It is demonstrated that the Cramer–Rao lower bound on direction‐of‐arrival estimation with two closely spaced, narrow‐band plane waves, with an arbitrary correlation coefficient, impinging on a uniform line array, is well‐approximated by an empirically derived, nonmatrix expression combining two previously published, special‐case approximations. The approximation is useful for a number of sensors down to about 6, signal‐to‐noise ratios from about −30 to +30 dB, and source separations down to about one‐sixth of a Rayleigh beamwidth. The root mean square error is about 11%.