NavList:

The discussion on analysing a fix based on 3 CN PLs using pen and paper is theory, and dare I say it, static. Presumably, the aim is to make a difficult landfall safer.

The same arguments could be used if the PLs were radio derived ADF or VOR bearings, or DME ranges, in an aircraft. A big practical difference would be that an aircraft on final approach is doing perhaps 160kts, and may run out of fuel in 20 minutes. No time to plot least-squares.

Traditionally an aircraft above cloud without voice contact would let down in a safe area and proceed visually, or home in to a radio range, if one existed. Plotting least-squares didn't come into it.

My first aircraft was fitted with 'radio range', usually called just 'range' or 'beam approach.'  There was a tuning crank, but no dials or pointers. The earphones were the only clue. Morse A, .- , said you were left. Morse N, -. , said you were right. A continuous tone said you were on course, and silence said you were overhead. You did this in your head, whilst flying on instruments. No speech, no paper, no least-squares.

Today's Boeings and Airbuses can show you bearings, pointers and PLs if you want them. So can the Garmin 2000 I fly now. There is no need to know about least-squares.