<strong>5.2 Radiotelephony procedures</strong>
<blockquote>When Selective Calling (SELCAL) equipment is used certain of the following procedures are superseded by those contained in 5.2.4.</blockquote>
<strong>220.127.116.11 PANS.</strong> When a controller or pilot communicates via voice, the response should be via voice. Except as provided by 18.104.22.168, when a controller or pilot communicates via CPDLC, the response should be via CPDLC.
<strong>22.214.171.124 PANS.</strong> When a CPDLC emergency message is received, the controller shall acknowledge receipt of the message by the most efficient means available.</ul>
Source: ICAO Annex 10.2