INTERACTIONS.ACM.ORG 56 INTERACTIONS JULY–AUGUST2014
FORUM LET'S GET PHYSICAL
must give an interception heading
clearance to another aircraft to let it
rejoin the landing pattern. As a physical
reminder, she holds the EZY4262 strip
in her left hand so she won’t forget to
send it to the tower controller.
Augmented strips as a mix of
virtual and physical media. The
system provides a hybrid artifact, in
which paper and digital media are
identical and have equal importance.
When one controller holds a paper
strip, the other controllers can use
the digital pen to interact with its
virtual twin: They can write on it or
move it by dragging on its border.
When repositioning the paper strip
on the board, the virtual strip is
aligned under it. The then obscured
handwritten notes of the virtual
strip are projected onto the paper
strip. The system lets the controller
extend the physical strip virtually.
Thirty minutes later, the traffic gets
quite intense, so Tessa’s sector needs to be
split up. Two colleagues are on standby
in the control room. Tessa initiates the
degrouping mode in the system. She
decides to hand off the area around the
MOLEK beacon, picks up the strips of the
flights that are in this area, and gives them
to Patrick, the planner of this new sector.
During this phase, the virtual twins of
the removed strips remain displayed on
her board. Until Patrick tells her that
he is ready to control the corresponding
aircraft, she continues to control them
with their virtual strips, rearranging
them on the stripboard and writing
clearances as necessary. The entered
information is simultaneously projected
onto the corresponding physical strips on
Patrick’s stripboard. Later, the crew of a
recently departed aircraft calls to signal
a sick passenger and report they must
return to the airport. Tessa wants to note
the problem on the corresponding strip,
but it is already quite full. She chooses to
enlarge the physical strip with a virtual
spatial arrangements of strips help
manage their workload [ 2, 5]. Some tacit
guidance on the given clearance level
may also have been provided through
physical manipulations of the strip.
Tessa is right-handed and must hold
the strip with her left hand to write on it.
Therefore she knows instinctively that
she has circled a high level, as its value is
located at the bottom right of the strip.
By contrast, since virtual strips do
not need to be held, they do not trigger
this type of embodied memory.
Now the lowest aircraft in her
sector, easyJet EZY4262, is five
nautical miles from the runway. She
needs to transfer control to the tower
controllers, but more urgently, she
(Top) A controller collaboratively optimizes an arrival sequence, using a paper strip, numeric pen,
and projected information. (Bottom) Free-hand writing and drawings convey key information.
The system provides a
hybrid artifact, in which
paper and digital media
are identical and have
strip. The system acknowledges this
order and signals it as consistent by
highlighting the drawn circle in green
(the feedback would have been red in case
of an inconsistent clearance, for instance
a new level above 90).
Enabling input from paper through
OCR. Tessa also asks TH Y1825 to turn
to heading 340. She writes 340 on the
The system recognizes the entered
Fostering embodied cognition.
values and can use it to check that there
is no risk of collision with other aircraft.
With Strip’ TIC, controllers can keep
interacting in the physical space and
rely on externalization to decrease
their cognitive load [ 4]. For instance,