APP/ACC

Upstream and Downstream Sectors

• Upstream Sector: The sector an aircraft is coming from before entering the current sector.
• Downstream Sector: The sector an aircraft is heading to after leaving the current sector.

Example
If an aircraft transitions through Sector A → B → C:

• From Sector B’s perspective:
  • Sector A is the upstream sector (where the aircraft is coming from).
  • Sector C is the downstream sector (where the aircraft is going).

Coordination Point (COP)

A Coordination Point (COP) is a designated waypoint near a sector boundary where aircraft are handed off between controllers.

Common COP types:

• COPN (Entry COP) – The point where an aircraft enters the sector.
• COPX (Exit COP) – The point where an aircraft leaves the sector.

Controllers should use well-known waypoints, VORs, or major aerodromes when coordinating handoffs. In VATSIM, specifying the exact location of an aircraft is useful since pre-planned coordination is less structured than in real-world operations.

Transfer of Control

The transfer of control occurs when responsibility for issuing flight instructions (altitude, heading, speed) moves from one controller to another.

Unless otherwise specified in a Letter of Agreement (LoA) or verbal coordination, control is transferred when the aircraft enters the new sector and has reached half of the required minimum separation distance from the boundary.

Example

• If the required separation is 3 NM, control is considered transferred once the aircraft is 1.5 NM into the receiving sector.

This ensures that both sectors maintain full separation without additional coordination.

Silent Transfer of Control

In some cases, an LoA allows for silent transfer of control, meaning an aircraft can be handed off without requiring additional verbal coordination.

This applies when:

• The aircraft meets pre-agreed conditions.
• The receiving controller is already aware of the aircraft.
• The route, level, and conditions do not require coordination.

Certain routes, levels, and airspace have predefined silent coordination agreements, eliminating the need for verbal coordination. However, restrictions may still apply, preventing changes close to sector boundaries.

Handoffs

A handoff occurs when control of an aircraft is transferred between controllers.

Once a receiving controller accepts a handoff, they can:

• Turn the aircraft up to 45 degrees left or right without further coordination.
• Climb or descend the aircraft to any level without additional coordination.

Handoff Restrictions

• Do not hand off an aircraft if a turn of more than 45 degrees or a level change will cause a conflict.
• If needed, apply restrictions before the handoff to ensure separation.

Full Control After Handoff

• Once the aircraft is within half the applicable lateral standard (2.5 NM for ENR, 1.5 NM for TWR/APP), the receiving controller can issue unrestricted turns and level changes.
• If a turn greater than 45 degrees is needed earlier, coordination is required.

Transfer of Communication

A transfer of communication happens when an aircraft is instructed to switch to a new ATC frequency.

• This does not always mean control has been transferred.
• Communication and control transfers can happen separately based on operational needs.

For example, a controller may hand off communication early while still retaining control of the aircraft for sequencing or separation purposes.

Controller Initials in Coordination

In real-world ATC, controllers are identified by unique initials (formed from their first and last names).

During verbal coordination, initials are exchanged as a confirmation that both controllers agree on the handover.

• The conversation is not complete until both controllers state their initials.

Approval Request

When a controller needs approval from another sector for a specific action, an Approval Request is used.

This is common for:

1. Direct Routing Requests
2. Climbing or Descending Across a Sector Boundary
3. Deviations from Agreed Flight Levels

Each type of request follows a standard format to ensure clarity and efficiency in coordination.

Direct Routing Request (Downstream Coordination)

Granting a direct-to waypoint clearance can improve efficiency, accommodate pilot requests, or resolve conflicts. Within a controller's own sector, this can be done without coordination. However, if the waypoint is in an adjacent sector, approval from the downstream controller is required.

This request can be made using Euroscope coordination functions or verbally.

Format for Verbal Coordination

APPROVAL REQUEST <COP/position> <call sign>
DCT <waypoint>

Procedure

1. Contact the receiving sector and wait for their "Go ahead" response.
2. This allows the receiving controller to check the aircraft’s position and potential conflicts.
3. Once permission is granted, the request is either approved or denied.

Climbing/Descending at Sector Boundaries

By default, aircraft should be level when crossing a sector boundary unless an LoA (Letter of Agreement) states otherwise.

• Any climb or descent at or near a boundary must be coordinated.
• Coordination is required if vertical movement occurs within half of the minimum separation distance before the aircraft enters the next sector.
• This type of coordination must be done verbally, as Euroscope does not handle altitude change requests automatically.

Format for Verbal Coordination

APPROVAL REQUEST <COP/position> <call sign>
CLIMBING <level> / DESCENDING <level>

Deviation from Agreed Flight Level

If an aircraft must cross a sector boundary at a different level than agreed in the LoA, coordination is required. This can be done using:

• Euroscope functions
• Verbal coordination

Clearing Through a Third-Party Sector

If an aircraft requires clearance through a sector that is not normally involved, additional coordination is needed.

• Standard Coordination Points (COPs) do not apply, as the aircraft is not expected to enter the third-party sector.
• The affected sector does not have flight details in Euroscope and does not consider the aircraft as relevant traffic.

Format for Verbal Coordination

APPROVAL REQUEST FOR AIRSPACE CROSSING <call sign> <position>
CLIMB UP TO FLxxx (routing) / DESCEND DOWN TO FLxxx (routing)

This is often mistaken for a release, but it is strictly an approval request. Releases are discussed in a separate section.

If the previously uninvolved sector assumes full control of the aircraft or takes over from the originally planned downstream sector, an additional request format is used:

APPROVAL REQUEST FOR ADDITIONAL TRAFFIC AIRBORNE MARRAKECH <call sign>
DCT SLK FL300

This shifts the responsibility of further downstream coordination to the accepting sector.

Boundary Coordination

Boundary coordination is required when an aircraft is expected to deviate within half of the required separation for another sector’s airspace.

This applies if an aircraft is within:

• 500 ft vertically
• 2.5 NM laterally (enroute sectors)
• 1.5 NM laterally (approach/tower sectors)

Boundary coordination informs the adjacent sector about the aircraft and allows them to impose restrictions if necessary.

Format for Verbal Coordination

• Controlling Sector → Boundary Sector:

For Ident, (Position), (Callsign), (Details as required)

• Boundary Sector → Controlling Sector:

(Callsign), (Restriction)

Example Phraseology

SOU → NOR: "For Ident, overhead SAK, RAM12, do you have any restrictions on descent?"
NOR → SOU: "RAM12, No restrictions on descent."

If the boundary sector has no restrictions, they may omit the restriction and simply read back the callsign. This confirms that no vertical or lateral restrictions apply.

Example Phraseology with Omission

WES → EAS: "For Ident, west of RAVMA, AB123"
EAS → WES: "AB123"

Spacing Below Standard Separation

Silent transfers of control typically requires 10 NM separation at the same speed. The following rules apply when transferring aircraft at the same flight level:

Example Scenario

Two aircraft are transferred with 15 NM separation, but the trailing aircraft is 30 knots faster.

• Since none of the above conditions are met, either:
  • Speed control must be applied to match speeds, or
  • Coordination is required before transfer.

Format for Coordination

APPROVAL REQUEST <COP/position> <call sign>
<distance> <speed difference>

Release Coordination

A release allows the receiving sector to issue instructions before an aircraft crosses the sector boundary and control is officially transferred.

• If the receiving controller wants to issue a turn, climb, or descent before transfer, they must request a release.
• Without a release, the aircraft must continue as planned until control is formally transferred.

Types of Releases

Requesting a Release

A release can be sent with the handoff via Euroscope (TopSky plug-in), but if this is not done, the receiving sector must request the release verbally.

Format for Verbal Request

REQUEST RELEASE <callsign>

Example Phraseology

NOR → SOU:

"REQUEST RELEASE (FOR (RIGHT/LEFT) TURNS / FOR CLIMB / FOR DESCENT) RAM123"

SOU → NOR:

"RAM123 RELEASED (FOR (RIGHT/LEFT) TURNS / FOR CLIMB / FOR DESCENT) <initials>"

NOR → SOU:

"<initials>"

A Coordination Point (COP) is not required in this communication.

Release Subject to Discretion (SYD)

A Release Subject Your Discretion (SYD) is used when the releasing sector has other aircraft that may impact the release.

• The aircraft is released, but the receiving sector is responsible for ensuring separation from specified traffic.
• The releasing sector provides traffic details, and the receiving controller must maintain separation accordingly.

Example of SYD Release

NOR → SOU:

"REQUEST RELEASE RAM123"

SOU → NOR:

"RAM123 RELEASED SYD RYR123 overhead FOBAC on R722, FL290 <initials>"

NOR → SOU:

"<initials>"

Explanation

• NOR wants to climb RAM123, but SOU has RYR123 crossing at FL290 on R722.
• With this SYD release, NOR can initially climb RAM123 to FL280.
• Once lateral separation is ensured, NOR can allow further climb.

The key to SYD releases is ensuring both controllers clearly understand who is responsible for separation.

Heads-Up Coordination

Heads-up coordination is used to notify the next sector about an incoming aircraft.

Format for Verbal Coordination

• Controlling Sector → Receiving Sector:

(Position), (Callsign)

• Receiving Sector → Controlling Sector:

(Callsign), (Level)

Example Phraseology

NOR → SOU:

"Via SLK, RAM1234"

SOU → NOR:

"RAM1234, F350"

If the assigned level at transfer of jurisdiction is different from the current CFL, the controlling sector must specify:

"Will be assigned (level)."

If the receiving sector needs a different level, they will respond with the amendment.

Example Phraseology with Level Change

NOR → SOU:

"Via SLK, RAM1234"

SOU → NOR:

"RAM1234, F300 due traffic"

NOR → SOU:

"F300, RAM1234"

Once coordination is completed, the aircraft’s level and route are locked in.
Any further changes must be re-coordinated.

Best Practice

• The best time to conduct Heads-Up Coordination is when the aircraft first checks in.
• Do not delay coordination until just before the transfer.

Reference Calls

When an action does not fit an Approval Request or Release, a Reference Call is used.

Primary Use Case

• A request to the upstream sector when an aircraft needs to enter a sector in a non-standard manner.

Example Reference Call

SOU → NOR:

"REFERENCE SLK RAM123"
"REFERENCE 20 MILES WEST OF SLK RAM123"

NOR → SOU:

"Go ahead"

SOU → NOR:

"REQUEST HIM DIRECT MABAP"
"REQUEST HIM DCT MAK, DESCENDING FL90"
"REQUEST HIM AT FL200"
"REQUEST HIM AT SPEED 250 KNOTS"

NOR → SOU:

"CONSIDER <initials>"
"WILCO <initials>"
"UNABLE <initials>"

SOU → NOR:

"<initials>"

Reference Call Responses

• WILCO = Request accepted.
• UNABLE = Request denied or renegotiation needed.

Using Reference Calls for Requests

A Reference Call can also be used instead of an Approval Request for open-ended coordination.

Format for Verbal Coordination

REFERENCE <COP/position> <callsign>
REQUEST HIGHER/LOWER LEVEL

Common Uses

• Transitioning between Approach (APP) and Center (CTR)
• Moving between Lower Center and Upper Center (or vice versa)
• Ensuring climb/descent clearance before handoff

If an aircraft has not yet completed a crossing, a Reference Call allows controllers to coordinate a higher/lower level for smoother sequencing.

Departure Release Requirements

At certain airports, a Departure Release must be obtained from the radar sector before each IFR departure.

• The radar sector (APP/ACC) ensures separation between IFR arrivals and departures.
• Whether a departure requires a release is determined by the airport’s Tower SOP.

Departure Release Coordination

If a release is required, coordination follows this structure:

Format for Verbal Coordination

TWR → Radar (APP/ACC):

"REQUEST RELEASE RAM123"

Radar (APP/ACC) → TWR:

"RAM123 RELEASED <initials>"
"RAM123 RELEASED AFTER LANDING RYR123 <initials>"
"RAM123 RELEASED, CLEARANCE EXPIRES AT 1530 <initials>"
"RAM123 RELEASED AT 1520 <initials>"
"UNABLE, CALL YOU BACK <initials>"

TWR → Radar (APP/ACC):

"<initials>"

If a release is denied, the radar controller will call back when the departure is approved.

Next Coordination

Departure release coordination is conducted between TWR and APP/ACC controllers to determine the next aircraft to depart.

• All IFR departures require Next Coordination unless the airport has Auto Release in place.
• Auto Release can be canceled at any time by mutual agreement between TWR and APP controllers.

Format for Verbal Coordination

TWR → APP:

"Next, (Callsign), (Runway)"

APP → TWR:

"(Callsign), (Runway), (Lateral and/or Vertical Instructions)"

Departure Instructions

• An amended level may be assigned.
• The term "unrestricted" may be used to indicate no vertical restrictions apply.

Note: "Unrestricted" is not a readback item.

Example Phraseology

Visual Departure Example (LAM departing from GMAD)

TWR → APP:

"Next, LAM, runway 27"

APP → TWR:

"LAM, runway 27, left turn, unrestricted"

TWR → APP:

"Left turn, LAM"

Procedural SID Example (EZY342 from GMAD, Auto Release cancelled)

TWR → APP:

"Next, EZY342, runway 27"

APP → TWR:

"EZY342, unrestricted"

Airways Clearance Coordination

At some aerodromes, TWR must coordinate with APP/ACC before issuing an airways clearance for certain aircraft.

• This allows the APP/ACC controller to evaluate current and projected traffic levels, position staffing, and overall airspace workload before approving clearance.
• Coordination ensures seamless integration of departing aircraft into enroute traffic.

Format for Verbal Coordination

TWR → ACC:

"(Callsign) requests clearance to (Destination), (Any Other Relevant Details)"

ACC→ TWR:

"(Callsign), clearance approved"

Example Phraseology

TWR → ACC:

"AB213 requests clearance to Fez"

ACC → TWR:

"AB213, clearance approved"

If a level change or route adjustment is required, APP/ACC will provide the update during the exchange.

Important Considerations

• This coordination is a negotiation—you can reject or renegotiate clearance requests based on airspace conditions.
• If a restriction is needed, it is best to take the aircraft on frequency before issuing clearance.

Types of Departure Clearance Responses

Clear understanding of these responses ensures smooth coordination and efficient traffic flow.

Estimate Coordination (Not Relevant for VATSIM)

In real-world ATC, an Estimate Call is used to exchange an aircraft’s:

• Squawk
• Handover level
• Estimated entry time into the next sector

Most estimates are automatically exchanged through flight data systems, but in case of system failures or special circumstances, verbal coordination is required.

Example Scenario: Casablanca (GMMN) to Paris (LFPG)

If the automated system is unavailable, controllers must verbally coordinate all estimates.

1. Tower reports the departure time to APP.
2. APP calculates the estimated time at the COP (Coordination Point) between APP and ACC.
3. APP transmits the estimate to ACC.

Format for Verbal Coordination

APP → ACC:

"ESTIMATE TOLSI AFR123"

ACC → APP:

"A320 to LFPG"

APP → ACC:

"SQUAWKING 6032, ESTIMATED TOLSI 1509, CLIMBING FL150 <initials>"

ACC → APP:

"<initials>"

By confirming the aircraft type and destination, both controllers ensure they are referencing the same flight.

Estimate - No Details

A variation of an Estimate Call is used when the receiving sector has no prior flight plan data for an aircraft.

• This is common in bad weather diversions or unexpected reroutes.
• Additional flight details must be exchanged to fill in missing information.

Additional Details Exchanged

• Aircraft type
• Speed
• Requested level
• Departure airport
• Destination airport
• Route

Estimates are not required on VATSIM, as Euroscope automatically exchanges flight data

Expedite Clearance & Revisions

Expedite Clearance

An Expedite Clearance is a short-term coordination request, similar to an Approval Request.

• Used when an aircraft is approaching a sector boundary faster than expected.
• Replaces a standard Estimate when coordination time is limited.

When to Use an Expedite Clearance

• The aircraft is reaching the sector boundary sooner than specified in agreements.
• The receiving sector needs to be informed immediately to adjust sequencing or separation.

Revisions

A Revision is issued when there is a change in the aircraft’s estimated boundary crossing parameters before reaching the sector boundary.

Common Revisions

• Updated estimated crossing time
• Change in flight level
• Routing adjustments

Revisions are generally unnecessary on VATSIM, as Euroscope automatically updates estimates.
Controllers can monitor changes in real-time without requiring verbal coordination.