A few days ago I mentioned a collection of cases where this happened on MD's or other's arplanes.
Obviously, the "tip of the iceberg", as even there I ommited another couple of cases where the mistake was caught right before the TOWS went off by one of the members of the crew or even passengers.
Here:
http://www.pprune.org/4408886-post1910.html
Most are docummented and the reports available on ASRS.com
But I guess the "system" doesn't work all that well.