Delphi to React: Why 85% of Aerospace Maintenance Software Requires Visual Reverse Engineering

70% of legacy rewrites fail or exceed their timelines, yet the aerospace industry continues to pour billions into "Big Bang" migrations that inevitably crash. In the high-stakes world of Aerospace Maintenance, Repair, and Overhaul (MRO), the transition from delphi to react isn't just a UI upgrade—it’s a mission-critical extraction of tribal knowledge buried under decades of undocumented Object Pascal code.

The global technical debt currently sits at a staggering $3.6 trillion. For aerospace firms, this debt is often locked inside monolithic Delphi applications that manage everything from turbine blade lifecycle tracking to FAA compliance logging. When the original developers have retired and the documentation is non-existent—a reality for 67% of legacy systems—a manual rewrite is no longer a viable strategy. It is a suicide mission.

TL;DR: Modernizing aerospace software from delphi to react requires moving away from manual code archaeology toward Visual Reverse Engineering, reducing migration timelines from years to weeks by using video as the source of truth.

The Delphi to React Migration Crisis in Aerospace#

Aerospace maintenance software is uniquely complex. A single screen in an MRO application might interact with twenty different database tables, enforce complex regulatory validation logic, and integrate with hardware sensors. Most of this logic was written in Delphi between 1995 and 2005.

The traditional approach to a delphi to react migration involves hiring expensive consultants to perform "code archaeology." They spend months reading through

and files, trying to map state transitions and business rules to a modern React architecture. This process takes an average of 40 hours per screen. In an enterprise suite with 500+ screens, you are looking at a 24-month timeline before a single line of production-ready React code is even written.

Why 85% of Aerospace Systems Require Visual Reverse Engineering#

In aerospace, the "source of truth" isn't the code—it's the workflow. Because 67% of these systems lack documentation, the only way to understand what the software actually does is to watch a technician use it. Visual Reverse Engineering flips the script: instead of reading dead code, we record live workflows.

By recording a user performing a "Part Inspection" workflow in the legacy Delphi app, Replay can automatically extract the underlying data structures, API contracts, and UI components. This shifts the focus from "What does this Pascal function do?" to "How do we replicate this validated business outcome in React?"

The Technical Debt Trap: From Black Box to Documented Codebase#

The $3.6 trillion technical debt problem is exacerbated by the "Black Box" effect. In many aerospace firms, the Delphi system is a black box where data goes in and reports come out, but no one knows the transformation logic in the middle.

When you attempt a delphi to react migration manually, you risk losing the "edge cases"—those tiny snippets of logic added in 2002 to handle a specific Boeing 747 engine variant that are no longer documented but remain vital for safety.

⚠️ Warning: Manual rewrites often miss 15-20% of hidden business logic found in legacy event handlers (TNotifyEvent), leading to critical failures post-deployment.

Bridging the Gap with Replay#

Replay bridges this gap by providing a "Visual Source of Truth." Instead of guessing how a Delphi TForm handles state, Replay records the interaction and generates the equivalent React functional components and hooks. This reduces the time spent per screen from 40 hours to just 4 hours.

delphi
// Legacy Delphi Logic: Part Validation
procedure TInspectionForm.ValidatePart(Sender: TObject);
begin
  if (StrToInt(PartIdEdit.Text) > 5000) and (StatusCombo.ItemIndex = 2) then
  begin
    ShowMessage('Restricted Component: Requires Supervisor Override');
    OverrideBtn.Visible := True;
  end;
end;

The example above shows a simple Delphi procedure. In a massive aerospace application, thousands of these procedures are scattered across hundreds of units. Replay identifies these patterns and generates clean, type-safe TypeScript code for your new React frontend.

typescript
// Replay Generated React Component: PartValidation.tsx
import React, { useState, useEffect } from 'react';
import { Alert, Button } from '@/components/ui';

export const PartValidation: React.FC<{ partId: number; status: string }> = ({ partId, status }) => {
  const [needsOverride, setNeedsOverride] = useState(false);

  // Business logic preserved from legacy Delphi system via Replay extraction
  useEffect(() => {
    if (partId > 5000 && status === 'REPAIR_PENDING') {
      setNeedsOverride(true);
    }
  }, [partId, status]);

  return (
    <div>
      {needsOverride && (
        <Alert type="warning">
          Restricted Component: Requires Supervisor Override
          <Button variant="primary">Request Override</Button>
        </Alert>
      )}
    </div>
  );
};

Visual Reverse Engineering: The Modern Path from Delphi to React#

For an Enterprise Architect, the goal isn't just to change the language; it's to modernize the architecture. Replay doesn't just "transpile" code (which creates "Pascal-flavored JavaScript"). It helps you re-architect.

Step 1: Workflow Recording#

The process begins by recording real users. In an aerospace context, this means capturing a technician's full journey through the MRO system. Replay's engine captures the DOM changes (or screen coordinates in legacy desktop apps), network calls, and state transitions.

Step 2: Extraction and Blueprinting#

Replay's AI Automation Suite analyzes the recording. It identifies recurring UI patterns—like a "Flight Log Table" or a "Maintenance Checklist"—and adds them to your Library (Design System). This ensures that your new React application maintains a consistent design language from day one.

Step 3: Generating API Contracts#

One of the hardest parts of a delphi to react migration is the backend. Most Delphi apps use direct database connections (BDE/FireDAC). Replay observes the data flow and generates modern API contracts (OpenAPI/Swagger) that your new React frontend will need, effectively mapping out the requirements for your new microservices layer.

💡 Pro Tip: Use Replay to generate E2E tests (Playwright/Cypress) based on the legacy recording. This ensures your new React app behaves exactly like the Delphi original before you flip the switch.

Architecture and Compliance in Regulated Environments#

Aerospace is one of the most heavily regulated industries on earth. You cannot simply "move fast and break things." Every change must be audited, and data sovereignty is paramount.

Replay is built for these environments. Whether you are dealing with ITAR-restricted data or FAA-regulated maintenance logs, Replay offers:

• •On-Premise Deployment: Keep your reverse engineering process behind your own firewall.
• •SOC2 & HIPAA-Ready: Enterprise-grade security for sensitive workflows.
• •Technical Debt Audit: Automatically generate a report of what was migrated and what was deprecated.

💰 ROI Insight: By automating the documentation and component generation phases, aerospace firms typically see a 70% average time savings, moving a 18-month project into a 3-month delivery cycle.

Implementing the Strangler Fig Pattern with Visual Extraction#

We don't recommend the "Big Bang" rewrite. Instead, we use Replay to facilitate a Strangler Fig approach. By extracting one module at a time—starting with the most critical or most outdated—you can run the new React components alongside the legacy Delphi system.

1. •Identify a high-value module (e.g., Inventory Management).
2. •Record the workflow using Replay.
3. •Generate the React components and the API contract.
4. •Deploy the new React module and proxy requests from the legacy app.
5. •Repeat until the "Delphi vine" is replaced by the "React fig."

This incremental approach reduces risk and allows for continuous delivery in an industry where downtime can cost millions per hour.

Frequently Asked Questions#

How does Replay handle Delphi's proprietary logic?#

Replay focuses on the observable behavior and data flow of the application. While it can analyze source code, its primary strength is "Visual Reverse Engineering"—understanding how the UI responds to user input and what data it sends to the server. This allows it to reconstruct business logic even when the original Delphi source is obfuscated or messy.

Can we use this for air-gapped systems?#

Yes. Replay offers an On-Premise version specifically designed for aerospace, defense, and government sectors where cloud-based tools are prohibited. All recording and code generation happen within your secure environment.

How long does the "Delphi to React" extraction take?#

While a manual assessment takes weeks, Replay can provide a full technical debt audit and a library of extracted React components within days of the initial recording. The average time savings is 40 hours of manual work reduced to 4 hours of automated extraction per screen.

Does Replay generate "spaghetti code"?#

No. Unlike basic transpilers, Replay generates clean, modular React components using your organization's specific coding standards. It uses an AI Automation Suite to ensure the output is idiomatic TypeScript/React, not just a literal translation of Pascal.

The Future of Legacy Modernization#

The future of the enterprise isn't found in a $50 million, three-year rewrite contract. It's found in understanding what you already have. For aerospace companies looking to move from delphi to react, the path forward requires a shift from archaeology to engineering.

By leveraging Replay, organizations can finally break free from the "Delphi Trap," turning their black-box legacy systems into documented, modern, and maintainable React codebases.

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Ready to modernize without rewriting? Book a pilot with Replay - see your legacy screen extracted live during the call.