What is Flow Control?

The purpose of this post is to outline the reasoning why an expert ATC controller would include flow control in the ATIS remarks.

Flow control is a traffic flow management technique used in order to regulate the rate at which aircraft enter congested resources such as airport airspace to a level no greater than the resource can accept. It can be added in the ATIS remarks for any period of time at any time.

Aircraft will be delayed at their departure airport in order to manage demand and capacity at their arrival airport, if the airports’ demand exceeds capacity for a sustained period. Flights will be delayed primarily at the gate, which in turn regulates their arrival time at the impacted airport.

Controllers will primarily use reminders in-app for each aircraft to keep track of the specific aircraft’s delay dependent on when they spawn at the gate.

Flow control is not to be to be confused for a gate hold, as a gate hold is not known as a traffic flow management technique because you are simply holding all traffic at the gate and not allowing any aircraft to push back.

An example of when flow control could be used is during a flash flight, to mitigate the bottlenecks that type of traffic would create at the destination airport.

As a pilot, keep in mind the following, which applies to Infinite Flight:

FAR 91.103 – Preflght action
Each pilot in command shall, before beginning a flight, become familiar with all available information concerning that flight. This information must include–
(a) For a flight under IFR or a flight not in the vicinity of an airport, weather reports and forecasts, fuel requirements, alternatives available if the planned flight cannot be completed, and any known traffic delays of which the pilot in command has been advised by ATC;

So when you hear flow control in ATIS, expect delays and be patient.

How to Back Taxi Aircraft at EGLC

If you are landing runway 09 or taking off runway 27 at London City Airport (EGLC), here is the steps you would follow as a controller to get aircraft to the gate or the runway:

Landing Runway 09

  1. Land
  2. Exit runway right (The aircraft will hold short of runway 27)
  3. Back Taxi Runway 09, contact ground when off the runway.

Taking Off Runway 27

Aircraft is holding short of the runway requesting takeoff, you have two options. The holding point for runway 27 can hold 3 aircraft at a time.

  • Back taxi runway 27, contact ground when off the runway (They’ll hold short of 27).
  • Back taxi runway 27, line up and wait.

Anticipated Separation: Departure / Departure

Takeoff clearance needs not be withheld until prescribed separation exists if there is a reasonable assurance it will exist when the aircraft starts takeoff roll.

The first aircraft must be airborne before the second aircraft commences the take-off roll (in addition, aircraft type should be taken into account).

For example, if aircraft A (B737) is above 100knts GS and aircraft B (A320) is holding short, simply clear aircraft B for takeoff. No need for a line up and wait instruction.

Runway Touchdown Zone Marking

The touchdown zone markings identify the touchdown zone for landing operations and are coded to provide distance information in 500 feet (150m) increments. These markings consist of groups of one, two, and three rectangular bars symmetrically arranged in pairs about the runway centerline. For runways having touchdown zone markings on both ends, those pairs of markings which extend to within 900 feet (270m) of the midpoint between the thresholds are eliminated.

Source: FAA

Runway Threshold Markings

Runway threshold markings come in two configurations. They either consist of eight longitudinal stripes of uniform dimensions disposed symmetrically about the runway centerline, or the number of stripes is related to the runway width as indicated. A threshold marking helps identify the beginning of the runway that is available for landing. In some instances the landing threshold may be relocated or displaced.

Source: FAA

Visual Runway Markings

Visual runways are used at small airstrips and are usually just a strip of grass, gravel, ice, asphalt, or concrete. Although there are usually no markings on a visual runway, they may have threshold markings, designators, and centerlines. Additionally, in the real world, they do not provide an instrument-based landing procedure; pilots must be able to see the runway to use it.

Picture Source: FAA

Runway Markings

There are runway markings and signs on most large runways. Larger runways have a distance remaining sign (black box with white numbers). This sign uses a single number to indicate the remaining distance of the runway in thousands of feet. For example, a 7 will indicate 7,000 ft (2,134 m) remaining. The runway threshold is marked by a line of green lights.

Thank You Team

I’d like to thank the following people who are hard at work behind the scenes to get the content you see every day out to you, whether that be videos, social media posts or blog posts.

Social Media Team

Video Editing Team

– Kyle Boas, ATC Education Group Manager