text: Chapter 3
  in a vague or hesitant voice. To ensure that traffic flows safely and smoothly, the pathfinder must speak
  firmly and confidently, using standard words and phrases. Pathfinders use the phonetic alphabet to indicate
  single letters or initials, or to spell words, whenever similar sounds or difficulties in communication require
  them to do so.
  3-6. Voice transmission offers a brief, concise, uniform flow of communication. The pathfinder
  controller must speak distinctly and pay special attention to numbers. When the accuracy of a message is
  doubtful, he repeats the complete message or essential parts. Radio operators use the following techniques
  to ensure clear understanding:
  y Speak directly into the microphone.
  y Speak in a normal, conversational tone.
  y Vary your pitch—avoid speaking in a monotone.
  y Speak at a comfortable speed—avoid speaking too slow or too fast.
  y Keep your tone clear, professional, and firm. Avoid showing fear, indecision, anger, or other
  negative emotions in your tone of voice.
  y Speak with confidence, especially in emergencies.
  3-7. The pathfinder ATC must transmit messages only as necessary for control or to help ensure safety.
  Specific procedures and control techniques vary, but the following rules apply regardless of the
  techniques used:
  y The pathfinder issues instructions and information about all known traffic conditions.
  y The pilot uses at lease one component of a standard traffic pattern (final approach), consistent
  with the pathfinder's instructions.
  y The pilot has the final authority about whether to accept clearances issued by a controller.
  FORMATS
  3-8. A pathfinder controller uses the following formats and sequences for ground-to-air radio
  communication:
  y To initially call up an aircraft, he--
  – Identifies the aircraft he wishes to call.
  – Says, "THIS IS."
  – Identifies the calling unit.
  – Identifies the type of message to follow (when this will help the pilot).
  – Says, "OVER."
  Example: TANGO TWO SIERRA TWO SIX (T2S26), THIS IS CHARLIE THREE
  DELTA THREE SIX (C3D36) (short pause), OVER.
  y To reply to an aircraft's initial call-up, he--
  – Identifies the aircraft initiating the call-up.
  – Says, "THIS IS."
  – Identifies the pathfinder control unit.
  – Says, "OVER." After establishing communications with an aircraft, shortens the
  transmission by using only the last three numbers (or letters) of each party's (his and the
  aircraft's) identification.
  Example: SIERRA TWO SIX, THIS IS DELTA THREE SIX, OVER.