Quantitative Risk Assessment

The risk assessment worksheet used by VMMT-204 helps Sailors and Marines determine the best protocol when facing a question of risk factors. (Graphic courtesy of Maj. Curtis Alexander)


On Nov. 21, 1970, a joint United States Air Force and United States Army mission launched to rescue 61 prisoners of war in Son Tây, North Vietnam. The plan was extremely risky, involving an assault on a fortified enemy position, deliberately crash landing a helicopter inside the enemy camp, and no feasible rescue option in the event of failure.

What did the flight risk assessment for the Son Tây raid look like? Based on the plan, it’s safe to assume that it was squarely in the extreme category. More importantly, what were the mitigation efforts to reduce the unavoidable risk factors?

• The mission was comprised solely of volunteers.

• A full scale rehearsal was conducted at Eglin Air Force Base.

• Mattresses were strapped to the floor of banana one to cushion the impact of the planned crash.

• A last-stand defensive position against the Song Con River was briefed in the event the raiders were overrun.

Every military leader manages risk; whether it’s for daily flight operations, crossing the line of departure on patrol, or executing a national level mission. In the case of Son Tây, Col Arthur D. Simons developed the plan, Maj. Herb Kalen deliberately piloted his HH-3E to crash inside the prison walls, and President Nixon approved the mission and the associated risks.

Deliberately crashing aircraft to attain a military objective is an extreme example, but it illustrates the process of a properly conducted risk assessment. As aviators we must plan, identify and mitigate risks, and seek approval for each mission. Each step in that process varies based on an organization’s mission, the level of routine risk, and the culture.

Complexity is added when transitioning from in-garrison to deployed operations, either as part of a joint environment or flying with coalition partners. The bottom line is there is no best way to conduct risk analysis for every situation; however, improvements can often be found by tailoring risk analysis to the specific mission and adopting best practices from other organizations conducting a similar mission.

This mindset was applied to Marine Medium Tiltrotor Training Squadron (VMMT) 204, the MV-22 Fleet Replacement Squadron (FRS). With very rare exception, VMMT-204 has trained every Air Force, Navy, Marine, and Japanese self defense force tilt-rotor pilot in the world. This inherently combined environment provides opportunities to standardize techniques and compare notes from multiple services. The result has been an in-depth analysis of risk identification, analysis, mitigation, and communication.

VMMT-204 falls under Marine Aircraft Group (MAG) 26 at MCAS New River and the 2nd Marine Aircraft Wing (2d MAW) located at Cherry Point. 2d MAW provides the overarching risk assessment guidance for VMMT-204. While this guidance was effective, it didn’t account for the FRS specific challenges like flying with zero hour students, cumulative and chronic fatigue, remediation sorties, legal but marginal weather, quality of training, and a total of 38 additional factors.

Another weakness came from the generic way risk was labeled: low (L), medium (M), high (H). Any single item identified as medium would raise the entire flight profile to that category. Thus, neither cumulative items marked medium nor mitigation efforts could be factored. Prior to a quantitative system, 1,375 of the 2,200 sorties flown in FY16 (62.5 percent) were identified as medium risk 24 hours prior to execution. This led to an artificially elevated risk assessment that depicted the standard mission, even if staying in the local pattern, as medium risk.

The L, M, H scale was replaced with a cumulative and quantitative system. Numerical thresholds for L, M, H were established so that cumulative low risk items could drive a medium and cumulative mediums could drive a high; yet, a single medium item would not classify the flight as medium risk. Furthermore, statistical risk analysis was now possible for different seasons, student phase, human factors, etc. This data then allows for root cause analysis to answer why risk factors are trending or expected to trend in the future, thus enabling prevention or lead turning mitigation.

Quantitative risk assessments are designed to enhance the commander’s visibility of risk through objective assessments and the elimination of human bias.

This methodology is used at the Air Force CV-22 FRS and has been employed successfully at VMMT-204 since August 2016. Furthermore, complacency toward medium risk missions has been eliminated as only 10 percent of sorties are now categorized as medium-risk, despite identifying and mitigating 38 additional factors.

Each flying organization is unique; therefore, each risk score assigned to a particular event will be different: an MV-22 traveling at 200 feet and 240 knots may or may not be riskier than an FRS MV-22 doing the same thing, or other T/M/S aircraft in the same flight regime. Any organization interested in adopting quantitative risk assessments should start by examining their mission, the level of “routine” risk, and the culture. If existing risk assessments are out of alignment with any of those elements, then it might be time to refine and tailor the assessment if command guidance allows, or adopt a quantitative model.

Just like the risk assessment President Nixon approved for the Son Tây raid, the product must accurately reflect the mission, provide visibility to the approval authority, and enable discussion and mitigation for the aircrew. Above all, the risk assessment is a tool to enhance safety. If it doesn’t accurately reflect the mission, it’s not working.


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