A rigorous normal mode error analysis is carried out for two
second-order projection type methods. It is shown that although the two
schemes provide second-order accuracy for the velocity in
$\L^2$-norm, their accuracies for the
velocity in $\H^1$-norm and for the pressure in $L^2$-norm are
different, and only the consistent splitting scheme introduced in
[6] provides full second-order accuracy for all variable in their
natural norms. The advantages and disadvantages of the normal mode
analysis vs. the energy method are also elaborated.