Weather and the calculated risk: exploiting forecast uncertainty for operational risk management

Air & Space Power Journal, Spring, 2008 by F. Anthony Eckel, Jeffrey G. Cunningham, Dale E. Hetke

In another common behavior--the "kneejerk" reaction--decisions are based upon a recent unfavorable outcome. When an operator gets hit with the bill from a loss or wasted effort, the natural reaction is to toss aside (maybe only temporarily) the optimized decision rules and do whatever it takes to ensure that bill doesn't come again. ironically, such shortsightedness ends up costing more in the long run. The real flaw lies in using a single unfavorable (or favorable) outcome as a measure of orm success.

The knee-jerk reaction was modeled in the DEAD Sim to demonstrate its impact. After wasting effort (flying a mission and finding unfavorable weather), the stochastic operator increased the decision threshold to 99 percent chance of ciG greater than or equal to 030 for the next cycle to prevent another wasted effort (the operator did not attack unless favorable weather became very certain). conversely, upon missing an opportunity (not flying a mission and favorable weather occurring), the stochastic operator decreased the decision threshold for the next cycle to 1 percent to prevent anothermissed opportunity (the operator attacked unless unfavorable weather was certain). This knee-jerk reaction produced an increase in average number of cycles to 10.7 (from 10.2) and in average fuel use to 415,000 lb. (from 398,000). This performance was still better than the deterministic operator's but a notable departure from optimal.

Summary/Recommendations

Two simple yet realistic decision scenarios were modeled to demonstrate how stochastic forecasts, which describe a range of likely outcomes, enable ORM. The Evac Sim showed how use of stochastic forecasts can significantly conserve resources (i.e., increased efficiency through defensive ORM). the DEAD Sim showed how use of stochastic forecasts can maximize combat capability (i.e., increased effectiveness through offensive ORM). The added benefit from using stochastic versus deterministic (single-valued) forecasts can vary greatly, depending upon a mission's sensitivity to weather, the skill of the deterministic forecasting, and the detrimental weather's frequency of occurrence. Additionally, human factors can have both positive and negative effects on the decision process.

Realizing the benefits will require considerable resources, effort, and patience in the development arenas of ensemble-data production and application. The effort would enhance one of our country's great strengths--advanced technology. Skilled use of stochastic forecasts from an ensemble system can provide a distinct advantage over an adversary in current and future conflicts. Alternatively, continuing with decision making based on deterministic forecasts may leave the DOD at a disadvantage, given increasing interest worldwide in stochastic forecasts, as mentioned earlier.

The DOD can and should exploit stochastic weather information available from external sources (e.g., the National Weather Service), but internal production of ensemble data is necessary to tailor forecasts to war fighters' requirements. For example, generating a reliable probability forecast for a high-impact event such as a dust storm at Balad Air Base, iraq, requires processing a fine-scale ensemble forecast to model the event. Such production is expensive but cost-effective. An ensemble system designed for a typical theater of operation (e.g., the middle east) costs several million dollars in today's computer hardware. The Evac Sim used rather conservative estimates to show how millions of dollars can be saved through optimal protection of a single aircraft. By multiplying that across all aircraft and DOD assets susceptible to adverse weather, including life-threatening conditions, and then adding in the increased combat capability for all missions with weather vulnerabilities, it quickly becomes obvious that returns far outweigh costs. The DOD should fully back Air Force Weather's planned implementation (beginning in 2009) of a robust ensemble system designed to deliver high-quality, operations-tailored stochastic forecasts for all theaters of operation.