The primary purpose of the ATC system is to prevent a collision involving aircraft
In addition, the ATC system also:
Provides a safe, orderly, and expeditious flow of air traffic
Supports National Security and Homeland Defense missions
Air Traffic Control services are governed by FAA JO 7110.65, except when one or more of the following conditions exists:
A deviation is necessary to conform with ICAO Documents, National Rules of the Air, or special agreements where the U.S. provides air traffic control service in airspace outside the U.S. and its possessions, or;
Pilots are still required to abide by CFRs or other applicable regulations regardless of the application of any procedure or minima
Other procedures/minima are prescribed in a letter of agreement, FAA directive, or a military document, or;
A deviation is necessary to assist an aircraft when an emergency has been declared
The ATC system must provide certain additional services to the extent permitted
The provision of additional services is not optional on the part of the controller, but rather required when the work situation permits
It is recognized that the provision of these services may be precluded by various factors, including, but not limited to:
Volume of traffic
Frequency congestion
Quality of surveillance
Controller workload
Higher priority duties
The physical inability to scan and detect situations falling in this category
Services depend on the phase of flight and the associated facility:
Air Traffic Control services are not provided for model aircraft operating at any altitude within the National Airspace System (NAS) or to any Unmanned Aircraft System (UAS) operating in the NAS at or below 400ft AGL
This does not prohibit ATC from providing services to civil and public UAS
Air Traffic Control Facilities:
The Federal Aviation Administration establishes facilities which serve to provide the aforementioned services
Everything in between these terminal, or approach/departure environments is controlled through Air Route Traffic Control Center (ARTCC) which provide enroute services, primarily to aircraft flying under instrument flight rules
Flight Service Stations (FSSs) are established to provide pilots with information and services which aid in flight planning and execution
These services include preflight, inflight, operational, emergency and special services
When an ATC clearance has been obtained, no PIC may deviate from that clearance unless:
An amended clearance is obtained
An emergency exists
The deviation is in response to a traffic alert and collision avoidance system resolution advisory
Except in Class A airspace, a pilot may cancel an IFR flight plan if the operation is being conducted in VFR weather conditions
Each pilot in command who, in an emergency, or in response to a traffic alert and collision avoidance system resolution advisory, deviates from an ATC clearance or instruction shall notify ATC of that deviation as soon as possible
Each pilot in command who (through not deviating from a rule of this subpart) is given priority by ATC in an emergency, shall submit a detailed report of that emergency within 48 hours to the manager of that ATC facility, if requested by ATC
When cleared to a point not on an airway you must hit that point before you turn, because that point is your clearance
If the point is on an airway or a transition you have been cleared for then you can go ahead and lead it with a turn
When a pilot is unsure about an ATC clearance, or unable to comply, the pilot shall immediately request clarification from ATC
I.e., if asked to expedite climb but you cannot increase your rate, state unable to climb faster
I.e., if cleared to a point on your flight plan that is dramatically off, ask if the expected point is unavailable
ATC System
Recording and Monitoring:
Calls to and between air traffic control facilities may be monitored and recorded for operational uses such as accident investigations, accident prevention, search and rescue purposes, specialist training and evaluation, and technical evaluation and repair of control and communications systems
Additionally, private sector services such as LiveATC.net will broadcast radio traffic
Compliance:
ATC is responsible for the safety of the national airspace system, and related to recording and monitoring, they must respond to possible procedural deviations
A pilot may have an Air Traffic Controller provide a phone number after landing and offer the guidance that a phone call is needed due to a possible pilot deviation
If that is the case, don't panic, it doesn't necessarily mean you're in trouble - ATC is data gathering
Still, if a mistake was made, own it, file a NASA report, and do some training either with a flight instructor or through programs like FAA Wings to demonstrate you are taking corrective action
Actual pilot deviations take time to play out, but can be mitigated so long as you own it and take corrective action
Operation Rain Check:
Operation Rain Check is a program designed and managed by local air traffic control facility management. Its purpose is to familiarize pilots and aspiring pilots with the ATC system, its functions, responsibilities and benefits
ATC-Alert, ATC-Limited, and ATC-Zero:
ATC Zero is a term for a condition where ATC services has shut down and goverend by JO 1900.47
Reasons to move to an ATC-Zero condition have included equipment outages, emergencies and the more familiar COVID-19 pandemic
Additional and supplemental information for pilots can be found in the current Aeronautical Information Manual (AIM), Notices to Air Missions, Advisory Circulars and aeronautical charts. Since there are many other excellent publications produced by non-government organizations, as well as other government organizations, with various updating cycles, questions concerning the latest or most current material can be resolved by cross-checking with the above mentioned documents
Remember, air traffic control works with and for pilots, but they never the pilot in command for the ultimate safe operation of the aircraft
The responsibilities of the pilot and the controller intentionally overlap in many areas providing a degree of redundancy
Realize that Air Traffic Controllers and Pilots alike are human, subject to error, but working toward the common goals of safe, expeditious traffic flow
There are many reasons to visit ATC facilities to keep pilot operations in perspective