Originally Posted by FliesWay2Much

188K is only a fraction of the cost -- landing fees and additional fuel. Here are some other costs that pop into my head:
- Costs of additional cops and other "security" costs to meet the terror threat upon landing -- 10's of thousands
- Additional cost for UK customs & immigration support to handle a flight they didn't expect for people they had already cleared to leave the country -- 10's of thousands
- UK MOD additional support for a diverted flight containing a "threat passenger" (could include tracking and analysis from air defense radars not normally used for commercial aviation) -- 100's of thousands
- Change in alert status of RAF interceptor aircraft -- 10's to 100's of thousands (if fighters actually launched or were on ramp alert)
- Additional cost of ground support equipment, crews, and consumables in Glascow not covered by landing fees -- 10's of thousands
- Cost of a planeload of missed connections -- 10's of thousands
- Additional operational costs such as: preflight briefings, crew rest requirements, accelerated scheduled maintenance on the aircraft, an additional flight plan creation & filing, etc -- 10's of thousands
- "Daisy chain" cost impacts resulting from a diverted aircraft and crew -- 10's of thousands

Intangibles:

- Increased risk to passengers & crew resulting from an unnecessary takeoff and landing at what presumably was an unfamiliar airfield. Can't put a pricetag on this other than the risks associated with this were certainly greater than being blown up by a terrorist on that flight.
- Disruption costs to other operations at Glasgow airport.

My rough guess is that this needless diversion cost at least a half million dollars.