Practice Pans - are there any genuine reasons not to use them? I'm a low time PPL.  In my personal opinion, practice pans, perhaps one or two a year, are a good thing.  Practice in a procedure that builds confidence removes one more item from the pucker factor list if it does all go wrong and lets your brain focus on the situation.

The D&amp;D cell are always happy to assist and I know that they welcome it as it gives them practice as much as it does me. They are always excellent and it's comforting to know that they are there if I ever need them for real.

However, I know that many pro pilots do not approve of this.  I am aware that they are often required to monitor guard and that practice pans can be a source of noise but is it really that disturbing?  I've even had that terse "transmitting on guard" broadcast which to me is a) entirely rhetorical and b) great irony.

If something genuine crops up on guard, then of course I'd shut up and continue on my way but are there any genuine reasons for amateurs to not practice?  Surely it's better for all users of the sky to be as good as they can?
I presume you are from UK since it is the only country I know of that uses practice pans. 

Basically, ICAO (ICAO Annex 10, Volume V, § 4.1.3.1.1) states that the emergency frequency 121.5 MHz (sometimes called "guard") shall be used only for genuine emergencies. So typically any other use is considered misuse. 

However, countries can file deviations from this rule and publish these deviations in their AIP. One such example is the UK, where 121.5 can be used for practice PAN calls to ensure pilot familiarity with the process.

Pilots not familiar with the situation in the UK sometimes frown upon this use, and as you mention, jump in with the dreaded "transmitting on guard" sentence. But those doing that seem to have the same reaction when a real emergency is going on. 

If you are flying in the UK and want to practice an emergency situation you are encouraged to do so by the D&amp;D cells. But remember to ask permission first:


  A/C > London Centre, callsign, request Practice Pan


If they have the time to accommodate you, the reply will be something like


  London > callsign, Practice Pan acknowledged, continue when ready 


And remember, it is not only a practice for you, but also for controllers. There is a benefit for everyone flying around.