Special Operational Procedures and Hazards

Air Regulations · Chapter 17 · DGCA CPL and ATPL

The things that can bite you in real operations, from ice and birds to fire, wind shear and the wake of a bigger aircraft, and the rules that keep each one in check.

Remember

Never take off with ice: a roughness of just 0.40 mm (1/64 in) disrupts the airflow. De-icing removes it; anti-icing protects only for the holdover time.
Fire classes: A solids, B liquids, C electrical, D metals. No water on B or C, and never Halon on D.
In a decompression the crew put on oxygen first, then descend to 10 000 ft or MEA; passenger masks drop by 14 000 ft.
A microburst on take-off gives a headwind surge, then a downdraft of up to 6000 fpm, then a tailwind: use full power and pitch towards maximum angle of attack.
Wake separation is 2 to 4 minutes by time, 5 to 8 NM by radar; the heavier the leader and the lighter the follower, the bigger the gap.

Where do the special hazards come from?

The big picture

Hazards grouped by when you meet them. Tap a box with + to open it.

Special hazards and the rules for each The special procedures and hazards of this chapter: equipment lists, icing, birds, noise, brakes, runways, fire, decompression, wind shear, wake turbulence and fuel jettison.
- Before departure defects and ice What decides whether the aircraft may go: the MMEL and MEL for unserviceable equipment, the Flight Manual limits, and a surface free of ice.
  - MMEL manufacturer's list, DGCA approved Lists equipment that may be unserviceable, and the conditions for flying with it.
  - Operator MEL part of the Operations Manual Part of the Operations Manual and approved by the DGCA. It lets the PIC decide whether a flight may start, or continue from an intermediate stop, with something inoperative.
  - Flight Manual (AFM) approved by the State of design Fly within the C of A and AFM limitations.
  - Clean aircraft concept no ice on critical surfaces In icing conditions on the ground, do not take off until the aircraft has been checked and, if needed, de-iced or anti-iced. Any ice at all matters.
- Around the aerodrome birds, noise, brakes, runways Hazards met on and near the aerodrome: bird strikes, noise abatement limits, overheated brakes, and wet or contaminated runways.
  - Bird strikes shell crackers work best In the air, the only real defence is to stay away from big groups of birds, so warnings are vital. Nine in ten strikes happen below 500 m; noise shells (shell crackers) scare birds away best.
  - Noise abatement not below 240 m (800 ft) Noise procedures are not flown below 240 m (800 ft), nor where wind shear is warned or suspected, and never at the expense of flight safety.
  - Overheated brakes after a rejected take-off Also after a heavy-braking landing. Ask for Fire and Rescue; the PIC decides on evacuation.
  - Wet runway, aquaplaning landing distance at least 115% If the runway may be wet at arrival, landing distance available must be at least 115% of that required. Tyres aquaplane on standing water deeper than the tread.
- Emergencies in flight decompression, fire, landing off Emergencies once airborne: loss of cabin pressure, fire on board, dumping fuel, and landing away from a runway or on water.
  - Depressurisation oxygen, then descend The great danger is crew incapacitation from hypoxia. Crew put on oxygen as soon as possible, then descend, conventionally to 10,000 ft.
  - Fire triangle: oxygen, heat, fuel Combustion needs oxygen, heat and fuel. Firefighting removes at least one of them, using the extinguisher that suits the class of fire.
  - Fuel jettison at or above 1800 m (6000 ft) Getting rid of fuel to come down to maximum landing weight. The crew tells ATC, the route keeps clear of towns, and the level should be 1800 m (6000 ft) or higher.
  - Forced, precautionary, ditching three kinds of emergency landing Forced: flight cannot continue. Precautionary: flight is possible but inadvisable. Ditching: either kind of landing on water.
- The air around you wind shear and wake Hazards in the air itself: wind shear, microbursts, and the wake vortices left by other aircraft.
  - Wind shear alert gates 25/40/50 kt at 500/1000/1500 ft Significant non-convective wind shear exists when the vector exceeds 25 kt within 500 ft, 40 kt within 1000 ft or 50 kt within 1500 ft AGL.
  - Microburst 1 NM core, 6000 fpm down A small, intense downdraft that spreads outward at the surface. About 1 NM across at 2000 ft AGL, with vertical winds up to 6000 ft per minute.
  - Wake vortices sink 500 to 900 ft Made only when a wing produces lift; strongest behind a heavy, clean, slow aircraft. They sink below its path and spread sideways up to 5 miles.
  - Wake categories Super, Heavy, Medium, Light By maximum certificated take-off mass. Heavy is 136 000 kg or more; Light is 7000 kg or less.

Takeaway: Defects and ice before departure, birds and noise at the aerodrome, decompression and fire in flight, wind shear and wake around you.

How do you get the ice off before take-off?

Ground icing

Four steps from walk-round to take-off.

Inspect critical surfaces clean aircraft concept Take-off is prohibited unless the aircraft is confirmed clean. There is no insignificant amount of ice.
De-ice heated fluid (ADF) Removes frost, ice, snow and slush already on the aircraft.
Anti-ice fluid (AAF), holdover time Applied on clean surfaces. Protects only for a limited holdover time until take-off.
Check for cold-soak ice touch check or detector Clear ice can form on cold-soaked wings even when the outside air is above 0 C. Shed ice can flame out rear engines or hit the tailplane.

Memory hook: De-ice removes, anti-ice protects.

Takeaway: Inspect, de-ice with heated fluid, anti-ice to protect, then check for clear ice on cold-soaked wings before you go.

Where does ice hurt the aircraft?

Where ice hurts

An airliner on a cold, wet ramp. Tap each number.

This lesson is part of the Exam-Ready plan. See plans

What shapes take-off and landing performance?

Performance factors

AFM, equipment lists, runways and birds. Tap + to open each.

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Which extinguisher for which fire?

Fire classes

Read each case and press the stamp that applies.

This lesson is part of the Core plan. See plans

Which extinguisher, by colour?

Extinguishers

Each canister shows its colour and the fire classes it fights. Tap a card.

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What happens when the cabin loses pressure?

Decompression

Blue is the aircraft, red dashes the cabin. Follow the numbers from the bang to level flight.

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What caused the decompression, and how bad is it?

Decompression

Answer about what happened.

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Why is a microburst so dangerous on take-off?

Microburst

Follow the take-off path left to right: headwind, then downdraft, then tailwind.

This lesson is part of the Core plan. See plans

How do wake vortices move, and how to avoid them?

Wake vortices

From behind, from the side, then how to stay clear. Tap each number.

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How far behind, how much shear, which runway?

Wake and wind

Three views: wake minima by pair, wind shear and the noise crosswind limit.

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Do wake turbulence minima apply here?

Wake minimum?

Answer for the two aircraft in question.

This lesson is part of the Exam-Ready plan. See plans

Noise abatement: what may and may not be done?

Noise abatement

From take-off to landing.

This lesson is part of the Exam-Ready plan. See plans

What must be reported, and what is forbidden?

Report or forbid

Security, landings, fuel dumping, dangerous goods and wind shear. Tap + to open each.

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Numbers to know

Numbers

The hazard figures examiners like, in one list.

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Pairs that catch students out

Don't mix up

Each pair looks alike. The rule underneath tells them apart.

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Test yourself

Ten questions from this chapter.

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