QRA Locator System: A Detailed Guide to Geographic Referencing
The QRA locator is a specialized geographic referencing system used to describe specific locations on Earth using a concise alphanumeric string. By dividing the globe into a hierarchy of increasingly smaller squares, it allows users to communicate coordinates efficiently without needing long strings of decimal degrees.
A typical QRA locator reference consists of five characters: two capital letters, two numerical digits, and one lowercase letter (for example, FG32c).
Key Facts
- Structure: References follow a format of two uppercase letters, two digits, and one lowercase letter.
- Primary Grid: The first two letters define a main square of 2° longitude by 1° latitude.
- Secondary Grid: Main squares are split into 80 smaller numbered squares (01–80).
- Tertiary Grid: Numbered squares are further divided into nine lettered sub-squares (a–j, excluding 'i').
- Maidenhead Relation: QRA square "AA" corresponds to Maidenhead locator square "JN00".
How the QRA Locator Hierarchy Works
The Main Squares (The First Two Letters)
The foundation of the system is the main square, identified by two capital letters. Each of these squares covers an area of two degrees of longitude by one degree of latitude. For instance, the bottom-left corner of square "AA" is located at 40.0° N and 0.0° E. To put this in perspective, the area covering part of Greater London, known as "IO91" in the Maidenhead locator system, falls within QRA locator square "ZL".
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The Numbered Sub-squares (The Two Digits)
To increase precision, each main square is subdivided into 80 smaller squares. Each of these smaller units covers an area of 12' (minutes) by 7'30" (minutes/seconds). These squares are numbered from 01 to 80, following a specific directional flow: they are ordered from North to South and West to East. Consequently, the northwest corner is designated as "01" and the southeastern corner as "80".
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The Final Precision Squares (The Lowercase Letter)
For maximum accuracy, every numbered square is further divided into nine tiny squares, each measuring 4' by 2'30". These are identified by the lowercase letters 'a' through 'j', though the letter 'i' is excluded to avoid confusion. These letters are assigned in a spiral pattern.
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Practical Application and Summary
By combining these three levels of granularity, a precise coordinate can be converted into a short code. For example, a location at 52° 26' 12" N and 0° 13' 6" E is represented by the QRA locator AM52g.
| Component | Format | Dimensions | Ordering Logic |
|---|---|---|---|
| Main Square | Two Capital Letters | 2° Longitude x 1° Latitude | Global Grid |
| Small Square | Two Digits (01-80) | 12' x 7'30" | North to South, West to East |
| Precision Square | One Lowercase Letter | 4' x 2'30" | Spiral pattern (a-j, no 'i') |
Frequently Asked Questions
What is the format of a QRA locator reference?
A QRA locator consists of two capital letters, followed by two numerical digits, and ending with one lowercase letter (e.g., FG32c).
How does the QRA system relate to the Maidenhead locator?
Both systems use grid squares. Specifically, QRA square "AA" is equivalent to Maidenhead square "JN00", and Maidenhead square "IO91" (Greater London) is part of QRA square "ZL".
Why is the letter 'i' not used in the final sub-square designation?
The system uses letters 'a' through 'j' but excludes 'i' to prevent visual confusion with the number '1'.
How are the 80 small squares numbered?
The numbering starts at 01 in the northwest corner of the main square and proceeds to 80 in the southeastern corner, moving from North to South and West to East.
What is the exact size of the smallest QRA sub-square?
The smallest sub-square, identified by a lowercase letter, covers an area of 4' by 2'30".