I was wondering, They fly North towards the North pole, once they reach Russia and start heading down towards the bottom of the earth which would be South. My main question is once the reach that point does the compass and their heading indicator switch to South heading or the general heading they are flying in? how does that work? they are not really turning to head South they are just flying straight which in their case would be north and at a certain point it just becomes south. I hope I'm making sense describing this and hope everyone understands what I'm trying to say.
This is just one of those curiosity question I have and always wondered how that all worked.
here is the link to a YouTube video of ACA flying the polar flight if your interested. http://www.youtube.com/watch?v=unYKJgUYmi8
Thanks for any replies.
What I do know, is that they'd have to be precise, and wouldn't leave it to VFR naviation (i.e. compass) instead it'd be some form of IFR routing.
So, now you've got my curiosity. Any Big Iron drivers want to comment on how it's done?
GPS satellites are in Medium Earth Orbit MEO (<-clickie)and there is nowhere on earth that isn't covered. I think you're thinking of the communications and broadcast sats which are in GEO (<-another clickie) and have limited view at +/- 70deg lat.
In the north the heading reference is switched to true which is maintained until well south into Russia again. Navigation is via INS/GPS, and contrary to a previous comment GPS satellite coverage is excellent over the north because in actual fact more satellites could be in view at any one time than down near the equator, although they may be very low on the horizon. The GPS satellites are on an inclined orbit that crosses the equator at a 55 degree angle meaning in half an orbit they go from 55 degrees north to 55 degrees south, so even standing on the ground at the north pole you should have at least 6 satellites in view at any given time.
Only one of the routes actually comes relatively near the North Pole but I can't remember the distance offhand. The displayed heading on the Navigation Display always shows true heading while up there and does indeed shift around to southerly. The closer you are to the pole the faster that occurs because of the diverging lines of longitude and you can actually watch the compass moving even though you are wings level.
Magnetic compass is of course absolutely useless up there, but transport aircraft don't measure magnetic heading anyway. The navigation system always knows where true north is through the inertial system and then applies a variation derived from the database and its known position to display a calculated magnetic heading. The displayed heading can be manually switched to true, but if you forget to do that it switches above a certain latitude automatically anyway. Some aircraft can also display grid headings that effectively does away with the problems of northern flying in true or magnetic heading. It's basically a special map projection that allows someone to fly from point A to point B in a straight line and the displayed track will never change even though it may not be anywhere near the true track. The military used to use it and may still and so might some airlines, but Air Canada doesn't because it isn't necessary.
What's the deal with this? With turbine engines can't we find something, anything that burns and stops fuel from freezing? Or is the chemistry more complex than I'm assuming it to be?Rockie wrote:Flights have been rerouted because either the level of solar radiation on the least time track was too high, or the temperature was below -65C for too long which would risk fuel freezing.
edit: I know about Prist and such, but I mean something a little bit more intense that goes to, say, -273C or something.
- Rank 10
- Posts: 2430
- Joined: Wed Mar 16, 2005 11:07 pm
- Location: Negative sequencial vortex
Grid is basically based and the concept of a flat earth with 0 degrees or the Prime Meridian separating West & East. This provides a so called constant reference direction with no convergence of lines on Longitude as would be the case with True headings. Grid North would therefor be 360 degrees north along the Prime Meridian with Grid South running along the 180 degree line of Longitude through the Pacific Ocean. Wind direction at South Pole Station is given in Grid otherwise the wind be always be from the north.
Once you are able to grasp the concept it is actually quite practical when operating in either Polar Region. In simple terms it's just like slicing the earth in half and laying it out flat like on a wall map that you used to study countries on when you were in Grade 4.
Now, someone made the comment on it being too cold for too long, is this not what brought down the BA 777 into heathrow? Something with cold fuel being frozen in a filter or something to that effect (and when more power was added, it was blocked by a cold ice/slush mix, not allowing the increase of power?
Sounds like they could find a way to heat the fuel, might solve some problems...not that this is something I know at all, just what I've gathered.
There are routes that we follow depending on the day and the winds. A few months ago going JKF to HKG we went straight north then more north east once we hit greenland. the closest suitable airport for us was somewhere in finland.
Btw there is very little wind in the polar region so the rides are almost always smooth.