GEN 3.5 - METEOROLOGICAL SERVICES

1.
Responsible Services
 

 

1.1.

The Meteorological Services for civil aviation are provided by the India Meteorological Department, Ministry of Earth Sciences (MoES), Government of India.

 

 

 

Director General of Meteorology

 

India Meteorological Department

 

Mausam Bhavan,

 

Lodhi Road, New Delhi - 110003

 

Telephone:

+91-11-24618241 to 8247

 

Fax:

+91-11-2469 9216, +91-11-24623220

 

Telegram:

DIRGENMET

 

Email:

dgm.hq@imd.gov.in dgmmet@gmail.com

 

Website:

www.imd.gov.in

2.
Area of responsibility
 

 

2.1

Meteorological service is provided within the Chennai, Delhi, Kolkata, and Mumbai Flight Information Regions (FIRs)

 

 

3.
Meteorological observations and reports
 

 

3.1

Meteorological observations and reports provided are listed at Section 9.

 

 

4.
Abbreviation and Legend

Abbreviation

Legend

DIWE

 

Distance Indicating Wind Equipment (DIWE)

 

CWIS

Current Weather Instrument System (CWIS) (Temperature, Humidity, Wind & Pressure sensors)

IAAMS

Integrated Automated Aviation Meteorological System (CWIS + Transmissometer).

AWOS

Automated Aviation Meteorological System (CWIS + Transmissometer).

SS

Wind wane, Cup anemometer, Stevenson Screen

A/R

As & when required

AMO

Aerodrome Meteorological Office (Formerly Class I Met Office)

AMS

Aerodrome Meteorological Station (Formerly Class III Met Office)

HJ

Observation from sun-rise to sun-set

H24

Continuous day and night service

HO

Service available to meet operational requirements

HS

Service available during hours of scheduled service

METAR

Coded Meteorological current weather routine report (+ Local Met. Report in abbreviated plain language for local ATC / Area / Approach control as applicable)

TREND

Landing forecast appended to aviation weather reports (METAR and Local Met. Reports in abbreviated plain language for local ATC / Area / Approach control as applicable).

5.
Types of services
 

 

5.1.
Area Forecast
5.1.1

Under the World Area Forecast system, WAFC London is responsible for the supply of forecast data of upper winds, upper-air temperatures, direction, speed and height of maximum winds and tropopause heights and temperatures. The products are valid for 6, 12, 18, 24, 30 and 36 hours after the time of synoptic data (0000, 0600, 1200 and 1800 UTC) on which the forecasts are based. The grid point data for upper wind/temperature and geopotential height are available for FL 50 (850 hPa), FL 100 (700 hPa), FL 140 (600 hPa), FL 180 (500 hPa), FL 240 (400 hPa), FL 270 (350 hPa), FL 300 (300 hPa), FL 320 (275 hPa), FL 340 (250 hPa), FL 360 (225 hPa), FL 390 (200 hPa) and FL 450 (150 hPa), FL530 (100 hPa). In addition, forecast Humidity for flight levels FL 50 (850 hPa), FL 100 (700 hPa), FL 140 (600 hPa) and FL 180 (500 hPa) are also available. The above data in chart form are made available through online aviation meteorological briefing system (OLBS) functioning at Chennai and New Delhi for the registered airline users through user name / password access and for those who are yet to register in hard copy form as part of chart form of documentation (CFD) briefing material.

5.1.2

Required data for the forecast of significant weather (SIGWX) phenomena are also provided by WAFC London, four times a day for fixed valid times of 0000, 0600, 1200 and 1800 UTC. These data are received through secured file transfer protocol (ftp) access by IMD, processed and the SIGWX charts for FL 100 - FL 250 and FL 250 - FL 630 are generated through OLBS in India for the documentation of international and domestic flights.

5.1.3

These charts are made available in OLBS for online self-briefing by pilots and flight despatchers and also disseminated through IMD’s communication channel to forecasting offices to meet the manual briefing requirements, if any.

5.1.4

In addition, national SIGWX charts and prognostic charts are also being prepared by the four Meteorological Watch Offices functioning at Chennai, Delhi, Kolkata and Mumbai for the documentation of national short-haul flights.

 

 

5.2
Route and Aerodrome Forecasts
 

 

5.2.1.

Route Forecast, terminal aerodrome forecast and local forecasts are issued by Aerodrome Meteorological Offices (Offices having forecasting facilities) for its own and its attached aeronautical meteorological stations (AMS). In addition, all Aerodrome Meteorological Offices (AMO) issue trend forecasts and some of the AMS also issue trend forecasts based on user requirements. All AMOs issue take-off forecast for its own as per user requirements. During the closed hours of watch of the offices with restricted forecasting hours, the necessary forecasts are issued by the meteorological offices at state/regional centres.

 

 

5.3.
Aerodrome Warning/Wind Shear Warnings
 

 

5.3.1

Aerodrome warnings are issued by AMOs functioning during the hours of forecasting watch and give concise information of meteorological condition, which could adversely affect aircraft on the ground, including parked aircraft and the aerodrome facilities and services. In cases of aerodromes with AMS, the associated AMO at the state centres or regional centres issue these warnings, if there is prior requisition.

5.3.2.

These warnings are supplied to ATS units of Airports Authority of India for further dissemination over the aerodrome to operators and other agencies.

5.3.3.

Aerodrome warnings are issued for strong surface winds, tropical cyclones, thunderstorms, squall, dust storm/sand storm, hail, frost, snow, freezing precipitation etc. as recommended in ICAO Annex 3.

5.3.4.

In addition, warnings for gliders and light aircraft and helicopters are issued and appended to the Local forecast when the wind speed is expected to reach 17 knots or more.

 

 

6.
Briefing and Display
 

 

6.1.

Briefing is provided through OLBS with user name and password access for the registered users. However, for those who do not have user name / password access, manual briefing is provided. In all AMOs briefing is available to the pilots and/ or flight operations personnel about the prevailing and anticipated weather conditions. Latest surface and upper-air synoptic charts, meteorological reports, and forecasts of destination and its alternate(s), SIGMET information, AIREP, prognostic charts, ground based weather radar information and satellite cloud imagery are readily available in PC monitors for consultation and briefing. In addition, hard copy form is supplied as part of briefing material based on the user requirements. Depending on the weather situation, the meteorological officer may insist that the pilot in command of a flight be present personally for briefing. Briefing is also provided at AMS (where forecasting facility is not available) after obtaining the same from its associated AMO.

 

 

7.
Documentation
 

 

7.1

Documentation consists of -

7.1.1

Flight forecast in tabular form/ pictorial cross-sectional form/ charts form / a single vertical cross section chart form covering various levels for the selected route.

7.1.2

Terminal aerodrome forecasts of destination and alternate aerodrome.

7.1.3

Take-off and ascent/descent data (wherever necessary) are provided to flights taking off from airports within the country.

 

 

7.2.

The chart form of forecast for domestic short-haul flights consists of prognostic SIGWX charts for medium level (FL 100 - FL 250) and high level (FL 250 - FL 630) and prognostic upper wind and temperature charts for the levels mentioned at 5.1.1 above for both international and domestic flights. The Chart form of documentation (CFD) is prepared at MWO, Chennai and Delhi using the gridded binary (GRIB1) data obtained through secured ftp access from WAFC, London and the same are made available for briefing at all AMOs and AMSs concerned. Forecasts are normally given up to the next halt where a meteorological forecasting office exists, when the duration of the halt is more than seventy-five minutes. Through online access, the users have the privilege to select and choose the forecast requirements covering the endurance and return flight requirements subject to the

halt duration at destination and procedural requirements of briefing at destination as per prevailing norms.

 

 

7.3

Return forecasts are provided for flights when the halt at the destination is less than 75 minutes and there is no change of crew. If sufficient notice is given, arrangements are also made to provide documentation even at airports without meteorological forecasting facility. If planned halt(s) at intermediate airports are for long periods, a decision whether fresh forecasts will be required at intermediate halt(s), will have to be taken by mutual consultation between the pilot and the meteorological office at the original departure aerodrome taking into consideration the expected weather developments.

 

 

7.4

A fresh forecast has to be obtained at intermediate halts when the period of validity of the route and/or aerodrome forecasts supplied has elapsed or is expected to elapse before the completion of the flights due to changes in the original plan. In such cases, the operator has to make arrangements to obtain fresh forecast from the Aviation Meteorological Office at the original departure aerodrome or from the nearest Aviation Meteorological Office. The responsibility for the collection and transmission of the forecasts to the pilot at intermediate halts rests with the operator.

8.
In-flight services
 

 

8.1.

SIGMET: Significant Meteorological Information pertaining to the FIRs are issued by the Meteorological Watch Office (MWO) functioning at Chennai, Delhi, Kolkata & Mumbai and are known as SIGMET. These are supplied to the ATS units at the Flight Information Center (FIC) and Area Control Center (ACC) for the transmission to aircraft in flight (Refer Para 12)

 

 

8.2.

VOLMET BROADCASTS: Current Weather Reports and Aerodrome Forecasts and SIGMETs of certain stations are broadcast on HF from Kolkata and Mumbai at half hourly intervals. Details of these broadcast are given in Para 12.

 

 

8.3.

ATIS BROADCAST: Latest Weather Report of the airport, together with trend forecast valid for the next 2 hours, is included in the Automatic Terminal Information Service (ATIS) broadcast from Chennai, Delhi, Kolkata & Mumbai.

 

 

8.4.

AD 2.11 of each aerodrome described in Part 3-Aerodrome (AD), Volume II gives metrological information provided by each aerodrome.

9.
Meteorological Observatories and Reports

Name of station/Location Indicator

Type and frequency of observatories/Automatic Observing Equipment

Type of Met reports and supp. information included

Observing system & site(s)

Hours of operation

Climatological Information

Agartala/VEAT

Hourly + Half hourly during HO

METAR/TREND

DIWE at ATC TOWER

HJ

NIL

Agatti/VOAT

Hourly + Half hourly during HO

METAR

DIWE at ATC TOWER

HO

NIL

Ahmedabad/VAAH

Half hourly

METAR/TREND

CWIS & Transmissometer at RWY 23;

additional DIWE near ATC TOWER

H24

Available

Amritsar/VIAR

Half hourly

METAR/TREND

IAAMS at RWY 34,

Transmissometer at RWY MID & RWY 16

H24

Nil

Aurangabad/VAAU

Hourly + Half hourly during HO

METAR/TREND

DIWE NEAR ATC

HO

Nil

Barapani (Shillong)/

VEBI

Hourly + Half hourly during HO

METAR

DIWE at ATC

HJ

Nil

Belgaum/VOBM

Hourly + Half hourly during HO

METAR

DIWE at ATC

HJ

Nil

Bengaluru (Devanahalli)/ VOBL

Half hourly

METAR/TREND

IAAMS at RWY 27;

CWIS & Transmissometer at RWY09;

H24

Available (VOBG)

Bengaluru/ VOBG

Hourly + Half hourly during HO

METAR

CWIS at RWY 27;

Additional DIWE at ATC TOWER

HJ

Available

Bhavnagar/VABV

Hourly + Half hourly during HO

METAR

DIWE at ATC

HO

Nil

Bhopal (Bairagarh)/

VABP

Hourly + Half hourly during HO

METAR/TREND

DIWE at ATC

 

HJ

Nil

Bhubneswar/VEBS

Hourly + Half hourly during HO

METAR/TREND

CWIS at RWY 32;

DIWE at ATC

H24

Nil

Calicut/VOCL

Hourly + Half hourly during HO

METAR/TREND

CWIS at RWY28;

DIWE at RWY10

H24

Nil

Chennai/VOMM

Half hourly

METAR/TREND

IAAMS at RWY07; CWIS at RWY 25;

Transmissometer at RWY25

CWIS at RWY12; CWIS at RWY30

H24

Available

Cochin Intl/VOCI

Half hourly

METAR/TREND

CWIS at RWY27;

DIWE at RWY 09

H24

Nil

Coimbatore/VOCB

Hourly + Half hourly during HO

METAR/TREND

DIWE at ATC

H24

Available

Cooch Behar/VECO

Hourly + Half hourly during HO

METAR

DIWE at ATC

HJ

Nil

Dehradun/VIDN

As & when required (A/R)

METAR

Transmissometer at RWY 08

Additional DIWE at Observatory.

HJ

Nil

Delhi/VIDP

Half hourly

METAR/TREND

IAAMS at RWY11, RWY 27, RWY29

CWIS at RWY10, RWY 28, RWY 09

Transmissometers at RWY09, MID, RWY27;

RWY11 BEG, RWY11 TDZ, RWY29 MID, RWY29 TDZ, RWY29 BEG;

RWY10, MID, RWY28.

H24

Available

Dibrugarh (Mohanbari)/

VEMN

Hourly + Half hourly during HO

METAR/TREND

DIWE at ATC

HJ

Nil

Dimapur/VEMR

Hourly + Half hourly during HO

METAR/TREND

 

DIWE at ATC

HJ

Nil

Durgapur/VEDG

Hourly + Half hourly during HO

METAR/TREND

CWIS at RWY

DIWE at RWY

HJ

Nil

Fursatganj/VERB

Hourly

METAR

SS

A/R

Nil

Gaya/VEGY

Hourly + Half hourly during HO

METAR/TREND

 

DIWE at ATC

 

HO

Nil

Gondia/VAGD

Hourly + Half hourly during HO

METAR

DCWIS at RWY04

HJ

Nil

Guwahati/VEGT

Hourly + Half hourly during HO

METAR/TREND

 

IAAMS at RWY 02; DIWE RWY 02;

Additional Transmissometer RWY 02;

H24

Nil

Hubli/VOHB

Hourly + Half hourly during HO

METAR

 

DIWE at ATC

HJ

Nil

Hyderabad/VOHY

Hourly + Half hourly during HO

METAR/TREND

 

CWIS at RWY27

HJ

Available

Imphal/VEIM

Hourly + Half hourly during HO

METAR/TREND

 

DIWE at ATC

 

HJ

Nil

Indore /VAID

Hourly + Half hourly during HO

METAR/TREND

 

DIWE at ATC

 

HJ

NIL

Jabalpur/VAJB

Hourly

METAR

DIWE at ATC

HS

NIL

Jaipur /VIJP

Hourly + Half hourly during HO

METAR/TREND

 

IAAMS at RWY27;

Transmissometer at RWY09, MID, RWY27.

CWIS at RWY 09

H24

Nil

Jamshedpur VEJS

Hourly + Half hourly during HO

METAR

DIWE at ATC

 

HJ

Nil

Juhu (Mumbai)/ VAJJ

Hourly + Half hourly during HO

METAR/TREND

 

CWIS at JUHU HELIPAD

HJ

Nil

Kadapa/VOCP

Hourly

METAR

Portable Kit.

A/R

Nil

Kandla/VAKE

Hourly

METAR

DIWE at ATC

A/R

Nil

Kangra (Gaggal)/VIGG

Hourly + Half hourly during HO

METAR

DIWE at ATC

HJ

Nil

Keshod /VAKS

Hourly

METAR

SS

A/R

Nil

Khajuraho/VEKO

Hourly

METAR

DIWE at ATC

HJ

Nil

Kolkata/VECC

Half hourly

METAR/TREND

Transmissometer at RWY 19L,

RWY 01L, MID;

Transmissometer at RWY 01R,

01R MID & 19R

H24

Available

Kota/VIKO

Hourly

METAR

SS

HJ

Nil

Kullu Manali (Bhuntar)/

VIBR

Hourly

METAR

DIWE at ATC

HJ

Nil

Lengpui (Aizwal)/ VELP

Hourly + Half hourly during HO

METAR/TREND

DIWE at ATC

HO

NIL

North Lakhimpur/VELR

Hourly + Half hourly during HO

METAR

DIWE at ATC

HJ

Nil

Lucknow/VILK

Hourly + Half hourly during HO

METAR TREND

CWIS at RWY27;

Transmissometer at RWY27, MID, RWY09

H24

Available

Ludhiana/VILD

As & when required (A/R)

METAR

DIWE at ATC

HJ

Nil

Madurai/VOMD

Hourly + Half hourly during HO

METAR/TREND

DIWE at ATC

 

H24

Nil

Mangalore/ VOML

Hourly + Half hourly during HO

METAR/TREND

AWOS at RWY 24

H24

Nil

Mumbai/VABB

 

Half hourly

METAR/TREND

IAAMS at RWY 27;

RWY 09, RWY14

H24

Available

Mysore/VOMY

Hourly

METAR

DIWE at ATC

A/R

Nil

Nagpur/VANP

Hourly + Half hourly during HO

METAR/TREND

CWIS at RWY 32

H24

Available

Nanded/VOND

Hourly

METAR

CWIS at RWY 28

A/R

Nil

Pantnagar /VIPT

Hourly

METAR

SS

A/R

Nil

Patna/VEPT

Hourly + Half hourly during HO

METAR/TREND

Transmissometer at RWY 25,

DIWE at ATC

H24

Available

Porbandar/VAPR

 

Hourly + Half hourly during HO

METAR

DIWE at ATC

HJ

Nil

Pondicherry/VOPC

Hourly + Half hourly during HO

METAR

SS

HJ

Nil

Raipur/VERP

Hourly + Half hourly during HO

METAR/TREND

DIWE at ATC

 

H24

Nil

Rajahmundry/VORY

Hourly + Half hourly during HO

METAR

DIWE at ATC

 

HJ

Nil

Rajkot/VARK

Hourly + Half hourly during HO

METAR

DIWE at ATC

 

HJ

Nil

Ranchi/ VERC

Hourly + Half hourly during HO

METAR/TREND

DIWE at ATC

 

HJ

Nil

Rohini Heliport

Hourly + Half hourly during HO

METAR

CWIS near HELIPAD

HJ

Nil

Safdarjung (Delhi)/

VIDD

Hourly + Half hourly during HO

METAR

DIWE at ATC

HJ

Available

Salem/VOSM

Hourly

METAR

DIWE at ATC

A/R

Nil

Shamshabad (Hyderabad)/VOHS

Half hourly

METAR/TREND

IAAMS at RWY 27;

CWIS & Transmissometer at RWY 09

H24

Available (VOHY)

Surat/VASU

Hourly

METAR

DIWE at ATC

A/R

NIL

Thiruvanthapuram/VOTV

Hourly + Half hourly

METAR/TREND

CWIS at RWY 32

H24

Available

Tiruchirapalli/VOTR

Hourly + Half hourly during HO

METAR/TREND

DIWE at ATC

 

H24

Available

Tirupati/VOTP

Hourly + Half hourly during HO

METAR

DIWE at RWY26

HO

Nil

Tuticorin/VOTK

HJ NIL

METAR

DIWE near ATC

HJ

Nil

Udaipur/VAUD

Hourly + Half hourly during HO

METAR/TREND

DIWE at ATC

HJ

Nil

Vadodara/VABO

Hourly + Half hourly during HO

METAR/TREND

 

DIWE at ATC

HJ

Nil

Varanasi/VEBN

Hourly + Half hourly during HO

METAR/TREND

 

DIWE at ATC; Transmissometer at RWY27

H24

Nil

Vijayawada/VOBZ

Hourly + Half hourly during HO

METAR/TREND

 

DIWE at RWY08

HJ

Nil

 

Note:

i. Observations are recorded at HH+00 and HH+30 for the issue of METARs.

ii. Local SPECIAL as per ICAO Annex 3 criteria and ADDITIONAL reports based on regional practice and requirements are prepared whenever warranted, throughout the hours of watch.

10.
Notification required from operators
10.1

Notification from operators for flight documentation and other meteorological service or for a change in the existing requirements should be received by the concerned Meteorological Office(s) sufficiently in advance. Normally the minimum notice required for non-scheduled flights are as follows:

For National & international flights

At AMOs

(offices having forecasting for facilities)

3 hours before ETD

At AMS

(offices without forecasting facilities)

At least 3 hours during watch (OR) 18 to 24 hours before ETD

11.
Aircraft reports
11.1

Routine air reports at the following designated MET reporting points (as given on para 11.4 & 11.5) shall be made by all aircraft.

11.2.

Special observations shall be made whenever the following weather phenomenon are encountered or observed -

 

i) severe turbulence; or

 

ii) severe icing; or

 

iii) severe mountain wave; or

 

iv) thunderstorm without hail, that are obscured, embedded, widespread or in squall lines; or

 

v) thunderstorm with hail, that are obscured, embedded, widespread or in squall lines; or

 

vi) heavy dust storm or heavy sandstorm; or

 

vii) volcanic ash cloud; or

 

viii) pre-eruption activity or a volcanic eruption

 

 

11.3.

The meteorological office shall make arrangements with the appropriate ATS unit to ensure that -

 

i) Routine and special air-reports by voice communications, the ATS units relay them without delay to their associated meteorological watch office

 

ii) Routine air-reports by data-link communications, the ATS units relay them without delay to WAFCs; and

 

iii) Special air-reports by data-link communications, the ATS units relay them without delay to their associated meteorological watch office and WAFCs.

 

 

11.4.

Meteorological reporting points on National ATS routes

ATS Route

Reporting points

Kolkata - Chennai

SANON

Kolkata - Port Blair

Crossing G472

Delhi - Kolkata

KUSMI

Delhi - Chennai

BHOPAL & GULBARGA

Delhi - Hyderabad - Bengaluru

BHOPAL

Delhi - Srinagar

PATHANKOT

Mumbai - Chennai

BELLARY

Mumbai - Cochin

DABOLIM/GOA

Mumbai - Delhi

PRATAPGARH

Mumbai - Kolkata

AURANGABAD & NIPAD

Mumbai - Thiruvananthapuram

DABOLIM/GOA

11.5.

Meteorological reporting points on International ATS routes

ATS Route

FIR

Reporting point designator/ Five letter name code

A456

Delhi

RABAN

A462

Kolkata

BEMAK

A466, L509, M890

Delhi

SAMAR

A474

Mumbai

MURUS

A474, G465

Mumbai

MONTO

A599

Kolkata

CHILA

A791, G208, G451, N895

Mumbai

SASRO

A325

Delhi

TASOP

A474, A791, L518, N877, A325

Mumbai

PRATAPGARH (PRA VOR)

B459, L756

Mumbai

CLAVA

B459

Mumbai

ATEMA

B459, L516

Mumbai

UGPEG

B466

Chennai

ANOKO

B466

Chennai

APASI

B466

Chennai

AVNOS

B211

Chennai

BELLARY (BBI VOR)

G210, G472, N893

Mumbai

VASLA

G424, L875

Mumbai

VUTAS

G424, G450, L516

Mumbai

UNRIV

G450

Kolkata

NIPAD

G450

Mumbai

ORLID

G333, G452, L333

Delhi

TIGER

G465, L516

Mumbai

ELGER

G472, N895

Kolkata

SAGOD

G472, M770, M773, N895

Kolkata

BUBKO

L301

Kolkata

RINDA

L301

Mumbai

RASKI

L516, L894, P570

Mumbai

KITAL

G450, L894, P323, UM551, UL425

Mumbai

 

DONSA

A474, L894

Mumbai

ESMIT

M770

Kolkata

MEPEL

N563

Chennai

MEMAK

P628

Chennai

IGREX

P751, UM551

Mumbai

ANGAL

M300, P751

Mumbai

LEMAX

P762

Chennai

LULDA

G590, P646, R460

Kolkata

VARANASI (BBN VOR)

R472

Kolkata

ATOGA

12.
VOLMET service

Name of Station

Call-sign

Ident

Freq (KHz)

Broadcast Period

Hours of Service

Aerodromes/ Heliports included

Content of report, forecast & remarks

 

 

 

Mumbai

 

 

Mumbai

Radio

(A3J)

 

11387

6676

 

H+25

to

H+30

 

0300

to

1300

Mumbai, Chennai

SIGMET

Mumbai, Colombo, Chennai, Karachi,

Male, Ahmedabad

METAR

SPECI

TREND

2965

 

H+55

to

H+60

 

1300

to

0300

Mumbai, Colombo,

Male

TAF

 

 

 

Kolkata

 

 

Kolkata

Radio

(A3J)

 

11387

6676

 

H-05

to

H+10

 

0300

to

1300

Kolkata, Delhi

SIGMET

Kolkata, Delhi,

Dhaka, Yangon,

Katmandu

METAR

SPECI

TREND

2965

 

H+35

to

H+40

 

1300

to

0300

Kolkata, Delhi,

Ho-Chi-Minh

TAF

13.
SIGMET Service

Name of

MWO/ Location

Indicators

Hours

FIR or CTA

Served

Validity of

SIGMET

ATS Unit

Served

Chennai VOMM

H24

Chennai FIR

4 hour

FIC/ACC

Delhi VIDP

H24

Delhi FIR

4 hour

FIC/ACC

Kolkata VECC

H24

Kolkata FIR

4 hour

FIC/ACC

Mumbai VABB

H24

Mumbai FIR

4 hour

FIC/ACC

14.
General
 
 
 

For the safety of air traffic, the meteorological offices maintain an Area Meteorological Watch and Warning Service. This service consists partly of a continuous weather watch within the FIR and the issuance of appropriate information (SIGMET) by Meteorological Watch Offices and partly of the issuing of warning for the respective aerodrome by all aviation forecasting offices.

 

 

15.
Area Meteorological Watch Service
 

 

15.1.

The Area Meteorological Watch Service is performed by the following Meteorological Watch Offices (MWO); Chennai, Delhi, Kolkata & Mumbai.

 

 

15.2.

The MWO issue information in the form of SIGMET messages about the occurrence and/or expected occurrence of one or more of the following phenomena within the FIR served by the MWO:

 

i) Thunderstorms

 

ii) Tropical Cyclone

 

iii) Turbulence

 

iv) Icing

 

v) Mountain waves

 

vi) Dust storm

 

vii) Sandstorm

 

viii) Volcanic ash cloud

 

ix) Cumulonimbus

 

x) Hail

 

 

15.3.

The SIGMET are issued in abbreviations and plain language using ICAO abbreviations and are numbered consecutively for each day commencing at 0001UTC. The period of validity of a SIGMET message shall be not more than 4 hours and in the exceptional case of tropical cyclone and volcanic ash it shall not be more than 6 hours.

 

 

15.4.

The SIGMET are issued in abbreviations and plain language using ICAO abbreviations and are numbered consecutively for each day commencing at 0001UTC. The period of validity of a SIGMET message shall be not more than 4 hours and in the exceptional case of tropical cyclone and volcanic ash it shall not be more than 6 hours.

 

 

15.5.

In addition to the issuance of SIGMET, the MWO inform the local FIC about the occurrence or expected occurrence of thunderstorms, moderate icing, light to moderate hail, or moderate turbulence within the FIR concerned. The information is intended for lower air-space.

 

 

16.
Warning Services
 

 

16.1.

Aerodrome warnings are issued by all forecasting offices and give the concise information of meteorological conditions, which would adversely affect aircraft on the ground, including parked aircraft and the aerodrome facilities and services, if one or several of the following phenomena are expected to occur at the airport -

 

i. Wind - speed expected to reach 30 knots or more even in gusts, direction changing rapidly by 45 DEG or more, wind speed before and after expected to be 20 knots or more

 

ii. Squall

 

iii. Tropical Cyclone

 

iv. Dust storm

 

v. Sandstorm

 

vi. Thunderstorm

 

vii. Hail

 

viii. Frost

 

ix. Hoar Frost or rime

 

x. Snow (including the expected or observed snow accumulation)

 

xi. Freezing precipitation

 

xii. Rising sand or dust

 

xiii. Volcanic ash

 

 

16.2.

Warning for gliders and light aircraft and helicopters are issued when wind speed is expected to reach 17Kt or more.

 

 

16.3.

Wind shear warning provide concise information of the observed or expected existence of wind shear which could adversely affect aircraft on the approach path or take-off path or during circling approach between runway level and 500 M above the level and aircraft on the runway during the landing roll or take-off run.

 

 

16.4.

These warning are issued in English and are issued only for the local aerodrome and are passed on to local ATS units for further dissemination over the aerodrome to the operators etc.

 

 

17.
Others automated meteorological services
 

 

17.1.

Online aviation meteorological briefing system (OLBS) is functioning from MWO, Chennai and Delhi. It provides through username / password access to the registered users of airlines to avail briefing material, current weather reports, SIGMET warnings, tropical cyclone and volcanic ash advisory bulletin issued by the designated centres (of ICAO) for international / domestic flight planning purposes.

 

 

18.
ICAO documents
 

 

18.1.

The standards and recommended practices and procedures contained in the following ICAO documents are applicable to the meteorological practice in India.

 

i. Annex 3

Meteorological services for International Air Navigation

 

ii. Doc 7030

Regional Supplementary Procedures

 

iii. Doc 8400

PANS-ICAO Abbreviations and Codes

 

iv. Doc 8700

Air Navigation Plan - Mild - Asia Region

 

v. ROBEX Handbook

 

19.
Departmental publications
 

 

19.1.

The following publication issued by India Meteorological Department contained National Regulations/Practices.

i. Manual on Meteorological Service for Aviation in India, 4th Edition, 2012.

ii. Aviation Weather Codes, 2004.