Weather Flashcards
Dry RWY defined as
One which is neither wet nor contaminated… AND/OR including grooved surfaces or porous pavement to retain “effectively dry” braking action even when moisture is present.”
Damp RWY
surface is not dry, but the moisture on it does not give it a shiny appearance.
Wet RWY
JAA: shiny in appearance, depth less than 3mm of water.
FAA: neither dry nor contaminated.
Contaminated RWY
JAA: when more than 25% of the rwy surface area within the required length and width being used is covered by:
i. more than 3.0mm of water, or by its equivalent loose snow or slush
ii. snow which has been compressed into a solid mass which resists further compression, or,
iii. ice
FAA “whenever standing [anything] is present.”
*** for t/o, consider the high-speed part of the rwy, also…
when are Mu reports given?
1/3 or more of rwy to be used is contaminated
when contamination is 13mm or more,
DO NOT take off
2 kinds of drag associated with contamination
Impingement: spray from wheels onto airframe
Displacement: from the contamination around wheels.
frozen precip is acceptable for t/o & Landing?
-FZRN
FZDZ
+SN
types of hydroplaning
Viscous: like a thin film, with oil, dust or other stuff in addition to the water (happens at lower speeds than
Dynamic: normal type. 9xSq.rt.PSI
Reverted Rubber: steam assisted planing. not really an issue for a/c made after 1980.
grooved RWY is wet?
only when reported as such, or +RA/SHRA or TS are reported
not using speed brakes / spoilers on landing?
on dry RWY, 5 sec’s late is 100 yards extra. not using them at all, 200 yds extra and 70kts overrun speed.
speed brakes / spoilers effectivity on stopping force
20-30% based on rwy condition
Weather Radar Cat eyes or Ghost targets
narrow green or yellow arc, or as two small targets, caused by side lobe returns, often between 4-8nm range, at about +/-45deg. If visible during AUTO gain, it indicates that repeated painting and/or patching has significantly reduced radome transmitivity.
wx radar most reflective for
wet hail
wx radar: turbulence detected using
doppler circuitry based on horizontal shere, therefore works only for turb associated with precip. It makes alert when exceeding mod-severe params. limited to first 40 nm. Displayed in Magenta
wx radar over ocean may reflect ____ side of a ____?
downward, wave
Using map mode, the far limit for ground return under ideal conditions is ____.
But, the practical use is limited to about ____ nm because the beam is _______.
around 200 nm, as the ground after drops beyond the horizon.
80-90
practically parallel.
Gnd returns v. wx. returns:
Smaller and more angular, well defined.
Radar possibly painting two targets as one?
Function of range and beam width
Reflectivity based on tilt angle:
Lowest (and below the frz level) is most reflective area.
Radar Top rule of thumb formula
Top = [(Tilt angle - 1.5) x (range) x 100] + your altitude.
AUTO function of Radar is ideal because
It optimizes angle based on range and EGPWS
Predictive Windshear (PWS) has aural alert priority over ___, and is always on unless___.
EVERYTHING, unless manually switched to off on radar panel.
PWS operates automatically below
2300 AGL, and gives alerts (advis, caution, warning based on location and not strength) between 15/1200 ft. AGL
Wx Radar turb band not near a red cell, avoid by at least
5 nm
Avoid cells by ___, ___, ___ !
10 nm upwind, 20 down, and 5k ft. above!
FOM 5-40
When is at least one radar req’d?
Dispatched into IMC or Night
Danger zone of wx radar?
about >4 meters from Radar Firewall in front of cockpit, about 240 degrees
PWS FAIL nuisance message when
-WXR has not been selected on at any time since electrical power up, and
• one or both engines are advanced for takeoff and the indicated airspeed is increasing
FOM says establish avoidance plan
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