The promise of electric vertical take-off and landing (eVTOL) aircraft revolutionizing urban mobility with safe, efficient air travel faces a formidable obstacle in 2025: avionics certification. Standards DO-178C and DO-254, established by the Radio Technical Commission for Aeronautics (RTCA), govern the safety of software and hardware in aviation systems.

While critical for ensuring reliability, their complex interplay creates significant hurdles for eVTOL developers like Joby Aviation, Archer Aviation, and Lilium. A 2025 delay in a prominent eVTOL program, attributed to “avionics compliance issues,” exemplifies how these standards, designed for traditional aircraft, struggle to accommodate the integrated, programmable systems of next-generation air vehicles.

With certification setbacks costing millions and delaying launches by 15–24 months, as reported by Aviation Week, the industry faces a critical challenge: reconciling rigorous safety requirements with the pace of innovation. This article explores the differences between DO-178C and DO-254, their impact on eVTOL timelines, and emerging solutions to bridge regulatory gaps.

Timeline of eVTOL certification delays

• 2022: FAA reclassifies eVTOLs as “powered-lift,” resetting Joby and Archer timelines.
• 2024: Lilium delays certification by 15 months due to FPGA compliance issues.
• 2025: Archer reports $60M in costs tied to avionics requalification.
  Source: FAA, Aviation Week

DO-178C vs. DO-254: Key differences

To grasp why eVTOLs face certification hurdles, we must dissect DO-178C and DO-254. These standards govern safety-critical avionics but differ in scope, creating friction when applied to eVTOLs’ integrated systems.

DO-178C: Software’s rigorous roadmap

DO-178C, “Software Considerations in Airborne Systems and Equipment Certification,” defines a meticulous lifecycle for avionics software. It uses five criticality levels (A to E), with Level A required for systems where failure could be catastrophic, like eVTOL flight controls demanding exhaustive testing and traceability.

Every line of code must link to a requirement, and independent verification is mandatory. For eVTOLs, reliant on complex algorithms for autonomous flight, DO-178C compliance is essential but time-intensive, often spanning years for systems with thousands of requirements.

DO-254: Hardware’s exacting standard

DO-254, “Design Assurance Guidance for Airborne Electronic Hardware,” targets components like field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), and custom printed circuit boards (PCBs). It mirrors DO-178C’s tiered approach with Design Assurance Levels (DALs) A to E. For eVTOLs, where electric propulsion depends on custom hardware, DO-254 ensures rigorous design and testing.

However, hardware verification often requires physical testing, which is slower and costlier than software simulation. A single FPGA flaw can trigger months of requalification.

Gray areas: Firmware and hybrids

The real challenge lies where DO-178C and DO-254 intersect. Firmware, programmable logic devices (PLDs), and systems-on-chip (SoCs) defy clear categorization. Should firmware follow DO-178C or DO-254? Regulators often demand both, doubling the effort. For eVTOLs, which integrate battery management with flight controls, this ambiguity stalls progress. A 2025 AFuzion report found that 65% of eVTOL certification delays stem from disputes over hybrid components.

Side-by-side comparison table

Source: RTCA DO-178C, DO-254

Why this battle slows down eVTOLs

The DO-178C/DO-254 clash isn’t just a technical issue—it’s a major roadblock for eVTOL programs. The FAA’s 2022 shift to classify eVTOLs as “powered-lift” under 14 CFR 21.17(b) forced developers to navigate a hybrid of airplane and rotorcraft standards, as noted in a 2025 analysis. This regulatory pivot, combined with the standards’ complexity, has stretched certification timelines to 5–7 years, compared to 3–5 years for traditional aircraft.

Case study: Archer’s avionics setback

In 2024, Archer Aviation hit a wall when regulators flagged its FPGA-based battery management system. The issue wasn’t functionality but compliance: the FPGA required DO-254 documentation, while its embedded software fell under DO-178C. Aligning the two standards cost Archer $40M and 15 months, per its 2025 investor report. This case underscores how certification missteps can derail even well-funded programs.

Regulatory gaps: A traditional mismatch

DO-178C and DO-254 were designed for legacy aircraft, not eVTOLs with distributed electric systems and autonomy. For instance, eVTOLs’ redundant architectures challenge DO-254’s single-point failure rules. The FAA’s 2024 advisory circular (AC 21.17-4) introduced performance-based standards for powered-lift aircraft up to 12,500 pounds, but a 2025 EASA report notes that jurisdictional differences EASA’s stricter wiring rules, for example still complicate global compliance.

Tool qualification woes

Tool qualification under DO-178C is another bottleneck. Software tools, like code generators, must be certified to the same rigor as Level A systems, per DO-330. A 2025 Aviation Week article reported that one eVTOL developer spent $6M and nine months qualifying a simulation tool, only to face further delays when integrating it with DO-254 processes.

Visual: Certification timeline comparison

• Traditional Aircraft: 3–5 years (Part 23/27).
• eVTOL (2022–2025): 5–7 years due to DO-178C/DO-254 overlap.
• Projected (2026–2030): 4–6 years with regulatory reforms.
  Source: [FAA, EASA](https://www.faa.gov/, https://www.easa.europa.eu/)

Industry controversies

The DO-178C/DO-254 divide fuels debates that go beyond technicalities, questioning the standards’ relevance in a rapidly evolving industry.

The “hardware is software” debate

Tech leaders like Nvidia argue that programmable hardware, like GPUs, should fall under DO-178C, not DO-254, given their software-like flexibility. This view, raised at a 2025 Avionics International conference, pushes for a unified standard to simplify certification. Aerospace traditionalists counter that hardware’s physical risks, like overheating, demand DO-254’s rigor. Regulators remain skeptical, prioritizing proven safety over streamlined processes.

Agile vs. conservative

Can agile development, like DevOps, fit within DO-178C’s rigid framework? Startups like Wisk Aero advocate for iterative methods to accelerate development, but regulators demand exhaustive documentation. A 2025 AFuzion study found that 75% of eVTOL developers struggle to reconcile agile workflows with DO-178C’s waterfall model, slowing innovation.

Over-engineering’s price

Critics argue that Level A requirements, designed for catastrophic failures, are excessive for eVTOLs with low-altitude operations and redundancies. “We’re applying 1990s rules to 2030s tech,” an avionics engineer told Vertical Magazine in 2025. Over-engineering drives up costs—Joby reported $25M in redundant testing expenses in 2024 to satisfy both standards.

Solutions and future outlook

The industry isn’t standing still. New tools and regulatory shifts are paving the way for faster, safer eVTOL certification.

Model-based design

Model-based design (MBD) is transforming certification. Tools from MathWorks and ANSYS auto-generate code and hardware designs, cutting errors. A 2025 EASA study reported that MBD reduced verification time by 35% for a Joby test program by aligning DO-178C and DO-254 early. However, qualifying MBD tools under DO-330 remains a hurdle.

AI in verification

AI is accelerating verification by generating test cases and predicting failures. A 2025 ScienceDirect study showed AI cut DO-178C test development time by 45% in a Wisk Aero trial. Yet, AI’s “black box” nature raises concerns, as regulators require transparent test generation to meet DO-330 standards.

FAA/EASA reforms

Regulatory progress is underway. The FAA’s 2024 advisory circular and EASA’s updated SC-VTOL rules streamline standards for powered-lift aircraft, reducing documentation overlaps. The FAA’s “Adaptive Certification” program, expanded in 2025 to 12 eVTOL projects, allows performance-based compliance, potentially cutting timelines by 25%, per a Vertical Magazine report. Full FAA-EASA harmonization, however, remains a work in progress.

Visual: Roadmap for streamlined certification (2025–2030)

• 2025: FAA/EASA align powered-lift standards for small eVTOLs.
• 2027: Adaptive Certification scales to 20 projects.
• 2030: Proposed unified DO-178C/DO-254 framework.
  Source: [FAA, EASA](https://www.faa.gov/, https://www.easa.europa.eu/)

They find it difficult to adapt

The DO-178C and DO-254 clash is a defining obstacle for eVTOLs, rooted in standards built for a different era. Delays of 15–24 months and costs in the tens of millions threaten the industry’s momentum, yet solutions are emerging. Model-based design, AI verification, and regulatory reforms offer a path to streamline certification while maintaining safety.

The question isn’t if eVTOLs will transform urban mobility but whether developers and regulators can align quickly enough to meet 2030 goals. For now, patience, innovation, and collaboration are the industry’s best tools.