Text 13905, 77 rader
Skriven 2011-02-04 17:09:07 av Michiel van der Vlist (2:280/5555)
     Kommentar till en text av Ward Dossche (2:292/854)
Ärende: The Smolensk crash on April 10, 2010
============================================
Hello Ward,

On Thursday February 03 2011 10:27, you wrote to me:

 Mv>> Why is the same technology not deployed te get aircraft to the
 Mv>> threshold of a runway?

 WD> Years ago ... I was in the cockpit of a Fokker-28 and the operator had
 WD> a TomTom intalled in the instrumentpanel. It was good enough for the
 WD> pilot to track his flight and announce "look to the left and you will
 WD> see ..." but too slow to track a landing.

A TomTom is optimised for use in a car. For an aircraft a different
optimisation would be required. I was not suggesting to use the same equipment,
just the same technology.

 WD> I would guess the precision and speed of a GPS-device as they are now
 WD> is insufficient for accurate up to the meter positioning of a craft
 WD> that comes down at 300km/h instead of your car travelling at 80km/h.

If it can be used ro let a smart bomb hit a building, I'd say it cab be used to
have an aircraft "hit" the threshold of a runway.

 WD> Plus it has no situational awareness,

My car knows where its nose is pointing. How else could it tell me ti turn
around when I should?

 WD> how high is it,

GPS provides altitude information. The build in maps will tell how high the
ground is and where the runway is.

 WD>  wind direction,

If it is coupled to the compass and speed indicator, it will be able to
calculate the wind from the differeve between speed and heading indicated and
speed and heading calculated from the derivate of the GPS position.

 WD> air-density,

If coupled  to the barometric altimeter it can be calculated from the
difference between barometric altitude and GPS altitude.

 WD>  other traffic.

ILS, VOR, NDB, can't do that either. For that you need ATC.

Granted, GPS is not accurate enough for a fully automatic zero visibility
landing. Its accuracy is 3 metres in the horizontal and somewhat less in the
vertical. But in the case of the Smolensk event, it would have been accurate
enough to get the aircraft within visible distance of the runway. And is
certainly would have warned when it got below the altitude of the runway, and
the crash would have been avoided.

 WD> The future no doubt will bring other wonderful technological
 WD> innovations.

The technology is already here.

 WD> So what's wrong with inertial navigation?

Too expensive, too maintenance intensive, too vulnerable and too inacurate.

 WD> The Brits during Operation Black Buck 1 flew from Ascension to Port
 WD> Stanley (Falklands) about 7.500km over open water with only inertial
 WD> navigation and when sighting land only needed a correction of less
 WD> than 100 meter prior to the bombing run.

Good show, but how much luck was involved in that? The military accept much
higher failure rates and risk factors than the civilians.


Cheers, Michiel

--- GoldED+/W32-MINGW 1.1.5-b20070503
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