On Friday, May 26, 2017 at 8:46:28 AM UTC-4, MNLou wrote:
Hi Evan -

Would you please expand a bit on why you think it is better to set reserve altitude to zero?

Thanks!

Lou

Uh, sure. This is a semi-religious issue, so opinions will vary. Here's my $0.02 on a rainy day:

Conditions vary. Airport environments vary. I happen to fly in a region of the world (Northern New England) that features a lot of terrain that runs between poorly landable and completely unlandable, and weather than runs from benign to a crash-waiting-to-happen. While my environment is more challenging than many, yours isn't uniform, either.

So, the basic point is: there is no one standard reserve height that is appropriate in all situations. You as PIC need to be making decisions based on environment, current conditions & anything else that affects safety of flight. The computer is your assistant, not your decision maker.

For example: At my home airport (also DC's home airport) our traffic pattern is high due to surrounding terrain and your final glide ought to be padded well beyond this because there is simply no safe place to land other than the airport for a radius of about 5 miles (and then only one or two places, not necessarily where you want them!). Furthermore, the "safe" (that is, landable) route into my home airport follows a river valley which often features a) valley winds and b) subsiding air. I'm usually looking for 1500' over an MC 2.0 (kts) final glide from 25 out, based on the airport elevation. When I was learning to fly XC here, it was more like 2000 over.

This is total overkill at a million flat lands airports.

The obvious, simple solution is to set your flight computer to report estimated arrival height at any destination without any reserve, then do the PIC decision making thing. For old Cambridge gear, that's trivial. For ClearNav, there's one gotcha involved (easily handled, set the purple amoeba to zero and the red one to 1000 agl), for SN-10, you have to build yourself a whole new database with fake-news airport elevations (yes, people really do this, I've watched).

Go fast, make good decisions, land safe!

best,
Evan Ludeman / T8