"Colin W Kingsbury" wrote in message
ink.net...

"C J Campbell" wrote in message
news

"Dan Thompson" wrote in message
. com...
This is an old horse and I almost hate to bring it up again, but are
you
aware you can legally accept direct FUBAR as a /U under IFR, and
monitor
your progress with a handheld GPS?

It is a sad day that people now assume clearance direct to an
intersection
can only be complied with if you have some sort of RNAV. Makes me wonder
how
we ever did it in the '70s with only a VOR and a TACAN.


Pray enlighten me to one thing- let's say I'm on V123 and cleared direct
to
FUBAR which is defined by the intersection of V456 and V789. Leaving out
the
legal-vs-practical debate, there is no way for me to navigate from my
present position to FUBAR in a straight line sans RNAV. It's always been
my
understanding that "direct" means they assume you will in fact go straight
there, not turn left 20 degrees, intercept V456, and then head to FUBAR.
Am
I missing something here?

The Air Force has written all kinds of instrument and navigation manuals
which you can download. They are considerably modernized from my day, but
all the old information is still there. An example may be found he
http://www.e-publishing.af.mil/pubfi...fpam11-216.pdf.
An MB-4 Computer is the Air Force version of the E6-B. From the Air Force
AFPAM 11-216 "Navigation Procedures:"

5.16. Fix-to-Fix Navigation (Using the MB-4 Computer). A fix-to-fix can also
be computed on the

wind face side of an MB-4 computer. First, give the pilot a general heading
toward the fix. (NOTE: You

can work in bearings; however, all work must be done in either bearings or
radials to compute the

solution.) For the following example, radials will be used. The fix you wish
to navigate to is the 280o

radial at 30 DME. Set up a graphic depiction on the wind face side of your
computer with your present

position (350o radial at 050 DME) and the desired fix (280o/030). Use the
following steps:

5.16.1. Place your present position (350o/050) on the wind face side using
the square grid at the bottom

of the MB-4. Align 350o on the compass rose under the true index. Mark the
point by counting down 50

NM from the true airspeed (TAS) grommet and mark with a +. Use the scale set
up on the square grid or

set up an applicable scale. The scale used must remain constant throughout
the problem (Figure 5.13).

5.16.2. Place the fix radial and DME (280o/030) on the computer the same way
you did in step one

(Figure 5.14). Mark as a fix symbol (?).

5.16.3. Determine the no wind heading by rotating the compass rose so that
the present position (+) is

directly above the fix (?). Use the square grid at the bottom to help with
alignment (Figure 5.15). Turn

the aircraft to MC under the true index (206o for this example) and kill the
drift. (NOTE: You can place

your present position (+) on the 0 NM horizontal baseline then, using your
NM increment scale, count

down to the fix position (?) to determine how far you are from the fix (48
NM in this example; Figure

5.15.)

5.16.4. Repeat the procedure as necessary to keep your progress updated.