Quote:
Originally Posted by urban
Nice pics.
At the airports they have the horizontal one then a vertical one, they work in tandem to give the position and glideslope for fully automatic landing (think they call it a cat 3 landing), this might be what the vertical one's for here all though if it's not at an airport they're unlikely to need glideslope indication.
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You're getting your Nav Aids muddled up mate, what you are thinking about is ILS which provides lateral and vertical references (known as the Localizer and Glideslope) to a point on the end of the runway (and can be used in an automated landing system). VOR/DME, in this instance, is merely a track/bearing indicator (VOR) and distance-to-go indicator (DME). Quite often DME/VOR stations are co-located on an airfield/airport along with ILS but the 2 systems do quite different jobs - DME/VOR will get you overhead the site whereas ILS will get you onto the tarmac
Although having said that... DME is also utilised to provide distance to touchdown when sited with ILS equipment: traditionally there are marker beacons sited at intervals (about 5 miles, 3/4 mile and 300 yards) from the end of runways, along the glidepath, which transmit a radio signal directly upwards - as aircraft fly over them they cause one of 3 lamps to flash in the cockpit thereby letting the pilot know how far he is from the end of the runway. But markers are being superceeded by DME nowadays.