The use of the Greenaway grid (curved) lines has enabled us to measure grid directions correctly on a Lambert chart (in middle latitudes). However, due to the fact that some charts are printed with only straight grid lines (such as the NAT 3071), a transport rate correction was devised which is supposed to combine both the correction for Earth rotation and the correction required because of the straight grid lines.

Whilst the idea is an interesting one, a basic mistake is introduced which leads to serious errors in grid direction measurement.