How do I read the range indicator that is placed next to aircraft? It says 5.03, or 1.23, or 0.54. In what units are they? Feet, meters, miles, kilometers? Or does 1.00 mean that it's the optimum gun range?
The distances are in Kilometres.
www.mission4today.com has an excellent beginners tutorial which also goes into optimum gun range, or convergence number.