File Header

The PFPX navdata file header contains essential metadata about the navigation database in plaintext format.

Structure

The header appears at the beginning of every navdata file and is not encoded. It provides information about the data source, version, and validity period.

Format Example

PFPX NAVDATA
NG2509
2025/09/04
2025/10/01
NAVIGRAPH

Field Descriptions

Line 1: Database Identifier

PFPX NAVDATA

• Purpose: Identifies the file as PFPX navigation data
• Format: Fixed string
• Required: Yes

Line 2: Database Version

NG2509

• Purpose: Database version/cycle identifier
• Format: Provider prefix + cycle number
• Examples:
  • NG2509 = Navigraph cycle 2509
  • AS2509 = Aerosoft cycle 2509

Line 3: Effective Date

2025/09/04

• Purpose: When the navigation data becomes valid
• Format: YYYY/MM/DD
• Standard: Follows AIRAC cycle dates

Line 4: Expiration Date

2025/10/01

• Purpose: When the navigation data expires
• Format: YYYY/MM/DD
• Standard: Follows AIRAC cycle dates (28-day intervals)

Line 5: Data Provider

NAVIGRAPH

• Purpose: Identifies the navigation data source
• Common Values:
  • NAVIGRAPH - Navigraph navigation data
  • AEROSOFT - Aerosoft navigation data
  • Custom provider names may appear

AIRAC Cycles

Navigation data follows the AIRAC (Aeronautical Information Regulation and Control) standard:

• Cycle Length: 28 days
• Global Standard: Ensures worldwide consistency
• Updates: Regular updates to reflect changes in airways, procedures, etc.

Cycle Numbering

AIRAC cycles are numbered sequentially:

• Format: YYWW (Year + Week number)
• Example: 2509 = 2025, cycle 9

Validation

When processing navdata files, always verify:

1. Date Validity: Check if current date is within effective period
2. Version Matching: Ensure compatibility with your PFPX version
3. Provider Consistency: Confirm expected data source

Common Issues

Encoding Problems

• Symptom: Garbled header text
• Cause: Wrong text encoding
• Solution: Use UTF-8 or ANSI encoding

Date Format Variations

• Standard: YYYY/MM/DD
• Alternatives: Some files may use different separators
• Handling: Implement flexible date parsing

Missing Lines

• Issue: Truncated headers
• Cause: File corruption or incomplete downloads
• Detection: Check for exactly 5 header lines

Next Steps

• Learn about runway data - First encoded section
• Understand the overall structure - How sections relate
• Use decoding tools - Process the encoded content