Concept of Operations for Meteorological Information for
Volcanic Clouds in Support of International Air Navigation
Document information
Edition
<tbd>
00.00.01
Concept of Operations for Meteorological Information for Volcanic Clouds
in Support of International Air NavigationEdition: 00.00.01
Document History
Edition
Date
Description
Justification
00.00.1
00.00.2
15 April 2011
06 May 2011
Internal draft
Initial draft
00.00.3
13 July 2011
Initial draft
00.00.4
08 February
2012
Revised draft
00.00.4.1
10 February
2012
Minor revision
New Document
Presented to IAVW
coordination group of
IVATF
Presented to IVATF/2
(Working Paper 04)
Complete rewrite based on
comments received on
initial draft.
Minor edits.
Presented to IAVW
coordination group at
IVATF/3
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Table of Contents
EXECUTIVE SUMMARY .................................................................................................................................... 4
1
INTRODUCTION.......................................................................................................................................... 5
1.1
1.2
2
BACKGROUND ........................................................................................................................................... 7
2.1
3
OPERATIONAL NEED FOR VOLCANIC CLOUD INFORMATION.................................................................. 7
CURRENT VOLCANIC CLOUD INFORMATION SERVICE ................................................................ 8
3.1
3.2
3.3
3.4
4
PURPOSE AND SCOPE OF THE DOCUMENT ............................................................................................. 5
ACRONYMS AND TERMINOLOGY ............................................................................................................. 5
MONITORING THE THREAT OF AN ERUPTION ......................................................................................... 8
VOLCANIC ASH CLOUD DETECTION ....................................................................................................... 8
VOLCANIC ASH CLOUD FORECASTS ...................................................................................................... 8
COMMUNICATE VOLCANIC ASH CLOUD INFORMATION TO USERS ........................................................ 9
FUTURE REQUIRED SERVICES ........................................................................................................... 12
4.1
NEAR-TERM CHANGES ......................................................................................................................... 12
4.1.1
Collaborative Decisions and Information Sharing ................................................................. 12
4.1.2
SIGMET Changes ...................................................................................................................... 13
4.1.3
Transition to all Digital Format for all Volcanic Ash Information .......................................... 13
4.2
FAR-TERM CHANGES ............................................................................................................................ 13
4.2.1
New Volcanic Cloud Forecasts ................................................................................................ 13
4.2.2
Integration of Volcanic Ash Cloud Forecasts into Decision Support Systems for
Performance-based Navigation ............................................................................................................... 14
4.2.3
Airspace Capacity ...................................................................................................................... 14
4.2.4
Development of Index Levels for Ash Tolerances................................................................. 15
5
FUTURE OPERATIONAL SCENARIO .................................................................................................. 16
5.1
AVOIDANCE OR FLIGHT INTO THE VOLCANIC ASH CLOUD ................................................................... 16
5.1.1
Nowcasts ..................................................................................................................................... 16
5.1.2
Forecasts ..................................................................................................................................... 16
5.1.3
The CDM Process ...................................................................................................................... 16
APPENDIX A
- SERVICE FUNCTION ..................................................................................................... 17
APPENDIX B
- FUNCTIONAL REQUIREMENTS FOR VOLCANIC CLOUD INFORMATION ..... 20
APPENDIX C
- PERFORMANCE REQUIREMENTS FOR VOLCANIC CLOUD OBSERVATIONS
AND FORECASTS ............................................................................................................................................ 22
C.1
C.2
C.3
C.4
- PERIMETER OF ASH CLOUD, NEAR-TERM ......................................................................................... 22
- PERIMETER OF ASH CLOUD, FAR-TERM ............................................................................................ 23
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List of tables
No table of figures entries found.
List of figures
Figure 3.3-1 Areas of responsibility for the nine VAACs ......................................................................... 9
Figure 3.3-1 High level information flow diagram representing present services and providers .......... 11
Figure 4.2-1 High level outline of the provision of future volcanic cloud information per airspace
capacity ................................................................................................................................................. 15
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Executive Summary
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1 Introduction
1.1 Purpose and scope of the document
The first edition of this Concept of Operations for Meteorological Information for Volcanic Clouds in
Support of International Air Navigation provides a description of the meteorological information related
to volcanic eruptions and clouds used by the aviation community for international air navigation. The
main focus is on volcanic ash. Appended to the Concept of Operations (ConOps) are functional and
performance requirements for the new meteorological information on volcanic clouds.
The matrix tables for the performance requirements have not been completed. It is expected that
these will be formulated and validated through the work of the International Civil Aviation
Organization’s (ICAO) International Airways Volcano Watch Operations Group (IAVWOPSG) and
published in subsequent editions of this ConOps.
This ConOps is intended to complement the ICAO ATM Volcanic Ash Contingency Plan1 and ICAO
Doc 9974 Flight Safety and Volcanic Ash.
1.2 Acronyms and Terminology
Term and Phrase
Definition
Acceptable ash
concentration levels
An ash concentration level that is acceptable to the operator and original
equipment manufacturer (OEM) or type certificate holder (TCH).
AIREP
Air-report. A report from an aircraft in flight prepared in conformity with
requirements for position, and operational and/or meteorological reporting.
AIREPs meeting specified criteria are classified as a “Special AIREP”
ASHTAM
A special series NOTAM notifying by means of a specific format change in
activity of a volcano, a volcanic eruption and/or volcanic ash cloud that is of
significance to aircraft operations.
AOC
Airline Operations Center
ANSP
Air Navigation Service Provider
ATC
Air Traffic Control
ATFM
Air Traffic Flow Management
ATM
Air Traffic Management
CDM
Collaborative Decision Making
ConOps
Concept of Operations
ESP
Eruption Source Parameters
FIR
Flight Information Region
IAVWOPSG
International Airways Volcano Watch Operations Group
ICAO
International Civil Aviation Organization
1
The ATM Volcanic Ash Contingency Plan, drafted by the International Volcanic Ash Task Force, will
be published in late 2012.
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Term and Phrase
Definition
MET
Meteorological Information
MWO
Meteorological Watch Office
NOTAM
A notice distributed by means of telecommunication containing information
concerning the establishment, condition or change in any aeronautical facility,
service, procedure or hazard, the timely knowledge of which is essential to
personnel concerned with flight operations.
Nowcast (volcanic
cloud)
The three-dimensional representation of the current or near-current volcanic
cloud, including depiction of the perimeter of the lowest acceptable level of
ash, in a common exchange format that provides integration into decision
making tools as well as offers a graphical depiction of the information.
OEM
Original Equipment Manufacturer
PBN
Performance-based Navigation
SIGMET Advisory
Proposed new product derived from Volcanic Ash Advisory
SIGMET Information
Information issued by a meteorological watch office (MWO) concerning the
occurrence or expected occurrence of specified en-route weather phenomena
which may affect the safety of aircraft operations.
The term “SIGMET Information” is often shortened to SIGMET in most
publications
SMS
Safety Management System
SRA
Safety Risk Assessment
Visible Ash
“Visible ash” is defined qualitatively as ash seen by eye or discernible from
satellite data. At present, there is no single quantitative threshold value for
visible ash that is common across different conditions and technologies. 2
VAA
Volcanic Ash Advisory
VAAC
Volcanic Ash Advisory Center
VAG
The graphical version of a Volcanic Ash Advisory
VONA
Volcano Observatory Notice for Aviation
Volcanic Cloud
When used in this ConOps refers to both volcanic particles (e.g., ash) and
gases (e.g., SO2).
IVATF TASK TF-SCI03 Progress Report (Part 1) – Understanding “Visible Ash”, IVATF Science
Sub-Group and WMO-IUGG Volcanic Ash Scientific Advisory Group. Working Paper 08, International
Volcanic Ash Task Force – Second Meeting
2
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2 Background
2.1 Operational Need for Volcanic Cloud Information
The Eyjafjallajökull volcanic event in April 2010 identified gaps in the services and the science of
volcanic ash cloud observations and forecasts. The Eyjafjallajökull volcanic event brought direct
attention to the need for a better understanding of volcanic ash information and the use of that
information in Air Traffic Management (ATM) and flight operations. In addition it was recognized that
there were no measureable certificated tolerances for volcanic ash for safe and permissible aircraft
operations.
The attention for a need to improve volcanic cloud information services was largely due to the location
of Eyjafjallajökull’s ash cloud. The synoptic pattern caused the ash cloud to persist over Western
Europe and the North Atlantic for days into weeks. The event affected the busy and often congested
air routes of many Flight Information Regions (FIRs), served by many Air Navigation Service
Providers (ANSP) and Meteorological Watch Offices (MWO). At one time during the event, over 40
SIGMETs were in effect for the ash cloud. Had the synoptic pattern been different, or if the event had
occurred in another part of the world, not affected highly congested airspace and traffic routes, and
not governed by scores of ANSPs, perhaps the concern for improving services would not be viewed
as urgent or critical.
In simplest terms, aviation users need to know the location and size of the ash cloud, and where it will
be in the future. In a perfect world, we would know the precise location and be able to predict the
future locations with great accuracy, and for time scales ranging from minutes out to days. But,
today’s level of the science of observing and forecasting volcanic ash clouds can not provide that
precision or accuracy. Therefore, some measure of uncertainty in the observation and forecast will
need to be considered order to improve ATM and flight operations during volcanic ash cloud events.
The way forward is described in the remainder of this ConOps.
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3 Current Volcanic Cloud Information Service
Services in support of the provision of meteorological information for volcanic ash cloud can be
categorized in four areas: (1) monitoring the threat of an eruption, (2) detecting the volcanic ash
cloud, (3) forecasting the volcanic ash cloud, and (4) communicating the information to the users.
3.1 Monitoring the Threat of an Eruption
The geophysical monitoring of volcanoes for the threat of an eruption is primarily provided by volcano
observatories and research institutes located around the high threat areas of the world. Pre-eruptive
activity may be come from several sources, including but not necessarily limited to these: seismic
monitors, physical observations of deformation, hydrologic activity, gaseous activity or debris flow.
Though the types of observations used vary, volcano observatories may issue “color codes” to
indicate the volcano’s eruption state. The system uses four color codes. The color codes are
defined to state of the volcano (i.e pre-eruptive vs. eruptive stage) and not to the volcanic cloud. The
color Green denotes a non-eruptive state; Yellow denotes a state of elevated unrest; Orange denotes
a state of heightened unrest with the likelihood of eruption, or eruption underway; and Red denotes
that an eruption is forecast to be imminent with significant emission of ash into the atmosphere likely,
or the eruption is underway with ash-plume height provided if possible. It should be noted that not all
observatories provide information in the color code format.
In 2008, the IAVWOPSG agreed to implement a message to assist volcanologist in providing
information on the state of a volcano to Air Traffic Services in support of the issuance of VA NOTAM.
The message referred to as Volcano Observatory Notice for Aviation (VONA) was introduced into
IAVW Handbook on the International Airways Volcano Watch, Doc 9766. The VONA can be issued
by an observatory when the aviation color code at a volcano is changed (up or down) or within a
color-code level when an ash-producing event or other significant change in volcanic behavior
occurs.
3.2 Volcanic Ash Cloud Detection
Depending on many variables, an ash cloud can be detected from the ground, air, or from space. A
large number of different ground-based instruments are available to monitor volcanic ash clouds, such
as lidar, ceilometers, sun photometers, radar, imaging cameras and aerosol sondes, but many of
these work in the research mode, and are not yet operational. Satellite-based sensors are used to
discern the perimeter of ash clouds. Ash clouds can be “seen” on visible satellite imagery, but only in
day time, and dependent on existing cloud cover and other features. Single and multi-band infrared
imagery and applied techniques can be used day and night and can provide means of estimating the
top of the ash cloud. Both visible and infrared imagery have limitations when meteorological clouds
(e.g., cirrus, etc.) are present, and depending on the thickness and height of the meteorological cloud
cover, may prohibit the volcanic cloud from being observed. Infrared measurements can only detect
volcanic ash if volcanic ash is the highest cloud layer, regardless of concentration.
What is “seen” or detected by satellite is often expressed as “visible ash cloud”. “Visible ash” also
refers to ash clouds seen by pilots in the air, and human observers on the ground. For this ConOps,
“visible ash” is defined qualitatively as ash seen by eye or discernible from satellite data. At present,
there is no single quantitative threshold value for visible ash that is common across different
conditions and technologies.
3.3 Volcanic Ash Cloud Forecasts
Today’s volcanic ash forecasts are simple textual and graphical products derived and produced using
the output from ash cloud models (numerical predication and atmospheric transport and dispersion
models) and the volcanic ash cloud detection methods described above. The accuracy of ash cloud
models is limited by the accuracy of the volcano’s Eruption Source Parameters (ESP), such as plume
height, mass eruption rate, eruption start/stop time, and the fraction of fine ash in the erupted mass.
The ash cloud models utilized by Volcanic Ash Advisory Centers (VAAC) as part of their volcanic ash
cloud forecasts are initialized by ESP. The movement, spread and dispersion of volcanic ash clouds
depend on a number of parameters, including the strength of the eruption and the altitude reached by
the ash particles, particle concentration and size distribution, wind shear and stability of the
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atmosphere, and the scavenging of ash particles by precipitation, as well as the underlying wind field
which is normally provided by numerical weather predication models. Value is added to the raw
model output through forecaster intervention. Such intervention is dependent on real time verification
of the ash cloud model output against a range of observational resources.
Today’s two primary volcanic cloud forecasts are the Volcanic Ash Advisory (VAA) and the SIGMET
information. Both of these forecasts are currently limited to ash clouds, and not gaseous (e.g., SO2,
O3, CO) clouds. The VAA is produced and issued by the VAAC and the SIGMET information is
issued by the MWO. The VAAC provides the VAA a text and/or graphic-based format (note, the
graphic version of the VAA is often referred to as a VAG) which provides a forecast on the trajectory
of the ash cloud and the associated flight levels which may be affected by the ash cloud. The VAAs
are produced and issued by the nine VAACs across the world, each with a defined geographical area
of responsibility, which are depicted in Figure 3.3-1. The VAAs are 18-hour forecasts and are issued
every 6-hours.
MWO issue Volcanic ash cloud SIGMETs based on the guidance provided by the VAAC. These
SIGMETs are valid for up to 6 hours and describe the location of the ash cloud within the FIR or area
of responsibility of the MWO.
Some VAACs issue Ash Concentration forecasts for their area of responsibility. These forecasts are
derived from ash cloud models and were developed in response to the Eyjafjallajökull volcanic event
of April 2010.
Figure 3.3-1 Areas of responsibility for the nine VAACs
3.4 Communicate Volcanic Ash Cloud Information to Users
In the simplest terms, the MET service provider gives volcanic cloud information to the ANSP who
then gives the information to the pilot. In reality, the process is much more complex as the provider’s
components become users and users become providers. Thus, just about every service provider is
also a user of volcanic cloud information. Appendix A is a matrix table of service providers.
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Figure 3.4-1 depicts an example of information flow following a volcanic eruption. The diagram
identifies participants in the provision of information for today’s services. The lines between the
providers in the diagram does not imply one-way communications or communication relationships,
rather they represent a general flow of volcanic ash information for a volcanic event. The box’s colors
do not represent significance, rather the help distinguish the information products (e.g., observations
and forecasts) (red) from the providers/users (shades of blue).
Note that an initial report of an ash cloud can result in many products delivered to the end user, in this
case the pilot. In just about all cases, information about a volcanic ash cloud will be provided to the
pilot, either in-flight or during pre-flight preparation, in the form of a SIGMET, NOTAM or ASHTAM,
Special AIREP, and VAA. Each of the aforementioned products are unique in format and content, but
basically provide information regarding the location of the volcanic ash cloud. It should be evident
that when one uses all of these products, it is critical that these products be consistent with their
message.
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Figure 3.4-1 High level information flow diagram representing present services and providers
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4 Future Required Services
Future services center on the following near-term and far-term changes. The time frames of near and
far are not defined in this ConOps, but instead serve as a reference as to what can be accomplished
perhaps in the upcoming 5 years, compared to what is possible 5 to 10 years in the future. These
changes do not directly address proposals for advancements in volcanic science and volcano
monitoring technology. Rather these changes will incorporate and utilize those advancements as
they become available.
 Near-term:
o Incorporation of CDM practices and information sharing into volcanic cloud forecasts
o Changes to SIGMETs for Volcanic Ash
o Transition to all digital format for all volcanic ash information

Far-term:
o New volcanic cloud forecasts, including the use of probability
o Integration of volcanic ash cloud forecasts into decision support systems for PBN
o Development of index levels for ash tolerances for the various types of engine/aircraft
combinations.
4.1 Near-term Changes
4.1.1 Collaborative Decisions and Information Sharing
The term Collaborative Decision Making (CDM) is a process used in ATM that allows all members of
the ATM community, especially airspace users, to participate in the ATM decisions that affects all
members. CDM means achieving an acceptable solution that takes into account the needs of those
involved. CDM for ATM is described in ICAO Document 9854 -Global Air Traffic Management
Operational Concept, and Document 9982 – Manual on Air Traffic Management System
Requirements.
From a high level perspective and for an example, collaboration on the perimeter of the volcanic cloud
can be done, at a minimum, for events that affect high density traffic areas, or several FIRs and
extend beyond the area of responsibility of one or more VAACs. This collaboration would be done
between predetermined partners, based on the event and extent. Table 4.1-2 lists some of the
volcanic cloud information needed by airspace users. As part of this process, information sharing
between the partners is essential so that all possible outcomes can be considered. Table 4.1-2 lists
the partners for the collaboration and information sharing as well as the expected role of the partners.
The final decision will depend on agreed upon guidelines that may vary depending on the size and
scope of the volcanic event, but the authority for the final decision must reside with one decision
maker (in this case, the Lead VAAC), otherwise the final output (e.g., forecast) would not serve other
decision makers (e.g., ATM) in an expected manor. Once the decision (e.g., outline of the volcanic
ash boudary) is finalized, is can be integrated into ATM decision tools for a CDM process by ATM
decision makers and airspace users.
Need to know
Location of the volcanic
ash cloud.
Information Sharing
Share data from ground,
air, and space observing
platforms
Output from a Collaborative Decision
Current horizontal and vertical extent (perimeter) of
the volcanic ash cloud, including the lowest
acceptable level of ash concentration, to be used in
decision support systems and forecast products.
How the cloud is
changing and where will
it be in the future.
Current and forecast ash
concentrations within
volcanic cloud
Share various outputs of
dispersion models
Forecast horizontal and vertical extent of the
volcanic ash cloud and produce seamless products
Share various outputs of
dispersion models
Forecast horizontal and vertical extent of the lowest
acceptable level of ash concentration, as well as
other levels, and produce seamless products
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Table 4.1-1 Collaborative decisions for volcanic ash cloud information
Partners
Lead VAAC
Other VAAC(s)
VO
MWO(s)
State’s NMHS
Role
Produces preliminary forecast and shares it with rest
of partners. Considers input and suggested changes
from participating partners. Has the final decision on
the forecast after considering information and input
from partners.
Shares new information with participating partners.
Reviews preliminary forecast and provides suggested
changes.
Table 4.1-2 Partners for the collaboration and information sharing and expected roles
4.1.2 SIGMET Changes
A large volcanic ash cloud over Europe could result in over 40 SIGMET information messages in
effect at the same time. Each of these SIGMETs becomes a puzzle piece for the user to put together
to obtain the entire area of the volcanic cloud. Since the SIGMETs are based on the first portion of
the VAA, that portion of the VAA/VAG could be elevated in status to serve as the SIGMET. Making
the VAA/VAG’s first 6 hour portion equivalent to the SIGMET would reduce the information overload
experienced by users (pilots, operators, etc) who must now track dozens of SIGMETs for their flight.




The first 6-hour portion of the VAA is elevated in status to a Volcanic Ash SIGMET Advisory3.
The first 6-hour portion of the VAA will be labeled as SIGMET Advisory.
The SIGMET Advisory will not be restricted to one FIRs, i.e., one SIGMET Advisory can be
valid for multiple FIRs
Traditional SIGMET Information messages (i.e., today’s SIGMETs) will not duplicate the
information in the SIGMET Advisory; rather it will refer the user to the SIGMET Advisory.
4.1.3 Transition to all Digital Format for all Volcanic Ash
Information
Today’s volcanic ash products are primarily text-based (e.g., SIGMET), with some supplementation of
graphic-based products (e.g., the VAA and its graphical version known as the VAG). Future volcanic
ash information must be provided in a digital format in order serve aviation users and decision
makers. The visualization of volcanic information must be capable of display on moving maps,
cockpit displays, radar screens, etc.
The transition from text and graphic-based products to all digital formats will take time as there will
continue to be a need for legacy text-based products for several years, especially in certain regions of
the world.
4.2 Far-term Changes
4.2.1 New Volcanic Cloud Forecasts
Appendix B and C contain the functional requirements and associated performance requirements for
new volcanic cloud forecasts. The performance requirements are left open with this version of the
ConOps, pending further assessments.
3
SIGMET Advisory is a SIGMET valid for one or multiple FIRs and is issued by a regional center,
such as a VAAC.
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4.2.1.1 Probabilistic and Deterministic Volcanic Cloud Forecasts
Current volcanic ash forecasts, such as the VAA/VAG, are deterministic forecasts. They are a yes/no
forecast with respect to the depiction of the ash cloud. Often, deterministic forecasts include a buffer
zone that is added by the forecaster. This buffer zone is included to either smooth the forecast area,
or to ensure the cloud fits into the simple sided polygon that describes the perimeter of the volcanic
cloud. Unfortunately these buffer zones are not depicted as a buffer, nor are they known to anyone
other than the producer (e.g., forecaster). The effect of the buffer zone is a larger area in the
deterministic forecast.
Volcanic ash transport and dispersion models can produce an array of solutions (e.g., forecasts) by
varying the input into the models. Changes in meteorological parameters and ESP will result in
different forecast outputs. The purpose of a probabilistic forecast is to provide decision makers with
assessments of all the likelihoods of a weather parameter’s risk of occurrence and magnitude.
Probabilistic forecasts help multiple decision makers use the same weather information, applying their
own operation constraints to determine risk to their operation. Appendix B identifies those functions
that should be provided in deterministic and probabilistic terms.
From a high level perspective, probability forecasts are like an ensemble approach. An ensemble
approach is one way to account for some of the uncertainty. For instance, the model can be run
many times, each time with a realistic variant of one of the uncertain parameters (e.g. ash amount,
ash column height, eruption start time and duration, input meteorology dataset, with and without wet
deposition, etc.).
Taken as a whole, the variability of the ensemble members’ output gives an
indication of the uncertainty associated with that particular ash forecast.
The application of probabilistic forecasts will best benefit high density (congested) traffic areas, where
decision makers can benefit from more than just a deterministic forecast. Also, decision support
systems can use the probabilistic information to provide route and altitude selections based on user’s
acceptance thresholds. For example, an airline may plan a route that has a 30 percent probability of
ash, while not accepting that same route with a 60 percent probability of ash.
4.2.2 Integration of Volcanic Ash Cloud Forecasts into Decision
Support Systems for Performance-based Navigation
Future ATM decision support systems need to directly incorporate volcanic cloud forecasts and
bypass the need for human interpretation, allowing decision makers to determine the best response to
the potential operational effects and minimizing the level of traffic restrictions. This integration of
volcanic cloud forecasts, combined with the use of probabilistic forecasts to address uncertainty,
reduces the effects of volcanic clouds on air traffic operations.
4.2.3 Airspace Capacity
The provision and use of deterministic and probabilistic forecasts of the volcanic cloud and their
integration into decision support systems, may depend on the needs of the ANSP. Deterministic
forecasts may adequately serve the users of airspace that is not congested, and offers amble options
for ash cloud avoidance without great fuel penalties for the operator. But for congested airspace, the
provision and use of probabilistic forecasts of the volcanic cloud will be essential in order to achieve
maximum efficiency of the air traffic system. Figure 4.2-1 provides a high level schematic of
meteorological service per airspace capacity.
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Figure 4.2-1 High level outline of the provision of future volcanic cloud information per
airspace capacity
4.2.4 Development of Index Levels for Ash Tolerances
The latest generation of jet engines are much different from older generation engines, and ash can
have greater effects on these newer engines. The development of a volcanic ash index for ash
tolerances for various types of engine/aircraft combinations would allow operators and ATM to take
maximum advantage of volcanic ash concentration forecasts.
It is foreseen that the development of index levels is a long term goal of the industry, as it would
involve considerable testing and evaluation.
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5 Future Operational Scenario
5.1 Avoidance or Flight into the Volcanic Ash Cloud
There are two kinds of operational scenarios, avoidance of the volcanic cloud, and planned flight into
a cloud. The meteorological information for both scenarios would in the form of the following:
5.1.1 Nowcasts
The three-dimensional representation of the current or near-current volcanic cloud, including depiction
of the perimeter of the lowest acceptable level of ash, in a common exchange format that provides
integration into decision making tools as well as offers a graphical depiction of the information. In the
avoidance scenario, the nowcast provides users with the location of the ash cloud. As the ash cloud
moves or changes, the nowcast is updated at a temporal frequency that meets user needs and
service provider capabilities. For flight into acceptable levels of ash, volcano ESP, in situ
measurements of the airborne volcanic cloud (from ground-based, space-based, or airborne-based
observing platforms) are required to provide a nowcast that has a high level of confidence of the ash
concentration levels inside the cloud.
5.1.2 Forecasts
The four-dimensional representation of the volcanic cloud, including depiction of the perimeter of the
lowest acceptable level of ash, ash concentration levels and indices, in both deterministic and
probabilistic terms, in a common exchange format that provides integration into decision making tools
as well as offers a graphical depiction of the information. For both scenarios, the forecasts would be
valid “X” hours and up to “Y” days, but would contain finer temporal resolution in the near time frame.
Forecasts would also be provided in terms of uncertainty (use of probability). For flight into
acceptable levels of ash, volcano ESP, in situ measurements of the airborne volcanic cloud (from
ground-based, space-based, or airborne-based observing platforms), would be needed to provide a
forecast of the ash concentration levels to support airline decision making. The provider of the
forecasts would be the VAACs, and these forecasts would be considered a next-generation VAA.
5.1.3 The CDM Process
Aligned with the above forecast process is the collaborative decision and information sharing process.
In this scenario, CDM will occur on a regular basis such that all users are afforded the opportunity to
contribute information. Information will be shared and could be made available on an information
database or web portal that is jointly run by the VAACs.
Civil aviation operators will then apply these new nowcasts and forecasts to their operations
specifications per their Safety Management System (SMS) and any specific Safety Risk Assessments
(SRA) for any operations other in areas of a volcanic ash cloud.
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Appendix A - Service Function
The matrix table below outlines service providers and their functions with respect to volcanic cloud
information. The exact role of each of the provider depends on various circumstances that are not
exhaustively described in the table.
Current Services and
Providers
Service Provider
Volcano
Observatory
(VO)
Functions for:
PreEruption
Monitor
volcano,
report
changes
in status.
MET Service Provider
Met Watch
Office (MWO)
Aerodrome Met
Office and
Stations
Air Traffic
Control Units
(Area,
Approach,
Aerodrome)
Air Traffic
Management
(ATM)
Volcanic
Cloud
Report
Report
Provide initial
warning
Provide
warning
Report
Report
Determine
initial forecast
Determine
and predict
location and
dimensions of
volcanic cloud
Produce
model derived
predictions of
volcanic cloud
Produce
model derived
predictions of
volcanic cloud
Establish
appropriate
areas within
airspace to
outline hazard
Establish
appropriate
areas within
airspace to
outline
hazard.
Reroute traffic
as necessary
Implement
contingency
plans
Lead CDM
process for
adjusting
traffic
capacity and
routes
Volcanic Ash
Advisory Center
(VAAC)
Dispersion
Modeling
Center (if
different from
the VAAC)
Air Navigation Service Provider (ANSP)
Report
preeruption
activity
Eruption
Information
Information
Received and
Used
Data from
ground-based
observing
networks
Information
Provided
(shared)
Report. Issue
VONA and Color
Codes. ESP if
able.
AIREP, report
from VO, VAA.,
METAR/SPECI,
NOTAM
Issue SIGMET
(Column is
intentionally left
blank)
METAR/SPECI,
VAR
Report from VO.
Data from
ground-based,
air-based,
satellite-based
observing
networks. Input
from other VAACs
and Dispersion
Modeling
Centers.
Data from
ground-based,
air-based,
satellite-based
observing
networks.
ESP.
SIGMET,
NOTAM/ASHTAM,
VAA/VAG, VONA
or report from
VO, Special AIREP
Issues VAA and
VAG. If able,
issue ash
concentration
forecasts
SIGMET,
NOTAM/ASHTAM,
VAA/VAG, VONA
or report from
VO, Special AIREP,
Ash concentration
forecast (if
provided)
FIR traffic
capacity
Deliver model
derived
predictions
(including ash
concentration if
able).
IFR clearances.
FIR’s sector
capacity.
Affected
aerodrome
arrival and
departure
acceptance rate
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Current Services and
Providers
Service Provider
Flight
Information
Center (FIC)
International
NOTAM Office
(NOF)
Aerodrome Operations
Functions for:
PreEruption
Information
Eruption
Volcanic
Cloud
Provide
preflight and
in-flight
information
about
eruption
Provide notice
of hazard
Provide
preflight and
in-flight
information
about volcanic
cloud
Provide notice
of hazard
Address ash
contamination
on runways,
taxiways,
ground
equipment,
planes
Reroute
planes from
eruption
Address ash
contamination
on runways,
taxiways,
ground
equipment,
planes
Apply SMS to
adjust routes.
Provide
information to
flight crew.
Plan for
reroute
Provide
information to
flight crew.
Plan for
reroute
Avoid.
Avoid.
Appropriate
decisions per
SMS for
operators of
Large and
Turbojet
Aeroplanes.
Report
volcanic
cloud, ash,
sulphur
Operator
Airline
Operations
Center (AOC)
Airline
Dispatchers
General
Aviation
Operators
Pilot / Flight
crew
(Commercial
and General
Aviation)
Report
eruption
Information
Received and
Used
SIGMET,
NOTAM/ASHTAM,
VAA/VAG, VONA
or report from
VO, Special AIREP
Information
Provided
(shared)
VOLMET, ATIS, DATIS
SIGMET, VONA or
report from VO,
Special AIREP
SIGMET,
NOTAM/ASHTAM,
VAA/VAG, VONA
or report from
VO, Special AIREP
Issues
NOTAM/ASHTAM
SIGMET,
NOTAM/ASHTAM,
VAA/VAG, VONA
or report from
VO, ash
concentration
forecast (if
provided), ash or
SO2 report from
flight crew, or
ANSP (ATS, FIS,
AIS).
SIGMET,
NOTAM/ASHTAM,
VAA/VAG, VONA
or report from
VO, ash
concentration
forecast (if
provided), ash or
SO2 report from
flight crew, or
ANSP (ATS, FIS,
AIS).
SIGMET,
NOTAM/ASHTAM,
Special AIREP, ash
or SO2 report
from ANSP (ATS,
FIS, AIS)
(Need input for
this cell)
SIGMET,
NOTAM/ASHTAM,
Special AIREP, ash
or SO2 report
from AOC or
ANSP (ATS, FIS,
AIS)
Special AIREP,
VAR
(Column is
intentionally left
blank)
(Need input for
this cell)
Route/altitude
selection, fuel,
go/no-go
decision, in-flight
route/destination
change.
Special AIREP,
VAR
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Current Services and
Providers
Service Provider
Functions for:
PreEruption
Eruption
Information
Volcanic
Cloud
Advice and
information to
operators
Original Equipment
Manufacturers (OEM) or
Type Certificate Holder
(TCH)
Other State, Research,
Commercial Services
Operate
aircraft for
airborne
sampling of
cloud
Information
Received and
Used
Reports from
operator.
Information
Provided
(shared)
Technical
information
about aircraft
operation in
volcanic ash,
future/ongoing
maintenance
information
requirements,
details of
inspection
requirements
Cloud ESP
particle/gas
concentrations
(Column is
intentionally left
blank)
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Concept of Operations for Meteorological Information for Volcanic Clouds
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Appendix B - Functional Requirements for Volcanic Cloud
Information
The matrix table below lists a set of functional requirements for volcanic cloud information based on
different types of airspace and aerodrome densities (i.e., capacity or congestion). An “X” in the table’s
cell indicates that this function is needed for this airspace and aerodrome. A “P” or “D” indicates
whether the forecast function is Probabilistic or Deterministic.
Functional Requirements for Volcanic Cloud
Route Operations
Terminal Control Area
(TMA) Operations
Aerodrome
Congested
(High
Density)
Noncongested
(Low
Density)
Congested
(High
Density)
Noncongested
(Low
Density)
Busy (High
Density)
Low Density
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
P
D
P
D
P
D
P
D
P
D
P
D
D
D
D
D
Volcano Eruption
Detect an Eruption in all
kinds of meteorological
and day/night conditions
(i.e., including tropical
regions where convective
activity is common)
Determine the Eruption
Source Parameters (ESP)
Determine the height of the
eruption plume
Determine the duration of
the eruption
Detect, determine and
report the heightened
volcanic activity (preeruption)
Volcanic Cloud
Determine the perimeter,
top and base of the
volcanic cloud in all kinds
of meteorological and
day/night conditions
Ash
SO2
Determine
when the
Electro“volcanic
magnetic
cloud” is a
risks to
hazard due
avionics
to:
Other
(TBD)
Determine the perimeter
of the lowest acceptable
ash concentration level
(ash cloud)
Determine the perimeter
of the gaseous cloud
Determine the eruption
source parameters
Forecast the perimeter of
the lowest acceptable ash
concentration level (ash
cloud)
Forecast the top and base
height of the lowest
acceptable ash
concentration level (ash
cloud)
Forecast the movement of
the lowest acceptable ash
concentration level
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Functional Requirements for Volcanic Cloud
Route Operations
Forecast the growth and
decay of the lowest
acceptable ash
concentration level (ash
cloud)
Forecast the location of the
gaseous cloud
Forecast the top and base
height of the gaseous
cloud
Forecast the movement of
the gaseous cloud
Forecast the growth and
decay of the gaseous
cloud
Determine when the
volcanic cloud is no longer
a hazard
Determine when the
volcanic cloud is hidden or
mixed with clouds,
especially cumulonimbus
clouds and cirrus clouds
Forecast when the
volcanic cloud is hidden or
mixed with meteorological
clouds
Terminal Control Area
(TMA) Operations
Congested
(High
Density)
Noncongested
(Low
Density)
Congested
(High
Density)
Noncongested
(Low
Density)
P
D
P
D
P
D
P
P
D
D
Aerodrome
Busy (High
Density)
Low Density
D
P
D
P
D
P
D
D
D
D
P
D
P
D
X
X
X
X
X
X
X
X
P
D
P
D
X
X
P
D
Volcanic Ash
Accumulation
Determine the ash
accumulation at the
aerodrome
Forecast the ash
accumulation at the
aerodrome
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Concept of Operations for Meteorological Information for Volcanic Clouds
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Appendix C - Performance Requirements for Volcanic
Cloud Observations and Forecasts
The tables in this appendix are sets of performance requirements for the functions listed in appendix
B. Each table addresses a volcanic cloud element, for example “determine and forecast the
perimeter of the lowest acceptable ash concentration level (ash cloud)”. Each table also represents
an operating capability, from near-term (e.g., next 1 to 5 years) next to far-term (e.g., 5-10 years).
The cells within this table are blank as these requirements are expected to be formalized through the
workings of ICAO’s International Airways Volcano Watch Operations Group (IAVWOPSG).
C.1 - Perimeter of Ash Cloud, Near-term
Performance Requirements
Volcanic Cloud Element = Perimeter of Ash Cloud (lowest acceptable level of ash)
Near-term Operating Capability (years 201x – 201x)
Route Operations
Congested
(High Density)
Uncongested
(Low
Density)
Terminal Control Area
(TMA) Operations
Congested
(High Density)
Uncongested
(Low
Density)
Aerodrome
Busy (High
Density)
Low Density
Observation
Vertical resolution
Horizontal resolution
Update frequency
Accuracy
Format
Nowcast: T1 to T2 (e.g.,
>0 to 2 hours)4
Vertical resolution
Horizontal resolution
Temporal resolution
Domain or range
Probabilistic range
Update frequency
Accuracy
Format
Forecast: T2 to T3 (e.g., 2
to 6 hours)
Vertical resolution
Horizontal resolution
Temporal resolution
Domain or range
Probabilistic range
Update frequency
Accuracy
Format
Forecast: Tn to Tn+1
Vertical resolution
Horizontal resolution
Temporal resolution
Domain or range
Probabilistic range
Update frequency
Accuracy
Format
4
All the temporal ranges for the nowcast and forecast are given in the table, e.g., 0 to 2 hours, 2 to 6
hours, etc., are just examples of possible ranges.
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C.2 - Perimeter of Ash Cloud, Far-term
Performance Requirements
Volcanic Cloud Element = Perimeter of Ash Cloud (lowest acceptable level of ash)
Near-term Operating Capability (years 201x – 201x)
Route Operations
Congested
(High Density)
Uncongested
(Low
Density)
Terminal Control Area
(TMA) Operations
Congested
(High Density)
Uncongested
(Low
Density)
Aerodrome
Busy (High
Density)
Low Density
Observation
Vertical resolution
Horizontal resolution
Update frequency
Accuracy
Format
Nowcast: T1 to T2 (e.g.,
>0 to 2 hours)5
Vertical resolution
Horizontal resolution
Temporal resolution
Domain or range
Probabilistic range
Update frequency
Accuracy
Format
Forecast: T2 to T3 (e.g.,2
to 6 hours)
Vertical resolution
Horizontal resolution
Temporal resolution
Domain or range
Probabilistic range
Update frequency
Accuracy
Format
Forecast: Tn to Tn+1
Vertical resolution
Horizontal resolution
Temporal resolution
Domain or range
Probabilistic range
Update frequency
Accuracy
Format
5
All the temporal ranges given in the table, e.g., 0 to 2 hours, 2 to 6 hours, etc., are just examples of
possible ranges.
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C.3 <tbd>
C.4 <tbd>
- END OF DOCUMENT -
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