Whenever you are controlling you have to have a way to handle things not going as you expected - in the case of arriving aircraft, always know what you will do if it goes around.
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But most of all, don't get into that situation.
Exactly. ATC is not about resolving 2 a/c head-on 100m apart scenarios
. BTW - at my place the aviation authority suggested training in re-establishing separation after it was lost. Management decided its not a good idea, as it would teach ATCo's how to circumvent separation minima
Situation from today - single runway ops, Ajet lining up with Bjet and Cjet on final. Cld for take-off (immediate), steady after 40 secs, Bjet too close, cancelled take-off and go around. Bjet turned early to allow Ajet to depart on rwy hdg before Cjet, but Ajet now deciding he needs 1 minute to prepare his departure after reclearance
, and Cjet also going around... So, to reiterate - do not line up if NOT ready (almost fully does not fit here
).