by Stephen Little, Manager, ATS Standards Compliance, NAV CANADA
Ensuring Canada’s air traffic control towers and flight service stations are appropriately staffed is a highly important, shared responsibility throughout NAV CANADA. However, in the event a situation occurs which may impact system capacity, such as the unplanned absence of an air traffic controller or flight service specialist, NAV CANADA has procedures in place to safely manage the impact and to ensure critical information is shared, within the established communication channels, with all impacted users.
Understanding those procedures; what information to expect, and within which channels this is communicated, will assist you in preparing should this occur when airspace you plan to operate in, is under the jurisdiction of an air traffic control tower or flight service station.
Reduced system capacity
When an impact to system capacity is identified at an air traffic services (ATS) unit, the NAV CANADA operations manager may, as a first step, implement procedures to reduce capacity at the impacted facility.
Notification of the reduced system capacity of an ATS facility would be communicated in a NOTAM, with specific details of any limitations detailed within it.
The following are examples of NOTAM which could be issued if a control tower within a Class C or D control zone has reduced system capacity:
Example 1: hxxxx/20
NOTAMN q) czul/qacch/iv/nbo/ae/000/030/4517n07317w006 a) CYJN
b) aammjjhhmm c) aammjjhhmmest e) due to reduced system capacity: limitations in effect within the St-Jean (CYJN) CTL zone: VFR training can expect delays up to 30min.
Example 2: hxxxx/20
NOTAMN q) czul/qacch/iv/nbo/ae/000/020/4531n07325w006 a) CYHU
b) aammjjhhmm c) aammjjhhmmest e) due to reduced system capacity: limitations in effect within the Montreal/St-Hubert (CYHU) CTL zone: VFR ACFT requested to remain clear of the CTL zone except DEP/ARR
Temporary closure of air traffic control tower or flight service station outside of published hours
In rare situations, personnel absences or shortages may also lead to temporary closures of an ATS unit outside published hours.
To determine the safest course of action, the decision as to the time and the duration of the closure will be made by NAV CANADA operations, with careful consideration of the unique circumstances of each facility (e.g. MEDEVAC or other high priority flights, commercial operations, flight school activity, or anticipated weather).
Closure of an air traffic control tower or flight service station does not mean that the airport is closed, as that remains the responsibility of the airport authority.
For air traffic control towers, the airspace classification of the control zone changes to Class E, and both VFR and IFR users may operate within it. Also, where a published mandatory frequency (MF) is established, MF procedures will apply.
Notification of a closure
The following channels may be used to notify a closure to impacted users.
- NOTAM
- Broadcasts on published ATS frequency
- ATIS
NOTAM
A NOTAM may be published as soon as it is known that a closure will be occurring. At air traffic control towers, when a control zone is designated Class C or D, a statement regarding the designation of airspace will be included.
Example of an air traffic control tower notam
(nxxxx/23 NOTAMN
q) czul/qstlc/iv/nbo/ae/000/040/4831n07103w005
a) cyrc b) aammjjhhmm c) aammjjhhmm est
e) due to <raison> [optional]
St-Honore (CYRC) twr clsd. mf proc apply on 118.4mhz.
the CTL zone surrounding CYRC is designated class e airspace.
IFR and VFR are using airspace.
IFR dep clearance are cancelled.
IFR dep clearance CTC Bagotville terminal 1-888-813-8508.
FREQ unmonitored: 118.4mhz, 121.9mhz and 121.5mhz.
for info ATIS 124.95mhz or 134.8mhz.
Examples of flight service station closure NOTAM
Example 1: n1009/19 notamn
q) czqm/qsslc/iv/nbo/ae/000/030/4726n06147w025
a) cygr b) aammjjhhmm c) aammjjhhmmest
e) Iles-de-la-Madeleine (CYGR) FSS CLSD.
ad LGT AVBL with ACFT RDO CTL ad LGT (ARCAL).
pre-taxi clearance (PTC) not AVBL, IFR dep clearance CTC Moncton acc 134.35mhz.
freq unmonitored: 123.15mhz, 121.5mhz and 243.0mhz.
metar and RVR not AVBL.
Example 2: n1005/19 notamn
q) czul/qsslc/iv/nbo/ae/000/032/4837n06812w005 a) cyyy
b) aammjjhhmm c) aammjjhhmmest e) Mont-Joli (CYYY) FSS CLSD. all ad LGT on continuously intst 3. apply proc for high intst APCH LGT inoperative (aip ad 2.22.4). pre-taxi clearance (PTC) not AVBL, IFR clearance CTC Montreal acc 134.65mhz or 1-800-633-1353. freq unmonitored: 122.1mhz and 121.5mhz. metar and RVR 06 not AVBL. Baie-Comeau RVR 10 not AVBL. remote ad advisory SVC (RAAS) and pre-taxi clearance (PTC) not AVBL: Baie-Comeau (CYBC) 118.3mhz, Gaspe (Michel-Pouliot) (CYGP) 122.3mhz remote ad advisory SVC (RAAS) not AVBL: Lourdes-de-Blanc-Sablon (CYBX) 122.0mhz.
Broadcasts on published ATS frequency
The air traffic controller or flight service specialist will make a broadcast advising of the closure.
Air traffic control tower broadcasts
“( unit id ) tower is closed. The ( unit id ) tower control zone is now class e airspace. All aircraft and vehicles broadcast intentions on frequency (xxx.x (mf)). Surveillance service terminated.”
When the unit is opening again you can expect to hear the following:
“This is ( unit id ), ( unit id ) is open. The ( unit id ) control zone is now class (class of airspace). All aircraft on the ground and vehicle operators contact (unit id) on (ground frequency). All aircraft in the air contact (unit id) on (tower frequency).”
Flight service station broadcasts
“This is ( unit id ), ( unit id ) is closing until ( time-4 digits ) zulu. [Remain on this frequency for ( name of service ) from ( unit id ) ]”
When the unit is reopening, you can expect to hear the following:
“This is ( unit id ), ( unit id ) is resuming normal operation”
ATIS broadcast
Both air traffic control towers and flight service stations will update ATIS to broadcast details of the closure.
Example of an air traffic control tower ATIS broadcast
“ (unit id) tower is closed; class echo airspace in effect.
Mandatory frequency procedures apply, broadcast intentions on (xxx.x (mf))
Contact London FIC for NOTAM and weather information on 123.15. All IFR clearances are cancelled. pilots must obtain IFR clearances with unit ID) on (freq). (unit) ID tower will reopen at xx:xx”
Further reading
Understanding the procedures in place—what information to expect, and within which channels this is communicated—will greatly assist you in preparing. However, it is also important you know your responsibilities within CARs.
CARs–‘Part VI: General Operating and Flight Rules–Subpart 2: Operating and Flight Rules–Division V: Operations at or in the Vicinity of an Aerodrome’ contains the following:
- 602.96 Operations at or in the Vicinity of an Aerodrome
- 602.97 VFR and IFR Aircraft Operations at Uncontrolled Aerodromes within an MF Area
- 602.98 General MF Reporting Procedures
- 602.99 MF Reporting Procedures before Entering Manoeuvring Area
- 602.100 MF Reporting Procedures on Departure
- 602.101 MF Reporting Procedures on Arrival
- 602.102 MF Reporting Procedures When Flying Continuous Circuits
- 602.103 Reporting Procedures When Flying through an MF Area
- 602.104 Reporting Procedures for IFR Aircraft When Approaching or Landing at an Uncontrolled Aerodrome
Also, TC AIM ‘RAC–Rules of the Air and Air Traffic Services’ provides flight crews with an additional single source of information on rules and procedures and contains the following
- 4.5 Aircraft Operations–Uncontrolled Aerodromes