Virtual Skies

Weather You Decide

Step 1
Questions Question 1 Question 2 Question 3
A.   Decision to be made
(Phrased as a question.):
Is the runway long enough for this aircraft to gain the speed and height needed to clear any obstructions at the end of the runway?
Will the flying speed and climb rate of the aircraft be great enough to fly safely above the mountains?
How will density altitude and temperature affect the aircraft's flight performance?
B.   Critical Factors Involved

runway length and aircraft's take off distance requirements

obstructions at end of runway

weight of loaded airplane

current temperature and density altitude

wind conditions

current and forecasted weather conditions

airport's elevation

aircraft's flight specifications for fuel, payload weight and climb rate

flying speed and climbing speed

tailwinds and headwinds

distance to mountains from airport

height of mountain peak

maximum climb performance of aircraft

air temperature and air pressure changes with altitude

temperature at peak of mountain

 

C.   Information known

runway is 8,544 feet long with a 50 foot obstruction at one end based on airport directory map

Takeoff speed can be computed from aircraft specifications manual based on weight of loaded aircraft

Climb Performance Chart will assist with climb information and calculations

Formula for computing flight time: Total # of gallons of fuel divided by fuel flow.

Formula for computing fuel consumed = fuel flow (gallons per hour) multiplied by time

Time = distance divided by speed
ground speed +/- wind speed = airspeed

Climb Performance Chart will assist with climb information and calculations

The temperature drops 1.8 degrees Celsius for every 1,000 feet


The peak's height is 11,743 feet based upon aeronautical chart

Airport's elevation is 6,264 feet.

D.   Information needed
(question)

A) What is the weight of this loaded aircraft?

B) According to the aircraft specifications what will be the maximum takeoff speed?

C) Will the wind at takeoff be a positive or negative factor?

D) How long is the runway?

E) How tall are any obstructions within takeoff path?

F) What is the airport's elevation or alittude?

G) What is the current air temperature?

H) What is the current density altitude?

I) Can I substitute density altitude calculations for air pressure altitude when using the Takeoff Performance Chart?

J) What information is needed to correctly calculate the aircraft's ability to takeoff safely under the current conditions using the Takeoff Performance Chart?


A) What is the distance from airport to peaks that need to be crossed?

B) What will be my flying speed (considering wind as a factor)?

C) How many minutes will it take the airplane to reach the mountain?

D) Based upon the aforementioned factors, how many feet per minute will the airplane need to climb in order to clear peaks safely? (calculated climb performance)

E) How does one read a Climb Performance Chart?

F) What do the weather reports indicate?

G) What is the formula for computing flight time given distance?

H) Does climb performance change along with changes in air temperature and air density?

I) What will be the maximum climb performance of this aircraft as indicated by aircraft flight specifications, weather, temperature and density altitude?

A) What happens to air temperature as altitude increases?

B) What information is needed to compute density altitude at the mountain's peak?

C) What is the density altitude at the mountain's peak?

D) Under the current flight conditions what will be the maximum climb performance for this aircraft?

E) How does the calculated climb performance compare to the aircraft's actual climb performance based upon the Climb Performance Chart?

F) What will the air temperature at the airport have to be in order for the aircraft to climb safely over the peaks?

E.   Resources for
fact-finding

airport directory map for runway length and obstructions

aircraft's flight specifications manual

aeronautical chart to determine distances

weather reports for airport and area

climb performance chart to compute climb rate

aeronautical chart to determine distances

climb performance chart to compute climb rate

density altitude chart to compute density at different altitudes and temperatures

F.   Answers to
each question

A) 2,550 pounds

B)

C) Positive factor.

D) 8,544 feet in length

E) Trees 50 feet tall.

F) 6,264 feet in elevation

G)

H)

I) Yes, you can substitute density altitude calculations for air pressure altitude when using the Takeoff Performance Chart.

J) You need the calculated density altitude, the current air temperature, airplane's total weight, headwind speed, runway distance and clearance height for obstructions (calculated takeoff distance).

 

 



Step 2
A.   Possible Decisions B.   Negative
Consequences
B.   Positive
Consequences
C.   Rationale

1) Do not even attempt to take off today. Reschedule flight for late tomorrow morning depending upon weather report.

A) You'll be late getting back home. B) You'll have to file another flight plan C) You'll have to do some more calculations in the morning after chacking the weather reports.

A) You will be able to fly safely out of the area, clearing the peaks within FAA regulations.
B) You will have a better chance to survive the flight.

 

2) Leaving behind any extra weight and recalculate all parameters. Take off as soon as possible. Circle the Lake Tahoe basin to attempt an altitude gain before crossing peaks.

A) You'll have to find another way to get all your stuff home.
B) It may still have a greater than normal level of risk depending upon how much weight you can shed and how much colder it will get.
C) Any sudden drops in temperature while you are in flight, will jeopardize your aircraft's ability to fly safely over the peaks.

If you make it you'll get home on schedule.

 

3) Go ahead and take off because you will clear the runway and who knows, there's a slim chance you could just clear the peaks.

A) You will not clear the peaks according to all the calculations.
B) With the temperature changes and the impending weather changes, the risk is too great for loss of life and aircraft.

A) You will clear the runway and obstructions.

 


Step 3
Final decision with rationale: TOP 3 CHOICES First Choice: Second choice: Third Choice:  
Reflect upon decision:

 

 

 

 

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