. Check maneuver for conflicts (overtaking and crossing)

– If no conflict will occur then grant request and issue maneuver clearance [“American 123.  Boston Center.  Climb and maintain FL 350.”]

– If a conflict will occur then deny the request and determine if the conflict can be avoided by delaying the maneuver [“American 123.  Boston Center.  Unable at present time due to traffic.  Maintain flight level 310 and await further clearance.”]

. Initiate Wait for Acknowledgment task

. If the conflict can be avoided by delaying the maneuver then determine when clearance can be issued and issue maneuver clearance at that time

. If the conflict cannot be avoided by delaying the maneuver then reassess the situation after 2 minutes

Evaluate Requested Speed
Causal Event:
. Pilot request for change in speed to avoid CAT [“Boston Center.  American 123.  Request speed reduction to mach 0.78 due to turbulence.”]

Controller Actions:
. Perform Sector Scan task to update aircraft positions and speeds

. Check new speed for conflicts (overtaking and crossing)

– If no conflict will occur then grant request and issue clearance [“American 123.  Boston Center.  Speed change approved, maintain mach 0.78.”]

– If the conflict will occur then deny request [“American 123.  Unable at present time due to traffic.  Maintain mach 0.82.”]

. Initiate Wait for Acknowledgment task

Assess Speed Change
Causal Event:
. Pilot changes speed to avoid CAT and notifies controller [“Boston Center.  American 123.  We have reduced speed to mach 0.78 due to turbulence.”]

Controller Actions:
. Perform Sector Scan task to update aircraft positions and speeds

. Check new speed for conflicts (overtaking and crossing)

– If no conflict will occur then approve speed change and issue clearance [“American 123.  Boston Center.  Speed change approved, maintain mach 0.78.”]

– If conflict will occur then request aircraft resumes original speed [“American 123.  Boston Center. Speed change disapproved due to traffic.  Maintain mach 0.82.”]

. Initiate Wait for Acknowledgment task

Issue Emergency Descent Clearance
Causal Event:
. Pilot request for emergency descent [“Boston Center.  American 123.  Request emergency descent due to turbulence injuries on board.”]

Controller Actions:
. Recall current course and altitude of current aircraft

. Plan emergency descent route clear of air routes

. Issue clearance to subject aircraft [“American 123.  Boston Center. Turn right heading 170 and commence emergency descent”]

. Initiate Wait for Acknowledgment task

. Wait for aircraft to reach the floor of the sector then issue handoff clearance [“American 123.  Contact Boston Center on 123.45.”]

. Initiate Wait for Acknowledgment task