Urban Aeronautics Ltd v. Shenzhen DJI Sciences & Technology Ltd

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Urban Aeronautics Limited (Israel)
  • Defendant: SZ DJI Technology Co., LTD (China)
  • Plaintiff’s Counsel: DNL Zito
• Case Identification: 2:24-cv-00903, E.D. Tex., 03/23/2025
• Venue Allegations: Plaintiff alleges venue is proper because Defendant is a foreign corporation subject to personal jurisdiction in the district, citing federal statutes applicable to foreign corporations.
• Core Dispute: Plaintiff alleges that Defendant’s high-end commercial drones infringe a patent related to redundant flight control systems that permit a controlled landing after a critical subsystem failure.
• Technical Context: The technology concerns fault-tolerant flight control systems for aircraft, particularly Vertical Take-Off and Landing (VTOL) vehicles like modern drones, where maintaining stability after a component failure is critical for safety.
• Key Procedural History: The complaint does not mention any prior litigation, Inter Partes Review (IPR) proceedings, or licensing history related to the patent-in-suit.

Case Timeline

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 7,946,528 - "FLIGHT CONTROL SYSTEM ESPECIALLY SUITED FOR VTOL VEHICLES"

• Patent Identification: U.S. Patent No. 7,946,528, "FLIGHT CONTROL SYSTEM ESPECIALLY SUITED FOR VTOL VEHICLES," issued May 24, 2011.

The Invention Explained

• Problem Addressed: The patent describes the challenge of ensuring safety in modern "fly-by-wire" aircraft, especially inherently unstable VTOL vehicles. It notes that prior art redundant systems often attempted to maintain 100% control power after a subsystem failure, which required complex and potentially fallible computer-managed backup systems that could lead to "catastrophic unexpected results" (’528 Patent, col. 1:48-61).
• The Patented Solution: The invention proposes a flight control system architecture with multiple independent control subsystems. Instead of trying to restore full functionality after a failure, the system is designed so that the remaining, unfailed subsystems provide "continued but degraded control power" that is sufficient to allow for a "controlled aircraft descent to a landing" (’528 Patent, Abstract; col. 4:19-24). This approach prioritizes a safe, controlled state over the complexity of full power restoration.
• Technical Importance: This design philosophy represented a shift in fault-tolerance strategy for flight controls, focusing on maintaining a predictable, safe-but-limited operational mode rather than attempting a complex and high-risk substitution of a failed subsystem (’528 Patent, col. 4:46-52).

Key Claims at a Glance

• The complaint asserts independent claim 1 and method claim 10, along with dependent claims 2-5, 9, 11-14, and 18 (Compl. ¶¶10, 22).
• Independent Claim 1, as recited in the complaint, requires:
  • An aircraft flight control system with plural control subsystems having redundancies.
  • The system is organized to provide continued but degraded control power over critical flight parameters if any one complete control subsystem catastrophically fails.
  • The system comprises pluralities of pilot-controlled input sensors, flight control actuators, and flight state sensors (for altitude, speed, etc.).
  • The plural control subsystems each have a control computer subsystem connected to receive inputs from the sensors and provide outputs to the actuators.
  • The inputs and outputs are selected such that a "catastrophic and complete failure" of one subsystem results in the remaining subsystems providing continued control power that is "degraded to less than 100% of total available control power, but sufficient to permit controlled aircraft descent to a landing."

III. The Accused Instrumentality

Product Identification

• The accused products are "DJI Drones, including the DJI Matrice, Matrice 300, Matrice 30, Matrice 350, FlyCart 30 and numerous other high-end drones with Three Propeller Emergency Landing (TPEL) capabilities" (Compl. ¶9).

Functionality and Market Context

• The complaint focuses on the "Three-Propeller Emergency Landing" (TPEL) functionality, which is a safety feature on certain DJI quadcopter-style drones (Compl. p. 7). This mode is allegedly automatically triggered by a propulsion system malfunction, such as a single motor failure (Compl. p. 10).
• Upon failure, the system allegedly enters the TPEL mode, where it "will re-establish stability before starting a controlled descent to land" (Compl. p. 7). The complaint alleges that in this mode, the aircraft descends at a controlled vertical speed while allowing the user limited directional control to land in a suitable location, thereby providing "continued but degraded control" (Compl. pp. 7, 10). A screenshot from a DJI white paper describes this function as a remedy for the "Achille's Heel" of quadcopter-style drones, where a single motor failure would historically cause the aircraft to become uncontrollable (Compl. p. 7).

IV. Analysis of Infringement Allegations

Claim Chart Summary

• The complaint provides a detailed comparison of the DJI Matrice 300 RTK to the elements of claim 1 (Compl. ¶21).

U.S. Patent No. 7,946,528 Infringement Allegations

Identified Points of Contention

• Scope Questions: A central question may be whether the patent’s term "control subsystem" reads on the integrated architecture of the accused drone. The patent’s primary embodiment describes four discrete groups of controls, each with its own computer, controlling distinct sets of actuators (’528 Patent, Abstract; Fig. 38). The infringement allegation appears to equate one of the drone’s four motor/propeller units with one "control subsystem" (Compl. p. 9). The defense may argue that a single motor is merely a component, not a "complete control subsystem" as contemplated by the patent.
• Technical Questions: What evidence demonstrates that the failure of one drone motor constitutes a "catastrophic and complete failure" of a "control subsystem"? Further, the complaint alleges the remaining subsystems provide control, but a factual dispute may arise over whether the drone's TPEL mode operates in the specific manner required by the claim—namely, that the remaining unfailed subsystems provide the degraded control, as opposed to a separate, singular emergency control program taking over.

V. Key Claim Terms for Construction

• The Term: "control subsystem"

• Context and Importance: The definition of this term is fundamental to the infringement case. The dispute will likely center on whether the term requires a structurally independent collection of sensors, computers, and actuators, as detailed in the patent's embodiments, or if it can be construed more broadly to cover a more functionally or logically defined grouping of components in a modern, integrated drone system.

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: The claim language itself is general, referring to "plural control subsystems" without specifying their physical separation or composition (Compl. ¶13; ’528 Patent, col. 21:31-34).
  • Evidence for a Narrower Interpretation: The specification repeatedly describes an exemplary embodiment where the system is divided into "plural (four, for example) independent control groups," with each group containing its own sensors, computers, and actuators responsible for a fraction (e.g., 25%) of the total control power (’528 Patent, col. 4:51-64). The figures, such as Figure 38, explicitly depict these distinct "groups" and "subsystems."

• The Term: "catastrophic and complete failure of any one of said plural control subsystems"

• Context and Importance: This term's construction is critical for determining what event triggers the claimed functionality. Plaintiff equates this with a single motor failure in a quadcopter (Compl. p. 10). Practitioners may focus on whether the failure of a single component (a motor) can be legally and technically equated to the "catastrophic and complete failure" of an entire "subsystem."

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: The specification discusses the overall goal of enabling a "safe descent to landing after some critical aircraft system or subsystem failure," suggesting a focus on the functional outcome rather than the precise nature of the internal failure (’528 Patent, col. 1:29-32).
  • Evidence for a Narrower Interpretation: The patent describes the failure of an entire "group" of controls, which in the embodiments includes not just actuators but also the associated computer and sensors (’528 Patent, col. 5:6-9, col. 20:2-4). A defendant may argue this requires more than just an actuator (motor) failure to meet the claim limitation.

VI. Other Allegations

• Indirect Infringement: The complaint alleges induced infringement under 35 U.S.C. §271(b), stating that Defendant provides instructions and user manuals (e.g., the Matrice 300 RTK User Manual) that direct customers on how to use the accused products in an infringing manner (Compl. ¶16, ¶34). It also alleges contributory infringement under §271(c), asserting that Defendant supplies material parts of the infringing systems with knowledge of the patent and that these parts are not staple articles of commerce (Compl. ¶17, ¶38).
• Willful Infringement: The complaint does not plead specific facts establishing pre-suit knowledge, such as a notice letter. However, it alleges that Defendant acted with "knowledge of the ‘528 Patent" in its contributory infringement allegations (Compl. ¶17). The prayer for relief seeks enhanced damages under 35 U.S.C. §284 and a judgment that the case is "exceptional" under §285, which are remedies associated with findings of willful or egregious infringement (Compl. p. 15).

VII. Analyst’s Conclusion: Key Questions for the Case

• A core issue will be one of definitional scope: can the term "control subsystem," which is exemplified in the patent as a discrete grouping of a computer, sensors, and actuators, be construed to cover one of the four motor-and-propeller assemblies of an integrated quadcopter drone? The outcome of this claim construction will significantly influence the infringement analysis.
• A key evidentiary question will be one of technical causation: does the accused drone's "Three-Propeller Emergency Landing" mode function because the three remaining unfailed subsystems provide continued, degraded control as required by Claim 1, or does a different, centralized emergency protocol take over upon a motor failure? This probes whether the accused product's method of achieving a controlled descent aligns with the specific architectural solution claimed in the patent.