Squawking 7600 as a convenience

flyingron said:
What the hell does squawking anything do in oceanic airspace.
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denverpilot said:
Certain military toys still work from other aircraft and they generally like you to be squawking something that they can see. Using a standard squawk that won't be used anywhere "ashore" is just common sense systems planning.
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Everybody squawks 2000 while oceanic anyhow. (At least in the North Atlantic and Pacific)
 
Sluggo63 said:
Everybody squawks 2000 while oceanic anyhow. (At least in the North Atlantic and Pacific)
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That was already covered in a previous post. Then someone asked "why squawk at all" in relation to there not being any ground stations that can trigger the transponders anyway.

My response was that 2000 is just a number everyone agrees isn't gonna be used anywhere else, but that the military toys that are out there from time to time, recognize.

Toys on other airplanes with big obnoxious radomes on their backs (and some without), toys on boats painted a lovely shade of grey... You get the idea.

The more interesting thing would be watching the transponder and seeing when it's being utilized in that airspace and wondering who's triggering it. And wondering if they're a good guy or a bad guy. ;)
 
Larry in TN said:
Also, to lose comm oceanic you'd have to lose your primary (CPDLC datalink), secondary, HF radios, and tertiary (VHF radio to get a relay from a nearby flight). Very unlikely five separate radios fail unless you had a total electric failure and then you've got a lot more to worry about than your lack of comm.
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Pardon my ignorance but didn't something similar happen with the Malaysian flight?
 
denverpilot said:
The more interesting thing would be watching the transponder and seeing when it's being utilized in that airspace and wondering who's triggering it. And wondering if they're a good guy or a bad guy. ;)
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The transponder is replying all the time while oceanic. Each airplane's TCAS is interrogating all the other transponders in the vicinity.

Jaybird180 said:
Pardon my ignorance but didn't something similar happen with the Malaysian flight?
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We don't know what happened to MH370. They did have a large quantity of Lithium batteries as cargo so a lithium battery fire is one possibility. If that was it then the loss of communication was the least of their problems.
 
Is squawking 7600 a lie? Isn't squawking a form of communication?
 
There are services like ADS-C (Automatic Dependent Surveillance - Contract) which is ACARS supported and could link via Satcom over an ocean to send occasional position reports (every 15 minutes or so).

As CPDLC comes on line, it would probably be used to report positions too.

Mode S transponders transmit information whether they are interrogated by ground Secondary Surveillance radar or not. That transmission is called the squitter. It's broadcast at a pseudo random interval less than 1 sec.

Every Mode S transmission contains the ICAO address that maps to the registration number of the aircraft.

When ADS-B came along, the squitter grew from 56 bits to 112 bits. The added bits now contain the GPS position among other things.

Airline pilots still refer to squawking when they dial a 4096 code in.

Squit is a radar term that's been around for a long time.

TCAS processors identify Mode S equipped airplanes by listening for the squitter transmissions and identify the range and azimuth using RF methods.

Mode S transponders were regulated into existence to support TCAS in the early 90s.
 
Squawk 7500, then blame a passenger of forcing you to leave your flight level.

;-D
 
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