ILS/MLS Flashcards
What does ILS mean?
Instrument Landing Systems
What does MLS mean?
Microwave Landing Systems
What is ILS/MLS used for?
they are designed to allow the flight crew the ability to land the aircraft with the aid of the instrument references
What is Decision Height?
if enough of the airport environment is visible to safety land
What is a Missed Approach?
If conditions are too bad they will pull up and try again
The ILS has three categories or subdivisions. What is Category 1?
Category 1 - the most common
200ft decision height and RVR of 2400 ft
What does RVR stand for?
Runway Visual Range
The ILS has three categories or subdivisions. What is Category 2?
international and large airports
Decision height 100ft
RVR 1200ft
CAT II requires the airplane to have what?
a second localizer and glide scope receiver and a Radar Altimeter
Category III is divided into subdivisions A, B, and C, with Decision Height and RVR decreasing each subdivision. What is Category III sub division C?
This is a fully blind landing. Conditions are zero-zero. No decision height and no RVR
What 3 separate systems is the ILS based around?
Localizer
Glidescope
Marker Beacons
What does the Localizer Provide?
provides a directional reference to the left and right of the center line or a horizontal reference
What does the glidescope provide?
provides vertical directional service
What do marker beacons provide?
provide the known distance points from the end of the runway for the pilot to help determine how knit only where they are in approach but also aid in decision height or RVR conditions
What does the ILS localizer consist of?
two RF transmitters and eight loop antenna array
A signal to the right of the localizer path will be modulated with what frequency?
150Hz
A signal to the left of the localizer path will be modulated at what frequency?
90Hz
The localizer receiver in the aircraft does what?
discriminates between the 90 and 150Hz
What frequencies does the localizer operate in?
VHF navigation frequencies below 112.00MHz
The frequencies used with the localizer have what when in the 100KHz position?
Odd numbers
The localizer station transmits an audio ID for the pilot to verify the correct station. How is this ID received?
in Morse Code and always begins with the letter i
Because there is only one inbound course when in the localizer mode, the OBS (or course selector) is:
inoperative and there is no “to/from” indication
On the front course: the needle shows:
the direction that the nose of the aircraft needs to move in to get back on course
In localizer mode, and indicator must never:
display a “from”
What if an indicator displays “from”?
there is a malfunction in the system
Localizer signals are adversely affected by:
tall buildings and mountains
The VOR composite has:
30Hz, plus the continuously changing 9960Hz reference frequency
What are converters used for?
to change the composite signal into voltages that can be displayed on an indicator
What is the discriminator used for?
to extract the 30Hz reference signal from the 9960Hz sub-carrier