4 ms·

Planes have a variety of transponder options available, all of which can be turned on/off independently. Mode C (and sometimes Mode S) is the most common today

by verelo 10y ago

Planes have a variety of transponder options available, all of which can be turned on/off independently. Mode C (and sometimes Mode S) is the most common today and most important for entering controlled airspace (most airspace in the US is controlled). While ADS-B is an option, it's not yet mandatory (making its practical uses less than ideal in many cases). It won't be mandated until Jan 1 2020 in the US, and the first FAA laws on the ADS-B transponders were not published until May 2010. Source: https://www.faa.gov/nextgen/programs/adsb/faq/#g1 https://www.faa.gov/nextgen/programs/adsb/faq/#g1 ADS-B is amazing, yet I also find it's amazing it took so long to become more popular given how helpful it is. With an ADS-B receiver (I always have a stratus 2S on board while i fly) you get info like the call signs, speeds, positions and altitudes of other aircraft, while a Mode C transponder simply is a pinging beacon that air traffic can use to identify primary (radar based) targets. Mode C/S will give the pilot no advantage other than knowing that ATC can see them. Sadly in my case I only have an ADS-B receiver and no transmitter combined with a Mode C transponder, so i get some situational awareness and weather updates, but I do not contribute to the 'vision' of other pilots with my device. Stratus 2S: http://www.sportys.com/pilotshop/ipad-iphone-android/ipad-gps-and-weather/stratus-2s-ads-b-receiver-for-ipad.html/ http://www.sportys.com/pilotshop/ipad-iphone-android/ipad-gp...

furyg3 10y ago
Amazing. Maybe I'm extremely naive, but it seems to me that you shouldn't be able to turn the transponder off in a commercial passenger flight, and that international medium/long-haul flights that are likely to be in areas with reduced transponder coverage should be required to have some sort of Iridium beacon (which also cannot be turned off). Even sending the coordinates every 15 minutes would greatly reduce the area to search, and preventing disabling the transponder safeguards against nefarious or suicidal crew/passengers/terrorists. If I didn't know better (MH370), as a laymen I would have assumed all major flights would be sending their GPS locations constantly via satellite already, for a slew of reasons (one of them being it's 2016).
- fbender 10y ago
  There's always a fuse you can pull. And there needs to be a fuse, per regulations on how to build aircraft. The stray MH370 signal was coming from the engines directly, presumably powered by the engine's internal power system, and it was engine performance telemetry to be sent to the engine manufacturer. The pilot might not have known about that system or unable to disable it (without shutting down the engines).
  - verelo 10y ago
    This is the key point, in the case that there is a fire on board (one of the likely possibilities with MH370) you want to be able to disable the offending circuit immediately. If that happened to be your transponder, so be it...the transponder really adds no value to the plane in terms of its ability to stay in the air, so disabling it and extinguishing the fire is the key priority over giving ATC the ability to identify you on radar via the transponder.
    - furyg3 10y ago
      But there can be a luggage fire? What fuse can you pull to disable that? I assume there are extinguishers for the luggage compartment? Put a GPS/Iridium suitcase in the plane?
      - Jtsummers 10y ago
        There are extinguishers in the cargo area. I'm not sure who manufactures it for the 777. The general setup is fire, smoke, and overheat detection systems throughout the aircraft. This information is relayed to the pilots. Some of the extinguishing mechanisms may be automatic (more common in military and not so common in commercial). Cargo areas probably use halon or similar.
      - verelo 10y ago
        The point is that you should be able to disable anything that is connected to the planes electrical system, to stop fires and prevent damaged systems causing issues with other functional systems (i.e. broken GPS causing electrical surges should be disabled to ensure other controls continue to work). Unless your luggage is plugged in, this is something that ground based security should be assessing the risk of prior to placing it in the plane, followed by the redundant fire suppression systems in the luggage hold as a last resort, this should be fairly under control by the time the plane is in the air.
knz 10y ago
> ADS-B is amazing, yet I also find it's amazing it took so long to become more popular given how helpful it is. How much of this is the FAA dragging it's feet on NextGen projects? It's astounding that after billions being poured into "security" they still don't know exactly where every aircraft it at all times.

by verelo 10y ago

furyg3 10y ago

Amazing. Maybe I'm extremely naive, but it seems to me that you shouldn't be able to turn the transponder off in a commercial passenger flight, and that international medium/long-haul flights that are likely to be in areas with reduced transponder coverage should be required to have some sort of Iridium beacon (which also cannot be turned off). Even sending the coordinates every 15 minutes would greatly reduce the area to search, and preventing disabling the transponder safeguards against nefarious or suicidal crew/passengers/terrorists. If I didn't know better (MH370), as a laymen I would have assumed all major flights would be sending their GPS locations constantly via satellite already, for a slew of reasons (one of them being it's 2016).

fbender 10y ago
There's always a fuse you can pull. And there needs to be a fuse, per regulations on how to build aircraft. The stray MH370 signal was coming from the engines directly, presumably powered by the engine's internal power system, and it was engine performance telemetry to be sent to the engine manufacturer. The pilot might not have known about that system or unable to disable it (without shutting down the engines).
- verelo 10y ago
  This is the key point, in the case that there is a fire on board (one of the likely possibilities with MH370) you want to be able to disable the offending circuit immediately. If that happened to be your transponder, so be it...the transponder really adds no value to the plane in terms of its ability to stay in the air, so disabling it and extinguishing the fire is the key priority over giving ATC the ability to identify you on radar via the transponder.
  - furyg3 10y ago
    But there can be a luggage fire? What fuse can you pull to disable that? I assume there are extinguishers for the luggage compartment? Put a GPS/Iridium suitcase in the plane?
    - Jtsummers 10y ago
      There are extinguishers in the cargo area. I'm not sure who manufactures it for the 777. The general setup is fire, smoke, and overheat detection systems throughout the aircraft. This information is relayed to the pilots. Some of the extinguishing mechanisms may be automatic (more common in military and not so common in commercial). Cargo areas probably use halon or similar.
    - verelo 10y ago
      The point is that you should be able to disable anything that is connected to the planes electrical system, to stop fires and prevent damaged systems causing issues with other functional systems (i.e. broken GPS causing electrical surges should be disabled to ensure other controls continue to work). Unless your luggage is plugged in, this is something that ground based security should be assessing the risk of prior to placing it in the plane, followed by the redundant fire suppression systems in the luggage hold as a last resort, this should be fairly under control by the time the plane is in the air.

knz 10y ago

> ADS-B is amazing, yet I also find it's amazing it took so long to become more popular given how helpful it is. How much of this is the FAA dragging it's feet on NextGen projects? It's astounding that after billions being poured into "security" they still don't know exactly where every aircraft it at all times.