ATPL · Navigation · Communications Atpl Ground Training Series… lesson — Page 127, Lesson 114

I want to walk you through the IFR arrival requirements and the SELCAL system. Let's start with the IFR descent and approach rules. When you're flying IFR and you've been given an expected approach time — that's the EAT — you must commence your descent at, or as close as possible to, that last EAT you received and acknowledged. If you never received an EAT, or didn't acknowledge one, then you descend at, or as close as possible to, the estimated time of arrival that results from your current flight plan. That's your ETA from the flight plan. Then, you must complete a normal instrument approach procedure as specified for the designated navigation aid or fix. So if the approach is an ILS to a particular runway, you fly that published procedure exactly. Finally, you must land, if possible, within 30 minutes after that estimated time of arrival or the last acknowledged EAT. That's a hard limit — 30 minutes. If you can't land within that window, you need to consider your options, but the rule says "if possible." Now let's move to SELCAL. SELCAL stands for selective calling. It's a system where voice calling is replaced by the transmission of coded tones to the aircraft over the radiotelephony channels — that's the RT channels. The big advantage is that the flight crew do not have to monitor the channel continuously. That's extremely useful, especially on long oceanic flights where you're using HF communications, because HF can be noisy and fatiguing to listen to for hours. A single selective call consists of a combination of four preselected audio tones. The transmission of those four tones takes about 2 seconds. When the aircraft receives its assigned tone code — that's the SELCAL code — it activates a cockpit call system. That system gives you light signals, or chime signals, or both. So you don't have to listen; the aircraft alerts you. The procedure for using SELCAL as a flight crew goes like this. First, you include your SELCAL code in the flight plan. Second, you establish HF communications temporarily while you're still within VHF coverage. That way you can ensure the HF aeronautical station has the correct SELCAL code information before you lose VHF contact. The aircraft station should also carry out a preflight SELCAL check, and if necessary, give its SELCAL code to the ground station. Finally, the excerpt introduces an IFR flight profile section. The idea is to put into practice some of the standard words and phrases from Doc 4444 — that's the ICAO Procedures for Air Navigation Services — or from the summary in Doc 9432. The example profile follows a typical IFR flight from Cardiff to Oxford with an ILS approach. The excerpt warns that the list of phrases used is not exhaustive, so private study of all possible phrases is essential. That's your cue to go beyond this book and learn the full phraseology.