Aztec Code: The Barcode Inside Your Boarding Pass

Aztec Code: The Barcode Inside Your Boarding Pass

quiet zone needed." data-category="2D & Matrix Symbologies">Aztec Code is a high-density 2D matrix symbology defined by ISO/IEC 24778. Developed by Andrew Longacre at Welch Allyn (now Honeywell) in 1995, it is best known as the barcode on airline boarding passes but also appears in transport tickets, government documents, and healthcare applications.

Unique Design Features

Aztec Code has two distinctive characteristics that set it apart from other 2D codes:

1. Central finder pattern: A bull's-eye target of concentric squares at the center of the symbol (unlike Data Matrix's L-shaped finder at the corner)
2. No quiet zone required: The finder pattern is self-contained, so Aztec Code does not need blank space around it. This allows symbols to be printed edge-to-edge

Symbol Modes

Aztec Code comes in two modes:

• Compact: 1 orientation ring, 1-4 data layers, up to 53 bytes
• Full-range: 2 orientation rings, 1-32 data layers, up to 1,914 bytes

Compact mode is used for short data (boarding pass barcodes are typically compact). Full-range handles larger payloads.

Data Capacity

Error Correction

Aztec Code uses Reed-Solomon error correction with configurable levels from 5% to 95% of data capacity. The default is 23%. The IATA BCBP standard for boarding passes specifies a minimum of 23%.

At 23% error correction, the symbol can recover from damage affecting roughly 11.5% of the modules (since each error requires two correction codewords to fix).

IATA BCBP: Boarding Pass Standard

The International Air Transport Association's Bar Coded Boarding Pass (BCBP) standard specifies Aztec Code as the primary symbology. The barcode encodes:

• Passenger name
• Flight number, date, and class
• Seat assignment
• Frequent flyer information
• Security and check-in data

Aztec was chosen for boarding passes because: - No quiet zone means smaller symbols - Excellent scanning from phone screens - Good performance under varying lighting conditions - High error correction for wear and tear

Aztec vs Data Matrix

Implementation Notes

• Use compact mode for data under 50 bytes
• Set error correction to 23% minimum for boarding passes
• Aztec Code handles phone screen scanning well due to high contrast requirements
• Minimum module size: 0.25mm for print, 3 pixels for screen display