Anatomy of a low frequency aviation radio beacon

Discussion in 'Amateur Radio News' started by KX4O, Aug 25, 2020.

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  1. W7IMM

    W7IMM Ham Member QRZ Page

    They've been gone for many years now. I was assigned to the 446 AW from 1987 to 2004 flying the C-141. We actually had navigators but they did not fly on "Airland" missions at all. That pretty much ended in the eighties....NAVs only flew on tactical airdrop missions then........ The C-141A had a sextant port (that we all used as a vacuum cleaner!!) When the 141's were lengthened and air refueling was added, the sextant port was eliminated.

    NO USAF pilot was taught celestial navigation as late as 1980 (when I entered UPT) and the Navs I know told me that they stopped issuing the sextants in the late 70's or early 80's. I know the C-5 has a port (also used as a vacuum cleaner) as does the C-130 but no navigators.

    I don't think there's any navigators used anymore in airlift at all now. SAC tankers used them to do the air refueling rendezvous' but when I was teaching air refueling, we (pilots) directed the rendezvous ourselves entirely. In the 90's, SAC (now AMC) tankers started directing the rendezvous again and I know the KC-135's had navigators but I don't think KC-10 did. I don't know what they do now.

    I retired in 2014 flying the C-17 and all navigation is GPS/IRU now. We didn't use VOR, TACAN, ADF, much at all (we did test the heck out if though) We stopped training ADF approaches a LONG time ago! (before 2000)

    I worked for a major airline (1988-2018) which also encompassed my last 21 years in the USAFR, and we did indeed perform ADF approaches until we started using GPS. now the airline uses exclusively GPS with the inertial reference system. (dual GPS and DUAL IRU's)

    While the GPS system can be jammed, I don't think the ground based GPS systems are as easy to jam and for navigation, aircraft can use Inertial navigation that doesn't rely on any outside reference.

    Even in the early 80's, we were able to navigate across the pond without any radio aids using INS (DELCO Carousel INS) and we did it routinely. it was fairly accurate. Once we got a land based "fix" either overflying a known position or TACAN (DME) update, the INS was accurate to about a mile or 2. That was using the old 70's vintage INS.

    The newer current IRU's now are VERY accurate and they also do not require any external source of info. Those that think degradation of the GPS will bring air travel to a halt are simply misinformed.

    The sky is in fact, not falling.

    K0UO, KA0HCP, YF8RQN and 2 others like this.
  2. W5UAA

    W5UAA Ham Member QRZ Page

    Well there ya go! Welcome to the future. If GPS is EMP'd out, you'd notice it, but it wouldn't be an issue. That's great news. If we can overcome our domestic enemies, we'll be able to overcome our foreign enemies for sure!

    I was in a different Air Force my father was in; the younger folks in the Air Force today are in a different Air Force I was in.

    Edit: Wish I had accepted the offer to XO for the 18th AF CC.
    Last edited: Sep 3, 2020
  3. W5UAA

    W5UAA Ham Member QRZ Page

    @WA6III - always glad to meet a fellow Airman out here in the wilderness! We are so few and far between!

    I befriended a navigator at SOS. He told me a lot.

    If I had accepted the offer to XO for the 18th AF CC, that would have assured Lt. Col for me. But that would have been a 12-16 hour normal duty day for me for 3 years. And then pinning on Lt. Col would have given me a commitment well beyond 30 years TAFMS and my last assignment would have been at the pentagon. Didn't want that.

    Some flyers forget what some of us support guys have to put up with at times. Learned that when I was XO at the 317 AG, Dyess. (That's where I was noticed by the 18th AF CC.)
    Last edited: Sep 3, 2020
    KX4O likes this.
  4. W7IMM

    W7IMM Ham Member QRZ Page


    if there was an EMP, I would venture to guess that lack of GPS would be low on the list of things "Fracked up"! (all my tube gear would be fine though!!

    My wife reminded me of that for nearly 30 years! I only did 24 years in the USAF. She did 28 and her last job was MSSQ CC @ KTCM
  5. K6CLS

    K6CLS Ham Member QRZ Page

    that may have happened to an F-18 pilot. It c ertainly happened to Jim Lovell, heroic Gemini and Apollo astronaut. F2H Banshee, looking for USS Shangri La. Great story!

    I'm sure WW2 pilots may have a similar story.

    One of the joys of offshore sailing, night watch, is my completely dark adapted eyes, and the Milky Way is soooo beautiful... and the bioluminescent trailing the boats.... just you and the rhythm of the waves, and the msgnificent canopy overhed, feels like a glimpse of eternit. Many folks stand a shift, then won't get out of th4e cockpit, so amazing. Sailors, astronomers, divers, cavers, are very protective of their dark adapt4d eyes and night vision.
    W5UAA and KX4O like this.
  6. W5UAA

    W5UAA Ham Member QRZ Page

    THAT'S the story I heard! Jim Lovell. I was speechless when I heard it.

    And yes! Been there, done that! Watched the moon rise about 8 miles off the north shore of Oahu at about 1AM, as I was sailing counter clock wise around the island in my 34' sloop. It causes a blend of emotions you don't get anywhere else.
    K6CLS likes this.
  7. W7IMM

    W7IMM Ham Member QRZ Page

    "seat of the pants flying" is pretty common. Just about every military pilot and airline pilot is taught it, and then practices it every year during recurrent training for just those kind of events.
  8. KE4IKY

    KE4IKY Ham Member QRZ Page

    Hi.... It may be worth double checking that assertion. The two radios I heard of that were actually tested in an EMP simulator were the AN/PRC-25 and the AN/PRC-77, the -25 was a tube radio, the -77 was almost identical except for using transistors. The -25 failed to operate after the test, the -77 was able to function. (both were really heavy and low power, like 2 watts).

    Maybe something having to do with coils being used?, which would have implications for people depending on old cars (that have ignition coils and points that convert 12 volts to 15,000 volts.

  9. KE4IKY

    KE4IKY Ham Member QRZ Page

    Which is unfortunate, the Secretary Brown crash in ?Bosnia? was blamed partially on not knowing how to do an ADF approach, as well as the approach not being cleared by USAF terminal procedure specialists.

  10. W7IMM

    W7IMM Ham Member QRZ Page

    Howdy Joel,

    I also watched a video of an EMP simulator. They drove several different cars "through" it when it was activated. Some cars died, some didn't. A few that died restarted, but the radio or instrument panel didn't work after etc......

    I am not sure you can make assertions at all about what would happen since it's pretty hard to estimate the E-M field levels that would result. A LOT of military equipment is "hardened" against expected EMP effects but so is some equipment hardened against lightning strikes. Sometimes a "strike" causes no damage and sometimes it causes complete destruction.

    I have been in an airplane that was struck by lightning and the only damage was a little hole burned in the RADOME and a static "wick" burned away. OTOH, there's aircraft that have been struck that experienced complete electrical failure with fused wires etc.....

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