Vernon Howells 1283665 Posted October 5, 2019 at 09:14 PM Posted October 5, 2019 at 09:14 PM After requesting push and start i was told by the GND controller at LIS to sqwuak MODE Charlie. I had my 737NG transponder at ALT OFF so I turned it on to ALT ON / XPDNR Why is the controller asking this? I know real world ops pilots use ALT OFF on the ground. Link to comment Share on other sites More sharing options...
Ryan Geckler Posted October 5, 2019 at 09:28 PM Posted October 5, 2019 at 09:28 PM After requesting push and start i was told by the GND controller at LIS to sqwuak MODE Charlie. I had my 737NG transponder at ALT OFF so I turned it on to ALT ON / XPDNR Why is the controller asking this? I know real world ops pilots use ALT OFF on the ground. Most airports now have a form of ground radar that will require you to have your transponder on in order to use - becoming very common. Ryan Geckler - GK | Former VATUSA3 - Division Training Manager VATSIM Minneapolis ARTCC | FAA Miami ARTCC Link to comment Share on other sites More sharing options...
Lars Bergmann Posted October 6, 2019 at 06:25 AM Posted October 6, 2019 at 06:25 AM This is an issue of VATSIM not simulating all transponder modes available in the real world. In the real world setting your 737s transponder to "ALT OFF" switches it into mode 3/A operations - this is not available on VATSIM. Our transponders only have two modes - off and 3/C. Sice VATSIM only has these two modes we use the only one that actually gets a SSR response for our gorund radars - mode 3/C. [All of this is ignoring mode S operations, which I don't want to get into here, because VATSIM does not support that properly anyways]. Link to comment Share on other sites More sharing options...
Andrew Crowley Posted October 18, 2019 at 10:21 PM Posted October 18, 2019 at 10:21 PM I can only speak to the US, Canada and Mexico, but pilots are definitely requested to squawk Mode C on taxiways. No one uses "alt off" here... Link to comment Share on other sites More sharing options...
Lars Bergmann Posted October 19, 2019 at 01:48 PM Posted October 19, 2019 at 01:48 PM Nice to know. My answer came from Europe, where we use 3/A (ALT OFF) on the ground and switch it to mode C on line-up (TA/RA). Link to comment Share on other sites More sharing options...
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