Ive pondered this a lot. When you say you are going to fly around the world it sounds simple enough, but is it?For example. You could take off from Alert in northern Canada and follow the line of latitude round the north pole and land back at Alert. In an airliner this can easily be done in one flight, but is it round the world? Is traveling through ever degree of longtitude enough? I dont think it is.On the other extreme there is the mathematical principle of a "Great Circle", which simply speaking is a circle that would cut the sphere perfectly in half, it doesn't have to follow any longtitude or latitude. However to fly around the world at the equator, or from pole to pole to pole along a meridian line is as close as you will get with out lots of mathematics to work it out. Im fortunately it's not that easy, as you will have to land at some point and that will most likely take you off the perfect great circle course.So, how does one judge that a RTW plan is valid?A few thoughts I had were.If you start or stray north of the equator, then you must travel to the same number of degrees south of the equator. So if you leave london, you will need to pass to at least 50 degrees South at some point. Not a problem if you are including Australia or New Zealand in the itinery.Or...You must cover the same distance as a great circle, even though you don't follow the course of one.Or...You must visit every continent on the way. The problem here is Antartica, it's not easy to land in all aircraft there (ice runways etc.) and it generally takes you well out of your way if you try.There is the question of, What is the purpose of the RTW flight? Is your aim is to simply fly around the glode? (Physical) Is your aim to visit lots of places like all the major capitals (geo-politcal). Is your aim to fly to all the major land masses, (geophysical).Does anyone have any thoughts? Maybe someone knows what the regulations are (if any) on world record attempts as circum navigation.EDIT:For examples I have recently flown some record breaking flights in Concorde (the amazing realistic Altitude version). First was:General:New York - Dallas - Oakland - Honalulu - Nadi - Christchurch - Syndney - Guam - Bali - Dakhar - Dheli - Narobi - Jeddah - Lisbon - New YorkSunchaser (remain in daylight, depart 2 hours after dawn, land 2 hours before sunset).Lisbon - Dominique Rep. - Aquapolco - Kona - Guam - Bangkok - Bahrain - Lisbon 32 hours (including fuel stops)The last was from a video I watched:New York - Vancouver - Kona - Nadi - Sydney - Guam - Bangkok - Madras - Narobi - Aqaba - Venice - Lisbon - New York. 30 hours flight time.

Here's all the answers: http://www.earthrounders.com/

I'd say as long as you made the trip partly in both the northern and southern hemispheres and went predominantly either easterly or westerly around the equator, then you've done the job.Gary

But then the globe isn

Here's a simple way to ensure that the distance is at least that of a "great circle":The route must start and end at the same point, and must circumnavigate the pole in the hemisphere OPPOSITE to that in which the route starts and ends.Ideally, you'd want to also insist that each flight leg has either no east component or no west component, but some east-west backtracking might be required from a practical standpoint.