All Weather Operations – DGCA CAR Simplified Guide

Based on: CIVIL AVIATION REQUIREMENT SECTION 8 - AIRCRAFT OPERATIONS, SERIES 'C' PART I, ISSUE II, DATED 28TH OCTOBER 2022

Chapter 1: Introduction to AWO & Regulatory Framework

1.1 ✈️ What are All Weather Operations (AWO)?

All Weather Operations (AWO) refer to any aircraft operations—including surface movements, take-offs, departures, approaches, or landings—conducted in conditions where weather limits the pilot's visual reference.

The primary goal of establishing Aerodrome Operating Minima (AOM) is to ensure a high level of safety by setting limits for operations in specific weather conditions. These minima guarantee that the pilot has sufficient information from both external visual cues and aircraft instruments to safely navigate the desired flight path.

1.2 📚 The Regulatory Framework

This guide is based on the Civil Aviation Requirement (CAR) issued by the Director General of Civil Aviation (DGCA), Government of India.

• Issuing Authority: Office of the Director General of Civil Aviation, New Delhi.
• Applicability: The requirements apply to all Scheduled, Non-scheduled, and General Aviation aeroplane operators.
• Legal Basis: The CAR is issued under the provisions of Schedule II, Rule 29C and Rule 133A of the Aircraft Rules, 1937.

1.3 👨‍✈️ Operator's Responsibility

An operator must establish approved Aerodrome Operating Minima (AOM) for each aerodrome they plan to use. The method for determining these minima must be approved by the DGCA and cannot be lower than the values specified in this CAR.

When establishing minima, operators must account for:

• Aeroplane: Type, performance, and handling characteristics.
• Flight Crew: Composition, competence, and experience.
• Aerodrome: Dimensions of runways, and the quality of visual and non-visual aids.
• Equipment: Navigation and flight control equipment available on the aircraft.
• Environment: Obstacles in the approach, missed approach, and climb-out areas.
• Meteorology: The means used to determine and report weather conditions.

Chapter 2: Low Visibility Take-off (LVTO)

Low Visibility Take-off (LVTO) is a take-off on a runway where the Runway Visual Range (RVR) is less than 400 meters.

2.1 🛫 LVTO Approval & Procedures

• DGCA Approval: Operators are not permitted to conduct take-offs in RVRs less than 400 m unless they are specifically approved by the DGCA. Operators can be authorized for LVTO minima as low as 75m.
• Low Visibility Procedures (LVP): An operator cannot conduct a take-off with an RVR/visibility below the standard Category I condition of 550m RVR / 800m visibility unless Low Visibility Procedures (LVP) are enforced at the aerodrome.

2.2 📊 Take-off Minima (RVR/Visibility)

The following minima apply to multi-engine aeroplanes that can safely continue the take-off or stop after a critical power unit failure.

(Table based on Table 10 of the CAR)

RVR/VIS Minima	Facilities Required
500 m	Adequate Visual Reference (Day only)
400 m	Runway edge lights or Runway Centre line markings
300 m	Runway edge lights and Runway Centre line markings
200 m	Runway edge lights and Runway Centre line lights
150 m	Runway edge lights and Runway Centre line lights and relevant RVR information
125 m	High intensity Runway edge lights and Runway Centre line lights (spacing 15 m or less) and relevant RVR information
75 m	High intensity Runway edge lights and Runway Centre line lights (spacing 15 m or less), approved lateral guidance system and relevant RVR information

2.3 🔄 Take-off Alternate Aerodrome

A take-off alternate must be selected and specified in the flight plan if:

1. Weather conditions at the departure aerodrome are below the operator's landing minima.
2. It is not possible to return to the departure aerodrome for other reasons.

Decision Flowchart: Do I Need a Take-off Alternate?

Chapter 3: Approach Categories (CAT I, CAT II, CAT III)

Instrument approach operations are classified based on the decision height (DH) and runway visual range (RVR) minima.

3.1 🟢 Category I (CAT I)

A precision instrument approach with:

• Decision Height (DH): Not lower than 200 ft (60 m).
• Visibility/RVR: Visibility not less than 800 m OR RVR not less than 550 m.

3.2 🟡 Category II (CAT II)

A precision instrument approach using ILS with:

• Decision Height (DH): Lower than 200 ft (60 m) but not lower than 100 ft (30 m).
• RVR: Not less than 300 m.

Required RVR for CAT II Operations

Decision Height	Aeroplane CAT A, B, C (RVR)	Aeroplane CAT D (RVR)
100 ft - 120 ft	300 m	350 m (or 300 m if autoland)
121 ft - 140 ft	400 m	400 m
141 ft - 199 ft	450 m	450 m

3.3 🔴 Category III (CAT III)

A precision instrument approach with a DH lower than 100 ft (30 m) or no DH, and an RVR less than 300 m. It is subdivided as follows:

• CAT III A:
  • Decision Height (DH): Lower than 100 ft or no DH.
  • RVR: Not less than 175 m.
• CAT III B:
  • Decision Height (DH): Lower than 50 ft, or no decision height.
  • RVR: Lower than 175 m but not less than 50 m.

Required RVR for CAT III Operations

Decision Height	Roll-out Control/Guidance System	RVR
< 100 ft (or no DH)	Not required	175 m
< 50 ft (or no DH)	Fail-operational required	50 m

Chapter 4: RVR, CMV, and Visibility Requirements

4.1 👁️ Definitions

• Runway Visual Range (RVR): The range over which a pilot on the centerline of a runway can see the runway surface markings or lights.
• Visibility: The greater of the distance at which a black object can be seen against a bright background, or the distance at which lights of ~1000 candelas can be seen against an unlit background.
• Converted Meteorological Visibility (CMV): A value equivalent to an RVR, derived from the reported meteorological visibility.

4.2 🔄 Conversion of Visibility to RVR

When RVR is not reported, a CMV may be derived from the reported meteorological visibility. This conversion must NOT be used for:

• Take-off.
• Calculating any RVR minimum less than 800 m.
• When a reported RVR is available.

Conversion Factors (Meteorological Visibility x Factor = RVR/CMV)

Lighting Elements in Operation	Day Factor	Night Factor
HI approach and runway lighting	1.5	2.0
Any other type of lighting	1.0	1.5
No lighting	1.0	Not Applicable

4.3 🚦 Approach Ban Policy

This policy dictates when an instrument approach can be commenced or continued based on reported weather.

Chapter 5: Adverse Weather & Icing Operations

This chapter summarizes the requirements from Annexure 1: Adverse Weather/Monsoon Operations, which applies to operations in conditions that degrade runway surfaces due to rain, snow, sleet, or other contaminants.

5.1 💧 Wet and Contaminated Runways

• Wet Runway: A runway surface covered by visible dampness or water up to 3 mm deep.
• Contaminated Runway: A significant portion of the runway is covered by substances like water, snow, or sleet.
• Aircraft Performance: Ground training must cover aircraft performance during take-off and landing on wet and contaminated runways.
• Approach Briefing: The approach briefing before Top of Descent must include the wet/contaminated Actual Landing Distance (ALD) calculation.

5.2 ❄️ Minimum Equipment List (MEL) for Adverse Weather

For all commercial transport flights to or from aerodromes with forecast or actual adverse weather, the following must be fully serviceable:

• Weather radar.
• Windshield wipers (where fitted).

For aircraft not certified for adverse weather performance, the following must also be serviceable:

• All deceleration devices (thrust reversers, speed brakes).
• Anti-skid system.
• Anti-icing/de-icing system.

Chapter 6: Aerodrome Operating Minima (AOM)

Operators must establish AOM for every planned aerodrome. There are two types: Normal and Restricted.

6.1 Normal vs. Restricted AOM

Type	Description	Application
Normal AOM	Standard minima calculated based on airport facilities, procedures, and obstacles.	Applied by scheduled and general aviation operators. Non-scheduled operators may apply if specific conditions are met.
Restricted AOM	Normal AOM with added height and visibility requirements.	Applied by non-scheduled operators not authorized for Normal AOM, or by PICs with less than 100 hours command experience on type.

6.2 🔄 Alternate Aerodrome Minima (For Dispatch)

Approach Facility Configuration	Required Ceiling	Required Visibility/RVR
Airport with one approach	Authorized DA/H or MDA/H + 400 ft	Authorized visibility + 1500 m
Airport with at least two approaches to different suitable runways	Authorized DA/H or MDA/H + 200 ft	Authorized visibility + 800 m

Chapter 7: Operational Procedures

This section consolidates key operational procedures from the CAR, which supersedes previous circulars on monsoon and LVTO operations.

7.1 Stabilized Approach

• Requirement: All approaches must be flown as stabilized approaches (SAp) unless specifically approved otherwise by the DGCA for a particular runway.
• Definition: An SAp is flown in a controlled manner (configuration, energy, flight path) from a pre-determined point down to 50 feet above the threshold or where the flare begins.

7.2 Non-Precision Approaches (NPA)

• Technique: All NPAs must be flown using the Continuous Descent Final Approaches (CDFA) technique, unless approved otherwise.
• Penalty for Non-CDFA: If not using the CDFA technique, the minimum RVR must be increased by 200 m for Cat A/B aeroplanes and 400 m for Cat C/D aeroplanes.

7.3 👨‍✈️ PIC Responsibilities Before Approach

Before commencing an approach, the PIC must be satisfied that:

• The weather at the aerodrome is safe for an approach, landing, or missed approach.
• The condition of the intended runway is acceptable.
• The status of visual and non-visual facilities is sufficient for the operation.
• For low visibility operations, appropriate Low Visibility Procedures (LVP) are in force.

Chapter 8: Training, Crew Qualification, and Operator Approval

8.1 📚 General Training for AWO

Operators must establish a comprehensive, DGCA-approved training programme for all flight crew. This includes ground, simulator, and flight training covering:

• Characteristics of visual aids and flight systems.
• Use of RVR/Visibility reports and the effects of fog.
• Procedures for take-off, approach, landing, and missed approach in reduced visibility.
• Actions to be taken in case of equipment failure.

8.2 Qualifications for CAT II / CAT III Operations

PIC Flying Experience

• Total Flying Experience: 2500 hrs.
• PIC on Type: 500 hrs (or less with previous CAT II/III authorization).
• Night Flying on Type: 100 hrs.

Co-pilot Flying Experience

• Total Flying Experience: 500 hrs.
• On Type Experience: 300 hrs (or 100 hrs with previous authorization).

Simulator Training (Initial)

Pilots must undergo specific ground training, simulator training sessions, and simulator checks for CAT II and CAT III authorization. This includes handling engine failures and go-arounds in simulated low visibility conditions.

Recency Requirements

To remain current for CAT II/III, a pilot must have performed a minimum of 6 CAT II/III approaches, including at least 3 landings, in an approved simulator within the preceding 6 months.

8.3 Qualifications for LVTO

• Experience: The PIC and Co-pilot should have 100 hours on the aeroplane type before being authorized for LVTO.
• Training: Pilots must complete a DGCA-approved LVTO training program, including simulator training covering:
  • Take-offs at authorized RVR.
  • Rejected take-offs at low and high speeds.
  • Diversion to a take-off alternate after an engine failure at V1.

Chapter 9: ✨ AI Scenario Trainer

Chapter 10: ✨ Quick Regulation Lookup

Appendices

Appendix A: Quick Reference Tables

Table A1: Take-off Minima (RVR/Visibility)

RVR/VIS	Facilities
500 m	Adequate Visual Reference (Day)
400 m	Runway edge lights OR Centre line markings
300 m	Runway edge lights AND Centre line markings
200 m	Runway edge lights AND Centre line lights
150 m	Edge & Centre line lights + RVR info
125 m	High-intensity Edge & Centre line lights (≤15 m spacing) + RVR info
75 m	High-intensity Edge & Centre line lights (≤15 m spacing) + lateral guidance + RVR info

Table A2: Alternate Aerodrome Minima (Dispatch)

Configuration	Ceiling Additive	Visibility Additive
One approach	+ 400 ft	+ 1500 m
≥ Two approaches	+ 200 ft	+ 800 m

Appendix B: Glossary of Key Terms

• Aerodrome operating minima: The limits of usability of an aerodrome for take-off or landing, expressed in terms of RVR/visibility, cloud conditions, and DA/H or MDA/H.
• All weather operations (AWO): Operations where visual reference is limited by weather conditions.
• Decision altitude (DA) / decision height (DH): A specified altitude or height in a 3D instrument approach at which a missed approach must be initiated if the required visual reference is not established.
• Low visibility take-off (LVTO): A take-off on a runway where the RVR is less than 400 m.
• Minimum descent altitude (MDA) / minimum descent height (MDH): A specified altitude or height in a 2D instrument approach or circling approach, below which descent must not be made without the required visual reference.
• Runway visual range (RVR): The range over which the pilot of an aircraft on the centreline of a runway can see the runway surface markings or lights.
• Stabilised Approach (SAp): An approach flown in a controlled and appropriate manner from a pre-determined point down to 50 feet above the threshold or the point where the flare is initiated.

Appendix C: Further Guidance

The DGCA CAR frequently references the ICAO Manual of All-Weather Operations (Doc 9365) for further guidance on topics such as the establishment of aerodrome operating minima and operational credits. Operators and pilots should consult this document for a deeper understanding of the principles behind all-weather operations.