information enquiry re air routes

[bbcc]

Have often wondered why planes going to America from England have to travel via Scotland to cross the Atlantic. Has always puzzled me but I expect there is a simple explanation to this, can anyone inform me please?

best wishes

[redcrx]

whenever ive flown to the US ive not gone over Scotland from heathrow or Luton.

[ChuckFickens]

the shortest route around a globe isn't the straight line you might think it would be when you look at it on a flat map.

http://plus.maths.org...eatures/greatcircles/

[grasscarp]

If you have a globe and a piece of string you will find the answer. Planes like to travel on a route which is fairly close to the great circle and to place the string on the globe starting at London and going across for example to New York you will see the great circle, which is the shortest distance, curves up to the north and over. If you stayed at the same latitude and whent due west it is closer to the equator and a longer distance. I am trying to make this lesson simple!

[Oiverbotel]

Commercial aircraft use what we 'land lubbers' might describe as imaginary roadmaps. They're actually called 'NATS' which is an acronym for 'North Atlantic Tracks'. They are not exactly in stone, but originally followed stationary beacons that the aircraft followed. When the aircraft arrived at one beacon, then the pilot would change their navigation system to head towards the next beacon. Now it's much more sophisticated, but essentially the same - westbound traffic and eastbound traffic, all travelling at different altitudes and well spaced between each aircraft. This is an extremely simplified explanation but I hope it helps.

[jno]

if you get a globe and hold a piece of string against it, with one end over London and the other over New York (say), you'll find the quickest route by pulling the string tight. Maps distort real distances by making places look further apart the further north (or south) they go. The North Pole in effect occupies the entire distance of the top of a map instead of being a dot in the snow in real life.

[grasscarp]

and Redcrx, I think you probably did go to the north first before crossing the Atlantic. I have worked in aviation flight planning for 23 years now so beginning to get the hang of it!

[jno]

yeah, well, grasscarp's post wasn't there when I started, honest guv...

[grasscarp]

Oiver, navigation is still largely beacons on the land, although computers have changed the necessity of only using beacons. Over the Atlantic you are absolutely right about the North Atlantic Tracks. These are drawn up each day to coincide with what the airlines want to fly and the weather patterns, e.g. avoiding jet streams which are very strong winds at altitude if they are against the track.

[grasscarp]

Thats ok JNO. It is just one of the few subjects on which I could bore you for hours!

[bbcc]

Thanks to all your answers I'm now clearer as to why they go that way, thank you.
best wishes

[Clanad]

Just a minor note... the North Atlantic Tracks mentioned earlier have a common entry point (and exit as well). Which would account for possibly entering over Scotland (Actually, just a little west for the entry point). There are several of these tracks, hence several entry points.
These change almost hourly and are designed to be flow west bound during daylight hours and east bound during night hours. Navigation still uses the older inertial navigation systems but the use of GPS is becoming almost universal...

[Prudie]

JNO could you then possibly help me then with something Ive always wanted to know. I live in Dorset near Dorchester and every day planes fly very high over my house due west, where are they going? I must add that I flew from LHR to New York and we were told when we were passing over Cornwall by the way.

[Prudie]

Apologies, should be asking grasscarp

[grasscarp]

I cant give you a proper answer tonight as I am at home. I would need to have a look at charts of the airways in your area to see where they might be going. There are routes which go west and then down towards Spain. There are also routes going out to the Azores or South America.

[grasscarp]

This site may help you
http://www.travelmath...ondon,+United+Kingdom
On this diagram the route is well north of Cornwell and the usual direction is always north west rather than due west. However, if the pilot said that is where you were I cannot argue!