IFR Formulae
 

Does anyone have any useful IFR 'rule of thumb' formulae suitable for a 180 kts aircraft.

I am conversant with the elementary stuff, such as 5xGS for RoD at 3deg GP, and max drift etc, but would appreciate anything more involved but useful in the cockpit. Especially, military MDR, holds, timings, VDP calcs, lead radials for Loc intercept etc.

Also if anyone could refresh my memory on VOR/TACAN point to point-ing I'd be most grateful.

Thanks in advance,

Miles Offtarget.

Have a browse here.

Lots of neat tricks sorted by flight phase via the drop-down menu..

http://www.flightinfo.com/rulesofthumb.asp

superb, thanks very much.

Point to point vor/tacan nav. Hmmmm, how to explain that with out a picture......

Imagine your RMI is a map. The scale is defined as the outer circle is either your dme, or the dme of the point that you are aiming for, whichever is the greater.

eg if you were hdg 090 and were on the 180r/100d, trying to get to a point 135/50d. the scale is 100nm and you imagine yourself on the circumference of your instrument at the 3 oclock position (180R, relative to hdg 090 which will be at the top, 12o'clock position))

now imagine your next point on the "map" in this case, it would be 45deg clockwise from the top, and half way between the centre and the circumference. (for goodness sake get a circular thing to look at while you imagine this!)

Now draw a line from your ppos to your next point and then "translate" it so that it runs through the middle. Read off the hdg and voila!

Alternatively turn so that the imaginary line from ppos to next point is vertically upwards and you will be pointing the right way! give or take the drift, of course.

Hope this hasn't given you a headache:ok:

No that's confirmed my half-baked recollections. I was taught this at Finningley many years ago but it soon atrophies if you don't use it regularly.

Any quick way to determine an ETA or distance to the new point, over and above usual MDR GS calc ?

Once again, thanks very much,

MoT

http://www.visi.com/~mim/nav/

A great little java applet that might help as an aid.

Mike

Miles off..., the scale of the point to point is constant for a given situation so the length of the line from the first point to the desired point is to the same scale as used to set up the point-to-point problem.

If the numbers are easy then you can try guestimate the track length compared to the scale used. Otherwise plot the problem on a CR5 type whiz wheel & you can read the track length using the underlying graticule.