This is a beta version of the FOD Risk Calculator (discussed here). The interactive version embedded below is a simplified version of the original spreadsheet (Excel version). The spreadsheet was originally used to demonstrate the importance of the probability of detection over detection time. It can be used to assess the reduction in risk achieved when installing a FOD detection system, or for comparing FOD detection systems.

Instructions (notes and definitions are at the bottom of the page):

• Only change the highlighted cells, i.e. parameters 1-7.
• The bar chart (and Line 12) shows the total risk from FOD, measured in “FOD minutes” (= quantity of FOD x time on runway)
• To reset all the parameters back to default simply refresh the browser page.
• If you set probability of detection to “0%” this is the same as using manual FOD checks only (useful for seeing the difference having a system makes)
• The default assumption is that when FOD is detected the runway is NOT closed. Setting retrieval time to “0” will change this i.e. the assumption will then be that when FOD is detected the runway is closed until it is retrieved.

Definitions and Notes:

• Line 1. Time taken for an object to appear as “detected” by the system after first appearing on the airfield surface.
• Line 2. The probability that the system will detect an object.
• Line 3. Total number of actual FOD items found on the airfield surface in 1 year (it includes those found by the FOD detection system and those found during manual checks).
• Line 4. The average time it takes to retrieve an object once it has been detected by the FOD detection system. This would typically be larger for larger airports.
• Line 5. The average time between manual FOD checks.
• Line 6. The average time between aircraft movements on a runway.
• Line 7. If 1/2 of all FOD found is from aircraft then this number would be 50%. This number should be known (assuming proper records of FOD finds are kept).
• Line 8. The Detection time + Retrieval time. i.e. how long an item is on the runway.
• Line 9. The total risk when no FOD detection system is installed.
• Line 10. Risk from items not found by the system, but found during manual inspection. (small number of items, but would have been on the runway for a long period i.e hours)
• Line 11. The risk from those items that were found by the FOD system (large number of items, but would have been on the runway for a short period i.e minutes)
• Line 12. The total risk from FOD when a FOD detection system is installed. This should typically be around a tenth of the risk when no FOD system is installed.

p.s. Thanks to Kartik Nathan at Microsoft for helping with this.