I made the mistake of mixing up MB and Mb per second
Remember that MB = Mega BYTES and Mb = Mega BITS
The
MA writes at 100 Mega Bits (Mb) per second
The U3 memory card above is rated at 60 Mega Bytes (MB) per second
So the card is at least 4 times as fast as it needs to be
According to specs a U1 card should also work-
Up to 95MB/s & 20MB/s read & write speeds respectively; Class 10 UHS 1
20 MB/s is about 160 Mb/s
Anyone have any issues with U1 cards?
It's not quite that simple, but you're right that it is easy to mix up MB and Mb and people do it all the time.
You do not want to use any U1 card with the Mavic Air, or any of DJI's drones that shoot at 100Mbps which is most of them now.
100Mbps is 12.5MB/s.
You are confusing one very important thing though - the cards rated speed is
*not* it's minimum sustained write speed. When card manufacturers say "up to 100 MB/s" (or similar), that is almost always the instantaneous maximum read speed. Maximum write speed is almost always lower, and more importantly,
minimum sustained write speed is almost always a lot lower. Minimum sustained write speed is never advertised beyond the symbols on the card, so it is extremely confusing for consumers who don't fully understand all the SD card ratings and symbols.
A U1 card means the minimum sustained write speed is only 10MB/s, so it is too slow for a Mavic Air which writes at 12.5MB/s. You want to give yourself some headroom too, so that is why we go with U3 cards (30MB/s minimum sustained write speed). There are no U2 cards.
Class 10 also just means minimum sustained write speed of 10MB/s, which is too slow. Almost every card has this symbol so you can pretty much ignore the "class" ratings because they don't go beyond 10 and 10 is too slow.
The only thing that matters is that you see a "U3" or "V30" (or higher) symbol on the card, both of which mean
minimum sustained write speed is 30MB/s.
If you look at the manufacturer's advertised speeds, those are
NOT minimum sustained write speeds, but theoretical instantaneous maximums, and almost always refer to read speed not write speed, which again does not matter for our purposes.
And lastly, you can ignore the UHS (bus speed) ratings. Those are the roman numerals on the card (either I, II, or III). The Mavic Air's card slot is UHS I and it is more than fast enough (up to 104MB/s or 832Mbps). If you do have a UHS II card though, they are backwards compatible so it will work, it just isn't necessary to pay the premium for one.
More info in my write up here:
Tips for New Flyers