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    Re: Regarding fix bearings
    From: Mike Burkes
    Date: 2008 Dec 21, 17:57 -0800

    Hey GL, Mike Burkes here I would love to! I had a 1962 C-172  based at
    El Monte(EMT). I have a Private Pilot with Instrument Rating and 1000+
    hrs total time but am not current.  Did your C-172 have an astrodome?
    Just make sure a B-747 does not appear in your bubble or it will burst
    more than your bubble ha! But seriously that sounds like super great
    stuff!
    Mike Burkes
    
    On Dec 21, 2:34�pm, "Gary J. LaPook"  wrote:
    > Not just the military teaches this technique Greg. I have attached an
    > illustration from the 1998 edition of the Jeppesen Instrument Commercial
    > Manual which shows the same thing. Note that this page also illustrates
    > the "double the angle on the bow" technique which works real well in
    > aircraft. I have been a CFI, airplane, instrument and multiengine since
    > 1972 and have taught this method.
    >
    > I fly out of Santa Paula and CMA and I used to flight instruct at Navy
    > Point Mugu. Are you still flying? About a month ago I had to fly on
    > business down to Corona from SZP. I rented a Cessna 172 with an
    > autopilot and shot two sunlines on the way with my MA-2. When checked
    > against the GPS one line was off by three NM and the other by five NM.
    > Want to go flying sometime and shoot some sunlines?
    >
    > gl
    >
    >
    >
    > Greg R. wrote:
    > > --- On Sun, 12/21/08, Gary J. LaPook  wrote:
    >
    > >> Another method is taught to every instrument rated pilot.
    > >> With the station near the wing tip (near the beam if talking about
    > >> ships) measure the time it takes for a certain number of degrees of
    > >> bearing change in seconds. Then divide the seconds by the number of
    > >> degrees of bearing change and the result is the distance to the station
    > >> in minutes.
    >
    > > Seems like I remember reading about that method in my instrument ground 
    school books way back when (mid-70s), but I can't recall ever using it in 
    practice (we mostly used DME back then, and GPS these days). I think you got 
    some/most/all of your flight training in the military (?), so that curriculum 
    might have been different from what us civilians were taught.
    >
    > > Of course, alternate methods of navigation are always good to have in your 
    back pocket, and I wouldn't sell it short by any means.
    >
    > > --
    > > GregR
    >
    > > --- On Sun, 12/21/08, Gary J. LaPook  wrote:
    >
    > >> From: Gary J. LaPook 
    > >> Subject: [NavList 6784] Re: Regarding fix bearings
    > >> To: NavList@fer3.com, "Beverley Maxwell" 
    > >> Date: Sunday, December 21, 2008, 1:59 AM
    > >> It looks like the classic "double the angle on the
    > >> bow" technique. I am
    > >> attaching Dutton's explanation.
    >
    > >> Another method is taught to every instrument rated pilot.
    > >> With the
    > >> station near the wing tip (near the beam if talking about
    > >> ships) measure
    > >> the time it takes for a certain number of degrees of
    > >> bearing change in
    > >> seconds. Then divide the seconds by the number of degrees
    > >> of bearing
    > >> change and the result is the distance to the station in
    > >> minutes. This
    > >> works because the tangent of �one degree is approximately
    > >> equal to 1/60
    > >> and this approximation holds true for small angles.
    > >> The actual formula is (time/degrees of bearing change) x 60
    > >> = time to
    > >> the station. By measuring the time in seconds the
    > >> multiplication by 60
    > >> is accomplished automatically when you take the result in
    > >> minutes. The
    > >> formula can also be worked to find distance. Simply measure
    > >> the time in
    > >> minutes and multiply by your speed in knot, then divide by
    > >> the number of
    > >> degrees of bearing change to give you your distance off in
    > >> nautical
    > >> miles. Measuring in minutes and multiplying by your speed
    > >> takes care of
    > >> the internal multiplying �by 60. In flying the bearings are
    > >> measured
    > >> with and ADF or VOR but the same technique works with
    > >> visual bearings.
    >
    > >> A simple example. Say it takes 120 seconds for the bearing
    > >> to change 10
    > >> degrees. 120/10 = 12 minutes to the station. The same
    > >> example, 120 knots
    > >> times 2 minutes divided by 10 puts you 24 NM from the
    > >> station. This is
    > >> the same result as multiplying the 120 knot speed by 12
    > >> minutes divided
    > >> by 60 minutes per hour. I have attached an excerpt from FM
    > >> 1-240 that
    > >> illustrates this.
    >
    > >> gl
    >
    > >> George Huxtable wrote:
    >
    > >>> in...@yahoo.com, or A-08, wrote the posting copied
    >
    > >> below.
    >
    > >>> That idea sounds original, simple, and interesting.
    >
    > >>> Tell us more, A-08.
    >
    > >>> George.
    >
    > >>> contact George Huxtable, at �geo...@hux.me.uk
    > >>> or at +44 1865 820222 (from UK, 01865 820222)
    > >>> or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13
    >
    > >> 5HX, UK.
    >
    > >>> ----- Original Message -----
    > >>> From: 
    > >>> To: 
    > >>> Sent: Saturday, December 20, 2008 2:12 AM
    > >>> Subject: [NavList 6773] Regarding fix bearings
    >
    > >>> |
    > >>> | Regarding fix bearings: A convenient practice of
    >
    > >> taking two bearings at
    >
    > >>> one landmark is to take the first bearing at 45 deg,
    >
    > >> then second bearing is
    >
    > >>> taken off beam (90 deg). �In this case distance off
    >
    > >> beam is equal distance
    >
    > >>> traveled.
    > >>> | There are also few so-called "magic"
    >
    > >> angles which play the same trick:
    >
    > >>> upon using them distance travelled is equal distance
    >
    > >> off.
    >
    > >>> |
    > >>> | I wrote a formula which permits for the first
    >
    > >> bearing chose any angle you
    >
    > >>> want and then calculate the angle for the second
    >
    > >> bearing which, as a result,
    >
    > >>> equals distance travelled to distance off.
    > >>> |
    > >>> | I think it gives some flexibility in bearing taking
    >
    > >> and especially in
    >
    > >>> calculating distance off.
    > >>> |
    > >>> | Respectfully,
    > >>> |
    > >>> | A-08
    > >>> |
    > >>> |
    > >>> | ------------------------------------------
    > >>> | [Sent from archive by: inuik-AT-yahoo.com]
    >
    >
    >
    > �jepp2-66.jpg
    > 558KViewDownload- Hide quoted text -
    >
    > - Show quoted text -
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