Basic Service or Traffic Service? Which One Should You Ask For?
It’s easy to make “request Basic Service” part of your departure routine. You leave the circuit, settle on heading and call the next frequency. The reply is reassuring, especially on an early solo cross-country, when hearing someone use your callsign makes the cockpit feel a little less solitary.
Before making that request, though, decide what you want the person on the ground to do. Basic Service provides useful flight information without a requirement to monitor your flight. Traffic Service adds specific traffic information from a surveillance system. In both cases, avoiding other aircraft remains your responsibility.
For a VFR pilot, the useful question is whether the conditions and traffic picture justify asking for that additional information. Here’s how to make the choice deliberately when flying in UK Class G airspace.
Contents
What a Basic Service gives you
A Basic Service can help with information such as weather at an aerodrome or known activity along your route. It can be provided by an air traffic controller or a Flight Information Service Officer, usually shortened to FISO. It does not require radar or another surveillance system.
You might hear about gliding activity ahead, for example. That gives you something useful to consider when reviewing your track and lookout. The provider’s knowledge and workload affect what can be passed, and you should expect gaps in the picture.
The common mistake is to assume that being on frequency means someone is continuously checking your position against surrounding aircraft. Under a Basic Service, the controller or FISO has no requirement to monitor your flight. A quiet radio gives you no assurance that the airspace ahead is clear.
A squawk does not change that. Nor does being told you are identified. A controller may identify you for coordination with other traffic while continuing to provide a Basic Service. The agreed service determines what you receive.
What a Traffic Service adds
Traffic Service requires a controller with access to an air traffic surveillance system. It gives you information about relevant observed aircraft, helping you find them visually and assess the potential conflict. The controller identifies your aircraft and maintains that identity while providing the service.
A useful traffic call narrows your search to a direction and distance, with the other aircraft’s movement and level when available. That can make a considerable difference when a small aeroplane is difficult to pick out against the ground. It also gives you a reason to look again at an apparently empty patch of sky.
The controller provides updates when traffic remains a definite hazard, or when you request them. You still decide and take the action needed to avoid a collision. Traffic Service does not provide deconfliction advice or promise a protected distance from other aircraft, even if the controller gives you a heading or level for positioning.
Use the information actively. Look in the indicated area, work out whether the traffic is approaching your flight path and tell the controller whether you have it in sight. If you have lost the picture, ask for an update. Waiting silently for another transmission can waste the time the first call has given you.
Choose for the next part of the flight
Service choice belongs in your pre-flight thinking alongside the route. Consider where detailed traffic information would help, which unit could provide it and what you would do if it were unavailable. The same choice can be reviewed in flight as conditions change.
The Lower Airspace Radar Service, or LARS, is a network of participating units that can provide UK flight information services. Check the published coverage and operating hours for your intended flight. Other appropriate radar units may also be able to help. London Information and Scottish Information provide Basic Service; requesting Traffic Service from a FISO will not produce a radar service.
Availability can change with controller workload or equipment limitations. If you request Traffic Service and receive an offer of Basic Service, make a fresh decision about the route you intend to fly. A plan which depends on detailed traffic calls needs an alternative when those calls cannot be provided.
A quiet cross-country in clear weather
Imagine a familiar route with generous visibility, good weather margins and no particular concentration of activity along the next leg. You mainly want access to useful flight information while navigating independently. Basic Service may suit that need.
Keep the outside scan going while you listen. The fact that the aircraft is trimmed and the next turning point is easy to recognise gives you an opportunity to spend more time looking out. A comfortable cruise can invite a surprisingly long conversation with the passenger sitting beside you.
You can still ask for Traffic Service if detailed traffic information would help. There is no requirement to prove that the sky is busy enough before requesting it. Equally, the word “Basic” should not make you feel that you have chosen badly when its actual provisions fit the flight.
Busy Class G and nearby instrument traffic
Now put the same aircraft on a route through a popular gap between controlled airspace, with several nearby aerodromes. You may expect aircraft arriving from different directions, some climbing or descending. Requesting Traffic Service in good time can help you build a more useful picture before reaching that area.
Timing is part of the decision. Make the call while you still have the capacity to pass your details clearly. Discovering that you need help just as you reach a turning point, meet turbulence and hear another aircraft report nearby makes a straightforward radio exchange much harder.
Take particular care around instrument approaches outside controlled airspace. The relevant aerodrome ATS unit is a sensible contact because it knows about its arriving and departing traffic. Make contact early when your route approaches a charted instrument approach, even if you are already receiving a service elsewhere; arrange the frequency change with your current unit.
Instrument traffic can extend well beyond the familiar visual circuit. An empty-looking overhead does not tell you what is approaching several miles away. Review the charted approach area during planning and consider a route that gives both you and the arriving aircraft more room.
Understanding how airspace and radio services fit together makes these decisions easier. QuizAero Bitesize explains the ground-school principles behind them, so you can connect the exam terminology with the choices you make on a cross-country.
Reduced visibility needs a wider decision
Haze can make an aircraft difficult to see even while your own flight remains within the applicable visual flight rules. In those circumstances, a Traffic Service may help direct your lookout towards a specific area. Ask early if you think that assistance would be useful.
Then consider the flight as a whole. If the view ahead is steadily deteriorating, changing the radio service is only one part of the response. Turning towards better conditions or choosing a suitable diversion may be the decision that restores a comfortable margin.
Neither Basic nor Traffic Service changes the weather conditions in which you may legally and safely fly VFR. A Traffic Service does not authorise entry into cloud. If a suggested heading or level would put you into unsuitable conditions, tell the controller promptly and explain what you can accept.
Deconfliction Service is available to IFR flights in Class G and has different provisions. A VFR pilot should not regard it as the next automatic step when visibility becomes uncomfortable. If you are getting into difficulty, say so clearly and ask for help while continuing to fly the aircraft.
Radar has limits, and so does the service
The controller’s traffic picture depends on what the surveillance system detects. Low-level coverage can be restricted, and clutter can obscure returns. Some aircraft may be difficult to detect; a system relying on transponder replies will not show aircraft without an operating transponder.
Consequently, even a Traffic Service can leave you with traffic that has never been called. Keep using an effective lookout and maintain room to manoeuvre. A traffic display in the cockpit also needs to be understood in terms of its own coverage and compatibility.
Listen carefully to any notification of reduced traffic information. Consider whether the remaining service still meets your needs and whether changing route would help. Controller workload can be high even when the frequency sounds quiet, so the pauses between transmissions are a poor measure of spare capacity.
There is also an important distinction within Basic Service: if the controller or FISO recognises a definite collision risk, a warning must be issued. A helpful warning on one flight should never become your expectation of continuous monitoring on the next.
Ask clearly and confirm what you have
Use the station’s published callsign and your aircraft callsign, followed by “request Traffic Service” or “request Basic Service”. Once invited to pass your message, give your aircraft type and route, present position and level, with your intentions and other relevant details.
Listen for the service that is actually agreed and acknowledge it with your callsign. If you are unsure what you are receiving, ask. A correctly set transponder and an acknowledged service are separate parts of the exchange.
Under Traffic Service, keep the controller informed of changes. Unless safety would be compromised, advise and obtain a response before changing your general route or manoeuvring area, or your level or level band. If following an allocated heading, the same prior advice and response applies before changing it. Take necessary collision-avoidance action immediately and advise the controller.
Under Basic Service, you have greater freedom to manoeuvre, unless you have agreed a particular restriction with the controller. Honour that agreement and communicate before changing it unless safety requires immediate action. In either case, tell the unit when you intend to leave its frequency.
For your next flight, choose the service by the help you actually need. Request detailed traffic information when it would be useful, understand any limits the controller explains and keep reassessing the conditions ahead. You can change your request as the flight develops.
QuizAero Bitesize is our online ground school, helping you connect radio-service terminology with practical airspace decisions. If Basic and Traffic Service still blur together when you’re planning a cross-country, the video below introduces the lessons and explanations available to support that learning.
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