Originally Posted by
mongo
until a shuttle blew up, there was no risk to using o-rings in cold weather conditions
until a shuttle came apart on re entry, there was no real risk to chunks of ice hitting the shuttle wings during lift off.
until there is no collision or other interaction with full scale above 400 ft, there is no risk there either,
but there is NO guarantee that it will not happen tomorrow, either.
one thing about life,
just because it has not happened yet, does not mean it will never happen.
There could be a collision between a model and a full scale at any altitude even below 400' but the fact is that such a collision is very unlikely below 2,000' except possible near a airport.
Most model flying except for gliders takes place well below 1,000' and that is the reason there has been so few incidents of conflict between models and full scale and telling models
they have to stay below 400' does not make anyone safer, however a case can be made to keep models below 2,000'.