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Instrument landing: why do all electronic devices need to be shut off?

Short answer: ILS is rather sensitive to interference and not all electronic devices take much precaution in avoiding the generation of interference. The pilot wants to be sure that the readings he's ...
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39 votes
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Was it possible to land a Boeing 707 with 300 feet cloud ceiling in the 70s?

ILS approaches were in common use in 1970 when I got my instrument rating. The normal (Cat I) ceiling minimum was 200 feet. So, yes, a 707 would have been able to land with a 300 foot cloud ceiling in ...
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35 votes
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Does a portable ILS ground station exist?

NASA did some research on it in 1986 and published this paper. Thales was contracted to build one that the US Army has ordered and it made it to prototype phase. Eventually it was tested for a while ...
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34 votes
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How is varying modulation depth achieved by localizer ground transmitters?

The beam strength decreases as you move away from it's own centreline, so is it actually that the entire modulated signal strength decreases which when de-modulated is effectively a difference in ...
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21 votes
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Can the ILS glideslope be intercepted from above?

Assuming that you're asking about intercepting the glideslope from above rather than the localizer, the answer is that it is definitely NOT recommended. There are at least two significant problems if ...
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20 votes

Instrument landing: why do all electronic devices need to be shut off?

Having worked as a software engineer on the lateral guidance subsystem of the FMCS (Flight Management and Control System) for the Airbus A310 about 30 years ago I found @reirab's answer fascinating. ...
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19 votes

Instrument landing: why do all electronic devices need to be shut off?

You can read this related question if you want to learn more about the interference between electronic devices and airplanes. An answer there links to a very good document written by NASA on the ...
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  • 1,655
18 votes

If you were to fly an ILS in a knife edge would you receve GS and LOC be flipped?

No, the directional part of ILS is located at the ground. (Ground) transmitter creates lobes with specified frequency and modulation to mark the high, low, right and left areas. LOC and GS signals ...
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17 votes

What is "(CFMCC)" on an ILS approach chart?

A point shown in parentheses like this is called a Computer Navigation Fix (CNF). If it didn't fall right at the end of the runway, it would be marked with a small X. It's defined in the legend on ...
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16 votes

What is the correct name for this ILS Indicator?

That image is a basic representation of a course deviation indicator, as mentioned by Steve H. An actual gauge would look like this: Image Source In your image, it shows that the aircraft needs to ...
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16 votes
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What's the point of having ILS on runway signs?

These markings designate the hold-short point during different runway operations. Runway hold-short points are marked by white text on a red background. They designate a point which any aircraft must ...
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16 votes
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What is the purpose of having different ILS categories?

Instrument landing system - ILS - is a very common precision approach system used in airports around the world. An ILS consists of two ground antennas and an airborne received in the aircraft. One of ...
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16 votes
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How does a pilot select the correct ILS when the airport has parallel runways?

The two ILS approaches on parallel runways will have a different ILS Localizer frequency. The pilots will select the correct approach from the charts and then either manually tune in the correct ...
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15 votes
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What is the correct name for this ILS Indicator?

That is the course deviation indicator, or CDI.
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15 votes
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Is it true an ILS CAT IIIc can automatically taxi-in an aircraft?

There is no provision in the ILS system to provide for an auto-taxi or runway vacate. IIIc is just zero-zero and roll-out control, not auto-vacate as the linked AvWeb article seems to suggest. Its a ...
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13 votes
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Precision Approach systems: Why is ILS used more frequently than PAR and MLS?

At least in the U.S., ILS is popular because it is popular. It's relatively cheap to install and operate, the receivers share technology with VOR, and it is already installed everywhere. Momentum (and ...
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13 votes
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What is different between a Cat IIIA, Cat IIIB, and Cat IIIC ILS approach?

ICAO and FAA CAT III definitions A CAT III operation is a precision approach at lower than CAT II minima. Sub-categories are listed below. A category III A approach is a precision instrument ...
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13 votes
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Is it possible for more than one airplane intercept the ILS at the same time?

Yes, since the ILS is just a set of radio signals emitted and received by aircraft, there can be more than one aircraft established on localizer and glidepath. The ILS does not lock or tune onto one ...
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  • 15.5k
13 votes

When do pilots disconnect the autopilot on an ILS approach?

The decision to disconnect the autopilot is made by the pilot and can be made at any point as long as the operational limitations of the aircraft are satisfied (according to the type of ILS). The ...
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13 votes

What makes a visual approach quicker than an ILS approach?

Visual approaches can be conducted from any point around the airport where the runway is in sight, e.g. if you are approaching from the north of the airport, you can be vectored to a position which is ...
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13 votes

Is there a list of airports with Category 3 ILS systems?

According to my current navigation database (AIRAC 1912), the following 228 airports have a category III ILS approach to at least one of their runways: ...
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12 votes
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Do non-towered airports commonly have ILS?

Nontowered airports absolutely can have ILS approaches, and it's fairly common, though of course not as common as at towered fields. Two examples in my neck of the woods are KIKK (Kankakee, IL) and ...
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12 votes
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Why haven't helicopter CAT III procedures ever been developed?

Because many copter autopilots are capable of flying a Cat I ILS to 200AGL, and then descending on autopilot into a hover at a pre-determined altitude above the runway. The pilot can then descend down ...
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12 votes
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What is the maximum interception angle for ILS when on radar vectoring?

45 degrees. 8.9.3.6 Aircraft vectored for final approach should be given a heading or a series of headings calculated to close with the final approach track. The final vector shall enable the ...
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12 votes

Do any aircraft have a "self-contained ILS"?

Approaches guided by GPS are called RNAV; it can provide both lateral and vertical guidance, in some cases to the same precision as ILS Cat I, without need for a radar altimeter--which is not standard ...
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12 votes
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What should I do if I intercept the glideslope before reaching the final approach fix?

JERIT is the FAF for the LOC approach, as indicated by the Maltese cross. However, the FAF for the ILS approach is not JERIT; it is the Glide Slope Intercept Point (at 2000 ft indicated altitude) ...
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11 votes
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Why would the USAF have no support for autolanding?

The Super Hornet can't even shoot a VOR approach, much less an ILS. We are TACAN/ PAR only. That's fine at the boat, because that's how we operate, but apparently the Navy still hasn't figured out ...
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11 votes
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What is the difference between "Land 2" and "Land 3" annunciations for Boeing autopilot systems?

From "Smart Cockpit" B777 Automatic Flight (PDF!) AFDS Status Annunciation The following AFDS status annunciations are displayed just above the PFD attitude display: • FLT DIR (the flight ...
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11 votes
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Why wouldn't KJFK offer the ILS for 22L?

JFK ARR ILS 22L/22R DEP 22R If conditions dictate the use of JFK ILS RWY 22L approach, then (1) the JFK Area owns Belmont airspace 3,000' and below, (2) releases Coney airspace to LGA and LIB, (3) ...
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