what is the CASA STODA?
 

And how does it differ from the TODA?

Presuming you are looking at the Australian situation, STODA replaced the old term EOL (effective operational length) eons ago.

Basically, the operator needs to know distances which will fit with the aircraft's performance requirements. Where the TODA EOS gradient is excessive, the runway STODA data provide reduced runway effective lengths which are associated with standard gradients.

For example, I picked one out of the ERSA RDA Albany.

R05, for instance, has no STODA data declared as the TODA EOS gradient presents no problems for heavy aircraft (forgetting first segment, which sometimes is a problem, the second segment WAT for heavy twins is 1.6 % net which is covered quite nicely by the 1.2% EOS gradient declared). Similar story applies for R14.

R23 and R32, on the other hand, present problems for TOD calculations determined by TODA so the standard STODA gradient distances are declared under the STODA figures.

In essence, TODA and STODA are similar. STODA provides effective TOD data for standard obstacle free gradients from the end of the relevant distances. TODA provides whatever obstacle free gradient is available at the end of TODA.

While the data can be determined by inclino survey, most would be calculated directly from Type A survey obstacle data.

Thanks JT very interesting...I remember seeing STODA in a performance discussion here but never came around to asking what it is exactly.

I remember seeing STODA in a performance discussion here

If you run a search on STODA, you will get around 15-20 threads, of which probably half a dozen have numerous posts on the specifics.

STODA allows an operator to produce a set of generic performance charts for various runway lengths, altitudes, and slope values, so that their aircraft can operate anywhere that has published STODA. Useful for a company that may find its aircraft at any aerodrome at short notice but without the means to maintain specific performance data for every conceivable aerodrome.

That's a pretty inefficient way to do the job. Better to provide a significantly cut down version of the AFM data suitable for pilot use with the ERSA figures. Both will work but the latter will provide better results for payload .. and quicker.