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Answers to 23 questions about avionics, instruments, radios and installations. Search or browse by topic.
Aviation oxygen for GA pilots: when you need it and how to choose a system
Under EASA Part-NCO, a pilot who cannot judge the effect of low oxygen has to use supplemental oxygen as crew for more than 30 minutes be...
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How to choose an aviation headset
Match the headset to the cockpit noise, connector, audio-system impedance, flight duration and operator requirements. Comfort and a corre...
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What does 8.33 kHz mean for an aircraft COM radio?
8.33 kHz is a VHF voice-channel spacing used to create more channels in congested European airspace. The radio must be approved and confi...
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What does 50 kHz receiver selectivity mean?
Receiver selectivity describes how well a COM receiver accepts the wanted signal while rejecting nearby channels. It is related to, but n...
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What is SELCAL?
SELCAL or Selective Calling is a function that allows a ground radio operator to alert an aircraft crew that the operator wishes to commu...
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How does a Selcal decoder work and why is it necessary in an HF installation with Selective Calling capability?
Selective Calling or SELCAL is a technique by which an aircraft has a unique identifier and a ground station can contact the aircraft for...
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Is an STC required for an HF system installation?
Not always. An HF installation needs approved design data, but the approval route may be an existing STC, a major or minor change approva...
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What is the difference between a radar altimeter and a radio altimeter?
In civilian aviation, these two terms are used interchangeably and essentially mean the same. They both can be abbreviated as "Rad Alt" s...
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What is a stripline in avionics?
A stripline is a controlled-impedance RF transmission line formed by a conductor embedded in dielectric material between ground planes. I...
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What is the meaning of the terms Nav, Comm and Nav/Comm?
Navigation (Nav) and Communication (Comm) radio receivers and transceivers are available as separate, individual radios or as a combined ...
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What is a heading bug?
On select DG and HSI instruments, the selected heading is marked by an orange heading bug that can be moved to any point around the perim...
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What does a bootstrap output mean on an HSI?
Certain versions of the KI-525A include a bootstrap heading synchro transmitter. This synchro outputs a voltage per degree of heading rot...
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What is the difference between a slaved and un-slaved compass system?
A slaved compass system, when installed in an aircraft, is continuously corrected by the remotely connected magnetic direction sensing de...
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What are the advantages of an RMI over an ADF indicator?
The use of a Radio Magnetic Indicator in an aircraft offers several benefits that improve navigation situational awareness and pilot work...
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What is the function of the course datum synchro?
Available as an option in some navigation CDIs, the course datum synchro is useful for autopilot interface. Course datum provides course ...
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What is the purpose of a slaving meter in a compass system?
On slaved compass systems, the HSI will automatically update its compass card with the flux detector which senses magnetic variation. The...
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How do I select a transponder antenna?
Choose the antenna and installation against the transponder’s approved installation data, aircraft structure and operating envelope—not b...
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What checks are required after replacing a transponder?
A like-for-like replacement does not automatically mean repeating every periodic test, but the installation and altitude-reporting interf...
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What is radar stabilization?
Radar stabilization uses an aircraft's vertical gyro (if equipped) to maintain the selected radar antenna beam relative to the horizon. T...
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Why does a newly installed or replacement avionics unit not work properly?
Many avionics systems require a configuration or setup process. This process is required to interface certain avionics systems to other s...
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How do I obtain the aircraft’s Mode S address?
The aircraft’s unique 24-bit Mode S address is assigned by the civil aviation or registry authority in its State of Registry. It is not c...
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How should I clean and disinfect Garmin avionics?
Use a lint-free cloth and a cleaner approved for anti-reflective coatings. Garmin generally recommends ammonia-free 70% isopropyl alcohol...
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What is the difference between a squawk and a squitter?
In relation to the transponder technology, a squawk refers to a response that a transmitter responder (i.e. transponder) is making to an ...
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