Preparing Offline Maps for the App

Sometimes you have a map in a ready-to-import format from another source—a friend, a website, or file storage. There are also many online sources that offer offline maps which the app doesn’t support natively.

In this tutorial, we will use aeronautical maps provided in GeoTIFF and PDF (GeoPDF) formats from the official faa.gov website as an example.

Download the VFR maps from:

https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/vfr/

faa-gov-maps

Currently, the formats provided by faa.gov are either GeoTIFF or PDF (GeoPDF).

Let’s download the TIFF map for Atlanta.

After unzipping, you can preview the TIFF map file in your file explorer as shown below:

map-offline-prepare-tiff

It has a size of approximately 88MB.

Now, let’s convert this TIFF map into MBTiles format so you can use it in the app.

Install GDAL (free) if you haven’t already: https://gdal.org/en/stable/download.html

In your terminal, navigate to the folder containing the TIFF map file, then run:

gdal_translate "Atlanta SEC.tif" Atlanta-VFR.mbtiles -of MBTILES

The command output should be similar to:

Input file size is 17951, 12354
Warning 1: Input dataset has a color table, which will likely lead to bad results when using a resampling method other than nearest neighbour or mode. Converting the dataset to 24/32 bit (e.g. with gdal_translate -expand rgb/rgba) is advised.
0...10...20...30...40...50...60...70...80...90...100 - done.

A new file named Atlanta-VFR.mbtiles should appear in the folder.

Copy this file to iCloud Files or any other shared/cloud storage accessible on your iPhone/iPad.

In the app, you can open this map directly^*) by tapping the ‘+’ button in the maps list:

map-list-import-map

Then, tap on Import offline map and use the file picker to import the map.

Alternatively, in the Files app (or any file storage app, or even in an email attachment), tap (or hold—starting in iOS 18) on the file and choose either Share or the Open In option. If the app is not visible, scroll to the “…” (more) button, tap it, and select our app from the complete list.

Using the first option with the file copied to your iCloud VFR folder:

map-offline-icloud-mbtiles

Tap the file, wait for it to download and open in the app. A new map will appear in your offline maps list; tap it to make it active and return to the main map screen.

If the map is not immediately visible, it may be because the displayed area does not match the area covered by the map. Pan the map slightly, then tap the map title button. On the live map, the map’s label turns into a button that lets you focus on the offline map region:

Select the Focus on a map region option, and the live map will zoom to the area covered by the offline map:

map-offline-imported-vfr

Have a new map source or technical information about GDAL or map conversion that you’d like to share? Please reach out to us at support@blocoware.com – we’d love to hear from you!

^*) The option to open/import the map file directly from the app will be available in all our relevant apps starting in March 2025.