AGENDA

# GDPE

## May 24-26, 2004

**Please Review:**

**Minutes of the April 27, 2004 GDPE meeting (CDM website)**

**Pop-up Management Procedures Overview (Attached)**

## May 24, 1:00 p.m. -- 5:00 p.m

+------------------+-----------------------------------+---------------+
| ## 1:00 p.m.     | #                                 | ##            |
|                  | # Adaptive TFM and the Resource R |  Roger Beatty |
|                  | eady Update (RRU) Message Concept |               |
+------------------+-----------------------------------+---------------+
| ## 2:00 p.m.     | ## Rolling Compressions           | ##            |
|                  |                                   |  Mike Brennan |
+------------------+-----------------------------------+---------------+
| ## 2:45 p.m.     | ## Ana                            | ## Ken Howard |
|                  | lysis on time-out cancel flights. |               |
+------------------+-----------------------------------+---------------+
| ## 4:00 p.m.     | ## GAAP Exemption Analysis        | ##            |
|                  |                                   |  Mike Brennan |
+------------------+-----------------------------------+---------------+

## May 25, 8:30 p.m. -- 5:00 p.m

+------------------+-----------------------------------+---------------+
| ## 8:30 a.m.     | ##                                | ##            |
|                  |  **Pop-up Management Procedures** |  Mike Brennan |
|                  |                                   |               |
|                  | ## And Discussion                 |               |
+------------------+-----------------------------------+---------------+
| ##               | ## Working Lunch                  | ##            |
+------------------+-----------------------------------+---------------+
| ## 1:30          | ## Es                             | ## Crannor    |
|                  | tablishing Data Quality Standards |               |
+------------------+-----------------------------------+---------------+
| ## 3:00          | ## ICE-FM (impact of MIT on GDP)  | ##            |
|                  |                                   | Klopfenstiein |
+------------------+-----------------------------------+---------------+
| ## 4:00 p.m.     | ## Using OOOI Times for SCS       |               |
+------------------+-----------------------------------+---------------+

## May 26, 8:30 p.m. -- 1:00 p.m.

+------------------+-----------------------------------+---------------+
| ## 8:30 a.m.     | ## Update on JAVA FSM             | ## Metron     |
+------------------+-----------------------------------+---------------+
| ## 9:00          | ## JAVA FSM HITL Objectives       | ## Kupper     |
+------------------+-----------------------------------+---------------+
| ## 9:30          | ## Real --Time and                | ##            |
|                  |  Historical Data Problem Tracking | Grovac/Kupper |
+------------------+-----------------------------------+---------------+
| ## 10:00-10:30   | ## 7.9 Review                     | ##            |
|                  |                                   |  Grovac/Volpe |
+------------------+-----------------------------------+---------------+
| ## 10:45-12:00   | ## Open Discussion/ New Ideas     | ##            |
+------------------+-----------------------------------+---------------+
| ## 12:00-13:00   | ## Wrap up and Review of          | ## Kupper     |
|                  |  Outstanding and New Action Items |               |
+------------------+-----------------------------------+---------------+

memorandum ![](media/image1.png){width="1.1659722222222222in"
height="0.44722222222222224in"}

**to:** CDM

**from:** Michael Brennan

**subject:** popup Management Procedures Overview

**date:** November 3, 2003

**cc:** Jim wetherly, Dan Horton, Ved Sud, Nayeem hoq

When a Ground Delay Program (GDP) is run for an airport, arrival slots
are allocated to all flights scheduled to land within the period of the
GDP that are in the Arrival Demand List (ADL) at the time the program is
run. Flights that later enter the ADL and express an intent to land
within the period of the GDP are referred to as popup flights or popups.
Popups have to be assigned controlled departure times (EDCTs) that are
considered fair and that limit the disruption to the program. Past
procedures for managing popups are generally considered to be
inequitable and inefficient.

The CDM community decided to pursue alternative approaches to managing
popup demand. Candidate procedures were discussed at several CDM and
GDPE meetings and a general approach was agreed to. This approach was
coded up in Metron Aviation's Jupiter simulation system and several
Human-in-the-Loop (HITL) tests were run, with participation from the
ATCSCC, representative airlines, the NBAA and the implementation
community in the form of Metron Aviation and the Volpe National
Transportation Center. These tests and ongoing discussions have led to a
number of refinements to the procedures and additional testing.

This paper presents a functional overview of the procedures in their
current state. The objective is to make the general procedures and their
intent clear to all involved parties. No attempt is made here to suggest
any particular implementation.

Several issues with the procedures remain unresolved. All known issues
can be addressed in the implementation through configurable parameters.
Future analysis and HITL testing will be designed to resolve any open
issues or ambiguities.

# Overview of the Proposed Popup Management Plan

Under current popup management procedures, when a popup flight appears
in the ADL during a GDP, the ETMS system

1.  Determines the average ATC delay assigned to flights that were
    scheduled to arrive near the intended arrival time for the popup
    flight.

2.  Assigns that delay, the FA delay, to the popup flight, giving the
    flight a delay but no arrival slot in the program.

3.  Issues an EDCT for the popup flight that adds the FA delay to the
    intended departure time.

Since no provisions in the assignment of scheduled flights have
typically been made to accommodate future popups, a popup flight entered
into the program in this way creates excess demand at its new arrival
time. If a large number of popups appear, as is common at many airports,
the excess demand cannot be accommodated with airborne holding and a
revision becomes necessary.

The fundamental premise of the new procedures is that it is better to
explicitly reserve capacity in the program for popup flights, in the
form of designated popup slots, and to assign those slots to popup
flights as they enter the system. The goal is the equitable distribution
of delay while minimizing airborne holding and maintaining a stable and
predictable program. An auxiliary goal is to encourage NAS users to make
their intent known early, to improve situational awareness and
predictability.

There are four principal components to the revised procedures. They are:

1.  Reserving arrival slots in the program for future popup flights.

2.  Determining the number of popup slots to allocate.

3.  Inserting popup flights into slots.

4.  Compressing slots before they may be lost.

The proposed approach to each of these functions is laid out in the
following sections.

# Reserving arrival slots in the program 

Under current procedures, when a GDP is run for an airport, a number of
arrival slots are created in each 15 minute period to match the Airport
Arrival Rate (AAR) for that period, and all of these slots are assigned
to flights already present in the ADL. In the revised procedures, a
designated number of slots in each hour are not assigned to existing
flights but are instead marked as reserved for popups.

Up to two types of popup slots will be defined, for two user types.
These user types have tentatively been set as CDM participants and CDM
non-participants, but this distinction will be reviewed before final
implementation.

The number of each type of slot to reserve in each hour will be set by
the specialist running the program, through the FSM Ground Delay Tools
interface. The slots for each type will be distributed throughout each
hour as smoothly as feasible.

These slots reserved for each user type will appear in the FSM timeline
with a special symbol, and will be included in the FSM bar chart under a
distinguishable category.

# Determining the number of popup slots to allocate 

The number of slots of each user type to reserve in each hour will
typically be based on historical popup activity at the airport. The
specialist running the program will be presented with information about
the frequency of popups historically observed over a designated time
period.

The number of historical popups presented to the operator will be based
on the arrival airport, the day of the week, the hours of the program,
and the time at which the program is being run. The default values for
the number of popup slots to create in each hour will be based on these
historical numbers.

The operator will have the capability to override the default values for
any or all hours, subject to a check on reasonability. This will
accommodate special events or holidays that may not be properly
reflected in the historical averages.

The number of slots reserved for popups will affect the distribution of
delay between scheduled flights and popups, the stability of the control
times in the program, and the incentive for early filing, so the popup
slot rate to use as the default will be a matter of policy. Additional
pre-deployment analysis and testing will be conducted to help set that
policy, and the policy will probably be adjusted after deployment.

# Inserting popup flights into slots

When a new flight enters the demand list, either through the filing of a
flight plan or through another mechanism, ETMS will try to assign the
popup flight to an existing unclaimed popup slot.

ETMS will compute the FA delay for the flight in the same manner as it
does now -- the average ATC delay for the flights in the 15-minute block
containing the requested arrival time for the flight.

This delay will be added to the requested arrival time to yield a target
CTA (TCTA). ETMS will try to place the flight at or near the TCTA using
an unclaimed popup slot. In all cases only popup slots of the same type
as the popup flight will be considered. For example, a popup slot
reserved for CDM participants could only be used by a popup flight
belonging to a CDM participant.

ETMS will first look in a small window around the TCTA, perhaps 5
minutes on either side. If any popup slot is available within the window
that slot will be assigned to the popup flight.

If no slot is available within the window, the system will look to
earlier times for any available popup slots. If such a slot exists, the
system will attempt to move the slot back to within the window around
the target CTA, using SCS-based bridging with other flights. If such a
slot is located and the bridging is successful then that popup slot will
be assigned to the popup flight.

If both of the operations above fail, then the system will next look
later in time for any available popup slots. The system will look for
such slots no later than a certain time, the maximum CTA (MCTA) for the
flight. If any available slots are found after the TCTA and before the
MCTA, then the earliest such slot will be assigned to the popup flight.

If each of these three attempts at finding slots fails then the flight
will handled in much the same way as popup flights are now. It will be
given an EDCT at the MCTA but no arrival slot.

The final formula for setting the MCTA has not been set. The current
position of the GDPE working group is that it should be set to the TCTA
as computed above plus either the average ATC delay for all flights in
the program or 30 minutes, whichever is greater.

When a popup slot is assigned to a flight, the CTA for the flight is set
to the slot time and the CTD is set to the CTA less the en route time.
The slot is marked as no longer available.

If a popup flight is canceled, the slot owned by that flight is marked
as available again.

When existing flights are moved forward to bridge a popup slot back,
flights for which the bridging has been turned off will not be affected.

Whether popup flights departing from exempt airports will be exempt from
ATC delay is an open question at this point. The current leaning of the
GDPE working group is that such flights will not be exempt.

# Compressing slots before they may be lost

If fewer popup flights appear than the number of slots allocated, then
there is the danger of an unclaimed slot going unused. To prevent this,
ETMS will monitor the ADL for slots that may be in danger of becoming
unusable. In the initial implementation, such slots will be any with
slot times within a designated time, say two hours, of the present. In
later implementations a more sophisticated testing criterion may be
used.

If a slot is identified as in danger of becoming unusable it will be
moved to a time later in the program. It may be moved back a certain
distance, say one hour, or to the end of the program, effectively
removing the slot from the program. This will be a policy decision to be
made later based on further analysis and testing.

The slot will be moved back using a series of SCS-based bridges using
other flights.

# Other considerations

When a program is compressed, unclaimed popup slots will be ignored.

When a program is revised, all unclaimed popup slots within the revision
hours will be removed from the demand list and new popup allocations
will be made.

When a program ends or is cancelled, all popup slots will be removed
from the demand list.

As with former popup flights today, popup flights cannot be substituted
to later times.