Article citation information:
Michalska, A., Brodzik, R., Izdebski, M. Reliability
analysis of the indicated airspeed sensor in unmanned aerial vehicles using
non-parametric methods. Scientific
Journal of Silesian University of Technology. Series Transport. 2026, 131, 137-150. ISSN: 0209-3324. DOI: https://doi.org/10.20858/sjsutst.2026.131.8
Anna MICHALSKA[1],
Robert BRODZIK[2],
Mariusz IZDEBSKI[3]
RELIABILITY ANALYSIS OF THE INDICATED AIRSPEED SENSOR IN UNMANNED AERIAL
VEHICLES USING NON-PARAMETRIC METHODS
Summary. Unmanned Aerial Vehicles (UAVs) play an increasingly
important role in civil and military aviation, supporting missions ranging from
infrastructure monitoring and parcel delivery to reconnaissance and combat
operations. Their widespread use in modern transport systems raises the demand
for reliable onboard equipment. Among critical subsystems, the Indicated
Airspeed (IAS) sensor provides key information for flight control, stability
management, and stall prevention. Failures of the IAS sensor – caused by contamination,
icing, mechanical damage, or electronic malfunction – pose a significant safety
hazard and may lead to flight instability or operational incidents. This study
investigates the reliability of the IAS sensor in UAVs using non-parametric
reliability analysis methods. Data collected from the SAMANTA maintenance
management system over a four-year observation period (2016-2019) were analyzed to determine the cumulative distribution function,
hazard rate, and instantaneous reliability function. The research highlights
that IAS-related failures account for the second-largest group of recorded UAV
malfunctions, underscoring the importance of proactive maintenance strategies.
The results provide insights into the operational reliability of IAS sensors
and lay the groundwork for the development of predictive maintenance models,
improved component design, and enhanced UAV safety in both civil and military
applications.
Keywords: Unmanned
Aerial Vehicle (UAV), Indicated Airspeed (IAS) sensor, reliability analysis,
non-parametric methods, hazard rate, predictive maintenance, flight safety
1. INTRODUCTION
Unmanned
Aerial Vehicles (UAVs), commonly known as drones, have become integral elements
of both civil and military aviation systems. Their rapid technological
development and expanding operational capabilities have led to widespread
adoption in diverse applications such as border surveillance, reconnaissance
missions, search and rescue operations, environmental monitoring,
infrastructure inspection, and combat operations. In the civil transport
sector, UAVs are increasingly deployed for power line inspections, geodetic
surveys, and parcel delivery, thereby reshaping logistics chains and
contributing to the concept of intelligent and sustainable transport systems.
The growing
operational significance of UAVs requires the development of highly reliable
onboard systems. Due to the limited possibility of real-time human
intervention, any failure of a critical component may result in a loss of
control, damage to equipment, and, in extreme cases, catastrophic accidents.
Ensuring the reliability of UAV subsystems is therefore fundamental for both
aviation safety and the continuity of operations.
One of the
most essential elements of a UAV’s navigation and flight control system is the
Indicated Airspeed (IAS) sensor. IAS provides vital information on airspeed
relative to the surrounding air mass, which allows for maintaining flight
stability, preventing aerodynamic stall, and optimizing performance parameters.
The IAS sensor operates based on the differential measurement of dynamic and
static pressures, and its accurate readings are crucial for autopilot
operation, energy management, and decision-making regarding operational
airspeeds.
Malfunctions
of the IAS sensor – caused by probe contamination, icing, mechanical damage, or
electronic faults – can lead to erroneous speed readings, incorrect maneuver
execution, and flight instability, which may further escalate into hardware
damage, including improper landing procedures. Service and maintenance
statistics collected from the SAMANTA system over a four-year observation
period (2016-2019) indicate that failures of the IAS sensor and its associated
measurement system represent the second most frequent category of recorded UAV
malfunctions, which is a significant proportion given the number of onboard
components. This high failure rate is largely attributed to the sensor’s
exposure to external factors such as precipitation, contamination, icing, and
vibrations.
Given the
considerable share of IAS-related failures in overall UAV malfunctions,
reliability analysis of this component is not only justified but necessary.
This study applies non-parametric reliability methods to assess the IAS sensor
performance, focusing on the cumulative distribution function, hazard rate
function, and instantaneous reliability function. The research aims to
establish a basis for improving UAV airspeed measurement systems and developing
advanced predictive maintenance models.
2. LITERATURE REVIEW AND THEORETICAL BACKGROUND
The reliability of Unmanned Aerial
Vehicles (UAVs) has become a critical research focus as their integration into
civil, military, and transport systems steadily grows. UAVs are now widely used
in logistics, infrastructure monitoring, environmental surveillance, and
emergency response [1, 2]. Operating in adverse weather conditions, often
without real-time human intervention, increases the importance of robust
reliability analysis [3].
One of the most vulnerable
components of UAV avionics is the Indicated Airspeed (IAS) sensor, which relies
on a Pitot‑static system to measure dynamic and static pressure
differences and compute airspeed [4]. Pitot‑static system failures,
especially due to tube icing or contamination, have historically caused severe
flight accidents (e.g., Air France 447, Birgenair
301) [5].
Environmental threats to Pitot‑static
sensors include:
·
Icing,
which affects measurement accuracy and control stability in small UAVs [1, 6];
·
Contamination
caused by dust, insects, or debris, leading to partial or total blockage of the
Pitot-tube [7];
·
Electronic
and telemetry faults that disrupt accurate data transmission between the sensor
and the flight control computer [8].
Numerous studies have addressed
airspeed sensor fault detection and isolation (FDI) techniques in UAVs.
Analytical redundancy approaches such as Extended Kalman Filters (EKF) and
statistical change detection have shown effectiveness in identifying Pitot‑tube
blockages and icing events in real flight conditions [9]. PCA-based and
neural-network‑driven fault detection methods also demonstrate strong
performance in reducing false alarms in airspeed measurements [10].
Reliability analysis of UAV
subsystems has been traditionally performed using parametric methods (e.g.,
Weibull, exponential), which assume a predefined failure distribution [11, 12].
While useful in some contexts, parametric models often fail to capture
heterogeneous operational conditions of UAVs [13].
In contrast, non-parametric methods
– including the Kaplan-Meier survival estimator and Nelson-Aalen cumulative
hazard model – allow direct computation of reliability functions, hazard rates,
and failure probabilities without assuming an underlying distribution [14, 15].
This makes them particularly valuable for components like IAS sensors, where
datasets are often sparse or incomplete.
Recent research highlights the
integration of reliability analysis with predictive maintenance frameworks,
which enable early fault detection, scheduled interventions, and improved UAV
operational safety in both civil and military transport logistics [2, 14, 16].
3. METHODOLOGY
The study employs a non-parametric reliability analysis
of the IAS sensor used in unmanned aerial vehicles. The methodology is divided
into several stages: data collection,
data processing,
and statistical analysis.
Failure data for IAS sensors were obtained from
the SAMANTA maintenance management
system, which records operational events, malfunctions, and
repairs of UAV fleets. The dataset covers a four-year observation period (2016-2019) and includes:
·
the
total number of UAVs equipped with IAS sensors under observation,
·
recorded
failures of IAS sensors and their causes,
·
time-to-failure
(TTF) data, representing operational time between failures,
·
operational
conditions during each recorded failure (e.g., weather, flight phase).
Data were verified for completeness and
consistency. Cases lacking clear failure timestamps or maintenance records were
excluded from the analysis.
The reliability analysis is based on non-parametric statistical methods,
enabling evaluation of IAS sensor performance without assuming a predefined
failure distribution. Data processing and analysis were performed using MATLAB and R statistical software, leveraging
built-in functions for survival and hazard modeling. Non-parametric estimators
such as the Kaplan-Meier estimator
were used to derive survival curves and reliability functions, while the Nelson-Aalen estimator was applied
for hazard rate calculations. The Kaplan-Meier estimator was applied to
non-censored complete failure data; in this study, all 44 failures were fully
observed, as UAVs were returned to service after each repair and the dataset
contains only complete time-to-failure records. Confidence intervals for the
reliability function R(t) were derived using the chi-squared approximation of
the Nelson-Aalen cumulative hazard estimator Λ(t), with β=0.95. It
should be noted that upper confidence bounds of Λ(t) may legitimately
exceed 1, since Λ(t) is a cumulative hazard function and is not bounded
above by 1; only the reliability function R(t)=exp[−Λ(t)] is
constrained to the interval [0,1]. Polynomial regression was applied to the
histogram data in MATLAB to produce smooth empirical curves of the reliability,
cumulative hazard, and instantaneous failure intensity functions, facilitating
visual identification of failure rate trends and aging thresholds. The
calculated reliability functions and hazard rates were compared with available
UAV maintenance literature and benchmarked against known reliability data from
other avionics components. Sensitivity analysis was performed to test the
robustness of the non-parametric models, particularly regarding sample size and
missing data points.
4. RELIABILITY
CALCULATIONS FOR THE INDICATED AIRSPEED (IAS) SYSTEM IN ORBITER 2B UNMANNED
AERIAL VEHICLES (UAVS)
The study encompassed a sample of n = 45 objects (each representing an
unmanned aerial vehicle, UAV). All identified damages were repaired, and the
UAVs were subsequently reintegrated into the testing process. Repair time was not taken into account,
as the total repair duration presented in Table 1 exceeds the actual operational time of the
UAVs.
Tab. 1
Repair and operational time of the objects in
the years 2016-2019
|
Element |
Type |
Time [h] |
|
UAV |
TworkUAV |
2265h 16' |
|
IAS |
TrepairIAS |
83h 30' |
Thus, the following
inequality is satisfied:
|
|
(1) |
Within the time interval [0, tm] a total of
m=44 failures were recorded. Table 2 presents the number of failures within
each specific time interval.
Tab. 2
Number of IAS failures over the entire study
period (2016-2019)
|
2016 |
Months |
July |
August |
September |
October |
November |
December |
|
Flight time in hours |
20 |
60 |
143 |
222 |
270 |
299 |
|
|
Number of failures |
1 |
- |
2 |
- |
2 |
- |
|
|
Cumulative number of failures |
1 |
- |
3 |
- |
5 |
- |
|
|
2017 |
Months |
January |
February |
March |
April |
May |
June |
|
Flight time in hours |
314 |
337 |
449 |
485 |
501 |
546 |
|
|
Number of failures |
14 |
- |
1 |
- |
- |
- |
|
|
Cumulative number of failures |
19 |
- |
20 |
- |
- |
- |
|
|
Month |
July |
August |
September |
October |
November |
December |
|
|
Flight time in hours |
583 |
598 |
620 |
712 |
756 |
775 |
|
|
Number of failures |
- |
- |
- |
1 |
2 |
- |
|
|
Cumulative number of failures |
- |
- |
- |
21 |
23 |
- |
|
|
2018 |
Month |
January |
February |
March |
April |
May |
June |
|
Flight time in hours |
812 |
849 |
939 |
1105 |
1141 |
1146 |
|
|
Number of failures |
- |
1 |
- |
6 |
2 |
1 |
|
|
Cumulative number of failures |
- |
24 |
- |
30 |
32 |
33 |
|
|
Months |
July |
August |
September |
October |
November |
December |
|
|
Flight time in hours |
1203 |
1256 |
1288 |
1337 |
1423 |
1474 |
|
|
Number of failures |
2 |
3 |
- |
- |
- |
2 |
|
|
Cumulative number of failures |
35 |
38 |
- |
- |
- |
40 |
|
|
2019 |
Months |
January |
February |
March |
April |
May |
June |
|
Flight time in hours |
1503 |
1599 |
1612 |
1723 |
1846 |
1944 |
|
|
Number of failures |
- |
- |
- |
- |
3 |
1 |
|
|
Cumulative number of failures |
- |
- |
- |
- |
43 |
44 |
An estimation of the expected value
of the reliability function R(tm) and the corresponding confidence intervals
0,95]. was performed. Using formulas:
|
|
(2) |
|
|
(3) |
|
|
(4) |
The function values were calculated.
Based on the estimated values presented in Table 3, a histogram was generated
in MATLAB, and the results were subsequently fitted using polynomial
regression.
Results of the reliability function analysis of the
IAS Components
|
tm [h] |
Number of failures [no.] |
Cumulative number of failures – m
[no.] |
Sample size – n [no.] |
|
|
|
|
20 |
1 |
1 |
45 |
0,978022872 |
0,983064 |
0,90763 |
|
143 |
2 |
3 |
45 |
0,935506985 |
0,90763 |
0,808944 |
|
270 |
2 |
5 |
45 |
0,894839317 |
0,908355 |
0,784247 |
|
314 |
14 |
19 |
45 |
0,655588337 |
0,899605 |
0,77232 |
|
449 |
1 |
20 |
45 |
0,641180388 |
0,89085 |
0,760651 |
|
712 |
1 |
21 |
45 |
0,627089085 |
0,8821 |
0,749226 |
|
756 |
2 |
23 |
45 |
0,599828732 |
0,864651 |
0,727064 |
|
849 |
1 |
24 |
45 |
0,58664622 |
0,723706 |
0,567894 |
|
1105 |
6 |
30 |
45 |
0,513417119 |
0,68561 |
0,529012 |
|
1141 |
2 |
32 |
45 |
0,49109823 |
0,670838 |
0,51429 |
|
1146 |
1 |
33 |
45 |
0,480305301 |
0,642101 |
0,486175 |
|
1203 |
2 |
35 |
45 |
0,459425824 |
0,600992 |
0,447077 |
|
1256 |
3 |
38 |
45 |
0,429796067 |
0,574897 |
0,422895 |
|
1474 |
2 |
40 |
45 |
0,411112291 |
0,543715 |
0,394605 |
|
1846 |
3 |
43 |
45 |
0,384598419 |
0,537667 |
0,389192 |
|
1944 |
1 |
44 |
45 |
0,376146051 |
0,525756 |
0,378598 |

Fig. 1. Reliability function of IAS Components
On the
histogram, the estimated quantile of
order p=0.5 for the object’s
failure-free operating time was marked. From the reliability function plot at p=R=0.5 the corresponding durability values were obtained as
T0,5=1170h,
0,5=1500h,
0,5=780h.
This result indicates that, at a confidence
level of β=0.95, the object’s
reliability in the time interval [780, 1500] will be
R(tm)=0,5.
The next step
was to estimate the expected value of
the leading distribution function
and the corresponding confidence intervals [
,
,
β=0,95], based on formulas:
|
|
(5) |
|
|
(6) |
|
|
(7) |
Using the estimated values, a results table and a histogram were generated, the latter
of which was subjected to polynomial
regression in MATLAB.
Tab. 4
Results of the leading distribution function
analysis for IAS components
|
tm [h] |
Number of failures [no.] |
Cumulative number of failures – m
[no.] |
Sample size – n [no.] |
|
|
|
|
20 |
1 |
1 |
45 |
0,022222222 |
0,00114 |
0,066572 |
|
143 |
2 |
3 |
45 |
0,066666667 |
0,018171 |
0,139907 |
|
270 |
2 |
5 |
45 |
0,111111111 |
0,043781 |
0,203412 |
|
314 |
14 |
19 |
45 |
0,422222222 |
0,276489 |
0,59315 |
|
449 |
1 |
20 |
45 |
0,444444444 |
0,294556 |
0,619539 |
|
712 |
1 |
21 |
45 |
0,466666667 |
0,312711 |
0,645823 |
|
756 |
2 |
23 |
45 |
0,511111111 |
0,349322 |
0,698107 |
|
849 |
1 |
24 |
45 |
0,533333333 |
0,367756 |
0,72412 |
|
1105 |
6 |
30 |
45 |
0,666666667 |
0,479866 |
0,878688 |
|
1141 |
2 |
32 |
45 |
0,711111111 |
0,517721 |
0,929725 |
|
1146 |
1 |
33 |
45 |
0,733333333 |
0,536726 |
0,955166 |
|
1203 |
2 |
35 |
45 |
0,777777778 |
0,574881 |
1,005902 |
|
1256 |
3 |
38 |
45 |
0,844444444 |
0,632442 |
1,081677 |
|
1474 |
2 |
40 |
45 |
0,888888889 |
0,671017 |
1,131989 |
|
1846 |
3 |
43 |
45 |
0,955555556 |
0,729148 |
1,207199 |
|
1944 |
1 |
44 |
45 |
0,977777778 |
0,748591 |
1,2322 |

Fig. 2. Leading distribution function of IAS
components
Using the graphical estimation
method based on Figure 2, the
expected value of the time to the m-th failure and
the time interval between the (m-1)-th and m-th failure (corresponding to a 60% resource depletion) were
determined, yielding respectively:
,
and
and ![]()
The obtained results provide a
numerical representation of the preliminary assessment of object aging by
determining the failure-free operating time.
|
|
(8) |
|
|
(9) |
|
|
(10) |
In the subsequent calculations, the Author
approximated the aging times of the
objects. For this purpose, an estimation of the instantaneous mean failure intensity function
of the tested objects,
along with the corresponding confidence intervals
,
,
β=0,95 was
performed. Using formulas:
|
|
|
(11) |
|
|
|
(12) |
|
|
|
(13) |
The
Author prepared Table 5
presenting the research results, as well as Figure (histogram), which was subjected to polynomial regression in MATLAB.
Tab. 5
Results of the instantaneous failure intensity
function analysis of IAS components
|
tm [h] |
Number of failures [no.] |
Cumulative number of failures – m
[no.] |
Sample size – n [no.] |
|
|
|
|
20 |
1 |
1 |
45 |
0,001111111 |
5,7E-05 |
0,003329 |
|
143 |
2 |
3 |
45 |
0,0004662 |
0,000127 |
0,000978 |
|
270 |
2 |
5 |
45 |
0,000411523 |
0,000162 |
0,000753 |
|
314 |
14 |
19 |
45 |
0,001344657 |
0,000881 |
0,001889 |
|
449 |
1 |
20 |
45 |
0,000989854 |
0,000656 |
0,00138 |
|
712 |
1 |
21 |
45 |
0,000655431 |
0,000439 |
0,000907 |
|
756 |
2 |
23 |
45 |
0,000676073 |
0,000462 |
0,000923 |
|
849 |
1 |
24 |
45 |
0,00062819 |
0,000433 |
0,000853 |
|
1105 |
6 |
30 |
45 |
0,000603318 |
0,000434 |
0,000795 |
|
1141 |
2 |
32 |
45 |
0,000623235 |
0,000454 |
0,000815 |
|
1146 |
1 |
33 |
45 |
0,000639907 |
0,000468 |
0,000833 |
|
1203 |
2 |
35 |
45 |
0,000646532 |
0,000478 |
0,000836 |
|
1256 |
3 |
38 |
45 |
0,000672328 |
0,000504 |
0,000861 |
|
1474 |
2 |
40 |
45 |
0,000603045 |
0,000455 |
0,000768 |
|
1846 |
3 |
43 |
45 |
0,000517636 |
0,000395 |
0,000654 |
|
1944 |
1 |
44 |
45 |
0,000502972 |
0,000385 |
0,000634 |

Fig. 3. Instantaneous failure intensity
function of IAS components
In
the study, a graphical method was applied to estimate the preliminary aging
time tS of the objects with
confidence intervals, as well as the preventive maintenance time tP (after which preventive actions, e.g.,
component replacement, are carried out), also with confidence intervals.
Assuming the
permissible failure intensity value of λd = 0,00088 [
],
the following results were obtained: ![]()
The graph shows the presence of
extrema. Since the UAV is a complex object, the extrema indicate the existence
of weak links within the system. Therefore, it is purposeful to estimate the
time of preventive maintenance actions ![]()
Looking comprehensively at the
selected IAS component through all the obtained research results – namely, the
instantaneous reliability function, the instantaneous failure intensity function,
and the instantaneous leading distribution function presented in Figure 4 – one
can observe their interdependencies.

Fig. 4. Comparison of the Instantaneous
reliability function, the instantaneous leading distribution function, and the
instantaneous failure intensity function for IAS components
At the beginning of the observation
(around 100 h), the characteristic curves show a tendency toward stabilization.
The Author notes that this is a typical behavior in
the early stage of observation, given the short observation time and the
limited amount of failure data. Therefore, it was considered justified to
conclude that the most failure-prone IAS component begins its aging process
already in the initial phase (tS=55 h).
In the next stage, a distinct
extremum is visible, resulting from a significant increase in the instantaneous
failure intensity (270-300 h of observation). This, in turn, causes the
instantaneous reliability of the objects to decrease sharply by 30%, accompanied
by a simultaneous 30% resource depletion. The lower bound of the maintenance
window (275 h) corresponds to the lower 95% confidence bound of the preventive
maintenance time tP derived from the instantaneous
failure intensity function at the permissible threshold λd = 0.00088 [1/h], while the upper
bound (314 h) corresponds to the point estimate tP
at which the failure intensity first peaks (see Table 2, cumulative failures
reaching 19 out of 45 at tm=314 h). The interval [275, 314] h thus represents
the range within which the failure intensity crosses the permissible threshold
with 95% statistical confidence. Consequently, it is considered reasonable to
carry out preventive maintenance activities within the range of 275-314 h of
flight time.
Further observation indicates that
at 50% resource depletion (time interval [314-1944 h]), the characteristics
tend toward stationarity of the failure process (instantaneous failure
intensity, instantaneous reliability, and resource consumption), with one
noticeable exception: at 80% resource depletion, a sudden increase in
instantaneous failure intensity is observed, along with a 10% drop in
reliability. Therefore, defining the object’s failure-free operating time as a
reflection of the aging assessment within the 20-80% resource depletion
interval was considered justified by the Author, yielding:
|
|
(14) |
Based on the examination of selected
components and the presented graphical solution for estimating the preliminary
aging times of Orbiter 2B UAV components, as well as estimating the time frames
for carrying out preventive maintenance activities, the Author found it
necessary to highlight the potential impact of implementing modern solutions on
UAV systems.
The reliability of airspeed
indicators in unmanned aircraft is of crucial importance for safe operation,
particularly due to the absence of a pilot capable of making real-time
decisions. Recent technological advances have led to various methods aimed at enhancing
the accuracy and reliability of these indicators. The following sections
present the key developments in this field.
5.
DISCUSSION
The reliability analysis of IAS
sensors in Orbiter 2B UAVs revealed clear aging patterns that align with known
vulnerabilities of Pitot-static systems reported in the literature [5, 7, 8].
The results demonstrated a significant increase in failure intensity within the
interval of 270-300 flight hours, followed by a stabilization phase, and
another failure intensity growth at around 80% resource depletion. This behavior is consistent with the “wear-out” phase of the
bathtub curve model, well established in reliability engineering literature for
avionic components [11, 13].
The comparison with earlier studies
confirms that the main causes of IAS sensor malfunctions – contamination and
icing – are dominant in both civil and military applications [1, 3, 5]. The
present findings reinforce previous accident investigations (e.g., Air France
Flight 447, Birgenair 301) that linked Pitot-tube
icing to critical flight incidents [5]. In UAV operations, these risks are
amplified by the lack of real-time pilot intervention, which increases the
importance of preventive maintenance and sensor redundancy.
A notable contribution of this study
is the application of non-parametric methods (Kaplan-Meier and Nelson-Aalen
estimators) to UAV reliability data. Unlike parametric models, these methods
provided reliable estimates of survival and hazard functions without assuming a
predefined failure distribution. The obtained results show good consistency
with previous works that applied non-parametric tools to avionics reliability
[14, 15], while also demonstrating their suitability for relatively small
datasets collected from operational fleets.
From a practical standpoint, the
analysis suggests that preventive maintenance actions should be scheduled
within the interval of 275-314 flight hours to mitigate the rapid growth in
failure intensity. This threshold provides a technical basis for optimizing
maintenance intervals, which can improve UAV availability and safety. The
findings also highlight the potential of integrating reliability analysis with
predictive maintenance frameworks, as proposed in recent studies [2, 16].
Nevertheless, several limitations
should be acknowledged. The study was based on a sample of 45 UAVs of a single
type (Orbiter 2B), which may limit the generalizability of results to other UAV
platforms. Additionally, repair times were excluded from the analysis, which
might slightly affect the accuracy of availability estimations. Future research
should expand the dataset, include multiple UAV types, and integrate condition
monitoring data to refine predictive models.
Overall, the study confirms that IAS
sensors represent a critical weak point in UAV avionics. By applying
non-parametric reliability methods, this research contributes to the
development of evidence-based maintenance policies and supports the implementation
of advanced diagnostic and preventive measures in UAV transport and defense operations.
6.
CONCLUSIONS
This study investigated the
reliability of the Indicated Airspeed (IAS) sensor in Orbiter 2B unmanned
aerial vehicles using non-parametric methods. The analysis confirmed that the
IAS sensor is one of the most failure-prone components of UAV avionics, with
failures constituting the second-largest group of recorded malfunctions in the
examined fleet. The results of the reliability function and hazard rate
estimation revealed clear aging behavior of the IAS
sensor. In particular, a sharp increase in failure intensity was observed
between 270 and 300 flight hours, which indicates that preventive maintenance
should be introduced within this operational interval.
The dominant failure causes were
associated with Pitot-tube contamination and icing, which together accounted
for the majority of recorded incidents. These findings are consistent with
earlier aviation accident investigations and confirm the environmental
vulnerability of the IAS system. By applying non-parametric reliability
methods, including the Kaplan-Meier and Nelson-Aalen estimators, the study
demonstrated that such approaches are effective in UAV reliability assessment,
particularly in situations where datasets are limited and no predefined failure
distribution can be assumed.
The results provide a quantitative
foundation for the development of predictive maintenance strategies for UAV
fleets. Their implementation could contribute to improved operational safety,
reduced downtime, and more efficient fleet management. At the same time, it
must be emphasized that the study was limited to a single UAV type (Orbiter 2B)
and a relatively small dataset. Therefore, future research should expand the
scope to include multiple UAV platforms and integrate condition monitoring
systems, which would further enhance prediction accuracy.
In conclusion, IAS sensor
reliability is a critical determinant of UAV operational safety. The findings
highlight the importance of implementing evidence-based maintenance policies
and technological improvements, such as anti-icing protection and self-cleaning
Pitot systems, to ensure safe and reliable UAV operations in both civil and
military transport applications.
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Received 26.12.2025; accepted in
revised form 02.06.2026
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Journal of Silesian University of Technology. Series Transport is licensed
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[1] The Institute of Logistics and
Transport, Polish Air Force University, Dywizjonu 303
nr 35 Street, 08-521 Dęblin, Poland. Email:
a.michalska@law.mil.pl. ORCID: https://orcid.org/0000-0002-9292-589X
[2] The Institute of Logistics and
Transport, Polish Air Force University, Dywizjonu 303
nr 35 Street, 08-521 Dęblin, Poland. Email:
r.brodzik@law.mil.pl. ORCID: https://orcid.org/0000-0001-9303-8785
[3] The Faculty of Transport, Warsaw
University of Technology, Koszykowa 75 Street, 00-662
Warszawa, Poland. Email: mariusz.izdebski@pw.edu.pl. ORCID: https://orcid.org/0000-0002-9157-7870