Interesting thread.
Assertive ATCO's are a blessing IMHO.Take some examples:
-Everglades crash.An assertive ATCO would have prevented that crash by issuing a direct command to the EAL crew to climb immediately to 2000 feet.Instead he asked "How are things going?" when he noticed the altitude readout dangerously low.
-A320 crash BAhrain.The controller authorized an orbital maneuver when the pilot was hot and high first time round.When the pilot screwed it up again,an assertive ATCO would have said "Fly the published Missed approach" followed by "Cleared for the procedural".The pilot was obviously incapable of flying a visual approach and an assertive ATCO would have tired of his incompetence and took command of the situation.
-Lexington just recently.Theres no doubt an assertive ATCO,or lets just say a competent ATCO,would have prevented this woeful tragedy.
-Tenerife,the most infamous disaster of them all.An assertive ATCO would have undoubtedly helped prevent it.
-Cali.This is a tricky one because just like Tenerife,language problems complicate the matter considerably.Sometimes its difficult for an ATCO to be assertive in his/her second language.They havent the confidence in their command of English to say what they want exactly.If the feedback from the pilots isnt immediate and explicit,they mustnt be afraid to get assertive and do what is required(ie.Approach clearance cancelled,climb immediately to MSA,enter the hold at Cali,report entering).His mindset just became"Look guys,you cant even give me your correct position,I dont have radar and I'm getting nervous about this,so to hell with the straight-in,you can damn well fly the full procedure."
All of the above accidents were caused by pilot error.However,an alert and assertive ATCO would have prevented each and every one.It comes down to the difference between a competent ATCO and a great ATCO.Admittedly,theres a bit of hindsight bias in all I say,but I still stand by it.
We have no shortage of assertive ATCO's in the States and I think its what makes the system work so well.You couldnt handle the traffic we have if they werent so intolerant.