Warning & Recording Systems, Radio Altimeters Flashcards
What are the three levels of alerting?
Warning, Cautions & Advisories
What is required of a Warning or Level A alert?
Immediate crew action
What is required of a Caution of Level B Alert?
Immediate crew alertness and possible future action
What is required of an Advisory or Level C Alert?
Crew alertness only
When are engine fire warning bells usually inhibited?
V1/Vr to 400ft
When are the Master Caution lights usually inhibited?
From about 80KT on takeoff to 400ft
When are Radio Altimeters most useful?
In the take off and landing
When are Radio Altimeters Active?
from 2500ft down to the surface
What is the primary function of the Radio Altimieter?
To provide accurate decision height information where precision approaches are flown down to a DH of 200ft
Where else is the Radio Altimeter signal used?
As an input to GPWS and TCAS
What is the size of the cone that the Radio altimeter transmits?
30°
What kind of radar to Radio Altimeters use?
A continuous wave radar, rather that a pulse radar
What is a problem with conventional radar measuring systems?
When the aircraft is very close to the ground the time delay for the returning signal is very small and so and difficult to measure.
Where are the receiver and transmitter ariels of a CW (Continuous wave) radar located?
Usually under the fuselage near to the gear position.
What frequencies does a CW Radio Altimeter operate on?
SHF - Between 4200Mhz to 4400Mhz (FM)
What is the principle of operation of the Radio Altimeter?
Measures the difference of the frequency being transmitted and the one being returned, this is called the beat frequency.
What height compensation is made for the Radio Altimeter?
For both the gear height and the wiring inside the aircraft.
What is the accuracy of a Radio Altimeter?
Plus/minus 2ft in the first 500ft or plus/minus 1.5% whichever is greater.
Where is Radio Altimeter information displayed in modern aircraft?
on the PFD.
how does the RA increase accuracy close to the ground?
The sweep rate increases
