Let’s pick up right where the runway operation begins — Page 337, Lesson 442

Let’s pick up right where the runway operation begins. I want to walk you through what happens once the aerodrome controller has that information about traffic, and how that drives clearances for both departing and arriving aircraft. First, for a departing aircraft, the aerodrome controller gives a take-off clearance. That clearance is de-facto permission to enter the runway and to take off from it. The word “de-facto” matters here — it means the clearance itself is the legal authority to get onto the runway and start the take-off. Once the pilot is airborne, he or she reports “airborne,” and only at that point can another aircraft be cleared to use the runway. So the sequence is: clearance to take off, enter and roll, become airborne, report airborne, then the next aircraft may be cleared. Now let’s look at how the runway itself is chosen. The aerodrome controller normally decides which runway will be used for take-off and landing. That chosen runway is called the “runway-in-use,” and it determines two things: the direction for instrument approaches and the direction for the visual circuit. Normally, wind direction is the deciding factor. But in calm or light wind conditions, another direction may be preferable for ATC reasons, airspace restrictions, or noise abatement requirements. Here’s a concrete example from the text: at London Heathrow, a departing aircraft is expected to accept a 5-knot tailwind and use the noise preferential runways. So even with a slight tailwind, the controller can still pick that runway for noise reasons. And there’s a generally accepted practice that only one aircraft is permitted on the runway at any time. Let’s move to departing aircraft in more detail. Aircraft waiting for take-off are held at a runway holding point on the taxiway, at a safe distance from the centre line of the runway. The normal procedure is to give a “take-off immediate” clearance. That requires the pilot to taxi onto the runway and, without stopping, line the aircraft up on the centre line and then apply the necessary power to commence the take-off run. So it’s a continuous action — no pause on the runway. Now, a succeeding aircraft may be permitted to enter the runway with the instruction “line up and wait” as soon as the preceding aircraft has commenced its take-off run. But that succeeding aircraft will not be given clearance to take off until the preceding aircraft has either crossed the upwind threshold, or has commenced a turn away from the runway direction. So there are two conditions that must be met before the next take-off clearance: the preceding aircraft has crossed the upwind threshold, or it has started turning away from the runway. Now for arriving aircraft. When an aircraft is established on final approach, it will be given clearance to land if the runway is available. For an arriving instrument approach, the clearance to land is normally given at about 4 nautical miles from the threshold, and certainly no later than 2 nautical miles from the threshold. If the pilot of an arriving instrument approach has not been given a landing clearance, the missed approach procedure is to be flown commencing at 2 nautical miles. So that 2 NM point is the decision boundary — if no clearance by then, you go around. Once the landing run is complete and the pilot has turned the aircraft onto the taxiway, he or she is required to make a report to the aerodrome controller to confirm that the aircraft has “vacated the runway.” That report is to be made when all of the aircraft has passed the appropriate holding point. So the vacating report isn’t just when you’re off the runway surface — it’s when the entire aircraft is past the holding point. Let me tie this together. The key sequence for departures: hold at the holding point, get “take-off immediate,” roll without stopping, report airborne, then the next aircraft can be cleared. For arrivals: get landing clearance by 4 NM, no later than 2 NM, otherwise fly the missed approach at 2 NM, then after landing and turning onto the taxiway, report “vacated the runway” once all of the aircraft is past the holding point. And throughout, only one aircraft on the runway at a time.