Southwest Airlines at IAD

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W4UVV

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I've been sleuthing the FCC licenses for Southwest Airlines at Dulles Airport and have come up with that not a one of the licensed freqs are used.



However, closely watching the waterfall near 460.7625 (a freq licensed to Southwest) I found 460.7675 (a freq NOT licensed to Southwest, nor is it licensed to anyone anywhere) with activity and concluded that this was a DMR single freq system used by Southwest Airlines. But then I wondered about the narrowbanding in the UHF band which leads me to this question.


Is 460.7675 a correct frequency? My understanding is that there is 6.25 khz between freqs so 460.7675 would not be an allocated freq.



If I run out a list of frequencies starting with 460.000 at 6.25 khz intervals there is no 460.7675 in that list. The closest freq is 460.76875. Then I zoom in tight on the SDR waterfall and lo and behold it looks like the center freq is 460.76875.


What fooled me initially was that I was receiving voice and data (Cap+, Color Code 12) on the SDR (DSD+) and the SDS100 on freq 460.7675. And I receive the same on 460.76875, which I am lead to believe is the correct frequency.



The odd thing of all of this is the Southwest Airlines is not licensed for 460.7675 or 460.76875 at Dulles Airport. Nonetheless, Southwest Airlines is using 460.76875. How is it not shown in the FCC licenses? Beats me.


If someone else can chime in on this subject I'm all ears.

----------------

FYI 460.76875 mhz. is a legitimate assignable frequency in compliance with the FCC 450-470 mhz. frequency band plan i.e., 12.5 khz. spacing and 6.25 khz spacing. Your comments regarding Southwest Airlines frequency license are correct.

If Southwest Airlines does not have a license for operating on this frequency, it is in violation of FCC regulations. It would be a simple matter for Southwest Airlines to submit a license modification application to change operatation on 460.76875 mhz. My frequency database shows no licensee in VA currently assigned to this frequency.

The radio installer/maintainer also has some accountability. But as long as Southwest Airline comms work ok it's happy.

As you might suspect exceptions may occur and have occurred and may and do result in certain FCC licensed frequencies not returned doing a FCC General Menu search. Here are two examples: In early 2000 when installation of STARS radio system began VITA and the state paid contractor consultant then after the fact both suddenly realized that the currently licensed vhf frequencies available were not enough to support a statewide radio system...another PPPPPPP situation. That resulted in an emergency application to the FCC from VITA for additional vhf frequencies for STARS installations. Fortunately for VA, at that time there were a few vhf frequencies available in the 151 mhz. and 152 mhz. range which quickly were licensed to VA. VITA received a FCC letter authorization for immediate use but subsequently these licensed frequencies did not appear in a FCC General Menu search. The second example is about 15+ years ago FCC selected frequencies in the 450-470 mhz. range, of which certain khz. spectrum ranges were auctioned to the general public for operation in VA. These frequencies are available in the ULS system but not easy to find and again not returned doing a General Menu search.

Good job on your analysis!

John
W4UVV
 

rbuxton

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----------------

FYI 460.76875 mhz. is a legitimate assignable frequency in compliance with the FCC 450-470 mhz. frequency band plan i.e., 12.5 khz. spacing and 6.25 khz spacing. Your comments regarding Southwest Airlines frequency license are correct.

If Southwest Airlines does not have a license for operating on this frequency, it is in violation of FCC regulations. It would be a simple matter for Southwest Airlines to submit a license modification application to change operatation on 460.76875 mhz. My frequency database shows no licensee in VA currently assigned to this frequency.

The radio installer/maintainer also has some accountability. But as long as Southwest Airline comms work ok it's happy.

As you might suspect exceptions may occur and have occurred and may and do result in certain FCC licensed frequencies not returned doing a FCC General Menu search. Here are two examples: In early 2000 when installation of STARS radio system began VITA and the state paid contractor consultant then after the fact both suddenly realized that the currently licensed vhf frequencies available were not enough to support a statewide radio system...another PPPPPPP situation. That resulted in an emergency application to the FCC from VITA for additional vhf frequencies for STARS installations. Fortunately for VA, at that time there were a few vhf frequencies available in the 151 mhz. and 152 mhz. range which quickly were licensed to VA. VITA received a FCC letter authorization for immediate use but subsequently these licensed frequencies did not appear in a FCC General Menu search. The second example is about 15+ years ago FCC selected frequencies in the 450-470 mhz. range, of which certain khz. spectrum ranges were auctioned to the general public for operation in VA. These frequencies are available in the ULS system but not easy to find and again not returned doing a General Menu search.

Good job on your analysis!

John
W4UVV


Looks like a phone call to the Southwest Airlines radio administrator is in order.
 

RFI-EMI-GUY

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If/when you locate this person, what will you tell them?


Sent from my iPhone using Tapatalk

Saying he is calling as a favor to stem off a potential $15K/day fine from the FCC should open the conversation nicely. Of course, depending upon the person he calls they may be freaked out that "sensitive airport operations" are being monitored by a civilian.

I once had a client that operated a repeater on the roof of a prominent downtown building for years without a license. They shared the building with another sister agency and each assumed the other held the license, although both equally used the repeater. I found this while doing an audit of the frequencies for narrow-banding. There were other unlicensed simplex operations as well. I made other recommendations as well that were ignored so, the client and I parted ways somewhat amicably when I realized I was risking my own business by going along with their game and sent them a letter to end the contract. I think the illegal operations persist to this day due to bad advice from within the agency.
 

rbuxton

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If/when you locate this person, what will you tell them?


Sent from my iPhone using Tapatalk



I sent an email:


Addressed to the licensee and contact for SWA at IAD.


I am doing research for a radio system at Dulles Airport in Virginia. I have discovered what I believe to be a frequency used by Southwest Airlines at Dulles Airport that is not licensed by the FCC.

I bring this to your attention as the licensee and contact for FCC license WQFM893, granted to Southwest Airline Company - Dulles Airport.

ULS License - Industrial/Business Pool, Conventional License - WQFM893 - Southwest Airline Company - Dulles Airport

The unlicensed frequency is 460.76875 and is utilized in a Motorola MotoTRBO two-slot single-frequency system by Southwest Airlines at Dulles Airport.

Please confirm my findings of the unlicensed frequency and the status of the aforementioned license in which the frequencies are not being used.
 

rbuxton

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Now that I think of it,,,,,,,,, what's to say that if a business utilizes a frequency that is not licensed to it that the business could/would utilize a frequency that is not allocated by the FCC?


I thought I was thoroughly convinced that the freq in use is 460.76875 since it is the closest allocated freq to 460.7675, which is what my SDR spectrum looks like.



Without a more precise way of figuring out if its 460.76875 (allocated freq) or 460.7675 (non-allocated freq) I'm at a loss. The SDS100 and DSD+ will decode DMR signals on both freqs equally well.
 

rbuxton

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I sent an email:


Addressed to the licensee and contact for SWA at IAD.


I am doing research for a radio system at Dulles Airport in Virginia. I have discovered what I believe to be a frequency used by Southwest Airlines at Dulles Airport that is not licensed by the FCC.

I bring this to your attention as the licensee and contact for FCC license WQFM893, granted to Southwest Airline Company - Dulles Airport.

ULS License - Industrial/Business Pool, Conventional License - WQFM893 - Southwest Airline Company - Dulles Airport

The unlicensed frequency is 460.76875 and is utilized in a Motorola MotoTRBO two-slot single-frequency system by Southwest Airlines at Dulles Airport.

Please confirm my findings of the unlicensed frequency and the status of the aforementioned license in which the frequencies are not being used.


Reply from contact for FCC license.



"We're correcting the issue; Will use 460.7625"
 

W4UVV

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Prince George, Virginia--Central Va.
Good Job Well Done!

Reply from contact for FCC license.



"We're correcting the issue; Will use 460.7625"

--------------

This was a non-threatening but informative response presenting only the facts with no judgemental comments. This is a good template example to use for anyone in the future wishing to respond to a similar situation.

Good job well done!

John
W4UVV
 

RFI-EMI-GUY

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I never could find exactly where it was specifically defined. I always thought it meant "direct operation".


ditto

noun plural -tos
the aforementioned; the above; the same. Used in accounts, lists, etc, to avoid repetition and symbolized by two small marks (ˌ) known as ditto marks , placed under the thing repeated Abbreviation: do
informal
  1. a duplicate
  2. (as modifier )a ditto copy
adverb
in the same way
sentence substitute
informal used to avoid repeating or to confirm agreement with an immediately preceding sentence
verb -tos, -toing or -toed
(tr) to copy; repeat

the definition of ditto
 

W4UVV

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Joined
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Location
Prince George, Virginia--Central Va.
ditto

noun plural -tos
the aforementioned; the above; the same. Used in accounts, lists, etc, to avoid repetition and symbolized by two small marks (ˌ) known as ditto marks , placed under the thing repeated Abbreviation: do
informal
  1. a duplicate
  2. (as modifier )a ditto copy
adverb
in the same way
sentence substitute
informal used to avoid repeating or to confirm agreement with an immediately preceding sentence
verb -tos, -toing or -toed
(tr) to copy; repeat

the definition of ditto
I remember using quotation marks when doing book reports, etc. in high school/university and knew "ditto" meant "same as above" and never had a reason to look up "ditto". But I don't remember seeing "do" until browsing the CFR as an abbreviation for "ditto" but obviously it is. Tnx. for the info update.

John
W4UVV
 
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