What is POS?
The Probability of Success (POS) is the most important metric in SAR planning. It represents the overall probability of finding the target, combining both area confidence and detection capability.
The Core Formula
POS = POC x POD
Probability of Containment
Is the target in the area?
Probability of Detection
Can you detect if present?
Both factors are essential — a high value in only one doesn't guarantee success.
Why Both Factors Matter
High POD, Low POC
POC = 20%, POD = 90%
POS = 18%
Excellent detection capability, but searching in the wrong area. Most effort is wasted.
High POC, Low POD
POC = 80%, POD = 25%
POS = 20%
Right area, but insufficient detection capability. The target may be missed.
Both Optimized
POC = 70%, POD = 85%
POS = 59.5%
Balanced values produce the best results. Optimizing both factors maximizes mission effectiveness.
Cumulative POS
With repeated searches in the same area, the cumulative probability of success increases:
POS_cum = 1 - (1 - POS1)(1 - POS2)...(1 - POSn)
Example with Two Searches
Search 1: POS1 = 40%
Search 2: POS2 = 35%
POS_cum = 1 - (1 - 0.40)(1 - 0.35)
POS_cum = 1 - (0.60 x 0.65)
POS_cum = 61%
Key Takeaways
POS is the ultimate mission effectiveness indicator
POS = POC x POD - both factors are essential
High POD doesn't help if you're in the wrong area
High POC doesn't help if you can't detect the target
Use POS to compare and prioritize search areas
Cumulative POS increases with repeated searches