First, the tail end of that departure list — Page 340, Lesson 449

Let’s pick this up right where the departure phase ends and the arrival phase begins. I’m going to walk you through the rest of the departure information requirements, then hand you over to the arriving aircraft procedures, and finally the initial approach clearance rules. First, the tail end of that departure list. When we talk about information that must be passed to a departing aircraft, we’re covering weather phenomena and operational status. The weather items are specific: the occurrence of a thunderstorm or cumulonimbus, moderate or severe turbulence, windshear, hail, moderate or severe icing, a severe squall line, freezing precipitation, severe mountain waves, sand storm, dust storm, blowing snow, tornado, or waterspout. Notice the qualifiers — “moderate or severe” for turbulence and icing, “severe” for squall line and mountain waves. That’s the professional standard: we don’t clutter the frequency with trivial weather, only the conditions that threaten the climb. Also on that list, for turbine engined aircraft, we include air temperature. Why? Because high air temperature directly affects engine performance and thrust on a turbine engine during take-off and climb. And we include visibility and runway visual range — RVR — because those determine whether the pilot can continue the departure visually or needs to rely on instruments. Now the next bullet: visual or non-visual aids. If there’s a change in the operational status of any visual or non-visual aid that is essential for take-off and climb, that information must be transmitted without delay to the departing aircraft — unless we already know the aircraft has received it. So the rule is: don’t hold it, don’t wait for a convenient moment; if a runway light fails or an ILS component goes unserviceable, the pilot gets that immediately. Then essential traffic information. If the controller knows about essential local traffic — traffic that could affect the departing aircraft’s path — that must also be transmitted without delay. This is about situational awareness during the most critical phase of flight. Now we move to 17.32, arriving aircraft. These are aircraft being handed over to approach from area control, which is the airways system. The controller may require them to report when leaving or passing a reporting point, or when starting a procedure turn or a base turn, or to provide other information needed to expedite departing aircraft. So the arriving aircraft’s reports are often in service of the departure flow — the controller uses that position information to sequence arrivals around the departures. Finally, 17.33, initial approach clearance. This is a hard rule. An IFR flight will not be cleared for an initial approach below the appropriate minimum altitude unless one of four conditions is met. First, the pilot has reported passing an appropriate point defined by a radio navigation aid — that gives the controller a positive fix. Second, the pilot reports that the aerodrome is in sight and can be maintained in sight — that’s a visual confirmation. Third, the aircraft is conducting a visual approach. Fourth, the aircraft’s position has been positively determined by radar. If none of those four is true, the clearance below the minimum altitude is not given. The point is: we never let an IFR aircraft descend into the approach environment without a positive position reference. So the whole picture here is about positive control and positive information — for departures, we push weather and aid status out immediately; for arrivals, we pull position reports in; and for the approach clearance, we gate the descent behind one of four positive position confirmations. That’s the structure.