A new training system for U.S. Air Force air-traffic controllers
will help reduce procedural errors and expedite student qualification,
said industry and military officials.
The service will spend up to $72.5 million on 94 simulators.
The so-called tower simulation system is designed to improve voice
command features and increase automation. Current technology relies
on pseudo-pilot mediation between controller and aircraft. The new
trainer’s voice recognition technology proposes to eliminate
a reliance on potentially fallible person-to-person communication
links in favor of more streamlined, code-structured operations.
A growing demand for qualified air-traffic controllers is driving
the Air Force to employ fully automated ATC simulation systems capable
of preparing controllers to handle any airframe, at any location,
under any conditions.
Regular adjustments to on-base air-wing strength—to meet
changing readiness requirement—has presented challenges in
maintaining sufficient levels of qualified controllers without available
simulation technology on site, officials said. There is an excessively
large time gap, these officials said, between initial technical
schooling and actual field qualification.
Without the capability to train seamlessly from school to flight
line, qualification time and safety risks are increased, as controllers
can train only periodically, relying on real, as opposed to simulated,
air traffic, explained Thomas L. Harris III, program manager for
the tower simulation system at the Air Force Training Systems Product
Group, Wright-Patterson Air Force Base, in Dayton, Ohio.
“The key is to provide a physical interface, complete with
real-time sensory cues, that will ensure an ongoing training environment
without the need for live air traffic,” he told National Defense.
“This system will provide students with their own ‘airspace’
to gain proficiency and certification on multiple types of airframes
in multiple types of scenarios.”
The trainer’s manufacturer is Adacel Systems Inc., in Montreal,
Canada—a subsidiary of Adacel Technologies Ltd., of Melbourne,
Australia.
Using voice recognition technology in place of current pseudo-pilot
methodology, the simulator will enable student air-traffic controllers
to hone their skills without the supervisory or location-specific
requirements of live traffic training. Substituting software technology
for human mediation between controller and aircraft, the system
is expected to speed up the time necessary to qualify student controllers—in
a simulation-based environment capable of replicating any live traffic
scenario.
“With the current reliance on a controller to pseudo-pilot
link in live and simulated air traffic scenarios, the potential
for procedural error caused by human-to-human miscommunication is
real,” said Gary Pearson, program director for ATC tower simulation
technology at Adacel. “With voice recognition, we remove the
need for a continuous human presence, and thus human error, through
the integration of a sound processing system that can interpret
a command much faster and more precisely than the human ear.”
In the system’s primary phase, a voice recognition engine
attempts to match an ATC vocal command against a text-speech module
or gram-o-file of acceptable commands. Once recognized, the command
is sent to the pilot behavior system, which compares the command
input with radio transmissions being received from the aircraft.
The radio transmissions are then matched with the ATC commands
via the text-speech module and routed back through the pilot behavior
system, which sends the appropriately matched command to the aircraft.
“This technology does in four steps what pseudo-pilots do
in one,” remarks Pearson. “Controller inputs are filtered
from voice recognition engine to text-speech module to pilot behavior
system and then back through text-speech module before they are
sent to the aircraft. Where pseudo-pilots have only one chance to
hear and process a controller command, the voice recognition system
has four chances to catch an inconsistency before a command is sent
out.”
The software, though automated, can also receive inputs from an
instructor who may want to override a controller command. By simply
requesting to “disregard” a transmission, the system
will delete a command, whether or not it has been received by the
aircraft, and simply re-issue a new one.
Working from a database of standard ATC commands, the Adacel system
comprises a series of training modules that offer controllers a
variety of scenarios—from routine to highly complex. The visuals
are realistic enough that they are comparable to actual flight operations.
“In keeping with the unpredictabilities of everyday air-traffic
management, success in the automation of any manually-operated function
depends on the software’s ability to recognize unusual variations
in commonly-seen patterns,” Pearson noted. “In response
to this reality, real-life variables such as weather, communications
and ground conditions were built into the system to be added or
subtracted per instructional needs.
“Though not a new concept, voice recognition technology has
yet to become fully self-sufficient in the face of ever-changing
input complexities,” Pearson said. Whether an unrecognized
command or a series of recognizable commands in the wrong order,
voice recognition software can only process the data that it is
programmed to understand.
Acknowledging this, the Adacel approach is built around an open
architecture of standard air-traffic control terminology that can
be manually overridden at any time. “If an instructor wants
to change a scenario in midstream to simulate a more complex situation,
he or she can do so without losing the real-time flow of events,”
Pearson added.
Current Training
Currently, Air Force ATC simulator training is conducted solely
at the formal technical school and radar approach-control stations
at. The technical training school for air-traffic controllers is
at Keesler Air Force Base, in Biloxi, Miss. The radar-control stations
used for simulation training are located at various installations
around the world.
Once graduated from technical school, personnel manning flight-line
control tower posts do not have access to simulation equipment,
working only with live traffic situations.
“A gap between technical school ATC training and on-site
qualification has existed, with no fill aside from removing needed
tower controllers for further instruction,” said Kip Spurio,
director of resources and requirements, of the Air Force Flight
Standards Agency, in Capitol Heights, Md. “Without continual
live traffic, controllers are often idle, unable to complete their
training cycles on time.”
Under the auspices of the Air Force tower simulation systems (TSS)
program, Adacel technology will recreate a virtual tower environment
consisting of ground controller, local controller, flight data controller
and station coordinator stations. MaxSim version 3.2 system software
will accurately replicate voice communications between controller
and simulated aircraft and ground support equipment. A high-fidelity
visual display, 270 degrees horizontal and 34 degrees vertical,
will offer a simulated, three-dimensional view of the specific airbase
as seen from the control tower. An exercise instructor position
also is provided, allowing for operational control and interaction
with a specific scenario as required.
One of the challenges facing on-base ATC training has been maintaining
a qualified core of personnel in the wake of constant trainee turnover.
“With duty station reassignments occurring regularly and ATC
qualifications being specific to each location due to differences
in aircraft, ground equipment, and runway layout, each new trainee
arriving needs to be qualified for that particular station,”
said Spurio. “Without simulation available, delays in training
without live traffic as well as the risks associated with live traffic
training have to be confronted. Using the Adacel system, trainees
will be able to qualify in advance for their new duty stations,
reducing both certification time and live-traffic safety risks.”
Another source of discontent among air-traffic controller instructors
has been the need for manual instruction at almost every level of
the training cycle. Currently, a minimum of four people are needed
to run a simulation scenario. Adacel technology proposes to decrease
that number to two, requiring only a trainee/controller and coordinator/instructor
to run the software.
“Technically, the student could run the system alone, however,
an instructor needs to be there to upgrade variations within a given
scenario,” Spurio noted.
As ATC training has gotten more complex in response to advances
in airframe technologies, the demand for greater system standardization
to ensure effective controller-aircraft communication has increased.
“Streamlining controller command phraseology has become a
necessity in accommodating both higher numbers and types of aircraft,”
Spurio pointed out. “When trying to land an F-16, followed
by a C-130, a controller had better make sure that each pilot receives
the specific command designated for that aircraft.”
To achieve this goal, voice recognition technology was built around
a limited set of recognizable commands. Once programmed, the software
cannot misinterpret a command, as might be the case with a live
pseudo-pilot. “An often-occurring problem in communications
between controller and pseudo-pilot is the use of non-standard terminology,”
Spurio says. “As soon as the controller gets away from standard
code, the risk that the pseudo-pilot will misinterpret increases
greatly. With a voice recognition system, there is no risk, because
it will not accept what it does not recognize.”
Beyond simple command recognition is the intelligence needed to
determine if a command is the most appropriate for a given scenario.
“Adacel’s software is constructed around a stored database
of integrated commands that work in conjunction with one another,
Pearson said. “For every one command, there are a given number
of matching responses. Using a built-in reasoning capability, the
software is able to choose the most logical command-response match
and then relay the information accordingly.”
As the foundation for the successful transmission of controller
commands, Adacel’s text speech module—programmed to
know what sounds make up which words—breaks down each spoken
word into its component sounds, according to elements such as pitch
and speed. It then recreates the words by matching them against
a gram-o-file of stored commands. With this capability, the software
can eliminate any extraneous sound that may be detrimental to clear
message transmission.
In the case of aircraft-radio transmissions, all static noise is
removed prior to controller reception, because the controller does
not actually receive the original transmission but a recreated version
of the same.
“In the same way that individual sounds are associated to
create words by the text speech module, individual words are associated
to create proper commands by the pilot behavior system,” Pearson
said. “The system, knowing what commands go with which responses,
takes inputs, breaks them down into their component words, and then
reconstitutes the message, matching it against radio responses from
the aircraft. If the system finds the transmissions do not match,
it will not transmit the controller command.”
Spoken commands may not be recognized for one of two reasons: either
the words themselves are not clear or the message content does not
make sense for a given situation. In either case, the command will
be rejected unless close enough to a recognizable match. “In
the case of poor diction by the controller, the words can often
be deciphered without command re-issuance,” Pearson indicated.
“If the wrong command is issued by the controller, the software
will attempt to find the appropriate one using the aircraft radio
transmission, however, this is more unlikely due to the greater
complexity of the match.”
Adacel’s technology also offers advances in screen display
and visual resolution. Using a series of mounted mirrors in the
rear of the simulation room, images are reflected to screen displays
in front of the room without interruption by personnel movement
or positioning. High image resolution is accomplished using an advanced
projection system, capable of four times the pixel output of other
systems. “Since each pixel only holds one color, the more
you have to work with the higher the definition of each image,”
Pearson notes.
In recreating a virtual control tower environment, Adacel software
is also capable of producing unexpected factors that are often encountered
in live traffic situations. Conditions such as inclement weather,
additional runway traffic, or even aircraft malfunctions can be
replicated in real-time. “As in the real world, at least half
of the conditions that a controller must deal with are less than
optimum,” Pearson said. “Though nothing prepares a controller
for the real thing like the real thing, the software enables training
for adverse scenarios that can be interjected or removed at any
time.”
In recent years, Air Force traffic-control centers have been under
mounting pressure to streamline both their information acquisition
and dissemination procedures, to produce qualified controllers.
“A big challenge is simply fulfilling the logistical supportability
requirements that must be met in order to keep air traffic moving
safely and efficiently,” Spurio noted. “This will help
shorten the time it takes to get a controller from the classroom
to ... where they are needed most.”
Along with the 94 simulation systems to be delivered under the
current contract, Adacel will provide the Air Force with training
system support for maintaining and updating hardware and software,
including creating, updating and maintaining a host of imagery databases.
“The plan for this system is to do a thorough factory acceptance
test only on the first three systems being delivered,” Harris
said. “Once the testing is complete and all the discrepancies
are corrected, this will become the system baseline for all other
systems delivered.
The initial contract with Adacel is worth $2.4 million for three
simulators and for the development of a computer-based instruction
course on the operation of the simulator. The contract has annual
production options through 2007. The Air Force currently is planning
on procuring approximately 94 simulators from 2002 through 2007.
Also, the contract contains annual options through 2011 for contractor
logistic support and for a training system center, to support the
fielded simulators. Estimated contract value is approximately $72.5
million if all the options are exercised by the Air Force.