Basic instruments (lesson 2) Flashcards
Position errors increase…although…
With speed, although generally cancelled out by computer
P errors reduced likelihood by having
A port on the other side
Height is above
Airfield QFE
ALT is above
Sea level QNH
FL is above
SPS (1013.25)
At transition altitude you switch from
Alt to FL
At transition level you switch from
FL to ALT
Transition altitude is given in the
Charts
The transition level is given by
The ATC
Barometric error
Differences of pressure in area, despite the QNH area being the same
Time lag / hysteresis is … & is mainly due to
Time it takes for pressure to go from port to instrument.Mainly due to friction of the gears and the linkages
Altimeter source is blocked….(altimeter still thinks it’s at altitude it was at before block.
With static pressure on decent / climb what happens?
With pitot pressure on decent /climb what happens?
SOD
SUC
PUD
POC
Simple altimeter consists of
One capsule. One pointer hand.
Rough scale. Typically 0 to 10,000ft.
No setting a reference pressure
The sensitive altimeter
Consists of
More accurate than the simple altimeter
Can set reference pressure = calibrate option
More than one capsule
Servo altimeter
Consists of
More accuracy & sensitive than the sensitive altimeter bc capsule stack only has to overcome lag of the capsule.
Lag is virtually eliminated.
E & I shaped things (transducer).
Mode C
_transmits to ATC => gives height info
Mode S
Expensive…
Allows a/c to coordinate for avoidance
Mode a
“There’s an aircraft” indication
How mode c works
- Sensitive altimeters with an encoding system, supply info to a/c’s transponder.
- This then transmits to ATC when mode C is selected on transponder.
Density altitude is
Air density given as a height above mean sea level .
Density altitude = formula
Pressure altitude + (ISA dev x120ft)
VSI
If blocked?
What else?
How work?
Will slowly return back to zero. (As no change in pressure)
⚫️Sensitive to lag
⚫️Not partially evacuated
Compares actual static pressure immediately with a delayed value of actual static pressure.
What does IVSI do?
Cancels out the time lag
From the table in the book, what two instruments don’t need a pitot source?
Altimeter & VSI
