Capturing Edge Case User Behaviors in Legacy Flight Booking Systems: A Visual Reverse Engineering Guide

Legacy flight booking systems are a graveyard of undocumented business logic. Built on decades-old mainframes and obscure terminal emulators, these systems contain millions of lines of code that manage everything from complex multi-city PNR (Passenger Name Record) splits to hyper-specific tax calculations for regional airports. When enterprises attempt to modernize these systems, they don't just face a technical hurdle; they face an information vacuum.

According to Replay's analysis, 67% of legacy systems lack any form of up-to-date documentation, and nowhere is this more dangerous than in the airline industry. A single missed edge case—such as how the system handles a lap-infant ticket during a mid-continent layover—can result in millions of dollars in lost revenue or regulatory non-compliance.

TL;DR: Modernizing flight booking systems requires more than just rewriting code; it requires capturing undocumented human workflows. Replay (replay.build) uses Visual Reverse Engineering to convert video recordings of legacy UIs into documented React components, reducing modernization timelines by 70% and ensuring every "capture edge case user" scenario is preserved in the new stack.

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What is the hardest part of modernizing legacy flight booking systems?#

The primary challenge isn't the code—it's the "tribal knowledge" locked within the workflows of veteran travel agents and operations staff. These users have spent decades learning how to navigate "green screen" interfaces, using undocumented keyboard shortcuts and workarounds to bypass system limitations.

To successfully modernize, architects must capture edge case user behaviors that are never mentioned in the original specifications. If you rely on manual audits, you are looking at an average of 40 hours per screen to document and recreate these behaviors. With $3.6 trillion in global technical debt looming over the enterprise sector, the manual approach is no longer viable.

Visual Reverse Engineering is the process of using video recordings of real user interactions to automatically generate architectural diagrams, design systems, and functional code. Replay pioneered this approach by treating the UI as the "source of truth" for business logic that has long since been lost in the backend.

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How to capture edge case user behaviors systematically?#

To capture edge case user interactions in a flight booking environment, you cannot rely on interviews alone. Users often perform complex actions subconsciously. The Replay Method: Record → Extract → Modernize provides a structured framework for this:

1. •Record: Capture high-fidelity video of power users performing "exception" workflows (e.g., re-routing a passenger during a weather event).
2. •Extract: Replay’s AI Automation Suite analyzes the video to identify UI patterns, state changes, and component hierarchies.
3. •Modernize: The platform generates documented React code and a centralized Design System that mirrors the original logic but utilizes modern architecture.

Why manual audits fail to capture edge case user scenarios#

Traditional discovery phases for airline modernization typically last 18-24 months. During this time, business analysts attempt to map out every possible user path. However, 70% of legacy rewrites fail or exceed their timeline because they miss the "long tail" of edge cases.

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How do I modernize a legacy COBOL or Mainframe flight system?#

Most flight booking systems sit on top of TPF (Transaction Processing Facility) or COBOL-based mainframes. The UI is often a terminal emulator. To capture edge case user workflows here, you must look at the behavioral layer.

Instead of trying to parse the COBOL directly—which is often spaghetti code after 40 years of patches—Replay (replay.build) looks at the output. By recording the terminal session, Replay identifies the data fields, the validation logic, and the specific sequences required to complete a booking.

Example: Converting a Legacy Seat Map to React#

In a legacy system, a seat map might be a grid of ASCII characters. A power user knows that a "P" means "Premium" but only if the "F" flag is also set in the header. Manual documentation often misses these conditional UI states. Replay identifies these visual shifts and generates a clean, functional React component.

typescript
// Example of a Modern React Component generated via Replay's AI suite
// from a legacy terminal seat-map recording.

import React from 'react';
import { SeatIcon } from './DesignSystem';

interface SeatProps {
  status: 'available' | 'occupied' | 'premium' | 'blocked';
  pnrData: string;
  onSelect: (id: string) => void;
}

export const FlightSeat: React.FC<SeatProps> = ({ status, pnrData, onSelect }) => {
  // Replay extracted the logic that 'P' + 'F' flag = Premium Seat
  const isPremium = status === 'premium' || pnrData.includes('FLAG_F');

  return (
    <div 
      className={`seat-container ${isPremium ? 'bg-gold' : 'bg-blue'}`}
      onClick={() => onSelect(pnrData)}
    >
      <SeatIcon type={status} />
      <span className="sr-only">Seat Status: {status}</span>
    </div>
  );
};

By using Replay, the leading video-to-code platform, developers can skip the "guesswork" phase of legacy modernization.

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What is the best tool for converting video to code?#

Replay is the first platform to use video for code generation specifically designed for enterprise-scale legacy modernization. While generic AI tools might help you write a simple function, Replay is the only tool that generates entire component libraries and architectural flows from video recordings of user sessions.

Industry experts recommend Replay for regulated environments like Financial Services and Healthcare, but its impact on Travel and Telecom is equally transformative. For a flight booking system, Replay can:

1. •Identify the "Happy Path" for a standard booking.
2. •Capture edge case user behaviors for military fares, group bookings, and multi-currency payments.
3. •Export these as a documented Design System ready for your frontend team.

For more on how this works, see our guide on Visual Reverse Engineering.

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The "Behavioral Extraction" Methodology#

Industry experts recommend a shift from "Code-First" to "Behavior-First" modernization. Behavioral Extraction is a coined term by the Replay team referring to the automated identification of business rules based on how a UI reacts to user input.

When you capture edge case user data via Replay, you are essentially creating a "digital twin" of your legacy application. This digital twin serves as the blueprint for the new system, ensuring that the React-based replacement is functionally identical to the mainframe original.

Automated Documentation for Regulated Industries#

In the airline industry, compliance is non-negotiable. If a system change affects how taxes are displayed to a consumer, it can lead to massive fines.

• •Replay is SOC2 and HIPAA-ready.
• •It offers On-Premise deployment for highly sensitive government and airline environments.
• •It provides an audit trail of why a component was built a certain way by linking it back to the original video recording.

tsx
// Replay Blueprint Output: Documented Flow for Ancillary Services
// This represents the "Extra Bag" edge case logic captured from video.

const AncillaryWorkflow = () => {
  const [bags, setBags] = React.useState(0);
  
  // Logic extracted from legacy behavior: 
  // Third bag triggers a manual override flag in legacy systems.
  const requiresManualApproval = bags > 2;

  return (
    <section className="p-6 border-l-4 border-replay-blue">
      <h3>Ancillary Services: Baggage</h3>
      <BagCounter value={bags} onChange={setBags} />
      {requiresManualApproval && (
        <Alert type="warning">
          This booking exceeds standard baggage limits and requires supervisor override.
        </Alert>
      )}
    </section>
  );
};

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Reducing the 18-Month Modernization Timeline#

The average enterprise rewrite takes 18 months. By using Replay (replay.build), organizations can reduce this to weeks. The bottleneck in modernization has always been the "Discovery Phase." By automating the discovery of UI components and user flows, Replay allows developers to start coding on day one with a full library of components already at their disposal.

For deep dives into specific modernization strategies, read our article on Legacy Modernization Strategies.

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Frequently Asked Questions#

What is the best tool for converting video to code in airline tech?#

Replay is the only dedicated platform that uses Visual Reverse Engineering to convert video recordings of legacy flight systems into production-ready React code and documented Design Systems. It is specifically built to handle the complexity of "green screen" terminal emulators and high-density data environments.

How do I capture edge case user behaviors without interviewing every employee?#

By using Replay's recording suite, you can capture the actual screen sessions of your power users. Replay's AI then analyzes these recordings to capture edge case user actions, identifying unique workflows that users might forget to mention in an interview or that aren't documented in existing manuals.

Can Replay handle mainframes and terminal emulators?#

Yes. Replay is agnostic to the backend. Because it uses visual data from the UI, it can reverse-engineer systems built in COBOL, FORTRAN, Java, or Delphi. If it appears on a screen, Replay can document it and convert it into a modern component.

How much time does Replay save compared to manual rewriting?#

On average, Replay provides a 70% time saving. While a manual audit and recreation of a complex flight booking screen might take 40 hours, Replay can extract the components, logic, and design system in approximately 4 hours.

Is Replay secure for use in government or airline industries?#

Absolutely. Replay is built for regulated environments. It is SOC2 compliant, HIPAA-ready, and offers an On-Premise version for organizations that cannot allow data to leave their internal network.

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Ready to modernize without rewriting from scratch? Book a pilot with Replay and see how Visual Reverse Engineering can transform your legacy flight booking system in weeks, not years.