Background: Army Aviators rely on the ANVIS for night operations. Human factors literature notes that the ANVIS
man-machine interface results in reports of visual and spinal complaints. This is the first study that has looked at these
issues in the much harsher combat environment. Last year, the authors reported on the statistically significant (p<0.01)
increased complaints of visual discomfort, degraded visual cues, and incidence of static and dynamic visual illusions in
the combat environment [Proc. SPIE, Vol. 7688, 76880G (2010)]. In this paper we present the findings regarding
increased spinal complaints and other man-machine interface issues found in the combat environment. Methods: A
survey was administered to Aircrew deployed in support of Operation Enduring Freedom (OEF). Results: 82 Aircrew
(representing an aggregate of >89,000 flight hours of which >22,000 were with ANVIS) participated. Analysis
demonstrated high complaints of almost all levels of back and neck pain. Additionally, the use of body armor and other
Aviation Life Support Equipment (ALSE) caused significant ergonomic complaints when used with ANVIS.
Conclusions: ANVIS use in a combat environment resulted in higher and different types of reports of spinal symptoms
and other man-machine interface issues over what was previously reported. Data from this study may be more
operationally relevant than that of the peacetime literature as it is derived from actual combat and not from training
flights, and it may have important implications about making combat predictions based on performance in training
scenarios. Notably, Aircrew remarked that they could not execute the mission without ANVIS and ALSE and accepted
the degraded ergonomic environment.
In 1973, the U.S. Army adopted night vision devices for use in the aviation environment. These devices are based on the
principle of image intensification (I2) and have become the mainstay for the aviator's capability to operate during
periods of low illumination, i.e., at night. In the nearly four decades that have followed, a number of engineering
advancements have significantly improved the performance of these devices. The current version, using 3rd generation I2
technology is known as the Aviator's Night Vision Imaging System (ANVIS). While considerable experience with
performance has been gained during training and peacetime operations, no previous studies have looked at user
acceptability and performance issues in a combat environment. This study was designed to compare Army Aircrew
experiences in a combat environment to currently available information in the published literature (all peacetime
laboratory and field training studies) and to determine if the latter is valid. The purpose of this study was to identify and
assess aircrew satisfaction with the ANVIS and any visual performance issues or problems relating to its use in
Operation Enduring Freedom (OEF). The study consisted of an anonymous survey (based on previous validated surveys
used in the laboratory and training environments) of 86 Aircrew members (64% Rated and 36% Non-rated) of an
Aviation Task Force approximately 6 months into their OEF deployment. This group represents an aggregate of >94,000
flight hours of which ~22,000 are ANVIS and ~16,000 during this deployment. Overall user acceptability of ANVIS in a
combat environment will be discussed.
A collaborative occupational health study has been undertaken by Headquarters Army Aviation, Middle Wallop, UK,
and the U.S. Army Aeromedical Research Laboratory, Fort Rucker, Alabama, to determine if the use of the Integrated
Helmet and Display Sighting System (IHADSS) monocular helmet-mounted display (HMD) in the Apache AH Mk 1
attack helicopter has any long-term (10-year) effect on visual performance. The test methodology consists primarily of a
detailed questionnaire and an annual battery of vision tests selected to capture changes in visual performance of Apache
aviators over their flight career (with an emphasis on binocular visual function). Pilots using binocular night vision
goggles serve as controls and undergo the same methodology. Currently, at the midpoint of the study, with the exception
of a possible colour discrimination effect, there are no data indicating that the long-term use of the IHADSS monocular
HMD results in negative effects on vision.
The Integrated Helmet and Display Sighting System (IHADSS) helmet-mounted display (HMD) has been flown for
over a quarter of a century on the U.S. Army's AH-64 Apache Attack Helicopter. The aircraft's successful deployment
in both peacetime and combat has validated the original design concept for the IHADSS HMD. During its 1970s
development phase, a number of design issues were identified as having the potential of introducing visual perception
problems for aviators. These issues include monocular design, monochromatic imagery, reduced field-of-view (FOV),
sensor spectrum, reduced resolution (effective visual acuity), and displaced visual input eye point. From their diverse
perspectives, a panel of four experts - an HMD researcher, a cognitive psychologist, a flight surgeon, and a veteran AH-64 aviator - discuss the impact of the design issues on visual perception and related performance.
In the late 1970s the U.S. Army developed the Integrated Helmet and Display Sighting System (IHADSS), which is a
helmet-mounted display (HMD) for use in the AH-64 Apache helicopter. The helicopter and the system were designed
with the Cold War in mind such that the Apache would be able to stand off far from the frontlines and attack deep target-primarily tanks-before they could engage our ground forces. The design used a right-sided monocular display optical
system that was intended to reduce head-supported weight. This novel monocular design introduced a number of issues
that had the potential of causing visual perception problems for pilots. Since the initial fielding of the Apache in the early
1980s, numerous reports have appeared in the literature that evaluated realized visual complaints voiced by Apache
aircrew. In this review, the authors provide a summary of seminal reports, surveys, and experiments conducted over the
past three decades. The extant literature described investigated these visual issues as the Apache's mission has evolved
from the stand-off engagement tactics of the Cold War to the new Apache missions of close air support, deep attack, and
raids currently occurring in the Global War on Terrorism.
In the first two decades of the fielding of the monocular helmet-mounted display (HMD) flown in the U.S. Army's AH-64 Apache attack helicopter, a number of studies reported a significant incidence of physical visual symptoms and illusions. In 2004, a similar study looked at the presence of these complaints during the first combat phase of Operation Iraqi Freedom (OIF). The study found a general trend of a reduced frequency of complaints associated with the AH-64's HMD. A follow-up study has been conducted to validate this downward trend and to investigate the impact the shift in mission role of the AH-64 from one of open-field tank hunter to one of close-quarter urban combat. Thirty-eight AH-64D pilots were asked to complete a survey questionnaire that solicited data about the presence and frequency of the visual complaints reported in previous studies. Data for physical visual symptoms and static and dynamic illusions were found not to be significantly different from frequencies reported in the previous OIF study. Both OIF studies reported headache as the prominent physical complaint with height judgment and slope estimation as the most frequently reported static illusions and with undetected drift and faulty closure judgment as the two most frequently reported dynamic illusions.
As part of a 2003 survey during Operation Iraqi Freedom, forty AH-64 Apache aviators were interviewed regarding their experience using the AH-64’s monocular helmet-mounted display (HMD). Participants represented a total of 8564 flight hours and 2260 combat hours in the OIF theatre of operation. The interview consisted of 12 questions that addressed previously identified potential problem areas (e.g., maintaining full field-of-view [FOV], combiner breakage, and sensor slew rate) and requested participant opinion on the best and worst features of the IHADSS, day versus night use of the IHADSS, and the acceptance of a hypothetical binocular IHADSS design. Participants expressed a desire for a larger FOV; emphasized the impact of poor helmet fit on ability to achieve and maintain a full FOV; decried the overall performance of the current FLIR sensors; and reported that the current slew rates for the PNVS and TADS are slower than desired (worse for TADS), necessitating compensation in normal head movement rates.
Forty AH-64 Apache aviators representing a total of 8564 flight hours and 2260 combat hours during Operation Iraqi Freedom and its aftermath were surveyed for their visual experiences with the AH-64's monocular Integrated Helmet and Display Sighting System (IHADSS) helmet-mounted display in a combat environment. A major objective of this study was to determine if the frequencies of reports of visual complaints and illusions reported in the previous studies, addressing mostly benign training environments, differ in the more stressful combat environments. The most frequently reported visual complaints, both while and after flying, were visual discomfort and headache, which is consistent with previous studies. Frequencies of complaints after flying in the current study were numerically lower for all complaint types, but differences from previous studies are statistically significant only for visual discomfort and disorientation (vertigo). With the exception of "brownout/whiteout," reports of degraded visual cues in the current study were numerically lower for all types, but statistically significant only for impaired depth perception, decreased field of view, and inadvertent instrumental meteorological conditions. This study also found statistically lower reports of all static and dynamic illusions (with one exception, disorientation). This important finding is attributed to the generally flat and featureless geography present in a large portion of the Iraqi theater and to the shift in the way that the aviators use the two disparate visual inputs presented by the IHADSS monocular design (i.e., greater use of both eyes as opposed to concentrating primarily on display imagery).
The Integrated Helmet and Display Sighting System (IHADSS), employed in the U.S. Army's AH-64 Apache helicopter, is used to present pilotage and targeting imagery and symbology. Therefore, in addition to the standard comfort and protection requirements of a helmet system, the IHADSS must provide a stable optical alignment. Fielded in the early 1980's, the IHADSS is still the Army's only integrated helmet-mounted display (HMD). In an attempt to perform both the standard protective role of a helmet and to serve as a mounting platform for an optical sight, the IHADSS had to make certain design compromises that have resulted in some user satisfaction issues. A joint survey of U.S. and U.K. AH-64 aviators was conducted to identify and quantify these issues. Survey findings indicated that while a majority of aviators found the quality, comfort and satisfaction of fit to be acceptable, a significant proportion of aviators have encountered problems associated with obtaining proper helmet size, availability of replacement components, and substantial variation in fitting expertise. Results of this survey can assist in ongoing and future HMD helmet system designs.
A collaborative occupational health study has been undertaken by Headquarters Director Army Aviation, Middle Wallop, UK, and the U.S. Army Aeromedical Research Laboratory, Fort Rucker, Alabama, to determine if the use of the monocular helmet-mounted display in the Apache AH Mk 1 attack helicopter has any long-term (10-year) effect on visual performance. This paper describes the protocol, methodology, development and initial execution phase of this study. The test methodology consists primarily of a battery of vision tests selected to capture changes in visual performance (with an emphasis on binocular visual functions) of Apache aviators over their flight career. It is anticipated that the number of Apache aviators will level out to approximately 70 by the end of the first three years of the study. Non-Apache aviators will serve as a control group.
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