.

METEOROLOGICAL HAZARDS IN AVIATION

Cpt. Ing. Naděžda Bartošová Ph.D.

1. DEFINITIONS

2. TYPES OF METEOROLOGICAL HAZARDS

3. KEY WORDS

1. DEFINITION

METEOROLOGICAL HAZARDS IN AVIATION are the phenomena, that can affect the safety of the flight.

2. TYPES OF METEOROLOGICAL HAZARDS

FOG

ICING

TURBULENCE

THUNDERSTORM

FOG

● Visibility is reduced under 1 km

● Types:

radiation fog (in the morning, local character)

advection fog (huge, with the drizzle)

frontal fog (moving with the frontal system)

ICING

● ICING IS NOT caused by ice in cloud, is caused by SUPER - COOLED liquid water droplets.

● ICING FACTORS:

- LWC

- Temperature (0 ;– 20)

- Droplet size

- Cloud type

- Airfoil geometry

- Airspeed

- Duration of exposure

ICING

● LUQIUD WATER CONTENT :

- is amout of available water,

- varies from cloud to cloud,

- depends on temperature

ICING

● CUMULATIVE AFFECTS OF ICING:

Decreases

Thrust

Radio communication problems , Blockage of pitot tubes and static vents ,

Adverse Aerodynamic Effects .

ICING TYPES

● Clear icing

- is often clear and smooth,

- Supercooled water droplets, or freezing rain, strike a surface but do not freeze

instantly.

● Rime icing

- is rough and opaque,

- formed by supercooled drops rapidly freezing on impact.

● Mixed icing is a combination of clear and rime ice.

● Frost icing is the result of water freezing on unprotected surfaces while the aircraft is stationary.

● SLD icing

- Supercooled Large Droplet (SLD) conditions,

- similar to clear ice.

ICING PREVENTION

● Mechanical means, which may be as simple as using a broom or brush to

remove snow

● Application of Deicing fluid

● Use of infrared heating to melt and remove contaminants

● Put the aircraft into a heated hangar until snow and ice have melted

● Position aircraft towards the sun

TURBULENCE

Def: Turbulence can be defined as small-scale, short-term, random and

frequent changes to the velocity of air

TYPES:

● Light, moderate, severe, extreme

● THERMAL

above a warm surface

● MECHANICAL

caused by interference of surface features on the horizontal flow of air

● SHEAR

wind changes dramatically within a short horizontal or vertical distance

● AERODYNAMIC

caused by an aircraft as it flys through the air (wake turbulence)

TURBULENCE

THERMAL MECHANICAL SHEAR

THUNDERSTORMDEF:

● a storm caused by strong rising air currents and characterized by thunder and lightning and usually heavy rain or hail.

● formed by a process called convection, defined as the

transport of heat energy

TYPES: frontal

non – frontal

HAZARDS:

● severe turbulence,

● low level windshear,

● low ceilings and visibilities,

● hail and lightning

THUNDERSTORM

3 STAGES:

Towering Cumulus Stage:

- visible clouds of liquid water,

- upward motion throughout the cloud,

- turbulence and icing.

Mature Stage:

- production of precipitation,

- updrafts /downdrafts motion,

- turbulence, lightning, icing, microburst.

Dissipating Stage:

- final stage,

- downdrafts,

- moderate precipitation.

THUNDERSTORM

STRUCTURE:

Single cell

Multi cell

Super cell

THUNDERSTORM

HAZARDS:

severe turbulence,

low level windshear,

low ceilings and visibilities,

hail and lightning

KEY WORDS

FOG - radiation/frontal/advection fog

ICING – clear/rime/mixed icing

TURBULENCE – light/moderate/severe/extreme

THUNDERSTORM - single/multi/super cell

THANK YOU FOR YOUR ATTENTION !