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ForeFlight, Mandatory Frequency Airports, Space for Downloads

By Linda Street-Ely and Liz Bednar, ForeFlight Pilot Support Team

June 2017

The following information was received from the above ForeFlight support specialists after I’d sent in a couple of questions, and I thought I’d share it. You might also save some time.

Our American readers may not be aware of a special category of small Canadian airports called mandatory frequency (MF) airports. These are airports where there is sufficient traffic at certain times of day to obligate the pilot to tune to the frequency within a 5 nautical mile radius up to an altitude of 3,000 feet. The significance is that the rules for approaching the airport change at an active MF airport. For instance, you can enter straight in to base or final or at a 45-degree angle to the downwind but not at a non-MF uncontrolled airport. —Ed.

Identifying MF airports in ForeFlight

With regard to the mandatory frequencies, we do not currently show the mandatory frequencies. As of now, ForeFlight does not have a way of distinguishing the unique mandatory frequency airports in Canada so it defaults to listing them as UNICOMs. ForeFlight is largely based on U.S. procedures, but we are actively working on making it more friendly and accustomed to our Canadian subscribers.

We recommend Canadian pilots do as you did, and take a look at the Canada Flight Supplement (CFS) in addition to the information provided on ForeFlight to make sure they aren’t missing anything.


Finding out if an airport has a mandatory frequency

Memory Requirements for Downloads

I also asked about the space required by ForeFlight for downloading map updates. The biggie is the airport and navigation database. Although it is only 183 MB in size (still quite sizeable,) it requires 1.26 GB to install once it is downloaded, and this is checked before it is downloaded. I was always getting a message that there was insufficient space to download it. This is what they told me. —Ed.

ForeFlight Mobile checks the amount of space available before starting a requested download and displays the “Not enough disk space” message if there may not be enough room to download the compressed data, expand it, and install it.

If you do not have enough memory on your device to hold both the current and the new data cycles, and you cannot free up other space on your device, we recommend you wait until after the new data cycle starts, then swipe-delete the expired airport database (swipe your finger from the right to left across the expired airport database entry, then tap the red “Delete” button), then try the downloads again.

We release the new data at least four days before the old cycle ends. If you download the new chart cycle during that time you will have two copies –  the current cycle and the next cycle. The Delta Downloads feature means that for charts and plates, you only have to download the changes for each data cycle.

When the previous chart cycle expires, the new charts will automatically become active and the expired downloads will slowly, but automatically, be deleted in the background. You can also manually delete the expired data by tapping More > Downloads > Delete > Delete Expired. IMPORTANT: If you delete expired data before the new data cycle is in effect, your monthly download will be larger because you will be doing a full download, not a Delta Download.

And that’s what was happening to me. I’d do a download, or try to, and thought that the new maps would just replace the old, but they don’t do that. The old maps stay until they expire and then are automatically updated. So, to put it simply, if you’re short of space on your device, don’t do the updates until the old maps have expired. —Ed 

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