Tag: A319

Amazing accuracy

Better navigational accuracy in the air may be approaching its limits.

For passengers travelling with scheduled airlines, times have changed, sadly, and no longer can you visit the flight deck, and see from there the views that pilots get.

New meaning to the term 'on track'.

It was not so long ago, that aircraft navigation was carried out using beacons on the ground, either on VHF, or Medium wavebands.

For longer trips with no ground aids a Navigator would plot your route using Astro (sun or the stars) navigation, until companies like Decca produced other radio systems to give you a position, but these from my memory had their problems.

Today in the modern aircraft we have Inertial Navigation Systems using laser gyros together with radio VHF back up, taking cross cuts from beacons, coupled with Distance measuring equipment to pinpoint your position, and now the magic Global Positioning System (GPS) with it`s startling accuracy.

Often with only 1000 feet between, you can see aircraft either above, or below you, often on the same track. This picture of an Emirates airline Airbus A380 was taken northbound over Turkey. The trails left behind are ice crystals which are left by the water vapour that passes through the engine, and freezes immediately at temperatures of some minus 60 degrees C.

The vortex from the wings causes the rotating trail from each engine to be disturbed, and if you pass through such disturbed air following the wake of another aircraft you often get a bump as your aircraft will be travelling at 500 MPH, some 7 miles per minute, a closing speed of 1000MPH if heading towards each other.

As the accuracy is so good these days, airlines have taken to introducing an offset of one or two miles to the left or right of track, just in case there is an error of timing, or in severe turbulence an aircraft could lose or gain the amount of separation which is between machines.

I think we get the best seats in the house!

By Bob Derham

[Bob is a Captain on a privately operated Airbus A319. Ed.]