id: 6.6-center title: 6.6 Center meta: How to control Center and IFR Semi-Circular Rules in Infinite Flight. order: 6 #

6.6 Center #

@vimeo

What is Center? #

6.6.1 #

Center airspace is from surface up to FL600 and is defined by the white boundaries on the map. The main two functions of Center are to:

• Provide separation and services to all IFR/VFR aircraft under their control

• And to provide sequence management to traffic during their flight to assist Departure/Approach Controller workload

It is important to note that Center does not replace Departure/Approach and therefore, should{.red} only be used to support a Departure/Approach frequency by providing upper air traffic management and sequencing. If however, no departure and/or approach frequency is present, the Center Controller can manage this airspace too.

Although Center airspace is defined by white boundaries on the map, it is important to note that any Center frequency has a radio emitter range of 400nm from the station selected. Controllers should{.red} choose a facility frequency based off of a location that provides the most coverage for the primary airport(s) served. For example, if serving as Center for LAX and SAN it may be operationally advantageous to select the Center frequency from SNA

Climb #

6.6.2 #

Aircraft contacting Center in the climb after departure, or after being handed over from a Departure Controller will usually utilize the “Check In” function. The Radar Control Service (or previous service if different) will just continue (see 6.4.4 above). Aircraft can however, still be vectored or issued altitude assignments if required (see 6.5.2 above). If you do issue a vector and/or altitude assignment, once the risk of conflict is no longer present, you should{.red} let the pilot know by sending “Continue as Filed” and/or “Altitude at your Discretion” respectively. “Resume Own Navigation” should{.red} be used instead of “Continue as Filed” if the aircraft is no longer expected to return to their flight plan or does not have a flight plan filed.

6.6.3 #

Aircraft may request a different service if they wish, the Center Controller must{.red} determine what level of service can be offered based on their workload. If aircraft are flying VFR or do not have a flight plan, the use of “Resume Own Navigation” should{.red} be used instead of “Continue as Filed” (see 6.5.3 and 6.5.5 above).

Cruise #

6.6.4 #

During this phase of flight for aircraft, Controllers should{.red} focus on:

• aircraft that are active/away to provide separation (see 6.6.5 below)
• issue speed commands for traffic flow management
• and pass aircraft onto adjacent facilities at the boundary of their airspace (see 5.1.1 above)

6.6.5 #

Center controllers will be able to see if an aircraft is “active” or “away” by looking at their flight progress strip. Due to this, “away” aircraft should{.red} be left alone and conflicts assumed unintentional.

Aircraft descending via VNAV may be issued a violation after a warning if they are unresponsive AND conflict with others (see 1B.2.1 above)

6.6.6 #

In the cruise phase speed control is essential in traffic flow management, controllers must{.red} ensure that they are familiar with typical Mach cruising speeds for aircraft under their control (see 6.14.5 below). An increase or decrease of Mach .01 can change an aircraft’s arrival time significantly (dependent on how far ahead the instruction is sent). Therefore to control traffic flow, Center Controllers should{.red} utilize speed control where possible (although altitude changes and vectors are always available if required). This will reduce Controller workload and prevent aircraft being taken hundreds of miles off their flight plan.

6.6.7 #

IFR/VFR Semi-circular rules are not implemented, however they are something that are good to be kept in mind and can assist Controllers with providing separation to large amounts of traffic in the cruise.

IFR - Assuming you are in RVSM airspace

VFR - Odd or even levels with an extra 500ft added to all levels

STARs #

6.6.8 #

Standard Terminal Arrival Routes, known as STARs, are a published flight procedure that are followed by aircraft on an IFR flight plan from an intermediate altitude. STARs allow aircraft to arrive following a pre-defined route (and in some cases with altitude/speed restrictions) that help them navigate adjacent airspaces, terrain and departing traffic. Controllers should{.red} let aircraft continue on a STAR to the maximum extent possible for arrival unless vectors are required for an expeditious service, sequencing or traffic avoidance (see 6.8.4 below).

6.6.9 #

The Controller can select preferred STARs, offering a variety of authorized procedures from different directions (see 4.2.2 above); Controllers should{.red} review aircraft flight plans on initial contact to determine whether or not they include the preferred STAR for their destination airport. Aircraft not on a preferred STAR should{.red} be instructed to “Amend Flight Plan to Include Preferred STAR at Destination” to give the aircraft time to refile.

Descent #

6.6.10 #

Aircraft with a filed STAR are expected to “Check In” on initial contact with Center, if no STAR is present in a pilots flight plan, they should{.red} initiate contact by requesting the desired service or approach for their destination airport. If aircraft make other requests such as an approach request, Controllers should{.red} respond with “Continue as Filed, Expect the [approach type/runway] at [location]” if the approach in use is known. The subsequent Approach Controller can still change the expected approach if required.

6.6.11 #

A pilot should{.red} request descent via the STAR just prior to their Top of Descent (TOD); which Center can respond with either “Descent via the STAR Approved” or “Unable, Expect Vectors”. Aircraft that are cleared to descend via the STAR will display their approved STAR on their flight progress strip, allowing all subsequent Controllers to view this information and removing the need for pilots to make duplicate requests with different Controllers. If they are told to expect vectors, then Center must{.red} provide vectors and altitude assignments, and “Continue as Filed” and “Altitude at your Discretion” when complete. Center may also instruct an aircraft to “Descend via the STAR” if the pilot has not yet requested descent (any built in or pilot amended altitudes assigned to a STAR will be shown on the Controllers scope when an aircraft’s icon is tapped).

6.6.12 #

Aircraft already descending before making contact with Center should{.red} be authorized to “Descend via the STAR”. Aircraft already established in the descent should not{.red} be instructed to “Amend Flight Plan to Include Preferred STAR at Destination” as this could increase pilot workload. Instead, Controllers should{.red} issue vectors for sequencing.

6.6.13 #

Handoffs to the next controlling facility should{.red} occur at or prior to the lateral and/or vertical boundary as long as all conflicts are resolved. In addition, Center must{.red} ensure all aircraft are continuing to their destination in an organized manner, on their respective procedures and sequenced prior to handing off to Approach.