On Sunday, January 13, 2013 11:04:43 AM UTC-7, Martin Gregorie wrote:
On Sun, 13 Jan 2013 07:59:41 -0800, Mike the Strike wrote:



As an ex hang-glider pilot, I also thought that the story was well

researched and nicely written, without the usual inaccuracies.



One interesting note - the article says that pilots had to land before

half-an-hour after sunset for the record to be valid. Is this true and,

if so, why do they get half-an-hour longer than glider pilots?





In the UK, anyway, a glider flight must take place during the day, i.e.

may not start or finish at night. The following definitions apply:



night ends 1/2 hour before astronomical sunrise

night starts 1/2 hour after astronomical sunset



...where astronomical sunrise and sunset must be calculated for a

specific lat/lon and day of the year. IIRC for the purposes of this

calculation the world is assumed to be a perfect ovoid, i.e. the effect

of nearby mountains between the sun and the required location is not

taken into account.



As this is an aviation definition of the start and end of night time, I'd

assume the same calculation is used in the USA.



This is why the article talked about the need to land before sunset + 30

minutes.


Out here in the US west, we are limited by the available daylight in summer and are very annoyed by the requirement to terminate flights by sunset - a typical requirement in sanctioned contests and also used by OLC.

We have attempted several times to address this issue, but no success so far. The problem appears to be several inconsistent regulations pertaining to definitions of night in the Federal Aviation Regulations.

I believe that the main problem is that aircraft are required to carry lights after sunset and, since most gliders don't have lights, flight after sunset is considered illegal. I assume that carrying a strobe permits hang-gliders to circumnavigate this requirement?

Mike