The United app doesn't show a gate A5 at DFW. According to that, the lowest numbered gate in Concourse A is A8.

But starting from there, it gives these directions:

 1. 4 minute walk to the escalator between gates A11 and A13. Take it up to level 3.
 2. 1 minute walk to the Skylink train stop. Board the train.
 3. 6 minute train ride to Terminal C.
 4. Exit the train. Walk 1 minute to the escalator. Take it down to Level 2.
 5. Walk 2 minutes to Gate C16.

You can generate your own directions using the interactive map at https://www.dfwairport.com/map/ The results look like this:

[![enter image description here][1]][1]


  [1]: https://i.sstatic.net/iVJYcJrj.png