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20 votes
Accepted

What does "Except" mean in this ATC request?

It is a typo. That is supposed to say EXPECT FLIGHT LEVEL 280 IN 10 MINUTES. This means Atlasjet 123 is not yet cleared to the new altitude of FL280, but they can expect this clearance in 10 minutes. ...
Bianfable's user avatar
  • 56.9k
19 votes
Accepted

Can the guard frequency be used by non-aircraft / general public?

As a former FAA ATC'er, National Association of Rocketry high-power Level 3 certificate holder, and the facility approver guy for high-power rocketry waivers in our facility airspace, if you are in ...
RetiredATC's user avatar
  • 1,954
19 votes

How can pilots get other pilots' attention without the use of radio

Anybody keying the mic on the same frequency the unfortunate PA-over-the-radio pilot is transmitting on is accomplishing nothing productive whatsoever, and anybody with access to such a microphone ...
Ralph J's user avatar
  • 51.8k
16 votes

Can the guard frequency be used by non-aircraft / general public?

At least in the "jurisdiction" I'm somewhat familiar with, EASA and my country, licences are required for both the radio device and the operator of the radio. The training required for ...
Jpe61's user avatar
  • 29.3k
16 votes

How can pilots get other pilots' attention without the use of radio

There is no way to get a pilot’s attention while they are transmitting. ATC frequencies are “simplex” meaning once you start transmitting, all incoming reception is blocked. Any pilot or ATC should ...
Mike Sowsun's user avatar
  • 37.8k
13 votes
Accepted

Why are lower VHF frequencies used for towers?

There's no specific reason why the lower frequencies are used for towers, but it's not a coincidence that they are grouped together (mostly, there are tower frequencies that are not at the lower end.) ...
Gerry's user avatar
  • 20k
10 votes

Can the guard frequency be used by non-aircraft / general public?

Speaking from my Canadian experience: You require a radio operator's license to transmit on frequencies used in aviation. Getting a license involves passing a knowledge test, after which the license ...
Anthony X's user avatar
  • 3,398
9 votes
Accepted

What is a metering frequency and why would an airport have it?

Use of a metering controller and frequency at an airport is one strategy used to prevent congestion on ramps and taxiways. When ready for push back from the gate, pilots call metering. The metering ...
Mike Cowan's user avatar
8 votes

Why is the VOR reference and variable signal modulated at 30 Hz?

In VOR early days, the 40s, the stable phase locked loop frequency generator was not available. A common frequency reference was the very stable public AC power grid frequency. The angular velocity of ...
mins's user avatar
  • 75.3k
8 votes

Why do so many airports have the same CTAF frequency?

The CTAF frequencies 122.7, 122.8 and 122.9 are called MULTICOM because they are deliberately not specific to one airport. These frequencies are holdovers from the days of 100kHz radios, when we didn’...
StephenS's user avatar
  • 27.8k
8 votes

Published VHF frequency shown in parentheses on a Sectional Chart. What does this indicate?

There is a VOR/DME for BUF on that frequency, BUT it's either been, or is in the process of being partially decommissioned, leaving just the DME portion. And when you've got just a DME you put the ...
William Walker III's user avatar
7 votes
Accepted

Question about congestion of the 1090MHz frequency

Additionally, there will be more aircraft interrogating (on 1030MHz) and responding to interrogations on 1090MHz for transponder based systems (TCAS, SSR). Actually, no. More Mode S (vs Mode A/C) ...
StephenS's user avatar
  • 27.8k
7 votes

Magnetic or True heading to determine approach frequency?

Neither heading nor bearing, but rather radial off the airport, as the Chart Supplement will tell you: Radar facility sectors are delineated by lines drawn on the radar scopes, and it is exceedingly ...
randomhead's user avatar
  • 15.9k
6 votes

How do I find all the frequencies for my local TRACON?

There are sector maps available, and each facility updates them periodically. They are published. My understanding is that sectors are joined and separated frequently, even based on the minute to ...
mongo's user avatar
  • 17.8k
6 votes
Accepted

Is there a radio frequency that is sure to be quiet?

From the document referenced by mongo, Frequencies (MHz): 121.425 - 121.475Use: Band Protection for 121.5 Frequencies (MHz): 121.525 - 121.575Use: Band Protection for 121.5 It seems that these ...
abelenky's user avatar
  • 30.8k
5 votes

How do I know which airports have ILS and for which runways?

There are published instrument approach procedures for all airports served by an instrument approach. These are commonly referred to as Approach Plates. (In paper form). Your local pilot shop should ...
Michael Hall's user avatar
5 votes

Is there a radio frequency that is sure to be quiet?

You might want to check out this list of assigned frequencies. These look like good bets. 136.100 Reserved for future unicom or automatic weather observation stations 122.975 Unicom ...
JScarry's user avatar
  • 7,474
4 votes

Why do localizer/glideslopes use 90/150Hz specifically?

An AC motor in the USA will turn at 60 RPM and 90 is 3/2 and 150 is 5/2 of 60. Both can be generated using a simple gear drive which would reduce the costs during development. Similarly there are ...
Javelin's user avatar
  • 201
4 votes

Why do localizer/glideslopes use 90/150Hz specifically?

The frequencies are chosen to allow the system to produce a localizer and glideslope 'beam' that provides proportional guidance that can adequately guide an aircraft on the approach. Read through ...
Gerry's user avatar
  • 20k
4 votes

Why are lower VHF frequencies used for towers?

in that frequency range (118-137MHz) you are correct, the percentage change in frequency from the bottom to the top of the range is small, so there will be no significant change in propagation ...
niels nielsen's user avatar
3 votes

Can the guard frequency be used by non-aircraft / general public?

In response to this: A further scenario that I am curious about ground use of the guard frequency would be in the case of witnessing a plane crash, if per chance you had an air band radio would it be ...
Stephan Samuel's user avatar
3 votes

Why are lower VHF frequencies used for towers?

May not have been an explicit consideration, but the bottom of the band is pretty close to Band II FM broadcast radio. 118MHz could interfere with 96.6MHz transmissions, the difference between them ...
user_1818839's user avatar
  • 1,378
3 votes

Where can I find current downloadable tower, ground and approach frequencies for USA airports?

I have found something that will work. It is not pretty and I swear I can still smell the punch cards that produced the text files, but here it is: https://www.faa.gov/air_traffic/flight_info/aeronav/...
OldNotBold's user avatar
3 votes

Is there a radio frequency that is sure to be quiet?

The FCC publishes the frequency assignments for aeronautical radio usage (Part 87). You may wish to "listen" anywhere, but technically one should be monitoring guard when a receiver is available. ...
mongo's user avatar
  • 17.8k
3 votes

Is there a radio frequency that is sure to be quiet?

I'd try 121.1 to 121.4. I am not aware of them having been assigned for routine use. There's no guarantee that an unassigned frequency won't be in use by someone, authorized or not. Use of ...
Gerry's user avatar
  • 20k
3 votes
Accepted

Why and how can TCAS and SSR transponder work at the received frequency of each other?

To clarify: A transponder replies on 1090 MHz to ATC interrogations received on 1030 MHz. A TCAS elicits nearby transponders replies by sending interrogations on 1030 MHz, and listens for replies on ...
mins's user avatar
  • 75.3k

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