I'm studying for the (EASA) Instrument Rating exam and I found several questions about radial intercept angles in sample exams but nothing in the books I've studied and my flight instructor doesn't know of any specific rules either.
Based on the answers, it appears that, depending on the current and desired positions and headings, the intercept angle can be 30°, 45°, a third of the heading difference or a combination of a 90° then 45° turns.
What is the rule to determine which intercept angle to use and where is it documented?
- current QDM 330, HDG 060, desired QDM 350, what should be the new heading? (answer: 305 for a 45° intercept)
- current QDM 120, HDG 120, desired QDR 060 after flying over VOR, what should be the heading after flying over? (answer: 040 for a 20° intercept angle, a third of the 60° heading difference between 120 and 060)
Note: I've found this document online that mentions the 45° and 90-45 techniques page 20 but it doesn't cover the other cases.
QDM: magnetic bearing to station
QDR: magnetic bearing from station