General Aviation

Published on September 26th, 2019 | by Mark Dwyer

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Requesting a VFR Clearance

The IAA have published guidance to general aviation pilots in Ireland about requesting a VFR Clearance. The guidance, which is reproduced below, outlines the steps and processes that happen in the background when you request a VFR clearance.

Introduction

Pilots are often surprised when there is a delay following a request for a VFR clearance. This material explains the internal processes that must occur within air traffic control (ATC) for such a request to be processed.

The processes described here are generalisations and may vary in detail depending on time of day and location. When requesting a clearance from ATC, make your request on the appropriate frequency for the area you are in, unless a particular frequency is specified in AIP IRELAND. ATC will transfer you to the correct frequency if necessary.

Step 1 – Clearance request

“Dublin Approach, Echo India India Alpha Alpha, Cessna 172, approaching Bray, two thousand feet, request entry to the zone routing to Weston.”

This shows a typical ATC air situation display, in this case showing the Dublin Control zone. Note the code 7000 (VFR) squawk south of Bray.

Step 2 – Establishing identification

Before any surveillance-based services can be provided, controllers must establish positive identification of the aircraft concerned. VFR aircraft squawking 7000 are shown on ATC air situation displays as relatively inconspicuous grey tracks. Furthermore, there may be more than one VFR track in the relevant area.

In this situation the usual means of establishing identification is to instruct the pilot to squawk a discrete (individual) code. To obtain a discrete code, it is normally necessary for a flight plan (flight notification) to exist within the ATC Eurocat system. However, inactive VFR plans are not always displayed to controllers, so the first question you are likely to get from a controller is “have you got a flight plan in the system?”

The ATC Eurocat flight plan window contains the flight plan details for an individual flight, including the SSR code which is automatically allocated by the system. Creation of a flight plan using this window is a time-consuming and complex process.

Step 3 – Activating flight plans

If a flight plan has been submitted, in most cases it is a relatively simple process for ATC to access and activate it. If not, then the controller will have to take details over the air and create a plan. This is a relatively time-consuming and complex process. Remember: even if your details have changed, it is much easier to amend an existing plan than to create one from scratch.

This photo shows the Air Movements Controller’s working position. The ATC Eurocat workstation consists of the two screens on the left of the picture, which display radar data as well as ancillary information such as flight plan data or weather information. At lower left is the communications control panel, and to its right is a board for managing flight strips. The screens to the right are used for controlling airfield lighting and the airfield surface movements radar system.

You can greatly speed up the clearance process, or improve your chances of getting a clearance, by submitting a flight plan before takeoff. If done via the online flight planning tool at www.iaa.ie/generalaviation. It costs nothing and if never activated will self-cancel in due course. However, if needed it will be there waiting for you.

Sometimes due to processing errors, flight plans can be “missing” from the ATC Eurocat system when you call. The more information you provide in your flight plan in relation to your point of departure, intended route, and destination, the easier it will be for ATC staff to initially process your flight plan.

In addition, an accurate departure time and estimated elapsed time will assist the ATCO in activating your flight plan, and the provision of contact information (such as a mobile phone number) in your flight plan will assist in the provision of an Alerting Service.

Step 4 – Linking identification to flight plan

Once your discrete code has been detected, Eurocat can couple the flight plan details to the track on the controller’s display. White tracks indicate the aircraft is under the control of the appropriate sector.

Once ATC has activated the flight plan and instructed you to squawk a discrete code, it will take a few moments for the surveillance system to detect your squawk, couple the flight plan details to it and display the details to the controller. Your aircraft’s track will now have an interactive label attached to it (see above), and there will also be a flight strip giving the controllers access to further information about your flight.

A ‘strip’ for each flight gives the controller information about the aircraft’s intentions derived from the flight plan, modified as necessary as the flight progresses.

Step 5 – Co-ordination with other controllers

Once the flight plan has coupled to a track, identification has been positively established. The controller talking to you will now need to coordinate with other controllers about your flight before a clearance is approved. For example, at Dublin this will include co-ordination with the Dublin Approach radar controller, Military control and also Weston ATC. Your progress through the control zone can impact on the processing of scheduled IFR traffic at Dublin airport, Baldonnel and Weston airports, depending on the active runway and traffic pattern.

Controllers use a touch-screen Voice Switching and Communications System to coordinate flights with other controllers.

Before you fly…

Each location has preferred routes and/or levels for accepting VFR traffic, which may vary depending on the day of the week, or the time of day. You can often help your chances of obtaining a clearance through busy terminal areas by telephoning the terminal area Station Manager before you flight plan. They will be able to advise on the best routes, levels or times to plan. This is particularly valuable if you want to do something unusual, for example some sightseeing or other air work. The applicable phone numbers are listed below.

Summary

You can see that there are a number of steps that must occur within ATC, not all of them visible to the pilot, before a VFR clearance can be issued. All of this takes time, and the controller will have other aircraft to manage as well. You can improve your chances of obtaining a clearance, reduce delays and minimise the risk of an airspace infringement by:

  • telephoning the supervisor at busy locations for advice prior to flight planning
  • submitting a flight plan, even if you may not need it
  • allowing plenty of time before the CTA boundary when you make your clearance request
  • always having an alternative plan and decision point in case a clearance is not available as requested.

Telephone Details

Cork Air Traffic Control Dublin Air Traffic Control Shannon Air Traffic Control

(021) 432 9667 (01) 844 5962 (061) 366 148

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About the Author

Mark Dwyer

Mark is an airline pilot by profession flying the Boeing 737 for a major European airline. In addition he is also a Type Rating Instructor on the B737. Outside of commercial flying Mark enjoys flying light aircraft from the smallest 3 Axis microlights up to heavier singles. He also instructs on them including tailwheel differences training and is a UK CAA Examiner. He also flies the Chipmunk for the Irish Historic Flight Foundation (IHFF). Mark became the Chairman of the National Microlight Association of Ireland (NMAI) in 2013 and has overseen a massive growth in the organisation. In this role he has worked at local and national levels. In 2015, Mark won ‘Upcoming Aviation Professional Award’ at the Aviation Industry Awards sponsored by the IAA. Mark launched this website back in 2002 while always managing the website, he has also been Editor and Deputy Editor of FlyingInIreland Magazine from 2005 to 2015.



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