Why can’t I add an aircraft?

The main reason for not able to add an aircraft to your OpsControl fleet is because it is already linked to another account.

A tail / aircraft can only be active on 1 account at the time, so please contact us for the options to remove the tail from the other account.

Can anyone see my aircraft?

Only you will see your fleet on Flight Watch and on your fleet list.

Can I add any tail that I like?

If it is connected to your company, then yes.
If it is an aircraft belonging to another fleet, then you would not be able to add it to your account.