FROSTSNOWICE

1
FROST/SNOW/ICE

• FAR 91.527 Operating in icing conditions.
• (a) No pilot may takeoff an airplane that has-
• (1)Frost, snow, or ice adhering to any
  propeller, windshield, or powerplant installation
  or to an airspeed, altimeter, rate of climb, or
  flight attitude instrument system
• (3)Any frost adhering to the wings or
  stabilizing or control surfaces, unless that
  frost, has been polished to make it smooth

2
FROST/SNOW/ICE

• Assuming that a thin coating of frost or ice is
  of no consequence, or that snow will blow off
  during takeoff is to court disaster!
• Frost/snow/ice on wing and tail surfaces during
  takeoff has been a contributing factor in a
  number of well-publicized aircraft accidents

3
FROST/SNOW/ICE

• All frost/snow/ice should be removed before
  attempting flight
• For frost or ice, place aircraft in heated
  hangar, if possible ( be sure water doesnt run
  into control surfaces re-freeze when aircraft
  is brought outside, again)

4
FROST/SNOW/ICE

• For snow, brush off (dont count on blowing off
  during takeoff roll!)
• Note Sometimes frost adheres to surfaces below
  snow covering
• Alcohol, glycol or other ice-removal chemicals
  can be used
• Exercise extra care when warm aircraft has been
  pulled from hangar and left out in snow conditions

5
FROST/SNOW/ICE

• Following snow conditions, be extra careful on
  pre-flight to check
• Inside pitot tube
• Static opening
• Fuel vents
• Heater intake
• Carburetor intake
• Trim tabs and controls
• Wheel wells

6
FROST/SNOW/ICE

• Unseen Frost
• Same conditions which cause frost formation on
  external surfaces can cause internal problems
• Moisture in fuel tanks can freeze (good reason
  for topping tanks after flight) and can cause
  blockage of fuel flow to engine

7
FROST/SNOW/ICE

• Every year, there are between 30 and 40 accidents
  involving icing, approximately half of which are
  fatal
• Many pilots underestimate rate of ice
  accumulation and its effect on aircraft
  performance
• If aircraft has enough ice to be unable to hold
  altitude, chances of making it safely to
  on-airport landing are poor

8
FROST/SNOW/ICE

• Typically, even small buildup of ice can cause
  30 reduction in max. coefficient of lift,
  decreasing the stall angle-of-attack
• Drag builds up, and if it exceeds max. thrust
  (full throttle), leads to descent, whether
  desired or not!
• Thrust also lost due to ice accumulation on
  propellor

9
FROST/SNOW/ICE

• First place ice accumulates is small-radius or
  sharp-edged surfaces (fuel vent, temp. probe,
  etc)
• Small leading edge on tail surfaces make them
  more efficient collectors of ice (almost twice as
  fast as wing ice accumulation) tail may reach
  stall angle-of-attack before wing becomes problem

10
FROST/SNOW/ICE

• Since horizontal tail produces down lift, stall
  results in tail going up, and aircraft nose
  pitching down
• Flap deflection increases downwash on tail,
  leading to higher (more negative)
  angle-of-attack, and earlier stall, if tail is
  iced

11
FROST/SNOW/ICE

• Bottom line, when experiencing icing
• If runway length permits, use 10 to 20 knots
  higher approach speed for the aircraft
  configuration being used
• Do not use full flaps if possible, do not use
  any flaps
• Use power all the way to touchdown (dont chop
  throttle while airborne)