Does Daylight Saving Time affect local airspace?
Aviation always uses UTC time. This is from the FAA's AIM, but other countries do the same for obvious reasons:


  4-2-12. Time
  
  a. FAA uses Coordinated Universal Time (UTC) for all operations. The
  word "local" or the time zone equivalent must be used to denote local
  when local time is given during radio and telephone communications.
  The term "Zulu" may be used to denote UTC.


This question covers in much more detail why UTC is used in preference to GMT, and this question explains why pilots need to know the time in the first place, at least under IFR (which applies to almost all airline flights).