• Military Menu                       

• Introduction
• Systems
• Facilities
• Agencies
• Industry
• Operations
• Countries
• Hot Documents
• News
• Reports
• Policy
• Budget
• Congress
• Links

• WMD
• Intelligence
• Homeland Security
• Space

Ajax - Noise and Vibration

The Ajax vehicles received from General Dynamics UK for trials were inherently noisy and came with vibration. It was a contractual requirement that GDUK design and build vehicles that complied with the Control of Noise at Work Regulations 2005 and the Control of Vibration at Work Regulations 2005 and could be operated safely. Under the Control of Noise at Work Regulations 2005, the Lower Exposure Action Value for noise at the ear of a user is 80 dB(A) and the Upper Exposure Action Value is 85 dB(A). The Exposure Limit Value is 87 dB(A). Maximum noise levels on Ajax platforms have consistently been in the region of 117db(A).

Noise and vibration in the Ajax family of vehicles have both electrical and mechanical origins from the following broad sources:

1. Track, suspension and running gear, in particular the tension and sprocket design/track interface.
2. Engine and its mounting into the vehicle.
3. Quality issues associated with, but not limited to, inconsistent routing of cabling, lack of bonding and weld quality; all of which can lead to potential electromagnetic compatibility issues with communication equipment. As witnessed during trials, insecure components and bolting within the vehicle can also lead to noise and vibration, and again this was noted by ATDU crews.
4. Headset performance and integration (noise only).

The cessation of the Army Noise and Vibration Working Group in 2018 may have contributed to this. Since the demise of the Army Personnel Research Establishment Farnborough and the Army Noise and Vibration Working Group, the Army lacked a focal point for noise and vibration issues. The cessation of the Army Noise and Vibration Working Group in 2018 may have contributed to this. Reports of noise and vibration were balanced against firm assertion and reporting from GDUK crews that they had not experienced these issues. Therefore, DE&S and Army were presented with conflicting and contradictory data on the cause, effect and presentation of noise and vibration issues.

The first internal GDUK safety notice seen by the Review relating to external noise was issued in 2014. A second GDUK safety notice was issued in 2016 relating to internal noise. The notices stated that extant occupational safety, health and environmental risk controls adequately mitigated any residual risk. The first formal safety notice relating to either noise or vibration from within the MOD was SNvE 425 in December 2018, issued by DE&S as a result of service personnel crew motion sickness reported in GDUK trials. It advised of high levels of vibration on early Ajax platforms, with long-term exposure potentially giving rise to Hand Arm Vibration (HAV) and Whole Body Vibration (WBV).

Rehearsal Battlefield Missions began in October 2019 on the ARES variant. It was during these rehearsal missions that concerns over the level of vibration, as a result of Army personnel operating the vehicle for a significant period for the first time, began to be raised within the programme, particularly between November 2019 and February 2020. It was noted that the WBV limit was exceeded on the first three days of the trial. ATDU called for vibration monitoring equipment to be installed on all Ajax platforms, and for an engineering solution to be found rapidly. In March 2020, the Defence Safety Authority (DSA) commenced a document-based review resulting in a report entitled “Serious Safety Concerns with AJAX” on 4 May 2020. On 14 September 2020, Bovington Medical Centre staff formally raised noise and vibration crew concerns to the ATDU Chain of Command.

Comparative Noise Trials were held at ATDU between 2 and 6 November 2020. The trial concluded that noise issues only previously associated with earlier ARES models were present on the production model. Based on the results of the Comparative Noise Trials, an immediate ban on the dynamic use of the Ajax vehicles was put in place. SNvE 1052, which directed zero activity when vehicle engines were running or with intercom headsets for all Ajax vehicles, was published to all units by DE&S on 9 November 2020.

On 16 November 2020, GDUK contracted the Institute of Sound and Vibration Research, which is part of the University of Southampton and independent of GDUK and MOD, to manage trial data. They reported on 7 December 2020 that there was excessive noise. This report led to the imposition of additional limitations of time exposure and speed. On 16 June 2021, ATDU raised concerns to the Duty Holding Chain, stating they were no longer satisfied that MOD had a safe and assured system for operating the Ajax vehicle, due to new instances of soldiers reporting symptoms connected to operating the vehicle.

As of 9 December 2021, it was determined that 310 individuals had been exposed to noise and vibration from Ajax vehicles. Of these: 238 have returned to duty with no health impact; 17 remain under specialist outpatient care, some of whom are expected to return to duty with no health impact; 4 individuals have been discharged, some of whom were for reasons unrelated to hearing loss; 11 individuals have been recommended for long term restrictions on noise exposure, potentially requiring a limitation in their military duties. 5 of these individuals had pre-existing problems with their hearing before working on Ajax. 6 individuals developed hearing problems while working on Ajax; 40 declined assessment or had been unable to attend.

The Ajax Noise and Vibration Review was commissioned by the MOD Permanent Under Secretary (PUS) following reports of potential harm associated with noise and vibration during the trialling of the Ajax family of vehicles. The Review was conducted by an internal team between 21 June and 14 July 2021 led by the MOD Director of Health, Safety and Environmental Protection (HS&EP) who is responsible for HS&EP Functional Leadership across Defence. Teh Review concluded that there was not yet a short-term pathway to resolve the noise and vibration issues. Whilst these issues need to be resolved as quickly and practicably as possible, the department also needs to take a longterm view and focus on the root cause of both aspects, which undoubtedly will require re-engineering of components and systems within the Ajax platform. When Army does put people back into the Ajax platform it needs to do so with the confidence that the design is being tested in a way that is not causing actual harm to those undertaking the trials. This confidence level needs to be significantly higher than it has historically been and based on appropriate in-vehicle and/or on-body measurement of data for both noise and vibration.

GDUK designed and built what MOD maintained was thus far a vehicle which was not fit for purpose and does not meet the contracted specification. The root cause that allowed a vehicle to cause potential harm to Army personnel through noise and vibration during the trials process was not a failure of a single individual or Defence Organisation. It was a complex combination of the Armed Forces’ relationship to harm and weaknesses in MOD’s acquisition system. The impact of Covid was also felt, both delaying trials and making communication more difficult. From a cultural perspective, the Army did not believe it was potentially causing harm to people, especially from vibration, as it was tacitly expected that soldiers can and should endure such issues. Society and the law expect MOD to do better and requires it to have systems in place that protect its people from harm.