Navigation Aids for VFR Flights | SKYbrary Aviation Safety

Sep. 23, 2024

Navigation Aids for VFR Flights | SKYbrary Aviation Safety

Introduction

To navigate in VFR conditions, current regulations mandate that pilots carry a certified, updated, and accurate VFR paper chart. Pilots must also be capable of identifying their aircraft's position on the chart. In addition to the chart, all relevant NOTAMs, AIPs data, weight and balance, and weather information must be obtained, calculated when necessary, and comprehended during the pre-flight briefing. This information should be readily available in the cockpit. The chart serves as the primary means of navigation because, being paper-based, it remains functional even if electronic systems like GPS fail. However, managing a paper chart can be challenging, especially in the confined spaces of single-engine piston aircraft. Furthermore, in regions with complex airspace structures, relying solely on charts may prove difficult, as pilots must maintain visual references and monitor for surrounding traffic while navigating. Additionally, accurately updating the aircraft's position under potentially turbulent conditions can compromise situational awareness, leading to inadvertent entry into controlled or prohibited airspace without proper clearance.

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To address these challenges, pilots can modify aircraft instrumentation to include modern GPS-based navigation systems, which can serve as primary navigation aids. However, such systems require certification for aircraft installation and in-flight use, often making them costly for the average VFR pilot.

In recent years, affordable alternatives to these products have become available for private users. The rise of tablets and smartphones has made navigation applications widely accessible and affordable. This trend is further supported by the low cost of GPS sensors and the availability of online aeronautical information, such as AIPs (EAD) and weather data. Preflight briefings are simplified as all NOTAMs, aeronautical information, and MET data can be directly downloaded and displayed on the latest charts. This reduces the pilot's workload, allowing them to concentrate more on flying.

However, it is essential to note that these modern products are not certified for primary navigation, making the paper chart a mandatory requirement. The current market offers a wide array of options, and users must choose the most suitable system for their needs. For assistance, refer to the VFR navigation tools table.

Each navigation system possesses unique advantages and disadvantages, summarized below:

VFR Certified Charts

Pros

Certified, legally compliant, and can be used as the primary navigation tool;
Insulated from technical failures;
Provides a high-level overview of extensive areas.

Cons

Being paper-based, challenging to manage in small cockpits;
Can be difficult to read in complex airspace;
Quickly becomes outdated due to airspace changes;
Requires constant attention to maintain position awareness;
Rerouting can be complicated;
Scale may not always be suitable (balancing ease of handling, detail, and positioning accuracy);
Additional documentation needed for airspace, NOTAMs, and weather updates.

GPS Navigation Equipment Integrated in the Aircraft

Pros

Certified for use as a primary navigation tool;
Often integrates with onboard systems (radio, etc.), reducing the pilot's workload;
Visibility is better than paper charts (zoom in/out functionality);
May include NOTAMs and AIP information, traffic, and weather updates;
Facilitates easy rerouting if required;
Always up-to-date if maintained properly.

Cons

Can be very expensive;
May be complex to operate for users of advanced systems;
Integration can make removal for use in other aircraft difficult;
Some systems require specific training and certification;
Susceptible to complete failure in case of electrical issues;
GPS systems can be targeted by jamming, spoofing, or blackouts.

Portable VFR Software

Pros

Combines benefits of GPS-integrated systems (accuracy, etc.);
Portable and easy to use;
Significantly cheaper compared to integrated navigation systems;
Expanding availability allows pilots to choose the most appropriate software;
Some programs assist in flight planning (many also have PC versions);
Most software updates provide the latest NOTAMs, weather, traffic data, and filtering for airspace view;
Information is always current;
Can issue warnings regarding airspace infringements, obstacle clearance, and traffic avoidance;
Facilitates direct-to navigation and rerouting;
Intuitive interface minimizes training requirements;
Some applications display vertical profiles for planned flights, helping to bypass specific areas;
Most allow filing of flight plans if needed;
Can provide access to critical information such as approach plates, ATC frequencies, and flight logs;
Useful for flight debriefing, as flight tracks are recorded.

Cons

Not certified (a paper chart must be available for regulatory compliance);
The GPS receiver in the device may not be approved for aviation, unlike onboard units;
Tablets or smartphones might not be suitable for viewing in sunlight, making information hard to read on bright days;
Device failure could leave an unprepared pilot unaware of their location (hence the importance of tracking progress with a paper map as a backup);
Pilots must ensure that data is adequately updated;
Over-reliance on technology can lead to hastily prepared flights or misuse of functions like "direct-to," potentially leading to unauthorized airspace crossings (though the device’s airspace warnings can help mitigate this).

Conclusion

While current regulations require the use of paper charts, they should also serve as backups to ensure the pilot is aware of their position on the map. The emergence of affordable and high-performance applications and tablets has considerably simplified VFR recreational flying and may enhance safety. This is largely due to the real-time updates available (as paper charts can quickly become outdated), along with the integration of NOTAMs, airspace data, weather, traffic, and own position information, supplemented by alerts for exceeding limits such as airspace boundaries, minimum safe altitudes, or obstacle data.

Pilots in command hold the ultimate responsibility to select suitable methods, or combinations thereof, ensuring compliance with regulations, conditions, skills, and mission objectives while balancing the use of old and new technologies, without compromising safety.

Accidents and Incidents

This section outlines events where the reliance on GPS as a primary navigation tool was identified as a contributing factor.

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B738 / C172, en route, near Falsterbo Sweden,

On July 20th, the pilot of a VFR Cessna 172 lost focus and inadvertently entered Class 'C' controlled airspace within two successive TMAs without clearance. In the second TMA, he was approached by a Boeing 738 heading to Copenhagen, maintaining less than 90 meters separation. The Boeing crew reported a late sighting of the 172 and assessed that evasive action was unnecessary. Despite the presence of a Mode C-capable transponder on the 172, it was not transmitting altitude prior to the incident, which rendered preventive ATC and TCAS safety barriers invalid, thereby compromising flight safety.

Navigation Aids for VFR Flights | SKYbrary Aviation Safety