Approval request is a coordination procedure when an upstream controller asks their downstream colleague to accept a plan that is not a subject to silent approval (i.e. is considered to be approved unless an explicit objection is made). The transferring (upstream) controller must keep the aircraft within their area of responsibility until the request is approved or an alternative plan is agreed upon. The main uses of this procedure are when the flight time to the boundary is short and therefore, information cannot be passed within the agreed time period or when a deviation from the agreed procedures is necessary. The rationale behind this is that the accepting controller must have enough time to review and assess the situation and come up with an appropriate plan to address it safely.