Re: Ramp Arrivals Technology

Date:         11 Jul 98 03:00:32 
From:         Pete Mellor <pm@csr.city.ac.uk>
References:   1
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On 6 Jul 1998, Ken <kenbyNOSPAM@pc.jaring.my> wrote:
> The new Kuala Lumpur International Airport (KLIA) has opening has been met
> with a lot of derision from passengers and flight crews alike; with plenty
> of associated press coverage. One of the procedural temporary changes has
> necessitated the aircraft to stop short of the ramp, disregarding the
> automatic guidance system, and then wait for the aircraft to be marshalled
> into position.
...
> Could someone shed some more light on how these latest technology guidance
> systems work?

By a timely coincidence, I flew back from Belfast in a British
Midland A321-200 earlier this evening, and managed to scrounge
a ride in the jump seat. As we taxied up to the disembarkation
point, the captain explained that he had to use a new positioning
system. He didn't feel that he needed this, but if he didn't use
it, and dented the terminal building, questions might be asked! :-)

The device consisted of a pair of vertical strip-lights, one red,
one green (or bluish green) about 10cm apart, inside what looked
like a hood, slighty above cockpit level. As we approached, both
lights were visible. I guess (although I did not specifically ask)
that if you can see both lights you are lined up; if you can see
red only you are too far to the right; if you can see green only
you are too far to the left. In daylight (as it was when we landed)
you could use the yellow line on the tarmac.

Having established alignment, you need to judge how far forward to
taxi. The second part of the system consisted of a metal screen with
a wide horizontal slit in it. About a metre behind the slit, a
vertical strip-light was mounted. The screen was about 10 metres
to the right of the vertical pair of lights. As the aircraft taxied
forward, the light behind the slit appeared to move along the
slit due to parallax. On the face of the metal plate were white
stripes (paint? sticky tape?) labelled "A320", "A321", "B737", etc.,
each with its own position along the slit. So, you simply creep
forward until you see the vertical strip light aligned with the
white stripe corresponding to your own model of aircraft. Simple!

In fact, precise positioning was not important in our case, since,
as a humble internal flight, we had to walk down the staircase on
wheels and stroll across the tarmac to the terminal building! :-)

Peter Mellor, Centre for Software Reliability, City University,
Northampton Square, London EC1V 0HB, p.mellor@csr.city.ac.uk
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