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COVER STORY

really not necessary. And if you see the total
pollution that you can save by not doing it,
it's quite significant. "
By not using aircraft engines near the
terminal, reduction of the local acute emissions, like Nitrogen, fine dust and other
pollutants that can be harmful to ground
personnel, also can be achieved.
" The reduced emissions, especially
locally, are of great importance to the
airport, " explain Simon Prent and Dirk
Bresser, innovators of autonomous airside
operations at Schiphol. " Less noise and pollution make the airport a better working
and living environment. "

How it Works
TaxiBot is a semi-robotic tow vehicle. It is
controlled by the pilot of the aircraft as the
tractor tows the plane from the terminal to
the runway. Because this is done without
the use of the aircraft's engines, a significant amount of jet fuel is preserved.
" TaxiBot offers advantages for Schiphol's
set-up, as less taxiing time and less fuel
usage is required to get aircraft to the
runway and ready for take-off, " say Prent
and Bresser, adding departing aircraft at
Schiphol take approximately 14 minutes

to taxi, and arriving aircraft take approximately 9 minutes to taxi to the gate.
Additionally, TaxiBot is powered by a
hybrid of electric and diesel engines that
allow for further green operations.
Metz describes the relationship between
TaxiBot and the aircraft as that of dance
partners. TaxiBot follows the lead of the
aircraft. When the combination of the
tractor and plane is in Pilot Mode, the
pilot of the aircraft is steering the entire
combination.
" TaxiBot is reading the inputs that the
pilot gives by the angle of the nose landing
gear and TaxiBot is following that as the
direction, " says Metz.
" The principle of TaxiBot is that they
basically reversed the logic, " he continues.
" It's the aircraft that does the braking - so
the pilot uses the normal brakes of the airplane. And there's a very advanced and sensitive measurement system in TaxiBot that
really feels, 'the aircraft is slowing down,
now I also have to slow down TaxiBot.' "
The predominant reason TaxiBot is
designed the way it is, explains Metz, is
due to strict rules from aircraft manufacturers regarding the loads that are put on
the nosewheel landing gear.

" It's both the absolute loads and the
fatigue pattern, " he explains.
" With a normal pushback tractor, they
of course, put force on the nose landing
gear, but it's still at a very low speed and
for a very short duration, " Metz continues.
" But if you do longer distance, high-speed
taxiing - certainly if you're taxiing with
an aircraft full of fuel and full of passengers - then the loads become higher than
acceptable. "
TaxiBot is programmed based on the
airport map, that identifies precisely the
maximum permitted speed for each area.
TaxiBot will accelerate to this maximum
speed allowed in a given area, unless the
pilot applies the brakes and slows down
the combination.
" For a pilot, it's very, very natural, " Metz
says. " There's no practical training, there's
no simulator training, it's only a computer-based training of less than 40 minutes
that can be done just before the first 'TaxiBoting' mission. This is half an hour to
be certified by Airbus and Boeing and the
feedback we get from pilots is that it is sufficient for them.
" It shows how close the experience is to
normal taxiing. "

For a pilot, it's very,
very natural. ... It
shows how close
the experience is to
normal taxiing.
- Vincent Metz

16 GROUND SUPPORT WORLDWIDE

DECEMBER 2020/JANUARY 2021

Ground_Support_December1220_January0121

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