Tuesday, May 26, 2009

How Planes Navigate

Have you ever wondered how planes navigate the skies. How they arrive at your chosen destination. From the early days of flight planes navigated by using landmarks on the ground ie( by following roads , rivers and paths) but nowadays commercial airline pilots cant rely on earth landmarks , so they navigate by highways in the skies. First of all there are 2 types of navigation . VFR (visual flight rules) flying using sight and landmarks such as rivers , mountains and roads. For this pilots need charts to show them the landscape and other detalis about the current airspace. But commercial pilots use IFR or instrument flight rules. For this pilots dont hav to see the ground. They navigate the plane using instruments. Firstly pilots used radio navigation using VORS all over the country. They would see where they are in accordance to the vor and fly to them or from them depending on where there going. Then gps came along. This enabled pilots to fly to their destination using the gps. imaginary waypoints were made and pilots route from one to another depending where there going. Planes cant just fly wehre they want there are highways in the skies where all the traffic follws. For example a flight plan from Gatwick UK to Rome looks like this:

Cruise altitude between FL330 and FL330
EGKK (0.0nm) -SID-> BOGNA (26.9nm) -UN615-> BENBO (44.9nm) -UN615->
HAWKE (50.5nm) -UN615-> XAMAB (62.7nm) -UL612-> VEULE (87.7nm) -UL612->
INPAX (122.3nm) -UL612-> RESMI (186.6nm) -UM975-> PEKIM (217.3nm) -UM975->
PILUL (231.9nm) -UM975-> PIMUP (267.3nm) -UM975-> PIXIS (306.3nm) -UY612->
PODEP (324.6nm) -UL612-> MOKIP (374.5nm) -UL612-> MILPA (408.3nm) -UM135->
GVA (419.2nm) -UM135-> MOBLO (455.4nm) -UM135-> VEROB (497.1nm) -UM135->
TOP (527.0nm) -UL50-> NEDED (545.3nm) -UL50-> LAGEN (569.0nm) -UL50->
ANAKI (584.1nm) -UL50-> IXITO (589.3nm) -UL50-> UNITA (604.2nm) -UL50->
KAFEE (615.5nm) -UL50-> KONER (638.5nm) -UL50-> MAURO (663.1nm) -UL50->
ELB (698.5nm) -UM729-> GILIO (730.6nm) -STAR-> LIRF (798.3nm)
(NOTE: the numbers and letters UM 729 etc refer to routeways or highways in the skies. SID stands for standard instrumnet departure meaning a pathway out of the airport on to the flightplan  and STAR refers to standard terminal arrival route defines a pathway into an airport from the airway.)
All these words between the two airports are way points in the skies which the plane flies to.Then when the plane comes close to the airport the pilots find out which runway is in use(as some airport can have many runways) then they follow a chart specific to that airport to find there way to the runway approach path. Pilots then guide the plane to the runway along glide slope using many landing systems and aids. Using these aids enables them to land the plane thick fog or at nighttime. Pilots mostly hand fly the plane on to the runway , the landing requires a lot of skill and accuracy.

Navigation is one of the main parts of aviation. Its wonderful to think that one can land in new york JFK airport 6 yours after taking off from London Heathrow airport. Navigation methods and skills are always being improved.

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