MGL US NaviBuilder User Guide

1. What this tool does

MGL EFIS systems (iEFIS, XTreme, Enigma, and related) read their airports, navaids, fixes, airspace and obstacles from one binary file called navidata (NAVIDATA.EWD). MGL Central can make this file, but poses some challenges for new users and is not completely configurable when merging data sources.

This builder reads free public data files from the FAA and navaid.com, combines them, lets you choose what to include, and writes a navidata file ready for the SD card or simulator use.

• Runs entirely in your browser. Your files are never shared.
• Nothing to install. Open the page, add files, build, download.
• Reference use only. See the disclaimer on the main page, and always check against current official publications.

2. Input data sources

To create a US navidata file, you need CIFP or GPX data (or both). DOF obstacle data is optional.

Identifiers

CIFP uses ICAO identifiers where they exist (KOSH, PANC, PHNL) and FAA identifiers otherwise (0WA1, 1G4). Each CIFP airport record also carries its FAA code, so FAA 3-letter codes are matched without guessing: OGG → PHOG, PPG → NSTU.

3. Step by step

Step 1: Add your data files

Click each box and choose the prescribed file. Files are only read when you build.

Step 2: Waypoint type mapping

Choose which kinds of CIFP records go into the file, and which MGL symbol each gets.

Step 3: CIFP + GPX merge

Leave on Recommended unless you have a reason to change it. Custom shows each option; see section 5.

Step 4: Build

• Cycle code: filled in from the CIFP header; not editable.
• Include obstacles: Yes adds obstacles from the DOF file. No leaves them out and skips reading the file.
• Min obstacle height (AGL ft): obstacles shorter than this above the ground are left out. 200 ft keeps about 183,000 of 632,000 US obstacles.
• Save as: NAVIDATA.EWD (primary) or SNAVI.EWD (secondary navidata). The contents are the same.

4. How CIFP records become MGL waypoints

ARINC 424 is the standard format for aviation navigation databases; CIFP is the FAA's ARINC 424-18 file. Each 132-character line is one record, and its type decides where it goes:

Airports

Fixes

The ARINC waypoint type letter means different things in enroute (EA) and terminal (PC/HC) records, so they are separate options.

CNF (Computer Navigation Fixes, names ending “(CNF)”) are internal FMS/ATC points and are off by default.

5. How CIFP and GPX are merged

GPX entries are matched to CIFP records by identifier. For each field you choose a policy:

Recommended settings: frequencies from GPX (fixed, since CIFP has none); runway surfaces from GPX, shortened to 4-character codes (ASPH, CONC, TURF…); elevation, names and runway geometry from CIFP; runways only in GPX (water lanes, helipads) added.

The yes/no options add records that exist only in GPX: airports, navaids, fixes (following your Step 2 choices) and offshore platforms (off by default; added as waypoints or heliports). Every record is tagged with its source (CIFP, GPX, CIFP+GPX or DOF) so you can filter by it in the results.

6. EFIS limits: keeping the database usable

The file itself can be large. What matters is how the EFIS loads it:

• 20,000 nearby waypoints. The EFIS keeps a list of waypoints within about 10 geographic degrees of the aircraft and builds the “nearest” list from it. The list holds at most 20,000; beyond that the rest are never loaded. Because the file is sorted west to east, the eastern part is what gets dropped, so a close airport can be missing from the nearest list while a manual search still finds it.
• The list is shared: primary navidata first, then SNAVI.EWD, then user waypoints. A dense primary file can push the others out.
• 800 points per airspace. Longer outlines are cut off. This tool simplifies outlines to stay under 400.
• Airspace memory. Decoded airspace shares about 10 MB of map memory with the vector map; the tool keeps point counts modest.

Waypoints in the area the EFIS loads, around busy US areas (sample CIFP, before GPX):

7. Results, editing and download

• Summary cards: Airports, Navaids, Fixes, Airspaces, Obstacles and file size. Click a card for a searchable list with source filters.
• ℹ on a row opens the full record. You can edit airport and waypoint names and airport frequencies, and delete any record or frequency. Save & rebuild writes a new file straight away without re-reading the source files.
• Breakdowns: CIFP by Step 2 category, CIFP record types, GPX types and DOF obstacle types show what was imported and what wasn't.

8. Installing on the EFIS

1. Copy the downloaded NAVIDATA.EWD (or SNAVI.EWD) to the SD card.
2. Insert it in the EFIS and install it from the Install tasks menu.
3. You can also open the file in the EFIS Simulator or MGL Central to inspect it.

9. Troubleshooting