In Turkey, the application of mechanized harvesting is currently limited
since harvesting machines are very expensive and highly correlated with
the fuel prices (Akay et al., 2004). They are also undesirable
due to negative effects of mechanization on the workforce. In Turkey,
most of the harvesting operations are performed using animals and manpower
while mechanized equipment (i.e., tractors) are employed in some areas
for mainly winching logs. The percentages of using manpower, animals,
mechanized equipment and skylines in the harvesting operations are 75,
15, 7 and 3%, respectively (Akay and Sessions, 2004).
In Turkish forestry, the trees have to be bucked into short lengths logs
(3-4 m) since longer logs can not be handled easily by traditional harvesting
methods. Also, the standards of the forest roads are low, which will not
allow using large logging trucks to haul longer logs. Thus, producing
short logs reduces the log values, which leads to significant reduction
in the potential profits. To produce and transport longer logs, aerial
harvesting methods such as cable logging and helicopter logging could
be implemented, especially in productive forests located in steep mountainous
regions of Turkey. Cable systems are not used very often by the logging
contractors due to lack of experienced and skilled cable yarding operators.
The General Directorate of Forestry (GDF) utilizes helicopters in firefighting
activities; however, helicopters have not been used in harvesting operations.
In Turkey, helicopter logging can be used in harvesting high quality logs
and in extraction of mature trees in environmentally sensitive areas where
road construction and logging operations are restricted. This study aims
to identify the variable factors influencing the productivity and cost
of helicopter logging and to present an overview of utilizing helicopter
logging in Turkish forestry.
Helicopter harvesting is an aerial harvesting system whereby logs are
removed vertically from the forest and flown to a roadside landing or
drop zone (Chua, 2001). Commercial helicopter logging, also called as
helilogging, dates back to early 1970`s in the Pacific Northwest of the
USA and in Western Canada. Table 1 shows various helicopter
models and their load capacities. Helicopter logging plays an important
role in timber production by providing logging managers with advantages
of applying environmentally friendly harvesting practices and ecologically
based silvicultural treatments and harvesting from timber salvage sites
and by enabling access to unreachable areas due to extreme terrain conditions
or remoteness from the road network (Christian and Brackley, 2007).
Compared with ground-based logging methods, helilogging operation increases
the woody biomass regrowth and minimizes the soil disturbance and sediment
yield (Aust and Lea, 1992). Table 2 compares various
harvesting systems. In order to develop a productive and cost effective
helilogging system, the stages of the logging operation should be carefully
planned and implemented considered various working conditions and different
The felling operations should be planned ahead of time and proper felling
techniques should be implemented during the operation. Felling should
be done prior to move in of the helicopter since the felling production
may be much lower than the helilogging production due to hard working
conditions (Stampfer et al., 2002). Directional felling should
be performed. The trees should be bucked into suitable log sizes according
to optimum payload capacity of the helicopter and logs selected for each
trip should be marked clearly (Hartsough et al., 1986). The logs
should be pre-bunched for lifting and any obstacles should be moved away
from the area (Chua, 2001).
After felling and bucking, the logs are extracted by the helicopter.
In helilogging, the logs are carried by a grapple or load-hook, which
is positioned at the end of a lifting cable below the helicopter. In more
recent helilogging operations, double load-hooks are utilized so that
pilots can release some of the logs when the load exceeds the payload
capacity (Krag, 1995).
||Scheduled payload capacities for some logging helicopters
reported by various helilogging companies (Logging and Sawmilling
Journal- Dec 2000/Jan 2001)
The grapple can be controlled electrically, hydraulically,
or mechanically. The following factors should be considered during the
||The length of the lifting cable might range from 75 to 100 m (Chua,
||During each trip, the grapple or load-hook should target precisely
the point where logs are prepared for lifting (i.e., well-experienced
and trained pilots are required for helilogging) (Sloan et al.,
||If there is a logging crew on the ground, they should stay clear
when helicopter is picking up the logs
||After picking up the logs, the helicopter lifts the logs clear of
the forest and then flies to the landing area (Stampfer et al.,
||Heavy logs should be extracted near the end of fuel cycle (i.e.,
weight of the helicopter is low) (Chua, 2001) and when the air temperature
is coolest (air is dense).
||In helilogging, the helicopter is usually flown by two pilots; one
for flying the helicopter and monitoring the operation and other for
controlling the instruments in the helicopter (Chua, 2001).
At the final stage of the helilogging, the logs are flown to the landing
area and placed on the drop zone (Chua, 2001) (Fig. 1):
||The landing areas should have a well organized drop zone with enough
space to ensure an efficient and safe helilogging operation.
||To perform economically, the location of the landing area should
be determined by considering the optimum flying distance (e.g., flying
distance should be within 2 km).
||The pilots should gently place the logs on the ground to minimize
||The landing area should be large enough to pile logs since helicopter
logging has a very short cycle time.
|| Comparisons of various harvesting systems (Far Eastern
Aerostatic Center, Russia)
||Lifting (left) and landing (right) operations in helilogging
(Ericson Air-Crane Inc., USA)
||The number of logging crew members at the landing should be kept
low to avoid accidents.
Timber volume per unit area, stem volume and optimum payload capacity
are critical parameters that affect the productivity of helilogging (Krag,
1995). An experienced ground crew and pilot increase the productivity
in helilogging (Hartsough et al., 1986; Sloan et al., 1994).
Jackson and Morris (1986), in South Carolina, reported that the unit cost
of helilogging (using Boeing Vertol07 II with the average cycle time of
2.57 min) under excellent weather and timber conditions was about $23
m-3 with production rate of 78.5 m3 h-1
and hourly cost of $1,781.
Sloan et al. (1994) studied helilogging in Virginia where they reported
that the unit cost of helilogging (using KMAX with the average cycle time of
2.2-3.0 min) was about $82 m-3 with production rate of 21.0 m3
h-1 and hourly cost of $1,713. They reported that the productivity
and cost of helilogging is mainly affected by the loading operation, flying
distance and pilot experiences. In another study, Sloan and Sherar (1997) reported
that the unit cost of helilogging (using KMAX) was about $60 m-3
with production rate of 37.2 m3 h-1 and hourly cost of
$2,232. In their study, estimation of suitable payload sizes was the main factor
affecting the productivity of the helilogging.
A study conducted by Stampfer et al. (2002) reported that the
productivity of the helilogging (using KMAX) highly depended on average
stem volume and flying distance. They also reported that predetermined
felling directions and bunching the logs prior to lifting operation increased
productivity. According to Stampfer et al. (2002), a well-experienced
helicopter pilot resulted in a 63% increase in productivity of helilogging
operation. Optimum payload is one of the major factors, which may be affected
by silvicultural treatment (Wang et al., 2005). Various retention
levels reflects the load per turn based on the site conditions (Lyons
and McNeel, 2004).
Wang et al. (2004a, b) reported that helilogging (using Boeing
Vertol-107 with the average cycle time of 3.29 min) was 6 and 11 times
more expensive than grapple and cable skidders, respectively; but the
production rate of helilogging operation was 1.5 to 2.8 times more than
these ground-based methods. They found that the unit cost of helilogging
was about $64 m-3 with production rate of 23.04 m3
h-1 and hourly cost of $1,479.
MATERIALS AND METHODS
In Turkey, the GDF uses helicopters in various forestry activities such
as fire fighting, forest protection, wildlife management, shipping and
other activities. The GDF owns USA-designed Eurocopter AS-355 F-2 Ecureuil
II/Twin Star and Aerospatiale AS-365 Dauphin II model helicopters
mainly for monitoring, reconand picture taking (Fig. 2).
The GDF utilizes Russian- designed Mil Mi-8M series helicopters for fire
fighting activities (Fig. 3).
||AS-355 F-2 Ecureuil II (left) and AS-365 Dauphin II
(right) model helicopters
||Mil Mi-17 Hip-H (left) and Mil Mi-8MTV-1 (right) model
The Mil Mi-17 Hip-H model
helicopters, owned by the Military Police (Gendarme), are used during
the fire season, based on a protocol between the GDF and the Gendarme.
The GDF also rents a number of Mil Mi-8MTV-1 model helicopters for fire
Since Mil Mi-8MTV-1 series helicopters are not owned by the GDF and are
utilized for only for fire fighting activities, they are not available
for helilogging. The AS-355 F-2 Ecureuil II can not be employed in helilogging
due to limited payload capabilities. Thus, AS-365 Dauphin II is the only
helicopter model owned by the GDF which can be available for helilogging
operations in Turkey. The hourly cost of renting the Mil Mi-8MTV-1 is
about $3000. The option of renting additional helicopters specifically
for helilogging was not considered for this study. Therefore, the analysis
of utilizing helilogging was performed for the AS-365 Dauphin II model
AS-365 dauphin II: The AS-365 Dauphin II (Fig. 4)
is categorized as a medium twin engine helicopter with following specifications
||With standard seat configurations, the AS-365 can carry 1 or 2 pilots
and 8 passengers
||The empty weight (including engine oil and fuel) and maximum take-off
weight are approximately 2400 and 4300 kg, respectively
||The maximum external cargo sling payload capacity is about 1600
||With maximum take-off weight, the recommended cruise speed and hourly
fuel consumption at this speed is 269 km h-1 and 314 kg
||The maximum continuous power is about 600 kW (800 HP)
||The helilogging operation with the AS-365 Dauphin II has some operating
limitations such as maximum flight altitude of 4575 m, maximum temperature
of 50°C and minimum temperature of -40°C.
Machine rate estimation: The unit cost of helilogging can be estimated
by dividing the hourly equipment cost of the helicopter (machine rate)
by the production rate. The machine rate is divided into three components;
labor costs, ownership costs and operating costs. The hourly cost of labor
is estimated as $150 h-1.
The ownership cost components include depreciation cost, interest cost
and insurance, tax and storage costs of the equipment. The yearly depreciation
cost is function of initial purchase price, salvage rate and economic
life. The initial purchase price, salvage rate and economic life were
estimated as $3.5 million, 25% and 16 years (i.e. considering 20000 h
service life and 1250 flight h per year with 60% utilization rate).
||Dimensions of an AS-365 Dauphin II (Eurocopter, 2007)
interest costs can be calculated by multiplying the interest rate (18%)
by the average annual investment (Akay and Sessions, 2004).
The costs of insurance, taxes and storage are computed as a function
of the initial purchase prices. The total rate of these three factors
is estimated as 11.5%. The main operating cost components include maintenance
and repair costs, fuel cost and lubricant cost. The maintenance and repair
cost can be estimated as a percent of depreciation. Wang et al.
(2005) suggested that the maintenance and repair rate was 100% of the
depreciation of the helicopter. Fuel and lubricant costs can be computed
based on hourly fuel consumption rate (314 kg h-1), weight
of fuel per liter (0.84 kg L-1) and local unit prices.
RESULTS AND DISCUSSION
In Turkish forestry, the trees have to be bucked into short lengths logs
(3-4 m) due to current harvesting methods and low road standards. Producing
short logs significantly reduces the potential profits from the logs.
However, longer logs can be produced if aerial harvesting methods such
as helicopter logging can be implemented in productive forests with commercially
important tree species. Helicopter logging can also be used in extraction
of mature trees in environmentally sensitive areas where road construction
and logging operations are restricted.
In this study, the analysis of helilogging was performed for the AS-365
Dauphin II model helicopter based on a hypothetical example. The hourly
cost of the AS-365 Dauphin II helicopter was estimated as $1950 h-1
(Table 3) using the machine rate method. Fuel cost was
the most important factor affecting the machine rate. The high purchase
price increased the costs of interest, insurance, taxes and storage, value
of the average annual investment, depreciation cost and maintenance and
repair costs. The average annual investment and depreciation cost was
greatly affected by the economic life of the helicopter. Interest, insurance,
taxes and storage costs were the second highest cost component due to
the high interest rate and taxes in Turkey.
By using the machine rate ($ h-1) and hourly production rate
(m3 h-1), the unit cost ($ m-3) of helilogging
can be computed. The production rate is a function of payload capacity
and average cycle time.
|| The hourly cost components of the helicopter
In a helilogging study by Wang et al. (2005),
the average cycle was found to be as 3.29 min in which fly empty, prebunch,
hook, fly loaded, release, unhook and delay/refuel times were 0.56, 1.04,
0.87, 0.57, 0.02, 0.22 and 3.00 min, respectively. This indicated that
the loaded fly time is about 2% greater than the unloaded fly time in
Based on cycle time data from Wang et al. (2005), a production
rate was estimated for the AS-365 Dauphin II helicopter. For the flight
distance of 2 km and average cruise speed of 269 km h-1, fly
unloaded and fly loaded times were 0.89 and 0.91 min, respectively. The
total time of other cycle time elements (i.e., prebunch, hook, release,
unhook and delay/refuel times) obtained from Wang et al. (2005)
were 2.16 min. Therefore, the total cycle time estimation was 3.96 min,
including fly unloaded and fly loaded times.
With the average payload utilization rate of 60%, the production rate
of the AS-365 Dauphin II with an average payload capacity of 1.6 m-3
(i.e., 1000 kg≈1 m3) was computed as 14.54 m3
h-1. This resulted in a unit cost of $134.11 m-3
for helilogging using the AS-365 Dauphin II helicopter. The unit cost
estimate is high compared with helilogging studies reviewed in this paper
due to the low production rate. However, this result may still generate
an acceptable net profit in Turkey since the average unit price of the
high quality and l onger logs can be over $200 m-3 based on
the tree species, the regions and market demand. The lower payload capacity
of the AS-365 Dauphin II played an important role in the unit cost of
helilogging. Utilizing the full payload capacity of the helicopter would
increase the production rate and lower the unit cost during a helilogging
Applying helilogging in Turkish forestry could be economically viable
and technically feasible based on the simple analysis used in this study.
In some situations, helilogging can be the only option in implementing
timber extraction in environmentally sensitive areas and in steep and
difficult terrain in Turkey. Helilogging operations may also provide logging
managers with the following advantages:
||Reducing damage to residual trees and forest vegetation, especially
during selection cutting systems in uneven aged mixed forests
||Minimizing sediment yield to streams and protecting water resources
by reducing forest road construction
||Providing access to remote forested areas and difficult terrain
||Maximizing logging productivity by providing a high production rate
||Increasing the quality and price of the logs by allowing extraction
of longer logs, which can not be transported otherwise due to low-standard
forest roads in Turkey
||Ensuring safer working environment for the loggers
In implementing helilogging, logging managers should also be aware of
the following potential disadvantages:
||Permitting logging operations in environmentally sensitive and steep
||Involving high investment to utilize a helicopter and Increasing
the unit cost of timber extraction operations
||Requiring skilled, well-trained and experienced personnel (i.e.,
pilots and technicians) who might be foreign rather than domestic
||Reducing road densities in the long run which may lead to an increase
in the cost of forest management
||Leaving large amount of low quality logs in the woods after extracting
only high quality logs