FAQ - FREQUENTLY ASKED QUESTIONS
HUB STRUCTURE REPORT
4) WHY ARE NO PLANES ON GATE AT NIGHT OR BETWEEN BANKS?
5) WHAT GATE SEPARATION TIME IS USED TO ESTIMATE GATE USAGE?
6) THE NUMBER OF GATES USED IS TOO LOW?
7) IS THIS SCHEDULED OR ACTUAL?
8) WHAT ARE THE HORIZONTAL LINES?
10) WHAT IS THE GRAY BLOCK OF DATA IN THE CORNER?
11) WHAT DOES THE DIRECTION MEAN?
12) WHAT IF A ROUTE IS NORTH AND EAST?
2) HOW DO I READ IT?
This report shows the number of occupied gates throughout the day for each minute for domestic flights. Local time at the hub is shown on the left side. The day begins at 4am or when the first gate goes live for departure. The number of gates shown on each side of the center is the same, but the colors are different. The left side shows the directional heading (North, South, East, or West in a color. Tow/Intl is explained here) of inbound flights. The right side shows the directional heading of outbound flights. For example, if a plane flew LAX to the hub in DFW and then the plane departed to Chicago the inbound leg would be reported as EAST and the outbound leg would be reported as NORTH. The information block is the corner is explained here. [This visualization was designed for this site and is (c)Enilria.]
3) WHAT IS TOW/INTL?
Any plane which sits at the hub for more than 90 minutes is assumed to towed off and back on. Tow ons are assumed to arrive at gate 45 minutes prior to departure making the gate Live for Departure. Tow offs are assumed to take place 30 minutes after arrival.
4) WHY ARE NO PLANES ON GATE AT NIGHT OR BETWEEN BANKS?
From DOT data we know which tail number turned another flight even if the flight number changed, but we do not get gate number. We do not know which planes were towed off gate and back on. Because the data is domestic we also do not know when a domestic plane turns an international flight. In all these cases we need to make assumptions.
5) WHAT GATE SEPARATION TIME IS USED TO ESTIMATE GATE USAGE?
Because DOT reports inbound and outbound aircraft (if they are domestic) there is no need to estimate gate usage based on separation. The chart shows all gates occupied, there is no assumption for time between flights.
6) THE NUMBER OF GATES USED IS TOO LOW?
This chart shows gates used throughout the day for all domestic flights or flights that turn from a domestic flight. The number of gates used is not how many gates you need. Depending upon time between banks it may be necessary to have as much 30% more gates than are occupied to facilitate a smooth operation.
7) IS THIS SCHEDULED OR ACTUAL?
In order to make the bank structure resemble its intended structure the times used are scheduled, BUT we are using tail numbers from that actual day for gate usage. If a flight cancelled on the day of the data it may not appear because no tail was assigned to a scheduled flight.
8) WHAT ARE THE HORIZONTAL LINES?
The lines are an attempt to present the peak of the bank. The balance moment when inbounds become outbounds at the median time of the bank. This is actually VERY HARD TO CALCULATE mathematically, so it may not always be accurate as it is created by program code. The letters in the center indicate if the bank is weighted toward one direction. N=North, S=South, E=East, W=West, and O=Omni=Omni-directional.
9) THIS LOOKS LIKE AN ERROR?
The data comes from DOT. It may be misfiled. It may have cancellations. It does not have international flights. Some carrier affiliates may also be exempt from reporting. We did the best we could with the data available.
10) WHAT IS THE GRAY BLOCK OF DATA IN THE CORNER?
The data in the image shows gates used, not flights. A flight may be on gate for 90 minutes and thus appear as part of the image as many as 90 times. The INFO BLOCK shows the flight data that makes up the image. e.g. Northbound: Arr 87; Dep 162. This means in the Northbound direction there were 87 inbound ARRiving flights throughout the day, but 162 outbound DEParting. This type of imbalance often happens because of geography. The Southbound row may show the same data simply reversed, but it may vary with non-daily flights or cancelled flights. TOW/INTL are not shown because they do not have a directional heading except toward the hangar.
11) WHAT DOES THE DIRECTION MEAN?
The direction is the heading of the aircraft on the flight. For example, if a plane flew LAX to the hub in DFW and then the plane departed to Chicago the inbound leg would be reported as EAST and the outbound leg would be reported as NORTH. North does not mean the city is North of the hub. If a city was North of the hub it would be North on departure/outbound from the hub and South on arrival/inbound to the hub.
12) WHAT IF A ROUTE IS NORTH AND EAST?
If it is more EAST than NORTH, it would appear as EAST.
13) WHAT IF MULTIPLE FLIGHTS DEPART FROM ONE GATE?
Gate here is defined as one aircraft parking position, rather than a door with a number on it. If a number of flights use a single gate number to bus to pad positions it is really counting the number of pad positions.
14) ARE REGIONAL AFFILIATES INCLUDED?
Report from 2018 onward have nearly all primary affiliates includes that operating under a legacy marketing IATA code. Prior to 2018 it gets more complicated and may only include some regionals or only mainline.