RE: [Paddlewise] RE: Michigan Paddler Lost on a Newfoundland Paddle trip

Thanks Craig - that is about what I thought - for the use of a standard ADF
set. 

 

However, with modern processors, I'm sure I could breadboard something with
some smarts to look at recent history (10s or 100s of seconds) and use quite
small heading changes to range-find  and display the 'target' beacon on a
Lat-Long grid on-screen (as well as the chopper's position). It would, of
course, become progressively more accurate with more seconds of data and
could then make a pretty good guess at any absolute drift of the beacon.

 

Usually I have these brilliant concepts - only to discover that somebody
else has been marketing the widget for years ;-)

 

There was a Hollywood film out a few years back about CG SAR using choppers
- but I didn't see it. Perhaps there was something in that, or someone with
more recent SAR experience. 

 

Best Regards

Paul

 

 

From: Craig Jungers [mailto:crjungers_at_gmail.com] 
Sent: Thursday, 8 July 2010 15:05
To: pdh_at_mmcl.co.nz
Cc: Martin, Jack; PeterO; Doug Lloyd; Paddlewise Paddlewise
Subject: Re: [Paddlewise] RE: Michigan Paddler Lost on a Newfoundland Paddle
trip

 

On Wed, Jul 7, 2010 at 7:02 PM, Paul Hayward <pdh_at_mmcl.co.nz> wrote:


So what is there in the SAR cockpit that says 'go left' or 'go back' as the
pilot homes in on a 121.5 MHz signal over a black ocean ?


 

That's a good question since technology has changed a lot over the past 10
years and I'm not familiar with all of the changes. However at one time an
"IFR" cockpit would have had an Automatic Direction Finder (ADF) as part of
its standard equipment. Many airports had nothing but ADF approaches (with
the minimums raised). Today, with relatively inexpensive GPS units, and
almost ubiquitous GPS approaches, I'm not sure that an ADF would be that
usual.

The ADF is a radio that can be tuned to the normal aviation channels and is
coupled to an indicator that is basically an arrow (similar to a compass)
that points toward the signal (or away from it - sometimes the trick is how
to know which way to the source). One of the channels it can be tuned to is,
of course, 121.5Mhz. However an ADF does not tell you how far away the
"beacon" (or whatever signal it's tuned to) is from you and generally you
only know you've gone over it when the needle suddenly swaps ends. One trick
is to fly at right angles to the signal and see how quickly the bearing to
the source changes. If it changes quickly you are close. 

A helicopter, with its ability to fly slowly, probably could home in on a
beacon transmitting on 121.5. 

Joq probably has a better insight to this.


Craig Jungers
Moses Lake, WA
www.nwkayaking.net 
***************************************************************************
PaddleWise Paddling Mailing List - Any opinions or suggestions expressed
here are solely those of the writer(s). You must assume the entire
responsibility for reliance upon them. All postings copyright the author.
Submissions:     PaddleWise_at_PaddleWise.net
Subscriptions:   PaddleWise-request_at_PaddleWise.net
Website:         http://www.paddlewise.net/
***************************************************************************