Lamberts Q
 

I have seemingly conflicting info in my notes concerning LCC and the following:

The scale on a Lambert conformal conic chart:

c) Varies slightly as a function of latitude and longitude
d) Is constant across the whole map

I guess both cannot be true and would appreciate some explanation. Thanks in advance for further info.

Scale on a Lambert chart is correct at the 2 standard parallels and nowhere else. It contracts within the standard parallels, being least at the parallel of origin, and expands outside them, being most at the N/S extremities of the chart.

However, scale is reasonably constant across quite a lot of Lambert charts. It depends on how many degrees of latitude there are between the 2 standard parallels. On a UK CAA half million Southern UK topo, for instance, the standard parallels are only five-and-a-third degrees apart, so the max scale error anywhere on the chart is about one-tenth of a percent. On the Jeppesen ED-6, used in the Flight Planning exam, the SPs are 28 degrees apart, so the maximum scale error is about 3% - which is why you can't use a Pooley's or Jeppesen ruler to measure distances - you get the wrong answer.

So (c) is correct. (d) is only approximately correct, and then only on some Lambert charts.

As an extra point it should be clear that it is impossible to make a flat chart with constant scale!