=Paper= {{Paper |id=Vol-2732/20200102 |storemode=property |title=Methodology for the Selection of an Optimal Location of Remote Tower Centre |pdfUrl=https://ceur-ws.org/Vol-2732/20200102.pdf |volume=Vol-2732 |authors=Tetiana Shmelova,Svitlana Kredentsar,Maksym Yastrub |dblpUrl=https://dblp.org/rec/conf/icteri/ShmelovaKY20 }} ==Methodology for the Selection of an Optimal Location of Remote Tower Centre== https://ceur-ws.org/Vol-2732/20200102.pdf
                  Methodology for the selection of an optimal location of
                                Remote Tower Centre

                     Tetiana Shmelova1[0000-0002-9737-6906], Svetlana Kredentsar 2[0000-0002-7731-138X],
                                         Maksym Yastrub 3[0000-0002-7434-0310]
                      1
                        National Aviation University, Komarova av., 1, 03058, Kyiv, Ukraine
                                               shmelova@ukr.net
                      2
                        National Aviation University, Komarova av., 1, 03058, Kyiv, Ukraine
                                                     ksm-na@ukr.net
                       3
                           National Aviation University, Komarova av., 1, 03058, Kyiv, Ukraine
                                                   yastrubmi@ukr.net



                      Abstract. According to the National transport strategy of Ukraine for the period
                      up to 2030, one of the tasks is to ensure consistent and coherent development of
                      regional airports of Ukraine and the consequent development of the Ukrainian air
                      transportation network. One of the ways to achieve this is to deploy a remote
                      tower concept in small regional airports of Ukraine. The main change introduced
                      by the remote tower concept compared to the conventional air traffic service
                      (ATS) provided from a local tower is that the aerodrome control tower will be
                      provided from a remote location and air traffic control and aerodrome flight in-
                      formation service officers (ATCO/AFISO) do not have to be physically present
                      at the airport. The provision of remote ATS requires a continuous exchange of
                      information between the infrastructure at the airport side and a Remote Tower
                      Module (RTM) to ensure that the data received by ATCO/AFISO can be used to
                      provide safe and orderly control of traffic. The aim of this article is to create a
                      methodology for the selection of an optimal location of Remote Tower Centres
                      (RTC) using a method of gradient descent for finding optimal locations of RTCs
                      to reduce the latency of data transmission. The optimal location of RTC will con-
                      tribute to the reliability of the ATS systems by balancing safety and economic
                      efficiency brought by the implementation of a remote tower concept.

                      Keywords: aerodrome flight information service, airport, air traffic control, air
                      traffic management, gradient descent method, regional airport, remote tower cen-
                      tre, remote tower concept.


              1       Introduction
              A small amount of flights in small regional airports is a common issue for many coun-
              tries around the world. Most of the small airports struggle to break even, however at
              the same time provide necessary points of access to remote locations and contribute to
              the local economic development [1; 2].
                 According to the National transport strategy of Ukraine for the period up to 2030,
              one of the tasks for this period is to ensure consistent development of regional airports




Copyright © 2020 for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0).
of Ukraine and consequently the development of the air transportation network of
Ukraine. One of the ways to achieve that is to decrease the costs of air transportation
for airspace users and attract more flight to regional airports with lower costs [3].
   The cost of a flight for an airspace user (e.g. airline) in the world and also Ukraine
consists of fuel, maintenance costs, airport charges, air navigation service (ANS) costs
[4; 5; 6].
   Reduction in one of them could lead to the reduction of the costs of air transportation
for the airspace user and make the flight to a certain airport more effective. In aviation
is always significant attention is paid to Safety Management [7; 8].
   In determining an acceptable level of safety, it is necessary to consider such factors
as the level of risk that applies the cost/benefits of improvements to the system, public
expectations on the safety of the aviation industry, that is, ensuring a balance between
safety and economical effectiveness when the flights’ intensity and the corresponding
workload on operators and maintenance equipment change [9 -12].
   Reduction in air navigation service costs can be achieved through the optimization
of operational costs and enhancement of operational efficiency of the air navigation
service provider (ANSP). A number of Single European Sky ATM Research (SESAR)
solutions have been developed to enhance the current airport operations and provision
of air traffic services (ATS) at an airport with an aim of improving operational effi-
ciency [13].
   A few of the SESAR solutions describe the implementation of a remote tower con-
cept in different operating environments. The concept offers a possibility to improve
the efficiency of operations and enhance safety at airports where maintenance or build-
ing of a conventional air traffic service tower is too expensive. The remote tower con-
cept has been successfully validated by the SESAR programme and deployed in a num-
ber of countries [14].


2      Analysis of the current airport operations in Ukraine
At the moment, air traffic services at Ukrainian airports are provided from conventional
ATS towers in accordance with ICAO Doc 4444, 9426 and EUROCONTROL Manual
for Aerodrome Flight Information Service (AFIS) and internal manuals of ANSP by air
traffic controllers or aerodrome flight information service officers that are located lo-
cally at the airport [4; 8; 15].
   The responsibility of the aerodrome control tower is to provide information and
clearance to the flight crew to ensure safe, orderly, and efficient flow of air traffic at
the aerodrome and in the vicinity of it. Air traffic control officers (ATCO)s at the aer-
odrome control tower should continuously monitor all flight operations on the aero-
drome and its vicinity as well as vehicles and personnel on the manoeuvrings area
through visual observation (augmented by ATS surveillance system in low visibility
conditions if available).
   Functions of the aerodrome control tower may be performed by different control
roles such as:

- aerodrome controller – responsible for operations on the runway and in the area of
  responsibility (AoR) of the aerodrome control tower;
- ground controller – responsible for traffic on the manoeuvring area (with the excep-
  tion of runways);
- clearance delivery position – responsible for delivery of start-up and air traffic con-
  trol clearance to departing instrument flight rule (IFR) flights [4].
   The main operational requirements for the aerodrome control tower to ensure safe
and efficient control of air traffic on and in the vicinity of the aerodrome are:

- The tower must permit the ATCO to visually observe and survey the portions of the
  aerodrome and its vicinity over which s/he has the control;
- The tower must be equipped to permit the controller rapid and reliable communica-
  tions with aircraft with which s/he is concerned [8].
   The airport network of Ukraine consists of 29 certified airports, 16 of which are
capable of serving international flights (equipped with international checkpoints). Air-
ports of Odesa, Kyiv (Boryspil), Kyiv (Zhuliany), Kharkiv, Dnipro and Lviv are con-
sidered as strategic airports, however, the main airport of Ukraine is Kyiv Boryspil
airport that serves over 67% of the total annual passenger flow of Ukraine and handles
more than 44% of all instrument flight rule (IFR) flights in Ukraine [14].
   The air traffic control service is provided at 17 airports of Ukraine (those are – Kyiv
(Boryspil), Kyiv (Zhuliany), Kharkiv, Chernivtsi, Kropyvnytskyi, Kryvyi Rih, Dnipro,
Lviv, Odesa, Poltava, Kherson, Rivne, Sumy, Vinnytsia, Zaporizhzhia, Uzhorod,
Ivano-Frankivsk). The AFIS is provided at 4 other airports (Mykolaiv, Cherkasy, Kaniv
and Ternopil). Almost half of the traffic is handled by the major airport of Ukraine –
Kyiv (Boryspil) while the rest is spread among other airports (Figure 1).
   As can be seen from Fig. 1 most of the regional airports in the observation period
provided regular air traffic service only to a few flights per day (on average 4 flights
per day).

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                     250
                     200
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   Fig. 1. The average amount of daily flight (only for airports with more than 1 flight/day) for
             Ukraine airports in the period from June 2016 to November 2019 [16]
   This means that the resources of the local air traffic service units were used ineffi-
ciently. In addition to that, it is possible to see that a number of airports (e.g Vinnytsia,
Kryvyi Rih and Chernivtsi) are affected by the variability of the traffic depending on
the season – more flights during the summer season and less or none during winter
(Figure 2).




Fig. 2. Seasonal variability of daily flight (only for airports with more than 1 flight per day) for
                                 regional airports of Ukraine [16]

   That is why it is not economically efficient to maintain the local aerodrome control
tower to provide service to a small number of flights per day. One of the ways to opti-
mize the use of resources at small regional airports is to implement a remote tower
concept that could provide a more flexible approach to the provision of air traffic ser-
vice, allocation of resources, through the effective using of RTCs for the performance
of functions of the aerodrome control towers in areas with different air traffic intensity.


3      Remote tower concept and examples of its implementation
   The main change introduced by the remote tower concept compared to the
conventional air traffic service provided from a local tower is that the aerodrome
control tower will be provided from a remote location and ATC and AFIS officers do
not have to be physically present at the airport constantly.
   As described in the previous section, one of the main operational requirements for
the provision of air traffic service at an aerodrome is the ability of the ATC/AFIS of-
ficers to visually observe and survey the aerodrome and its portions that are under their
responsibility.
   That is why one of the main challenges for the remote tower concept is to comply
with this requirement and provide ATC/AFIS officers with the necessary tools and
means to reproduce the out of the window (OTW) view of the aerodrome. The OTW
view is received through a number of cameras and can be combined with the data from
sensors (e.g. surface movement radar, automatic dependent surveillance–broadcast
(ADS-B), etc.) to improve the situational awareness of the ATC/AFIS officers [20].
   Besides that, the ATC/AFIS officers should be equipped with a binocular function-
ality to replace a manual binocular which is currently is in use at conventional aero-
drome control towers. Similarly, to the manual binocular, the functionality should allow
ATC/AFIS officers to visually survey certain items that could be of interest (e.g. land-
ing gear of an aircraft, runway, etc.) [17].
   The controller working position (CWP) is another significant part of the remote
tower that allows ATS/AFIS officers to control air traffic from a remote location. To
provide air traffic service all necessary systems and tools have to be available to
ATC/AFIS officers that’s why all systems (e.g. voice communication system, flight
strip system, etc.) that are used in the conventional aerodrome control tower should be
connected to the CWP in the remote tower.
   Within the SESAR Programme a number of possible implementation options for the
remote tower concept have been identified:
   -      Remotely provided ATS for a single airport;
   -      Remotely provided ATS for multiple airports;
   -      Remotely provided ATS for contingency cases.
   In case of remotely provided ATS for a single airport, a remote tower module (RTM)
has to be set up with CWP and OTW View of a single airport. This RTM might have
more than one position (e.g. for another ATC officer or supervisor) depending on the
complexity of the operating environment. For the remote ATS provision for multiple
airports two configurations are possible:
   -      Sequential – RTM is connected to two or more airports but provide ATS to
one airport at a time;
   -      Simultaneous – RTM is connected to two or more airports and provide ATS
to multiple airports at the same time [18; 19].
   To maximize the benefits from the implementation of remote tower concept a set of
RTMs can be grouped into one centralized facility. This facility might provide ATS to
multiple airports from the same location allowing to use resources more efficiently and
reduce costs.
   A set of RTMs might be grouped into a centralized facility that is known as an RTC.
The RTC might house one or more RTMs providing ATS for one or several aerodromes
from the same location allowing to optimise resources and costs (Figure 3) [20].
   The remote tower concept has been already successfully implemented in a number
of airports around the world. The first fully operational remote tower has been set up at
Örnsköldsvik airport (Sweden) in 2015. The service is provided from a city Sundsvall
that is located around 150 km away from the airport. After some time, the service has
been extended to cover also Sundsvall Timra airport, which means that both airports
are served from a single RTC [20].
   Norway has followed the example of Sweden and started a project to implement the
remote tower concept and provide remote ATS from an RTC in Bodø. The aim of the
project is to provide remote ATS service to 15 airports in 2020 [21].




                          Fig. 3. Example of a set-up of an RTC

   The German ANSP – Deutsche Flugsicherung (DFS) has launched a project to set-
up an RTC in Leipzig to provide remote service to three international airports of Ger-
many: Saarbrucken, Dresden and Erfurt. The target deadline for the project is the end
of 2020 [22].
   In addition to the abovementioned projects, a number of other projects have been
launched in various countries in Europe and around the world: the United Kingdom,
Hungary, the Netherlands, Australia, etc.
   As presented above (statistics of Ukraine’s air traffic), Ukraine belongs to countries
with developed airport infrastructure, but at the same time with an uneven distribution
of flights at airports and seasonally. It is necessary to create a methodology for the
selection of an optimal location of Remote Tower Centre (RTC) and to take investiga-
tions an application of a method of gradient descent to reduce the network latency or
data transmission delay by minimizing the distance between the airport sites and RTCs.


4      Selection of an optimal location of a Remote Tower Centre
  The provision of remote ATS requires a continuous exchange of information be-
tween the infrastructure at airport side and an RTM to ensure that the data received by
ATCO/AFISO can be used to provide safe and orderly control of traffic. The typical
equipment that is required to provide remote ATS include:
  -     High-resolution video cameras;
  -     Pan-tilt-zoom cameras;
  -     Video signal encoding equipment;
  -     High-resolution displays to provide the out-the-window view;
  -     Navigation and light systems;
  -     Surveillance and meteorological sensors, etc.
   Due to the amount of video and audio data that has to be exchanged between an
RTM or RTC and the local airport site in addition to other required data such as data
from surveillance sensors, meteorological sensors, etc., the requirements for the net-
work connection are very high [22].
   However, one of the factors that have a high impact on network performance is la-
tency in time. The network latency or data transmission delay can be defined as an
expression of time needed for a data packet or message to travel from one end of the
network to another. Ideally, the latency should be as close to zero as possible. The value
of the latency depends on three main components [23]:
   -      Speed-of-light propagation delay that depends on the medium through which
the light travels.
   -      Amount of time to transmit a unit of data that depends on the network band-
width and the size of the data.
   -      Queuing-related delays.
   This research focuses on the reduction of the propagation delay for the exchange of
information to ensure that the latency of the network is as low as possible. The propa-
gation delay can be determined as a ratio between distance over which the data has to
travel and speed of the propagation. Since the speed is relatively constant and equals to
speed of light in the given medium the only variable that can be changed is the distance.
In the context of the remote tower concept, this is a distance between the airport site
and RTM (or RTC).
   Taking into account that the regional airports of Ukraine with small amounts of traf-
fic are scattered throughout Ukraine, the most optimal way is to ensure the minimal
distance between airport sites and RTCs would be grouping airports that are located
nearby into segments and deploying RTCs per segment to serve airports within it. The
proposed structure for the deployment of the remote tower concept in Ukraine is pre-
sented in Figure 4.




Fig. 4. The structure of the implementation of remote tower concept in Ukraine (N – number of
                      segments; M – number of airports within a segment)
   Based on this, a set of steps for the definition of an optimal location of Remote Tower
Centre can be defined:
   1.     Grouping of airports into segments (for example, made in accordance with the
map of Ukraine and the location of airports).
   2.     Calculation of coordinates of the Remote Tower Centre to minimize the dis-
tance between Remote Tower Centre and airports within the segment.
   3.     Refinement of coordinates based on other parameters (density of traffic, avail-
ability of resources, etc.).
   In the mathematical terms the Methodology (algorithm) can be described as follow-
ing:
   STEP 1. For each airport, a list of the closest neighbours K is composed and fre-
quency of appearance w is calculated. For each airport distances among it and other
                                           j


airports are calculated, and based on them three (3) airports with the smaller distances
are selected. Then in the list of the closest airports (which contains three closest airports
for each airport) a frequency of appearance of an airport in the common list is calculated
- w.
   j


   If w = max w then for j airport 1 £ w £ w . All airports with the same frequency i are
                   *
                               j                        j
                                                                *



added to the list S .              i


   The lower limit for the frequency of appearance is calculated using the following
equation:
                                          &     ∗
                                  𝜔" = %' ∑-  ,/& 𝑖 ∙ 𝑍, 0 + 1                            (1)
   where
   Z – number of airports in the list S ;
           i                                        i

    &     ∗
   [' ∑ -
        ,/& 𝑖 ∙ 𝑍, ] – an integer part of a number;
   n -number of airports.
   STEP 2. Determine the initial set of coordinates for candidate locations of the Re-
mote Tower Centre Sw . After that, a set of airports is added in order of decrement of
                                       *


frequencies: w £ 1 £ w taking into account that their number is limited by n/2.
                           a
                                       *



   The initial coordinates of the RTC are calculated as an average of airport coordinates
within a segment:
                                               &
                                     𝑥456 = ∑',/& 𝑥, ,                                    (2)
                                                            '
                                                            &
                                               𝑦456 = ' ∑',/& 𝑦, ;                       (3)
    where:
    x , y – coordinates of airports within a segment;
       i       i


    n – number of airports in the segment.
    These coordinates are used as a start point for the Method of Gradient Descent [24;
25].
    STEP 3. To refine coordinates and optimize the coordinates of the RTC a method of
gradient descent is used. During this step, it is necessary to minimize the sum of dis-
tances between an RTC and airports which are served by it. Therefore, for each segment
it is necessary to minimize functional:
                                                    ?               B   ?   B
                       𝐹(𝑥456 , 𝑦456 ) = ∑',/& =>𝑥456 − 𝑥, A + >𝑦456 − 𝑦, A → 𝑚𝑖𝑛        (4)
   where 𝑥456 ∊ 𝐸𝑗, 𝑦456 ∊ 𝐸𝑗.
  Minimization of the functional is made according to this algorithm:
  3.1. Perform a search of initial approximation of RTC coordinates with (4). Deter-
mine the gradient of the functional 𝐹(𝑥456 , 𝑦456 ) in the initial approximation point:
                                                      N
                                                     JKLM O JP
                        𝐵& = ∑',/&                  S            S
                                                                                              (5)
                                        =QJ N      R
                                                       N
                                                               R
                                          KLM O JP TQUKLM O UP
                                                 N
                                   '           UKLM O UP
                        𝐵B = ∑     ,/&               S           S
                                                                                              (6)
                                       =QJ N O JP R TQUN O UP R
                                          KLM          KLM

  Calculate V(𝐵&B + 𝐵BB ) < 𝑒,
  where 𝑒 ≈ 0.01 – accuracy.
  If V(𝐵&B + 𝐵BB ) less than the accuracy than the necessary coordinates are found. Oth-
erwise, move to the point of extreme.
                                  ?T&     ?
                                𝑥456 = 𝑥456 − ℎ𝐵&                                    (7)
                                  ?T&     ?
                                𝑦456 = 𝑦456 − ℎ𝐵B                                    (8)
   where h – step towards gradient.
                                         ?     ?
   After recalculation of coordinates 𝑥456 , 𝑦456 by (7) and (8), the new values of func-
tional 𝐹(𝑥456 , 𝑦456 ) are calculated and verified against V(𝐵&B + 𝐵BB ) < 𝑒. This process
is repeated until the value of the functional decreases. If on a step i the value of the
functional increased and the condition V(𝐵&B + 𝐵BB ) < 𝑒 is not satisfied, proceed to step
3.2.
   3.2. During this step, a method of golden-section search. Compared to other meth-
ods, it requires the least amount of calculations and ensures the internal narrowing to
the given accuracy. Step h is divided into uneven parts. These parts are selected in such
a way that the ration of the length of the bigger segment (𝑍&) to the length of the whole
interval (𝑍) equals to the ration of the smaller segment (𝑍B ) to the bigger segment
(“golden-section”):
                                ]^    ]
                                   = ]S , 𝑍& + 𝑍B = 𝑍                                  (9)
                                ]        ^
                              ]S                 &
                              ]
                                = Q√5 − BR ≈ 0.618                                           (10)
                               ^

   On every step, the interval of uncertainty is decreased by 1/0.618. For the further
                                                                       ?       ?
minimization, an interval of [a; b] is considered, where a= 𝐹>𝑥456 , 𝐹𝑦456 A and
       ?T&   ?T&
b=𝐹>𝑥456 , 𝑦456 A. To change the value of the step h let’s set a = h , b = h . Then, ac-
                                                                                 0   1


cording to the method of golden-section search, the new values of the steps are calcu-
lated using (11) and (12):
                           ℎB = ℎc + 0.382(ℎ& − ℎc );                              (11)
                           ℎf = ℎ& + 0.382(ℎ& − ℎc );                              (12)
                                ?      ?
   Calculate the values of 𝐹>𝑥456 , 𝐹𝑦456 A using the steps h and h and if F(h ) < F(h )
                                                                         2   3           2     3


then h = h (the right limit has changed), otherwise h = h (the left limit has changed).
      3    1                                                     0   2


The process is continued until h – h does not become less than the given accuracy.
                                    1        0


After that go back to step 3.1.
   The result will be a set of coordinates of optimal locations of RTCs from a point of
view of minimization of distances between airports within one segment. However, this
is not the only factor that influences the decision of the selection of the location for the
RTC, other such as the density of the traffic of airports within a segment, availability
of resources at certain airports to house the RTC, availability of human resources, etc.
should be also taken into account.
   The defined methodology has been implemented as a computer program that takes
a set of airports as an input and calculates a number of segments, performs allocation
of airports to segments, calculates and refines coordinates of RTCs per each segment.
The result of the execution of the computer program is shown in Figure 5. A set of
airports is taken as an example and can be changed depending on the variation of the
traffic. The received data and the analysis of abovementioned factors can be used to
support the decision-making process of the selection of an optimal location for the RTC.




  Fig. 5. The example of calculation of optimal locations (to minimize distance) of RTCs for
     Ukrainian airports (green dots – initial coordinates; blue dots – refined coordinates)

   As seen from the received results, further analysis of them is required to select the
most optimal locations for the RTCs. For example, the coordinates for the RTC of the
Segment 4 point to a location in an open sea which makes it impossible to use it. That’s
why, as mentioned above, the minimization of distance to reduce the data transmission
delay should be used in conjunction with other factors that could impact the location of
the RTC, e.g. density of traffic, availability of resources, etc. Based on these other fac-
tors it might be considered more efficient to implement the RTC in Kherson or Odesa
airport or another site even though it might have an impact on the network latency.
Also, as seen, not all airports have been included in segments; it is meant that they will
not be controlled remotely. For example, Boryspil has many flights and must be
controlled typically, Kharkiv is situated far away from others and distance will not al-
low providing real-time control from RTC because of delays.
   To find the optimal location of the RTC, used the minimax/maximin decision crite-
rion (Wald criterion) under conditions of uncertainty and compose a decision matrix
(Table 1). If the Wald criterion is used, a guaranteed solution is obtained:
                                          ìï              üï
   Wald criterion (maximin): A* = maxímin uij ( Ai ,l j )ý .
                                       Ai ïîlj             ïþ
   The factors that influence on the alternative decision are defined as:
   λ1 – remoteness between RTCs;
   λ2 – location of the airports;
   λ2 – density of traffic;
   λ3 – availability of resources;
   λ4 – technical capabilities;
   λ5 – economic capabilities;
   λ6 –availability of RTCs to connections, etc.
   Possible results in a matrix (u , i=1,…, n; j=1,…, 6) are determined with the Expert
                                  ij


Judgment Method by rating scales or based on statistical data.

Table 1. The matrix of decision making for choosing optimum location of the RTC.
 Alternative deci-                     Factors that influence decision making
 sions of location
 of the RTCs
 А                   λ1     λ2            λ3           λ4            λ5         λ6
 А1                  u 11   u12           u13          u 14          u15        u  16


 …                   …      …             …            …             …          …
 Аi                  u i1   ui2           ui3          u i4          ui5        u  i6


 …                   …      …             …            …             …          …
 Аn                  u n1   un2           un3          u n4          un5        u  n6




   Computer program "Classic Decision Criteria: Wald, Laplace, Hurwitz, Savage" for
DM modeling was designed [26].
   Therefore, it is necessary to perform an additional study to define and investigate
other factors that could have an impact on the selection of the optimal location of the
RTC and to enrich the current methodology with the defined factors. Once the method-
ology is defined completely it can be used also for other countries to select optimal
locations for the RTCs.


5      Conclusion
To ensure consistent and coherent development of regional airports of Ukraine and
consequently the development of air transportation network of Ukraine, there is a need
to increase the level of traffic in the Ukrainian regional airports. One of the ways to
achieve that is to decrease the costs of air transportation for airspace users and attract
more flight to regional airports with lower costs.
   The implementation of a remote tower concept allows to decrease the costs of air
transportation through optimization of the use of resources and increase the cost effi-
ciency of the provision of air traffic service at the airport. The remote tower concept
has been successfully implemented or in the progress of implementation in multiple
airports around the world (Sweden, Germany, Norway, etc.).
   To ensure the availability of the necessary data for ATCO/AFISO to provide the safe
and orderly remote ATS there is a need for continuous exchange of data between the
infrastructure at airport site and RTM or RTC. Due to the amount of video and audio
data that has to be exchanged in addition to other required data (surveillance, meteoro-
logical data, etc.) the requirements for the network performance are very high. One of
the factors that have a high impact on network performance is latency.
   This research focused on the reduction of one of the components of latency (the
propagation delay) for the exchange of data to ensure that the latency of the network is
as low as possible. The propagation delay can be determined as a ratio between distance
over which the data has to travel and speed of the propagation. Since the speed is rela-
tively constant and equals to speed of light in the given medium the only variable that
can be changed is the distance. In the context of the remote tower concept, this is a
distance between the airport site and RTM or RTC.
   To minimize the distance between airports and RTCs and select optimal locations of
RTCs the method of gradient descent has been used and adapted to fit the context of
the regional airports of Ukraine.
   The received method provides a set of coordinates of optimal locations of RTCs
from a point of view of minimization of a distance between airports within one segment.
However, this is not the only factor that influences the decision of the selection of the
location for the RTC, other such as the density of the traffic of airports within a seg-
ment, availability of resources at certain airports to house the RTC, availability of hu-
man resources, etc. should be also considered. A separate follow-up study to define
such factors and investigate their influence on the decision of the selection of the opti-
mal location is needed.
   Further research it is proposed to find the optimal location of the stations depending
on the influence of several factors (the specific location of the RTCs depending on the
location of the airports, the current intensity of air traffic, the workload of nearby air-
ports, technical and economic capabilities, the availability of RTCs to connections with
existing airports) using decision-making methods under risk and uncertainty [9; 12; 26;
27]. To evaluate the expected outcomes and the formation of the pay-off matrix, it is
advisable to use artificial intelligence methods such as Big Data, Data Mining, Expert
systems, Collaborative Decision Making, and others. Incorporating the promising ap-
proaches and technological advances will allow to evolve according to the increasing
demands while offering safety and quality in the operation Air Traffic Management
system [28].
   In cases of large and complex big data, methods can be integrated into traditional
and next-generation hybrid decision-making systems by processing unsupervised situ-
ation data in the deep landscape models, potentially at high data rates and in near real-
time, producing a structured representation of input data with clusters that correspond
to common situation types that is useful for minimizing latency in time when working
RTCs and processing large amounts of information [27; 29].
   The new methodology will include the process of integration deterministic, stochas-
tic, and non-stochastic uncertainty models in complex situations. The Collaborative
Decision-making models an uninterrupted process of presenting information between
various interacting participants, as well as providing synchronization of decisions taken
by participants and the exchange of information between them. It is important to ensure
the possibility of making a joint, integrated solution with different operators at an ac-
ceptable level of efficiency. This is achieved by completeness, the accuracy of available
information, and optimal solutions obtained [30].


References
 1. Kazda, A., Hromadka, M., Mrekaj, B.: Small regional airports operation: unnecessary bur-
    dens or key to regional development. In: 6th International Conference on Air Transport
    (INAIR 2017), pp. 59-68. Elsevier, Prague (2018).
 2. Button, K., Doh, S., Yuan, J.: The role of small airports in economic development. Journal
    of Air Transport Management 4(2), 125 – 136 (2010).
 3. Cabinet of Ministers of Ukraine: National transport strategy of Ukraine for the period up to
    2030. Available at: https://zakon.rada.gov.ua/laws/show/430-2018-%D1%80, last accessed
    2020/02/16.
 4. Air Traffic Management: Doc. ICAO 4444-RAC/5011 (5th еd.). International Civil Aviation
    Organization, Montreal, Canada (2007).
 5. Aircraft Operations: Doc. ICAO 8168-OPS/611 (5th еd.). Vol. I. Flight Procedures. Inter-
    national Civil Aviation Organization, Montreal, Canada (2006).
 6. Regulations on the Department of Air Traffic and Work with Airspace Users: Order of
    UkSATSE, Kyiv, Ukraine (2015)
 7. Safety Management Manual (SMM): Doc. ICAO 9859-AN 474 (3rd ed.). International Civil
    Aviation Organization, Montreal, Canada (2013)
 8. Air Traffic Services Planning Manual: Doc 9426. International Civil Aviation Organization,
    Montreal, Canada (2016).
 9. Kharchenko, V., Shmelova, T., Sikirda, Y.: Decision-making of operator in Air Navigation
    System: monograph. KFA of NAU, Kirovograd (2012)
10. Rizun, N., Shmelova, Т.: Decision-Making Models of the Human-Operator as an Element
    of the Socio-Technical Systems. Іn: Strategic Imperatives and Core Competencies in the Era
    of Robotics and Artificial Intelligence, рр. 167–204. USA, Hershey, IGI Global (2016)
11. Sikirda Yu., Kasatkin M., Tkachenko D.: Intelligent Automated System for Supporting the
    Collaborative Decision Making by Operators of the Air Navigation System During Flight
    Emergencies. In: Handbook of Artificial Intelligence Applications in the Aviation and
    Aerospace Industries, pp.66-90. USA, Hershey, IGI Global (2020)
12. Shmelova T.: Artificial Intelligence for Evaluating the Mental Workload of Air Traffic
    Controllerst. In: Evaluating Mental Workload for Improved Workplace Performance.
    pp.184-212. USA, Hershey, IGI Global (2019)
13. SKYbrary: SESAR. Description. Available at: https://www.skybrary.aero/in-
    dex.php/SESAR, last accessed 2020/07/08.
14. EUROCONTROL: Local Single Sky Implementation 2017 – Ukraine, Level 1- Implemen-
    tation Overview. Brussels (2016).
15. EUROCONTROL: Manual for Aerodrome Flight Information Service (AFIS), Brussels
    (2010).
16. EUROCONTROL STATFOR Dashboard: Average Daily Flights – Airport. Available at:
    https://www.eurocontrol.int/statfor, last accessed 2019/12/11
17. EASA: Guidance material on the implementation of the remote tower concept for single
    mode of operation – Annex to ED Decision 2015/014/R. Cologne (2015).
18. SESAR Joint Undertaking: D02/D04 OSED for Remote Provision of ATS to Aerodromes
    including Functional Specification. Brussels (2014).
19. Frequentis AG: Whitepaper: Introduction to remote virtual tower. Vienna (2016).
20. SESAR Joint Undertaking: Remote Towers Demonstration Report. Brussels (2015).
21. Van Beek, S. D.: Remote Towers: A Better Future for America’s Small Airports. Reason
    Foundation Policy Brief #143. Los Angeles (2017).
22. European Commission: Deploying Remote Tower Control (RTC): Implementation of SES
    by Improving Performance and Modernising ATM for Tower Service Provision in Germany.
    Brussels (2016).
23. Peterson, L., Davie, B.: Computer Networks – a systems approach. 5 edn. Elsevier, USA
                                                                           th



    (2012).
24. Ovchinnikov, P., Lisitsyn, B., Mikhailenko, V.: Higher mathematics: Handbook. Kiev
    (1989).
25. Sergienko, I., Shilo, V.: Discrete optimization problems - problems, methods of solving,
    research: manuscript. Kyiv (2003).
26. Shmelova, T., Shulimov, O., Chorna, M., Kovtunets, O.: Classic Decision Criteria: Wald,
    Laplace, Hurwitz, Savage (computer program): author's certificate No. 60624. Kyiv, State
    Service of Intellectual Property of Ukraine (2015).
27. Shmelova T.,, Sterenharz A., Dolgikh S. Artificial Intelligence in Aviation Industries: Meth-
    odologies, Education, Applications, and Opportunities. In: Handbook of Artificial
    Intelligence Applications in the Aviation and Aerospace Industries, pp.1-35. USA, Hershey,
    IGI Global (2020).
28. Ostroumov, I.V., Kuzmenko, N.S. Risk Analysis of Positioning by Navigational AIDS: In:
    Signal Processing Symposium, SPSympo (2019).
29. Dolgikh S. Spontaneous Concept Learning with Deep Autoencoder In: International Journal
    of Computational Intelligence Systems, Volume 12, Issue 1, November,Canada, pp. 1 – 12,
    (2018).
30. Shmelova T. Integration Deterministic, Stochastic and Non-Stochastic Uncertainty Models
    in Conflict Situations. In: Proceedings of the International Workshop on Conflict
    Management in Global Information Networks (CMiGIN) co-located with 1st International
    Conference on Cyber Hygiene and Conflict Management in Global Information Networks
    (CyberConf 2019), Lviv, Ukraine, November 29, pp. 47-56 (2019).