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Navigation Aids for VFR Flights
From SKYbrary Wiki
In order to navigate in VFR conditions, current regulations require the pilot to carry a certified, updated and accurate VFR paper chart with the obligation to be able to find their own aircraft position on it. Besides the chart, all relevant NOTAMs, AIPs data, weight and balance, as well as weather information needs to be obtained, calculated (where required) and understood (during the pre-flight briefing) and kept in the cockpit. The chart is the primary mean of navigation due to the fact, that being paper-based, it never fails even if an on-board system such as GPS is out of service. The main disadvantages are that, being paper-based, it is not easy to handle (especially in small cockpits as found in most single engine piston aircraft) and in some regions the airspace structure is so complex that the use of such charts can be a difficult task, especially because the pilot has to maintain visual references and scan for traffic outside of the window (see-and-avoid principle) while at the same time having to search on the chart for frequencies, minimum altitude and avoiding controlled airspace. Add to this the difficulty of accurately updating the aircraft position and handling the chart in potentially turbulent conditions by a pilot who may not have significant flight experience and the potential for losing situational awareness and venturing into controlled or notified airspace without clearance can be a common outcome.
To ease the problem, aircraft instrumentation can be modified to include a modern navigation system based on GPS which can be used as a primary mean of navigation. However, such systems must be certified for aircraft installation and in-flight use so they can be very expensive for the average VFR pilot.
For a number of years now, less expensive variants of these types of product have been available to the private user. The arrival of tablets and smartphones has made the applications ubiquitous and inexpensive. This is also helped by the low price of the GPS sensors as well as the availability of other aeronautical information on the internet, such as the AIPs (EAD), weather etc. The preflight briefing is also made easier because all the NOTAMs, aeronautical information and MET information are directly downloaded and depicted on the most current chart. This will reduce the workload of the pilot who can therefore focus on the actual flying.
Importantly however, such products are NOT certified for use as a primary means of navigation, therefore a the paper chart is still mandatory.The offer currently on the market is quite large and the user has to choose the most suitable one. For some help see the VFR navigation tools table.
Naturally, each system has its own advantages and disadvantages. These are summarised below:
VFR certified charts
- Certified, legally compliant and can be used as primary navigation means;
- Insensitive to technical failures;
- Can provide a high-level view of a large area.
- Is paper based and therefore problematic to handle in small size cockpits;
- Can become very hard to read in areas of complex airspace ;
- Become quickly obsolete due to airspace changes;
- Requires constant attention to maintain ownship position;
- Difficult to do any rerouting;
- Scale may not be always appropriate (antagonism between ease of handling, level of detail and precision of positioning);
- Requires update with additional documents for airspace, NOTAMs, weather.
- Certified and can be used as a primary navigation mean;
- Often integrated with the on-board systems (radio etc.), thus easing the pilot’s workload to select appropriate frequencies etc.;
- Clearer than the paper chart (zoom in/out possible);
- May include NOTAM and AIP Information, traffic and weather;
- Easy re-routing if necessary;
- Chart is always up-to-date (if maintained).
- Very expensive;
- Can be complex to use for the pilot in case of the most advanced systems;
- Is integrated and difficult to take away from the plane in case the pilot wants to change aircraft;
- Some require a specific training and rating;
- Can fail completely in case of an electrical failure;
- GPS can be subject to jamming, spoofing or blackout.
Portable VFR Software
- Integrates all the benefits from the GPS integrated system (accuracy etc.);
- They are portable;
- Very cheap compared to the integrated navigation systems;
- The availability of such software is increasing and the pilot can choose the most appropriate;
- Can be used for flight planning (most come with a PC-version too)
- Most incorporate the latest NOTAM, weather, can include traffic and can filter airspace view;
- The information is always up-to-date;
- Can give important warnings in case of airspace infringements, obstacle clearance, traffic avoidance etc.;
- Can be used easily as direct-to and rerouting;
- Relatively easy to use (intuitive) with little to no training required;
- Some show the vertical profile for planned flights, helping to avoid certain areas if necessary;
- Most can file a flight plan, if needed;
- Can give access to other important information, such as approach plates, ATC frequencies, flight logs etc;
- Can be used for flight debriefing as the flight track is recorded.
- Not certified (a chart has to be taken at least for regulatory compliance);
- The GPS receiver in the device may not be certified for aeronautical use which is not the case for specifically designed on-board equipment;
- The tablet or smartphone used may not be adequate for sunlight reading and it can be difficult to see the information on a bright, sunny day;
- The device can fail, leaving the unprepared pilot totally unaware of their position (which is why it is important to keep track of the flight progress on a paper map, to have a backup in case of failure);
- It is the responsibility of the pilot to verify that the data are updated adequately;
- The capability can be easily misused, e.g. hasty flight preparation; over-reliance on the tool, “direct-to” function used too easily, crossing restricted use airspace (but the device can help through its airspace warnings function).
While the paper charts are still required by the applicable regulations in force and the paper chart is strongly advised as a backup in any case (provided the pilot maintains awareness of own position on that map), the arrival of cheap and high-performance applications and tablets have made VFR, recreational flying easier and possibly safer. This is due to the availability of the always up-to-date information (a paper chart is often out of date by the time it hits the shelves), integration of NOTAM, airspace data, weather, traffic and own position, by the provision of alerts in case of exceeded thresholds such as airspace limits, minimum safe altitudes or obstacle data.
It is the ultimate responsibility of the pilot in command to choose the most appropriate method, or combination of methods, to enable him to fly in accordance with the applicable regulations, conditions, skills and mission objectives, choosing between old and new technology and making sure safety is never compromised.
Accidents and Incidents
This section includes events where the use of GPS as a primary navigation tool was considered a contributor.
- B738 / C172, en route, near Falsterbo Sweden, 2014 (On 20 July 2014, the pilot of a VFR Cessna 172 became distracted and entered the Class 'C' controlled airspace of two successive TMAs without clearance. In the second one he was overtaken by a Boeing 738 inbound to Copenhagen with less than 90 metres separation. The 738 crew reported a late sighting of the 172 and "seemingly" assessed that avoiding action was unnecessary. Although the 172 had a Mode C-capable transponder, it was not transmitting altitude prior to the incident and the Investigation noted that this had invalidated preventive ATC and TCAS safety barriers and compromised flight safety.)
- Airspace Infringement
- Visual Navigation
- Airspace Infringement and Navigation
- Using GNSS as a VFR Navigation Tool
- VFR Navigation - Line Features
- Airspace Infringement: Guidance Notes for GA Pilots
EUROCONTROL Guidance Notes for GA pilots
EUROCONTROL Airspace Infringement Initiative: