As drone operations grow more complex with BVLOS flights, automation, and integration into controlled airspace, human-machine interaction (HMI) and human error prevention have become central to safety and regulatory compliance.

To support this, EASA released Certification Memorandum CM-HF-001 (Issue 01), which provides detailed guidance on two critical safety objectives from the SORA framework:

• OSO #19: Systems must detect and help recover from human error

• OSO #20: Human-machine interfaces must be designed to minimize mistakes and support effective decision-making

This edition of the AirHub Knowledge Series explores what these objectives mean for operators and how these principles can be applied in real-world drone operations.

Why Human Factors Matter in Drone Operations

Whether operating a drone-in-a-box setup from a remote location or coordinating complex multi-pilot missions, humans remain at the center of the operational decision loop. Errors can stem from:

• Misinterpreting system status

• Poor interface design (e.g., ambiguous button labels)

• Stressful or unclear operational procedures

The goal of both OSO #19 and #20 is to minimize human error and improve decision reliability, especially during high-stakes or complex missions.

OSO #19 – Detecting and Recovering from Human Errors

According to EASA, systems should be designed to help operators:

• Avoid making mistakes (e.g., by locking out unsafe commands)

• Recognize errors early (e.g., clear visual or auditory alerts)

• Recover from errors before they escalate (e.g., safe-mode activation)

For operations in SAIL III, this requires at least a low level of assurance, meaning you must declare and justify the design choices that reduce the chance of human error.

Examples include:

• Confirmation prompts for critical actions like arming the FTS or switching flight modes

• Automatic status monitoring (e.g., battery health or GPS quality)

• Physical barriers or interlocks to avoid accidental activation of key systems

OSO #20 – Human-Machine Interface (HMI) Design

A well-designed interface helps the operator:

• Understand system status at a glance

• Receive and interpret warnings or alerts clearly

• Perform tasks confidently and without ambiguity

EASA highlights that HMI design must be intuitive, especially for remote pilot stations, tablets, or multi-control setups.

At a minimum, your interface should:

• Use standard color codes (green = safe, amber = caution, red = warning)

• Display key system information clearly (e.g., mode, position, health, telemetry)

• Provide quick, unambiguous feedback after every operator input

• Avoid information overload or confusing visual layouts

Depending on the complexity of your setup, EASA expects some level of human factors validation, from usability walkthroughs to full scenario-based testing with representative users.

The Feedback Loop: How Operators Interact with Systems

EASA identifies five essential elements of HMI feedback loops in UAS operations:

1. Detect – The system or operator identifies an issue or change

2. Decide – The operator interprets the data and determines a course of action

3. Command – A control input is made (e.g., return-to-home triggered)

4. Execute – The system carries out the command

5. Feedback – The system confirms the action and provides updated status

If any link in this loop is weak (e.g., poor feedback, unclear options), error risk increases. A good HMI design supports all five stages clearly and reliably.

How AirHub Supports Better HMI and Error Management

At AirHub, we integrate human factors thinking directly into our software and services:

• Clear workflows in our Drone Operations Center (DOC), including visual status indicators and confirmations for critical steps

• Pre- and post-flight checklists aligned with your operations manual and user manual

• Scenario testing support as part of our consultancy services for SORA authorizations

• Customizable training support to ensure your pilots know how to use systems under both normal and abnormal conditions

We also support clients in documenting compliance with OSO #19 and #20, including declarations, evidence collection, and usability validations.

Final Thoughts

HMI design and human error prevention are no longer just best practices, they are regulatory requirements for advanced drone operations. By prioritizing clear interfaces, predictable workflows, and scenario-based testing, operators can reduce risk, improve safety, and meet SORA expectations for SAIL III and beyond.

Whether you are working on your SORA documentation, evaluating a CMU, or training your team, these principles will keep your operation safe, efficient, and future-ready.

If you would like help evaluating your interface or ensuring OSO compliance, our team is ready to support you.