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Case Study #123 — 300 Software Failure Case Studies

Delta Air Lines' prolonged CrowdStrike-outage recovery

While most airlines recovered from the global CrowdStrike outage within a day, Delta continued cancelling thousands of flights for nearly a week, the worst and longest recovery of any major carrier, drawing a DOT investigation and lawsuits.

2024-07-19
When it happened
Aviation
Sector
#123 of 300
Ranked by documented impact
01 — What Happened

The damage was public. The root cause was preventable.

While most airlines recovered from the global CrowdStrike outage within a day, Delta continued cancelling thousands of flights for nearly a week, the worst and longest recovery of any major carrier, drawing a DOT investigation and lawsuits.

Aviation
Sector affected
2024-07-19
Date of the event
#123
Rank in the 300 Software Failure Case Studies
1
Distinct root-cause clause identified below
02 — The Root Cause

What the software actually got wrong

Delta's crew-tracking and scheduling software could not efficiently re-match tens of thousands of displaced crew members to aircraft once the underlying Windows-based systems came back online, a software recovery limitation that other airlines with more modern crew-scheduling tools did not share.

01Root Cause

Delta's crew-tracking and scheduling software could not efficiently re-match...

What Happened

Delta's crew-tracking and scheduling software could not efficiently re-match tens of thousands of displaced crew members to aircraft once the underlying Windows-based systems came back online, a software recovery limitation that other airlines with more modern crew-scheduling tools did not share.

How Requs AI Catches This

Requs AI Edge Case flags this exact pattern at the requirements and architecture stage — before a single line of code implementing it exists — so the assumption behind it gets challenged while it is still cheap to fix.

03 — How This Gets Caught Before It Happens

Beyond code coverage and "shall" testing

Root causes like this one rarely show up in code coverage or requirements-compliance testing, because nobody wrote a requirement anticipating the specific edge case that broke. Requs AI Edge Case and Requs AI Software FMEA are built to surface exactly this class of overlooked failure mode — before the software is written.

Requs AI Edge Case

Surfaces this before code exists

Identifies edge cases like this one at requirements and architecture time, using the Common Defect Enumeration to catalog failure patterns seen across hundreds of real-world software failures — including this one.

Requs AI Software FMEA

Connects the failure mode to the hazard

Traces this class of root cause directly to the system-level hazard it can produce, so a defect pattern like this one gets flagged during design review instead of after it ships.

Find the overlooked root causes before they ship.

Schedule a demonstration, or explore how Requs AI Edge Case and Software FMEA use the Common Defect Enumeration.