DCRO: Drone Flyaway Risks Overstated in SORA 2.5

The Dutch Association of Certified RPAS Operators (DCRO) has released a white paper challenging the probability assumptions for unmanned aircraft system (UAS) flyaways in the upcoming Specific Operations Risk Assessment (SORA) 2.5 guidelines. Drawing on extensive data from professional operators and a statement from DJI, a leading drone manufacturer, DCRO argues that real-world flyaway risks are far lower than regulators estimate—potentially by a factor of 100. This discrepancy prompts a call for uniform safety data collection and a rethink of ground risk assessments for adjacent areas.

What Is SORA and Why It Matters

SORA is a risk assessment framework developed by the Joint Authorities for Rulemaking on Unmanned Systems (JARUS) and adopted by the European Union Aviation Safety Agency (EASA) to evaluate drone operations in the Specific Category. This category includes operations beyond the Open Category’s limits, such as beyond visual line of sight (BVLOS) flights or missions over populated areas. The methodology helps regulators and operators determine safety requirements, balancing operational freedom with public safety.

With SORA 2.5, set to take effect across EASA member states in 2025, a key change emerges: operators must now account for ground risks in areas adjacent to their operational volume. This shift, outlined in step #8 of the updated guidelines, aims to enhance safety but has sparked debate. DCRO contends that the assumed probabilities driving these requirements overestimate the likelihood of flyaways, leading to overly stringent containment measures.

The Core Disagreement: Assumptions vs. Reality

SORA 2.5 assumes a UAS has a 1 in 1,000 flight-hour chance (10^-3) of leaving its operational volume due to technical failure or loss of control. It further posits a 10% chance that a flight termination system (FTS) fails to stop the drone, resulting in a combined flyaway probability of 1 in 10,000 flight hours (10^-4). A flyaway, as defined by DCRO, occurs when a UAS exits its designated area without operator control and lands outside that zone, posing potential ground risks.

DCRO’s data paints a starkly different picture. From 37 member operators and four large foreign operators, totaling 1,411,183 flight hours, only one flyaway was reported. This yields an empirical probability of roughly 1 in 714,000 flight hours (1.4 x 10^-6)—orders of magnitude lower than SORA’s estimate. Supporting this, DJI provided probabilities for its enterprise models (e.g., M300, M350 RTK, M30), averaging a 1.75 x 10^-5 chance of leaving the operational volume. Applying JARUS’s 10% FTS failure rate, this translates to a flyaway probability of 1.75 x 10^-6—closely aligning with DCRO’s findings.

This gap suggests that SORA 2.5’s assumptions may not reflect the safety record of professional operators, who follow strict maintenance and contingency protocols.

Evidence from the Field

Operator Data

DCRO’s dataset spans flight logs from 2011 to 2023, covering a diverse range of UAS models and conditions. Despite technological limitations in earlier years—think exposed connectors and unreliable batteries—the single flyaway stands out as an anomaly. The association attributes this to rigorous training, enabling pilots to regain control in most loss-of-control scenarios before a flyaway occurs.

DJI’s Contribution

DJI’s statement, based on millions of flight hours (including 5.4 million for the Dock 1 and M30), offers a manufacturer’s perspective. Models like the FlyCart 30 show a probability as low as 6.82 x 10^-6 for leaving the operational volume, while the M300 reaches 3.2 x 10^-5. Averaging these figures reinforces DCRO’s claim that real-world risks are significantly lower than regulatory assumptions.

Professional vs. Non-Professional Operators

DCRO stresses a critical distinction: professional operators, unlike hobbyists, operate under audited procedures and are trained for emergencies. This reduces flyaway risks, a factor SORA 2.5 doesn’t explicitly account for, potentially skewing its one-size-fits-all approach.

Implications for Drone Operations

The conservative probabilities in SORA 2.5 could force operators to adopt costly and complex containment measures, such as FTS. These systems, designed to end flights if a drone strays, come with a catch. DCRO warns that an FTS’s failure rate may exceed the UAS’s inherent risk, potentially causing unintended crashes—say, into a highway or waterway—rather than preventing them. For a small operator, the added expense (likely thousands of dollars per unit) could also strain budgets without clear safety gains.

Historically, DCRO’s data has influenced policy. In 2016, Dutch regulators reduced the no-fly buffer near highways from 492 feet (150 meters) to 82 feet (25 meters) after similar evidence showed minimal flyaway risks. Today’s debate echoes that success, questioning whether SORA 2.5’s adjacent-area rules are equally out of step.

DCRO’s Call to Action

DCRO proposes two solutions:

• Uniform Safety Data Collection: EASA and national authorities should mandate standardized reporting of flight safety statistics across the EU. This mirrors manned aviation’s data-driven approach, ensuring regulations reflect actual risks rather than theoretical worst-case scenarios.
• Reassess Adjacent Ground Risks: Given the negligible flyaway probabilities for professional operators, DCRO argues that ground risk in adjacent areas shouldn’t dictate containment levels in the Specific Category. This could ease requirements like FTS, fostering innovation without compromising safety.

Toward Data-Driven Drone Rules

The clash over SORA 2.5’s flyaway probabilities reveals a broader tension in drone regulation: balancing precaution with practicality. DCRO’s white paper, backed by operator and manufacturer data, suggests that professional UAS operations are safer than regulators assume. If substantiated, this could reshape how containment is approached, avoiding unnecessary burdens on an industry poised for growth.

Standardized data collection stands out as the linchpin. Without it, regulators risk crafting rules based on outliers—like non-professional mishaps—rather than the norm. As drones expand into delivery, inspection, and beyond, aligning safety frameworks with real-world evidence will be key to unlocking their potential responsibly.

DroneXL’s Take

DCRO’s challenge to SORA 2.5 underscores a recurring hurdle: drone regulations lagging behind technology. The data hints that professional operators have already dialed in safety, yet blanket assumptions could penalize them with red tape. Mandating FTS, for instance, feels like a solution chasing a problem—especially if it introduces new failure points.

The push for uniform statistics is a no-brainer. Manned aviation thrives on crash data and near-miss reports; drones deserve the same rigor. Until then, policies like SORA 2.5 risk being more speculative than scientific, potentially stunting growth in a sector that’s still finding its wings. Collaboration—not confrontation—between regulators and industry will be the difference-maker.

Photo courtesy of the Dutch Association of Certified RPAS Operators (DCRO)