DGCA (Director General of Civil Aviation) has defined a NPNT i.e. No Permission No Take-off as mandatory compliance for all RPA in India. One of the fantastic architectural concepts of NPNT framework is capability of RPA to take permission in digital format using digital certificate keys. The Digital Sky and RPA requires an active Digital certificate for data security. The digital certificate is used to sign the data and encrypt/decrypt it. This end-to-end secure communication of data is meant to avoid any kind of man-in-middle attack.

As per Exhibit C i.e. Sequence Diagram of RPAS defined by DGCA on page #37 at section number #3.2 of DGCA guidance manual, entire solution of NPNT is expected to be a software solution. The overall NPNT solution has four different components as per the following diagram.


Each component has different role to play for management of NPNT process. Here are roles of each component.

A. Drone/RPA

Drone/RPA as defined at left side of sequence diagram has to perform following functions.

    1. Key Pair Generation
    2. Parsing Permission Artefact and Validation
    3. Monitoring the geo-fence for breach and take necessary action incase of breach
    4. Signing Logs using private keys
    5. Storing UUID (Universally Unique Identifier)

B. GCS Software

Ground Control Stations must perform following functions.

    1. Triggering init() process every time and checking if a drone is registered or not. If not registered, it must get it done.
    2. Checking if key needs to be rotated on every init() process on every power on. Rotating keys according to the need.
    3. Mission Planning with geo-fence details, time of mission details and sending mission information to Digital Sky platform for Permission artefact ID.
    4. Get the Permission Artefact and pass it to RPA
    5. Upload the approved plan to flight.
    6. Mapping of Internal ID and UUID Mapping
    7. Communication between drone and management server.

C. Manufacturer/RFM Provider’s IT Infrastructure

Ground Control Stations must perform following functions.

    1. Manage the digital certificates and keys
    2. Get the drone registration
    3. Manage the key pair rotation policy
    4. Communication with DGCA for drone registration

D. Digital Sky Platform

Digital Sky platform must perform following functions.

    1. Primarily hold the drone registration information
    2. And manage the permission artefact information.
    3. And perform other various activities.

From the above role of each component of the NPNT framework, it looks that entire process manageable using the software stack at drone. However, to manage the functions of RPA, development at firmware of flight controller software is required. This is complex task and requires dedicated skill sets. PDRL has implemented these functionalities into the firmware that goes into the Autopilot developed by PDRL.

Another way to manage functions of RPA/Drone is by means of an additional hardware instead of making changes in firmware. When additional hardware is used for managing functions of RPA/Drone then it becomes Level 0 compliant, which is certainly less secure. Technically, this method is accepted as compliant, however it has following impact on RPA/Drone performance.

    1. Since hardware module is required to be deployed on the drone, it increases the weight of RPA. Every gram weight certainly impacts the flight time.
    2. Hardware module on RPA consumes power from the core power source. This further reduces the flight time.
    3. Hardware module is level 0 compliance and therefore it is less secure. Possibility of exposure and anonymous control becomes high.
    4. The life of hardware module is always limited. Therefore, it attracts separate repair and maintenance. This may attract more cost in future.
    5. If someone has already perfectly designed the drone considering certain performance expectations, then due to hardware based NPNT solution, there may arise a need for redesigning the RPA, which is a lengthy process at it impacts the Airworthiness of RPA.
    6. Once hardware is integrated on RPA and certification is done, the there is equal to zero possibility of inter-portability of NPNT solution. Which is not the case incase of a software solution.
    7. The hardware solution increases the capital cost of RPA. While software solution can be offered as monthly service. This reduces upfront cost of RPA.
    8. If there is any update in DGCA policy in lieu with technology, it will be difficult to meet those requirements in case of a hardware based NPNT solution. It would require changes in hardware and then certainly, may demand a re-certification process for an already certified RPA.

To conclude, the software based NPNT solution from an RFM provider becomes a more viable solution over hardware NPNT solution. If you are using hardware based NPNT solution, rethink.

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