Avoiding a VCA
Thorough flight planning provides the enhanced mental model and awareness of local airspace and other issues.
When preparing a Flight Plan, consider Control Area (CTA) steps along and around the planned route, consider the navigation tolerances (see AIP ENR 1.1 [Section 19.11] ) that apply to your proposed level.
Ensure reference is made to up to date documentation, sources:
- VTC (Visual Terminal Chart)
- WAC (World Aeronautical Chart)
- VNC (Visual Navigation Chart)
- ERSA (Enroute Supplement Australia)
- AIP (Aeronautical Information Publication)
- NOTAMS (Notices to Airman)
- Visual Pilot Guide (CASA produced)
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If you are considering requesting an airways clearance enroute, submit a flight plan, as it will speed up the availability of an airways clearance. Consider the tutorial on submitting an Australian Domestic Flight Plan Notification (ADFN). |
Accurately knowing where you are, where you are going and what to look for is paramount to avoiding unintentionally flying into controlled airspace. Identify potential traps that you might encounter, such as a reservoir that might be confused with another nearby. If you seem to reach a position ahead of time, consider that you may have misidentified the position and double check.
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Remember the navigation tolerances (see AIP ENR 1.1 [Section 19.11] ) while navigating visually, better to have definitely passed a location by a couple of miles before commencing climb, than hugging the CTA steps and causing uncertainty to the controllers monitoring. |
If in doubt, ask for navigation assistance from ATC, they are only too willing to help.
Ensure that your transponder is selected to ON/ALT with code 1200. The ALT (Mode C) information is very important to not only ATC but aircraft equipped with Traffic Collision Avoidance System (TCAS).
Controllers use their radar displays to monitor aircraft positions, the altitude (Mode C) is often used to determine whether a VFR aircraft is in or clear of CTA. RPT (Regular Public Transport) and other aircraft equipped with TCAS use your transponder, position and altitude information to accurately ‘see’ you. If your altitude is not displayed, false information may be generated.
VFR aircraft should monitor the appropriate area frequency, these are listed on navigation charts and within ERSA. Be aware that ATC may direct calls to you based upon your position, altitude or heading. Don’t be afraid to respond, it may be a request to assist another aircraft, or it might be a friendly reminder that you are approaching controlled airspace. ATC are not the police, so speak up if you think transmissions are directed to you.
Pilots on VFR flights, who navigate with the assistance of GPS, have been noted to operate very closely to CTA. VFR flight rules require pilots to navigate with visual reference to the ground. GPS is a useful tool with a high accuracy rate, however air traffic control get a little alarmed when they see aircraft tracking too close to airspace boundaries, so you must not forget to apply the appropriate tolerances.
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Be aware that CTA steps are generally based upon the location of the DME/VOR at the aerodrome , whereas GPS often uses the aerodrome reference point which might be a couple of miles away from the DME/VOR; therefore apply a safety buffer. |
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Controllers will monitor aircraft as they approach CTA steps to try and determine the possibility of the aircraft penetrating. If, as the pilot, you are flying directly at a CTA step (at right angles), with the intention of turning to parallel the step at the last moment, this will cause concern to the controller. The controller may assume, incorrectly, that you will continue on the same track and potentially penetrate, and will proactively direct calls to the aircraft. A better technique would be to start your turn at least 3nm prior to the CTA step, this way the controller will notice the turn sooner and will be unlikely to be concerned with communication checks. |
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If due weather or other factors, a change to your pre-planned route is required, be cautious as this situation has historically led to VCA occurrences. If you require assistance with an in-flight diversion or a clearance request, contact ATC as soon as this is recognised. |
Whenever practicable, anticipate the need for a diversion well in advance, plan what you need to do and don’t corner yourself into a bad situation by not requesting an airways clearance; ATC are there to help!
Don't be afraid of ATC. It is a readily available resource for VFR flights. Subject to workload, a controller can assist with navigation advice, traffic information and limited weather appreciation advice.
Be aware that if ATC is not transmitting, this does not mean that the controller is not doing other tasks, such as: coordinating with other units, interacting with TAAATS equipment, or using other tools; therefore be patient to requests.
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Remember, if in doubt about anything, ask ATC for assistance. |
Give yourself (and the controller) plenty of time to obtain an airways clearance. Remember that if you have submitted a flight plan, then that will expedite clearance availability (subject to traffic).
Upon a VFR pilot requesting clearance, the controller has many tasks to perform:
- locate flight plan within TAAATS
- create flight plan if not within TAAATS (causing increased delay)
- interact with flight plan to produce squawk code, then issue to aircraft
- identify position of aircraft
- verify altitude of aircraft (from Mode C)
- assess clearance availability (traffic/airspace restrictions)
- coordinate with other units
- issue airways clearance to aircraft
These actions may take 5 minutes or more to complete, so therefore request clearance a minimum 5 minutes prior to reaching the CTA step. Convert that time to a distance based upon your ground speed, then see if there is a geographic location that matches the distance. When you approach that position request your clearance. Also plan ideally at the flight planning stage on an alternative if a clearance is not available.
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Note, submitting a flight plan will speed up the process of clearance availability. |
CASA has produced several information sources for VFR pilots, namely:
- VFR Flight Guide
- Visual Pilot Guides
- Operations In and Around Controlled Airspace (CD-ROM/DVD)
Also the following Internet sites provide useful information:
- ATSB (Australian Transport Safety Bureau)
- BOM (Bureau of Meteorology)
- CASA (Civil Aviation Safety Authority)
