft RDF in 1967
    From: Gary LaPook
    Date: 2014 Jul 30, 23:11 -0700
    Some air non-directional beacons are usable for long distances. I posted this back in 2009:

    This type of equipment is good for a very long distance mainly determined by the power of the transmitting station. For enroute navigation, airways, like "highways in the sky" were created with radio transmitters placed on the ground at each end of each leg of the airway. The signals have to be strong enough so that you can receive them at the halfway point of each airway leg. You track outbound from one station until halfway to the next station then start following the signal to the second station. As an example, a route I flew many times was  "A17" from Bimini, Bahamas to Puerto Rico. You take off from Miami or Ft. Lauderdale and tune in the radio station on Bimini which transmits on 396 kcs with a Morse code  identification of "ZBB." You use the radio direction finder to head for Bimini which is 55 NM from Ft. Lauderdale. After passing over Bimini you turn to a heading of 121º magnetic and track outbound until halfway to the next radio station located on the island of Grand Turk at the very southeast end of the Bahamas chain. Grand Turk transmits on a freq. of  232 kcs with the ident of "GT." After passing GT the next station is located on the north shore of Puerto Rico about 60 miles west of San Juan transmitting on the frequency of 391 kcs, ident "DDP." Now here is the important part, the leg from ZBB to GT is 516 NM (593 miles). This means that you can receive the signal 258 NM at least from each station. It is reasonable to believe that had AE's radio direction finder been working she would have been able to hear Itasca at a similar distance. This is born out by the fact that Itasca heard AE's much less powerful transmitter several hundred NM out.

    I see now from skyvector that the Bimini NDB, ZBB is no longer operating and the low frequency airway, "AMBER 17" (A17) from ZBB to GT, is no longer depicted on the chart. It looks like everybody is now depending on GPS alone. I remember looking up the Grand Turk NDB and it puts out 400 watts.



    gl


    From: Francis Upchurch <NoReply_Upchurch@fer3.com>
    To: garylapook---.net
    Sent: Wednesday, July 30, 2014 6:11 PM
    Subject: [NavList] Re: Small craft RDF in 1967

    Sorry, Culdrose bearing 109 deg. This skyvector is very good and gives route, bearing etc. The only problem seems to be the short range of the NDBs, so it will definitely be an emergency coastal nav system(in fog) here unless I can find any more radio stations like RTE ( I cant). But it is fun and surprisingly accurate.
    What an interesting discovery.
    Thanks again.
    Francis
     
    From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of Noell Wilson
    Sent: 30 July 2014 17:11
    To: francisupchurch---.com
    Subject: [NavList] Re: Small craft RDF in 1967
     
    My copy and paste didn't work.
    Zoom in almost anywhere in the USA and a beacon with morse code identifier will show up.
    Regards, Noell


       
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