Joint Helmet Mounted Cueing System Research Articles

The effect of helmet mass and aircraft acceleration on cervical spine loads during typical fast jet aircraft pilot head motions

ObjectivesGravitational Force (Gz), head motion, and helmet mass are associated with neck pain in high performance aircraft pilots. Few studies have quantified neck kinetics (intersegmental neck moments) during aerial combat manoeuvres. DesignCross-sectional. MethodsWe quantified net joint moments between the skull and C1, and C6–7 during typical flight related headchecks using the Musculoskeletal Model for the Analysis of Spinal Injuries (MASI). We measured the influence of pilot-specific helmets and Gz on joint moments. Nineteen fighter pilots performed four head checks (check6 left, check6 right, extension hold and extension scan) under two helmet conditions. Motion data were transferred to OpenSim where joint moments were calculated at 1G to 9G. Net joint moments were compared across helmet conditions, Gz and headchecks. ResultsThe Joint Helmet Mounted Cueing System (JHMCS) resulted in higher moments at each segment- by a factor of 1.25 per unit of Gz, at C1, and by a factor of 1.08 per unit of Gz for C7. ExtensionScan and Check6Left were associated with the highest peak (96.13 Nm and 92.56 Nm). ExtensionScan and ExtensionHold accrued the highest mean cumulative loads at C7 at 9Gz (607.35 Nm.sec/motion, 362.99 Nm.sec/motion respectively). Asymmetries were observed between the Left and Right Check6 motions. High variability was evident between and within pilots. ConclusionsThe MASI model has been successfully applied to quantify intersegmental neck joint moments for typical headchecks that are performed during combat flight manoeuvres. In future, data derived from this model may inform conditioning, rehabilitative and preventative interventions to reduce neck pain in fast jet pilots.

Head Movements and Neck Muscle Activity During Air Combat Maneuvering.

BACKGROUND: The aim of the study was to determine the characteristics of cervical muscle activity in different head movements when using helmet mounted display in air combat maneuvering.METHODS: Cervical EMG was measured with eight F/A-18 pilots using the Joint Helmet Mounted Cueing System (JHMCS) during air combat maneuvering. In-flight Gz acceleration and continuous head position were recorded. Muscular activity was compared between head movements in isolation and combined with torso movement. In addition, the effect of the direction of head movements and the use of head support of the ejection seat on muscle activity was determined.RESULTS: Muscular loading increased in the cervical flexors and extensors when using the torso during targeting beyond the field of vision in the neutral sitting posture; the difference was significant in the flexors, but activity levels were higher in the extensors. Cervical muscles are loaded to a lesser extent if the head is kept in a stable position during Gz loading. Muscular activity in the neck muscles was higher when the pilot was moving the head out of neutral posture rather than toward neutral posture. The use of the headrest as a support decreased muscle activity in the extensors, but resulted in higher activity in the flexor muscles.DISCUSSION: All analyzed conditions were significantly affected by an increase in Gz. An increase of muscle activity with torso movements is considered as a positive factor as it reflects maintained muscular support for the cervical spine. Presented results may be helpful when specific conditioning programs and cockpit ergonomics are developed for fighter pilots.Sovelius R, Mäntylä M, Huhtala H, Oksa J, Valtonen R, Tiitola L, Leino T. Head movements and neck muscle activity during air combat maneuvering. Aerosp Med Hum Perform. 2020; 91(1):26-31.

Joint Helmet-Mounted Cueing System and Neck Muscle Activity During Air Combat Maneuvering.

BACKGROUND: The aim of the study was to determine the characteristics of cervical muscle activity in different head postures when using helmet-mounted display in one fighter vs. two aircraft air combat within visual range (WVR).METHODS: Cervical EMG was measured with eight F/A-18 pilots using the Joint Helmet Mounted Cueing System (JHMCS) during air combat maneuvering. In-flight Gz acceleration and continuous head position were recorded. EMG activity is divided and presented in a matrix with three-class rotation and five-class flexion-extension postures.RESULTS: The mean muscle activity in sternocleidomastoids and cervical extensors was 28.9% of maximal voluntary contraction (MVC) and 44.8% MVC, respectively. Cervical flexor and extensor muscles are subjected to loading over MVC during high Gz sorties. Cervical rotation combined with extension exceeded muscle force-producing capacity during high Gz, resulting in a decline in muscle activity.DISCUSSION: Awkward postures, especially rotational ones, are more prone to increase loading over muscles' capacity. Overloading of muscles increases the risk of muscular and ligamentous injury. In addition, the lack of muscular support potentially leads to the Gz loading being transferred to spinal structures via intervertebral discs and the vertebral column. The JHMCS helmet seems to change the pattern of most loading muscles toward the extensor (posterior) neck muscles.Sovelius R, Mäntylä M, Heini H, Oksa J, Valtonen R, Tiitola L, Leino T. Joint helmet-mounted cueing system and neck muscle activity during air combat maneuvering. Aerosp Med Hum Perform. 2019; 90(10):834-840.

Risk Factors for Cervical Pain in F-15C Pilots.

Many fighter pilots report cervical pain during their careers. Etiology likely relates to +Gz exposure, physical positioning with maneuvers, and varying load associated with headgear. We evaluated whether selected risk factors predicted cervical pain in this population. An Institutional Review Board-approved, Health Insurance Portability and Accountability Act-compliant, controlled crossover study of the use of home cervical traction was undertaken with 20 male F-15C pilots. We recorded pilot age (mean 38 yr, range 34-49), total high-G hours (2338 h, range 1038-4645), and previous neck problems and measured cervical range of motion. For 12 wk, pilots logged pre- and postflight pain, whether the Joint Helmet Mounted Cueing System (JHMCS) was employed, maximum +Gz experienced, and sortie duration. Pain with and without JHMCS was compared using paired t-tests and correlations assessed with Pearson or Spearman coefficients. Mean flight-related pain increased by 0.73 on the numerical rating scale with JHMCS and 0.52 without. Neck extension coupled with JHMCS use correlated negatively with increased pain (r = -0.551). Higher numbers of previously reported neck problems correlated with pain when using JHMCS (r = 0.629). Age, maximum +Gz per sortie, total high-Gz hours flown, and hours per sortie did not correlate. To our knowledge, this is the first prospective evaluation of risk factors for fighter pilots' cervical pain. Neck pain was significantly worse with JHMCS use and with flexed posture or history of prior neck problems combined with JHMCS use. This information will help guide countermeasure development for high-G pilots.Chumbley EM, Stolfi A, McEachen JC. Risk factors for cervical pain in F-15C pilots. Aerosp Med Hum Perform. 2017; 88(11):1000-1007.

Modern Air Combat Developments and Their Influence on Neck and Back Pain in F-16 Pilots.

Neck and back pain in fighter pilots remains a serious occupational problem. We hypothesized that recent advances such as the joint helmet mounted cueing system (JHMCS) in modern air combat might contribute to the development of spinal complaints in F-16 pilots. Surveyed were 59 F-16 pilots of the Royal Netherlands Air Force who were compared to 49 F-16 pilots who filled in a similar questionnaire in 2007. The prevalence of neck and back pain, work situations, and capacity of the pilot were analyzed. The self-reported 1-yr prevalence of regular or continuous neck and lower back pain in 2014 were 22% and 31%, respectively, compared to both being 12% in 2007. Age, military flying experience, total number of flying hours, flying hours on the F-16, and total number of hours flown with night vision goggles (NVG) were significantly higher in 2014. In 2014, 95% flew with JHMCS, compared to 0% in 2007. Flying with JHMCS (88%), NVG (88%), type of flight (63%), and sitting posture (50%) were the most reported causes of flight-related neck pain. Sitting posture (89%), duration of flight (56%), and seat (44%) were among the reported causes of back pain. The increasing trend of neck and lower back pain might be caused by multiple changes in both the work situation and capacity of the pilots since 2007. Future innovations will increase the load on the pilot's spine. To successfully address their spinal problems in the future, fighter pilots must be monitored continuously.

2.4.2 Cost As an Independent Variable (CAIV) on the Joint Helmet Mounted Cueing System (JHMCS) Program

ABSTRACTThe Cost As an Independent Variable (CAIV) process is the next evolutionary step in the Department of Defense's ongoing effort to continue to modernize, operate and support its forces within a shrinking Defense budget. The Joint Helmet Mounted Cueing System (JHMCS) program was one of the first development programs to implement the CAIV process. The objective undertaken by the JHMCS program was to establish in the integrated product teams the process to control the design factors affecting the production and life cycle costs. This was accomplished through the detailed breakdown of the costs, the open communication between Boeing and the U.S. Government and the active participation of the U.S. Government in reducing all cost areas. The incentive for Boeing to have a successful CAIV process on the JHMCS program was through its profit determination (award fee), but the criticality for the U.S. Government came through its program's budget projections. Program affordability goals must be realized in order to ensure the program's future. This paper presents some of the lessons from the JHMCS program. More importantly, it describes the significance and affordability related results of key actions and decisions made during the formulation and execution of the JHMCS program.