All Posts By

Guido Manfredi

adsb_density

Is there enough ADS-B for everyone ?

By | RPAS World News | No Comments

The air traffic can be divided into cooperative and non-cooperative traffic. The cooperative traffic is equipped with avionics facilitating its detection. The non-cooperative traffic has no such equipment and detection is solely based on ground or onboard sensors. It is important to note that detecting cooperative traffic is a lot easier and more precise than detecting non-cooperative traffic. This is why many experts advocate for all low altitude traffic to be cooperative, at least in high density airspaces, and a proposed solution is to use ADS-B. This solution seem acceptable considering that a large part of the existing traffic is already required (or will be soon) to carry ADS-B out, the technical solutions exist and they are affordable both in terms of SWaP (Size, Weight and Power) and cost. Now, a crucial questions remains: is it possible to introduce hundreds of ADS-B users in already busy (radio frequency wise) airspaces without disturbing the performances of existing systems, e.g. ATM systems ?

To answer this question, the MITRE conducted a study on the impact of equipping low level drones with Universal Access Transceiver (UAT) ADS-B. Both air-to-air and air-to-ground communications were considered. According to this study the crucial parameters are the traffic density and ADS-B transmission power. The following table, extracted from the study, shows the probability to decode a message depending on drones density and transmission power with values in bold being acceptable for ATM applications. With a density of 5 drones per square kilometer the emission power cannot be higher than 0.01W, which strongly limits the communication range, though experiments to know the precise range depending on the transmit power should be conducted.

adsb_power_vs_density

The left column should be read as “number of drone per square kilometer / total number of drones in a 16NM radius and 400ft height cylindre

Overall, the results of this study show that using ADS-B UAT in high density airspaces will prove difficult has reducing the transmission power of ADS-B is likely to decrease detection ranges and impact safety. For the particular case of UAT, considering the fact that it is only used in the US, principally aimed at General Aviation (GA) and with the current grow in GA traffic, the FAA is unlikely to approve such solution to make the drones cooperative. From a broader perspective, the study showed how quickly a cooperative method can overload a communication mean. Having only cooperative traffic is desirable but this kind of study make it look like an unreachable objective. For now…

airprox

How to upset an ATCO with a UAV

By | RPAS World News | No Comments

A recent report, from the John A. Volpe National Transportation Center, prepared for the FAA, presents an analysis of 220 reports of the Aviation Safety Reporting System (ASRS) related to UAVs. The ones filled by Air Traffic Control Operators (ATCOs) are of particular interest as they are crucial players for the integration of UAS in controlled airspaces.

On top of different statistics concerning the events, the report puts forward seven events particularly surprising for ATCOs:

  • An unanticipated appearance of the UAV in the airspace;
  • Difficulties to contact the UAS pilot;
  • The UAV does not comply with pre-coordinated route;
  • The UAV cannot accept (comply with) an instruction issued by the ATCO;
  • The behavior of the UAV is unexpected; and
  • The required actions for the controller are unknown or unclear.

When reading this report, keep in mind that most of these encounters imply military UAS pilots, which explains the high number of remote pilots disregarding ATC instructions.

This type of study is very useful when designing Real Time Simulations with ATCOs in the loop. Indeed, it allows creating worst case scenarios to experiment with ATCOs workload while representing realistic scenarios.

jarus_categories

The SORA finally out for external consultation

By | RPAS World News | No Comments

According to the JARUS operational categorization, drone operations fall into one of three categories: A, B and C (or  Open, Specific and Certified in EASA vocabulary). Flying in category A just requires to follow a fixed set of rules (altitude limitation, mandatory equipage, etc) while flying in category C requires a certified drone system. To operate in category B, an operator needs to demonstrate that operational risks are mitigated by available systems; such demonstration requires a risk assessment approach.

However existing safety tools are complex to use and not always suited to drone operation specificities. In order to provide adapted, accessible and universal tools to the drone community, the JARUS WG-6 developed the Specific Operations Risk Assessment (SORA), a somewhat simple yet powerful methodology allowing to perform risk assessment for drone operations. The full description of the SORA methodology has been recently published for external consultation on the JARUS website.

Though it is unlikely that using the SORA will be mandatory (other risk assessment methods will remain an option), its design will probably make it the best choice for operators willing to build a safety case. So if you plan on using drones in category B scenarios, you can start reading this document as it is likely to become your bedside book. For those interested, we will publish a more detailed article on the SORA methodology in the months to come.

satellite

Laggy RPAS

By | ENAC, RPAS Chair | No Comments

The integration of large drones flying under Instrument Fllight Rules in controlled airspaces is a complex task, yet a desirable objective. However, to benefit from the ATC, the Remote Pilote needs to communicate properly with the ATCOs. And that is where latency messes everything up.

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drone_power_line

All about drones for the Electric Industry

By | RPAS World News | No Comments

As UAS technology and regulation evolve, more missions get added to the list of drone applications. Among the earliest to be identified were the missions related to the electric industry (e.g. power line surveillance, windmill inspection). Last month (February), the Oak Ridge National Laboratory released a 168p survey entitled: “An Early Survey of Best Practices for the Use of Small UAS by the Electric Utility Industry”.

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