My IFR Flashcards
(13 cards)
Blocked static port - what happens to instruments?
Summary
Altimeter frozen, VSI zero
ASI
Climb go up, airspeed goes down
Descend go down, airspeed goes up
(Normal indications but more extreme reading)
Cruise- no changes, frozen
Descent -
VSI and Altimeter frozen, static pressure trapped
ASI :
Descend to higher pressure, so pitot pressure will increase and static pressure stays same (trapped). Pitot pressure gets reading from ambient entering back of tube and adds on ram pressure. Exaggerated and inaccurate difference makes extra HIGH READING (airspeed like 180mph) - even though ram pressure could still be same, but the ambient pressure enters back of pitot tube and causes higher readings as we descend to higher pressure
Climb -
VSI and Altimeter frozen, static pressure trapped
ASI:
Climb to lower pressure with ascent, so pitot tube will send pressure reading that drops, but static pressure reads same (trapped). This will cause extra LOW READING
Blocked intake of pitot tube - what happens to instruments?
Turn on pitot heat!
Summary
Altimeter and VSI unaffected
ASI zero
Cruise:
No ram pressure
Outflow drain not blocked- brings in static air pressure
Difference between pitot pressure and static pressure is 0, so ASI shows zero
Climb and Descent:
Altimeter and VSI read accurately
Pressure starts to increase
But pitot and static pressure are still zero so airspeed still shows zero
What to do if static port blocked?
Use alt static- pull it out, brings cabin air into static system. No slipstream pressure in cabin, like happens sometimes with static. Pressure is different. Could see small jump in altitude and VSI.
Last resort:
Break glass on VSI no
Entire pitot tube blocked- what happens to instruments?
Turn on pitot heat!
Summary
Altimeter and VSI unaffected
ASI acts like altimeter (go down, low speed/ go up, high speed)
Backwards from what I’m used to seeing
Now pitot air pressure is trapped, it’s a closed system. Pressure reading stay same.
Cruise:
No indication change on all 3 instruments
Climb:
VSI and altimeter work fine
ASI:
Static port reads lower pressure but pitot static air pressure reading doesn’t change
Difference between pitot and static is getting bigger, and shows a higher airspeed
Works like altimeter!
Descent:
VSI and altimeter work fine
ASI:
Airspeed reads lower
ASI is altimeter
Illusions
ICEFLAGS
Inversion illusion
Level off too fast out of climb and it feels like I am back in my seat so I put the nose down too much because I think I’m still in a climb - dangerous low nose attitude (inner ear fluid hasn’t had time to adjust)
Transition gently between phases of flight to reduce misinterpretation of body signals
Trust instruments
Coriolis illusion
Steady turn for a while, fluid settles, but look down at chart or bend down to get on floor, now fluid is tossed around and dizzy, not sure which flight attitude I’m in- tumbling
Keep head movements slow and head steady when in turns
Trust instruments
Elevator illusion
Updraft gives quick boost and inner ear tells brain that I’m in a climb, so I push nose down to descend. Can feel like floating when elevator suddenly moves up.
Always cross check instruments before taking corrective action.
False horizon illusion
Line of lights is horizon, but really could be a line of homes going up a hill.
Ignore the lights and rely on instrumentation
Leans illusion
I’m in a slow gentle bank, but don’t know it. I correct to straight and level, but now inner ear sends signal that we are banking in opposite direction. Feel like I am leaning even though I’m straight and level.
Avoid slow gradual turns
Trust and cross check instruments
Autokinesis illusion
Misjudging movement of lights and other aircraft at night. Perceive motion when there is none.
Flying at night, keep eyes moving and scan portions of sky.
Graveyard spiral illusion
Gentle turn without knowing, and inner ear is not sending signals to brain. When I correct it, feel I’m turning in opposite direction, so I return to gentle bank thinking I’m straight and level. This is the leans!
The leans becomes a graveyard spiral because nose drops in a turn and when pull back on yoke I tighten the turn and descend faster. Deadly descent.
Cross check and trust instruments!
Somatogravic illusion
Increase power and accelerate quickly, so I’m pushed back in my seat, think I’m pitching up. Brain interprets a climb. So I push down and enter dangerous descent. Opposite can happen if descelerate fast, head cocks forward and brain thinks we are pitching down so I could enter unnecessary climb.
Avoid unnecessary rapid acceleration or deceleration.
Scan instruments!!!
