Observations and forecasts for a location away from an aerdrome

[blchoy]

Ashwin of BoM has kindly provided a use case after the discussion on 2 Sep 2026 for providing AMFIS forecast for a location away from an aerodrome. The text was further supplemented by Tim on 23 Sep 2026:

"Hi BL Choy,

Thank you for organising the meeting. I would like to provide a practical Australian use case that highlights why it is important for the IWXXM schema to support locations that are operationally significant but are not traditional aerodromes. Our objective is to ensure the schema can accurately represent and exchange observation and forecast information for these locations, which play a critical role in aviation decision-making.

In Australia, we provide observations at some waypoints (known as critical locations) in addition to aerodromes such as YSWS, YSRI, and YSSY. As shown in the attached image, the red circles represent aerodromes, while the blue square represents a critical location.

These critical locations are used by pilots to make key operational decisions before continuing to one or more destination aerodromes, including YSWS, YSRI, and YSSY. Given the critical locations are not associated with a single aerodrome, it does make sense to only offer the data associated with this location itself.

The availability of meteorological observations and forecasts for these critical locations is essential to supporting safe and efficient flight operations across multiple aviation sectors. Currently pilots receive OPMET information for waypoints in TAC format, and IWXXM support for these waypoints is required.

A key challenge is that these critical locations are waypoints and are not an airport or Heliport as defined in AIXM, and therefore IWXXM schema needs to be modified to support their use (including three-letter code rather than an ICAO aerodrome code).

As discussed, and agreed during the MRAD meetings, the observation and forecast information service could instead be defined using the location’s coordinates (latitude and longitude) together with a reference name. Supporting this capability within IWXXM would enable the schema to accommodate operationally important non-aerodrome locations, provide greater flexibility in how meteorological services are represented, and ensure that critical weather information can be delivered effectively to all aviation users, including the General Aviation community. This would better meet Australian and other Asia Pacific operational requirements while remaining aligned with real-world aviation practices.

I am sure Canada and US has similar examples as well.

Kind regards,
Ashwin"

As a matter of fact, Tim raised the same wish in #1 back in 2023.

[blchoy]

Ashwin further supplement on 16 Sep 2026 with the following. More elaborations were provided by Tim on 23 Sep 2026 :

"Key points to clarify:

1. These critical locations are often used by GA operators and may not be associated with a major aerodrome. Operators are primarily interested in observations and forecasts for these locations to help determine whether they can safely transit through a mountain pass.
2. I realised that Mount Victoria (MVI) is also referred to as Mount Boyce (MTB) in the briefing services. It appears that observations for this location use MTB, while forecasts use MVI. I am not sure why this inconsistency exists; however, we will ensure it is resolved when we move to AMOIS and AMFIS.

I don’t have any flight path example, but I tried to log into Airservices briefing service to provide some examples.

Example1 - The below is an example when a pilot get a briefing for an area, in this case, I have selected Area 20 (see example below)

They will get observations and forecasts for a number of locations – as below

PREPARED FOR: BOMAVIATION
VALID FROM 1205 UTC SEP 16, 2026 TO 1805 UTC SEP 16, 2026

                               WEATHER INFORMATION
                               -------------------

AREA21 (21)
    AREA QNH 13/16
    AREA 21: 1030
    AREA QNH 10/13
    AREA 21: 1031
MOSS VALE (MSV) – this is another critical location with 3 letter code
    METAR MSV 161200Z AUTO 17009KT 9999 // NCD 05/02 Q1030 RMK
    RF00.0/000.0
MOUNT BOYCE (MTB) – this is the one critical location that I have been referring to
    METAR MTB 161200Z AUTO 15004KT 9999 // NCD 03/M01 Q//// RMK
    RF00.0/000.0
BATHURST (YBTH)
    TAF YBTH 160732Z 1608/1620
    19008KT CAVOK
    RMK
    T 10 06 03 02 Q 1028 1031 1030 1029

METAR YBTH 161200Z AUTO 15005KT 9999 // NCD 05/M02 Q1030 RMK
    RF00.0/000.0

COOMA - SNOWY MOUNTAINS (YCOM)
METAR YCOM 161200Z AUTO 22009KT 9999 // OVC023 02/M00 Q1031 RMK
RF00.0/000.0
COWRA (YCWR)
METAR YCWR 161200Z AUTO 00000KT //// // ////// 04/01 Q1031 RMK
    RF00.0/000.0
…
…
…
SYDNEY (YSSY)
    TAF AMD YSSY 161104Z 1612/1718
    20017KT 9999 SCT045
    FM161700 25014KT 9999 SCT025 BKN040
    FM162300 20014KT 9999 SCT030 BKN045
    FM170300 15013KT 9999 FEW045
    FM170900 05007KT CAVOK
    FM171100 30005KT CAVOK
    RMK
    T 14 13 11 11 Q 1030 1030 1029 1031
    TAF3 
METAR YSSY 161200Z AUTO 20018KT 9999 // FEW045 SCT061 14/06 Q1030 RMK
    RF00.0/000.0
 ATIS YSSY A   161144
      APCH: EXP INDEPENDENT VISUAL APCH.
            DO NOT PASS THRU ASSIGNED RWY CL
      RWY: 16L AND R FOR ARRS AND DEPS
    + OPR INFO: INDEPENDENT PARL APPROACHES AND DEPARTURES IN
                PROGRESS.
                CURFEW RESTRICTIONS APPLY FROM TIME 1245,
                ARRS RWY 34L AFTER TIME 1300.
                ALL DEPS 16 DIRECTION AFTER TIME 1245
    + WIND: 180/15-25
      WX: CAVOK
      TMP: 14
      QNH: 1030

Note: I do not have an example of a standalone forecast for this critical location, as these forecasts are not published through the location or area briefing service. Instead, they are provided in the Graphical Area Forecast (GAF), where this location is identified as MVI. I am not sure why this inconsistency exists*, but we will ensure it is resolved when AMOIS and AMFIS are implemented.

*Pierre Kemmers made a note saying that "It’s interesting indeed. Do AFC make them as separate forecasts that are then incorporated into the GAF, or do these critical locations’ forecasts only exist in the text of the GAF?"

When AMOIS and AMFIS are implemented, we want to ensure operators can obtain observations and forecasts for critical locations in their own right, without needing to reference a major aerodrome or the GAF. This will support operators who require meteorological information for a specific critical location, such as a mountain pass, to assist with operational decision-making.

A pilot may request a location briefing for MTB to understand the weather conditions at Mount Boyce. In that case, they would receive the following observation information:

MOUNT BOYCE (MTB)
METAR MTB 161200Z AUTO 15004KT 9999 // NCD 03/M01 Q//// RMK
RF00.0/000.0

As noted above, pilots may request information for a critical location without referencing a major aerodrome. Some operators may include an aerodrome in their request; however, I do not have an example of this, as I do not have access to individual pilot briefing requests.

Example 2:
Another example of a critical location which pilots would only use and not reference to any major aerodrome is Murrunrundi (MUI). Examples provided below:

MURRURUNDI (Critical Location) MUI 16/09/2026 UTC
SPECI MUI 161230Z AUTO 13025G35KT 9999 // NCD 06/00 Q1027 RMK
RF00.0/000.0

The forecast is published in the GAF as

[blchoy]

In Ashwins' e-mail dated 23 Sep 2026, he reminded us that a related paper had been discussed at ICAO APAC MET/IE WG/22:

... Tim also noted that he wrote a paper on this matter for the ICAO APAC MET/IE WG and shared it with the relevant MRAD/IWXXM experts (see this paper).

Furthermore, the ICAO APAC MET/IE WG meeting supported this paper, and other States raised examples of similar requirements. The meeting report included the following:

“… The meeting noted similar issues in other States and agreed it would be beneficial for IWXXM and future SWIM services to support creation and dissemination of non-aerodrome meteorological information to the aviation industry. Therefore, the meeting requested the Secretariat and Chair to forward the outcomes of its discussion to the MET Panel for further consideration.

MET/IE WG/22-07 Action IWXXM dissemination – issues for non-ROBEX locations
Forward the MET/IE WG/22 discussion outcomes concerning the issue of disseminating METAR/SPECI in the IWXXM form for weather stations not listed in the ROBEX handbook (as presented in MET/IE WG/22 WP/15) to the MET Panel for further consideration."

[blchoy]

Anu also shared her views on 23 Sep 2026:

Dear Ashwin, all,

Thank you for sharing the paper Tim wrote for the ICAO APAC meeting. Just a quick note to let you know that we in Finland have a similar process in place regarding met observation information in aviation friendly format.

We have several automated AWS stations; some at unmanned airfields and some at other locations that we provide the information from (in METAR format). The difference to the Australian convention is, that our CAA is strict that the term METAR is not allowed with these reports, so we call them AWS-AVIATION messages. Also the location indicator used does not start with the official “EFxx” that is used at aerodromes but with “ILxx” (IL is the abbreviation for FMI in Finnish). We share them currently in our official briefing website, but have no plans of including them in our AMOIS solution in the future.

You can see some examples here.

Kind regards,
Anu

[blchoy]

Thanks Ashwin for the information and clarification. It is clear that for this application you are going to use AMOIS and AMFIS formats, but instead of marking it as being observed at or forecast for an aerodrome it will be more natural to mark it for a location.

During the 16 Sep 2026 discussion one asked if these observations and forecasts could also be regarded as observations and forecasts for an aerodrome. My gut feeling is that (1) the locations where these observations and forecasts are made are pretty far away from the aerodrome as well as its vicinity, and (2) these locations are supposed to be on the flight path which could subsequently lead to different aerodromes, following the thoughts raised in the enquiry that means we will need to include these observations and forecasts in all involved aerodromes?

I will consider AMOIS and AMFIS as clusters of observations and forecasts for an aerodrome and in your situation it is just a special case in which the reference location is not an aerodrome.

Having said that, since the name of the aerodrome is the key (or unique identifier) of its observations and forecasts which will be used for information identification and retrieval whether we need to identify the name as a globally coordinated aerodrome name or a location name which is likely to be handled by local authorities will have to be confirmed by MRAD as this affects schema design.

[blchoy]

One side discussion with Kenneth Cheung (who used to be with BoM and now is with us) is whether IWXXM can be used to represent the area QNH forecast which is also mentioned in #22:

AREA21 (21)
    AREA QNH 13/16
    AREA 21: 1030
    AREA QNH 10/13
    AREA 21: 1031

While the above looks simple, Ken said it could have sub-sections (different QNH values across a line cutting across the area) and disc/rings of different QNH values when there is a cyclone within the area. This is certainly out of scope for AMFIS but may eventually needed to be handled when we need IWXXM area forecasts.

Ditto your "graphical area forecast".