Dear astronomers,
I am looking for a (rather easy than very accurate) formula to determine the amount of night flight time between two points of given lat/lon.
I.e. I depart at an airport with a known lat/lon at a known time and land at an airport with a known lat/lon at at known time.
There are formulas to calculate sunset/sunrise (or ECET/BMCT) for a given lat/lon. (If anyone has something like that in an easy to use form it would be appreciated, too)
What I am looking for is a formula that does a rough calculation on how much of the flight time is spent after sunset / before sunrise.
Complications such as polar crossings on midsummer day, etc. could be excluded
This is mostly required for flights within Europe
Anyone able to help?