I always listen to my transceiver at KPHX and the tower would clear a helicopter for a “sharp alpha”. I was just curious what a sharp alpha is.
Thanks in advance 
I am not from Phoenix but local ATC towers quite often have local routes for VFR airplanes and helicopters that are locally published and named rather than having to give a long drawn out clearance that ties up the radio frequency every time a helicopter takes off. I imagine a sharp alpha is one of those types of clearances.
Ok, thanks! That would make sense.
The latest revision is actually called “Sharp Echo”. Sharp Echo is the procedural name of a Letter of Agreement between the KPHX Tower and local helicopter operators that “Specifies responsibilities, defines terms, and establishes procedures to be used between Phoenix Tower and signatory operators for the control and operation of VFR and Special VFR helicopters within the Phoenix Class B Airspace.” An operator who is a Sharp Echo signatory states the words “Sharp Echo” upon the initial radio call to notify the Controller that the operator is a participant of the LOA, and will abide by the procedures defined by the LOA. This then greatly reduces Pilot/Controller workload by reducing necessary monitoring and subsequent radio calls.
Sharp Echo Letter of Agreement
Thanks for the thorough and clear information. 
I stand corrected.
The other day as I was shortening the stack on my desk a memo surfaced… It was dated several months ago, but the LOA has been revised with the latest designation of ALPHA. The meat of the LOA remains with very little change.
I started to wonder as just last week (after this subject came up) I was departing PHX and was on the North Tower frequency when I heard a local EMS ship transiting the airspace with the “Sharp Alpha” call. On that flight I didn’t get a chance to ask the controller, but came across the memo a few days later.
For now I don’t have copy of the revised Alpha that I can post. So for reference of intent, the link above to the LOA is still valid.