1. Welcome
Kevin McNulty, Aerospace Education Officer
• Email: kevmcnulty@gmail.com
• Home phone: 941-729-8928
• Cell phone: 941-737-8575
• Send me email if you would like a copy of this
PowerPoint!

2. Welcome
Module 3:
The Air Environment
Part Deaux

3. Overview
Module Learning Objectives
Chapter 1 - Air Circulation
 Describe how the Sun heats the Earth
 Describe the Earth’s rotation and revolution and
its effect on the seasons
 Explain the various theories of circulation
 Describe Coriolis Force
 Define the jet stream
(give three examples…just kidding)

4. Overview
Module Learning Objectives
Chapter 2 - Weather Elements
 Define wind
 Describe the Beaufort Scale
• Define heat
• Explain what temperature is and how it can be
expressed
• Describe what wind chill is and what it does
• Describe how a microburst can affect a plane

5. Overview
Module Learning Objectives
Chapter 3 - Moisture and Clouds
• Describe the condensation process
• Describe how saturation occurs
• Define dew point
• Define what precipitation is and give some
examples (not kidding this time)
• Define fog
• Define turbulence

6. Overview
Module Learning Objectives
Chapter 4 - Weather Systems and Changes
• Define an air mass and their characteristics
• Define a front and describe types of fronts
• Describe hurricanes, thunderstorms, and
tornadoes
• Identify the stages of a thunderstorm
• Outline safety precautions for thunderstorms and
tornadoes

7. Chapter two
Temperature and Pressure
NOT
• Heat = total energy
HOT • As heat increases,
pressure increases.

8. Chapter three
Moisture
Water Vapor & Saturation
• Water has solid (ice), liquid (water), and gaseous
(water vapor) forms
• Air always holds some amount of water vapor
• Warm air can hold more water vapor than cold air
• When air is holding as much water vapor as
possible, it is saturated

9. Chapter three
Moisture
Dew Point, Condensation & Humidity
• The temperature at which the air is saturated is
called the dew point
• When the temperature falls below the dew point,
condensation occurs
• Clouds and fog are products of condensation
• Relative humidity is is the amount of moisture in
the air vs. the amount the air can hold (I.e. - 90%)

10. Chapter three
Moisture
=
+

11. Chapter three
Moisture
Cumulus
Formation
• Rising air
cools
• Hits dew pt
• Condenses
into cloud
• Convection = TURBULENCE

12. Chapter three
Moisture
Precipitation
• Condensed water vapor that falls to ground
• Examples: rain, snow, ice, hail, ducks, trains
• Rain reduces visibility & runway traction
• Falling ice/hail can damage aircraft
• Snow and freezing rain reduce visibility & traction,
but can also lead to icing

13. Focus on
Icing
Triple Threat
• Ice on runway causes loss of directional control,
excessive landing roll, and accidents
• Ice on aircraft causes excessive weight, loss of lift
by altering airfoil camber, loss of thrust by changing
propellor camber, visibiity problems on windshield
• Ice in engines can cause restricted fuel flow (in
carburetor of piston engine) or clogged or
malfunctioning sensors in jets

14. icing
Air Florida 90
• January 13, 1982, Air Florida 90 failed to achieve takeoff
due to ice on airfoil and engines underpowered due to
ice/snow-clogged pressure sensors
• 4 crew, 70 passengers, 4 on ground killed - 5 survived

15. icing
Air Florida Flight 90, January 13, 1982
Sequence of Events Leading up to Crash
• January 1982 was one of the worst periods of
exceptionally cold weather in history on the east coast.
• For several days, freezing temps had brought traffic to a
standstill and interfered with activities around the capital.
• On January 13, Washington National Airport had opened
at noon under marginal conditions.
• That day, AF 90 left Miami International at 11:00 a.m.
EST and arrived at National at about 1:45 p.m. EST.

16. icing
Air Florida Flight 90, January 13, 1982
Sequence of Events Leading up to Crash
• That afternoon the plane was to return south to
Fort Lauderdale-Hollywood International Airport (FLL),
with an stop at Tampa International Airport (TPA).
• Departure time was delayed about 1 hour 45 minutes
due to snow, which temporarily closed the airport.
• The aircraft was de-iced by spraying the wings with the
monopropylene glycol before leaving the gate.

17. icing
Air Florida Flight 90, January 13, 1982
Sequence of Events Leading up to Crash
• AF90 was delayed leaving the gate when the ground
services tow motor could not get traction on the ice.
• For almost 5 min the crew tried to back away using
reverse thrust, which proved futile and evidently resulted
in the engines ingesting ice and snow.
• Eventually a tug unit properly equipped with snow chains
was used to push the aircraft back from the gate.
• After finally leaving the gate AF90 waited on taxiway for
49 minutes in line with other aircraft for clearance to use
the congested airport's only instrument-rated runway

18. icing
Air Florida Flight 90, January 13, 1982
Sequence of Events Leading up to Crash
• The pilot apparently decided not to return to the gate for
reapplication of de-icing, fearing the flight's departure
would be even further delayed, and chose to continue
waiting to take off.
• Then, with snow and ice on the airfoil surfaces of the
aircraft, the aircraft attempted to take off on the main
(and only open) runway in heavy snow at 3:59 p.m. EST.

19. icing
Air Florida Flight 90, January 13, 1982
Sequence of Events Leading up to Crash
• Even though it was freezing and snowing, the crew did
not activate the anti-ice systems.
• Analysis of CVR determined that during the departure
checklist, the copilot announced, and the pilot confirmed,
that the plane's own anti-icing system was turned off.
• Also, the pilots maneuvered closely behind a DC-9 in
front of them, thinking the warmth from the DC-9's
engines would melt the snow and ice on their wings.
(Contrary to flight manual recommendations for an icing
situation and actually contributing to icing on the 737.)

20. icing
Air Florida Flight 90, January 13, 1982
Sequence of Events Leading up to Crash
• Without the engine anti-icing system the
engine pressure ratio (EPR) thrust indicators provided
false high readings.
• When the pilots thought they throttled up to the correct
take-off EPR of 2.04, the actual EPR was only 1.70.
• As the plane began its takeoff roll the FO noted several
times to the CPT that instrument readings did not seem
to reflect reality - the plane did not seem to have
developed as much power as it needed for takeoff,
despite the instruments indicating otherwise.

21. icing
Air Florida Flight 90, January 13, 1982
Sequence of Events Leading up to Crash
• The CPT dismissed the FO’s concerns and let the
takeoff proceed.
• The captain likely felt pressure to depart quickly because
he knew another aircraft was on final approach using the
same runway. Indeed, that aircraft landed just as the Air
Florida plane took off and had Flight 90 aborted its
takeoff the aircraft on final would have been instructed
by air traffic controllers to execute a missed approach,
delaying its arrival.

22. icing
Air Florida Flight 90, January 13, 1982
Sequence of Events Leading up to Crash
• Although AF90 did manage to become airborne, it
attained a max altitude of just 352 ft before it began
losing altitude. The aircraft was airborne for just 30 sec.
• At 4:01 it crashed into the 14th Street Bridge across the
Potomac River, .75 nm from the end of the runway,
hitting 7 vehicles and plunging into the freezing river.
• All but the tail section quickly became submerged.

23. icing
Air Florida Flight 90, January 13, 1982
Video & CVR

25. icing
Air Florida Flight 90, January 13, 1982
NTSB Determination
• Probable cause: pilot error
• failure to use engine anti-ice
• decision to take off with snow/ice
on the airfoil surfaces
• captain’s failure to reject the
takeoff during the early stage
when attention was called to anomalous engine
instrument readings
• maneuvering behind DC9; reverse thrust at gate

26. icing
Air Florida Flight 90, January 13, 1982
NTSB Determination
• Contributing to the accident
• prolonged ground delay between de-icing and the
receipt of ATC takeoff clearance during which the
aircraft was exposed to continual precipitation
• the known inherent pitch up characteristics of the
B-737 aircraft when the leading edge is contaminated
with even small amounts of snow or ice
• the limited experience of the flight crew in jet transport
winter operations

27. Exercise
friendly rivalry
Instructions
• Individual and team effort needed: make sure you get each others’
phone & email & work together
• If you can’t agree, commander makes decision
• I will be available at 1730 next two Mondays
• Start with wikipedia & www.globalsecurity.org
• Summary Reports due by 2100 on AUG 18
•Include map with routes
•Aircraft assignments
•Individual answer sheets from team members

28. Exercise
friendly rivalry
Team Member Grade
• 70% grade based on individual effort
•Answer sheet should be complete and NEAT
• 30% grade based on commander’s evaluation of your team effort
Team Commander Grade
• 50% grade based on individual effort
• 50% grade based on mission report, maps, & team communication