Why code 2000 at LHR
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It's not so much for the next flight, as transponders are filtered out from being displayed on the ground radar when the target is on stand. It's so that we see the aircraft registration on the radar if the aircraft is towed from one stand to another. Ground handling procedures say that the towing crew must tow with the transponder on.
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No, that code wold have been allocated to a different flight. In fact it's quite regular to see a BA 747 being towed with a label saying EZY5HW or RYR7AB when it comes off stand.
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Managed to find a link to the instructions for operating at Heathrow (jump to top of page 17). http://www.ead.eurocontrol.int/eadba...2015-09-17.pdf
As I understand it (I might be wrong) the reason for this, is to avoid confusion.
Most large airports use ground radar. If the transponder is turned off with the last code used still being displayed, when it comes back on the ground controller sees a ghost aircraft that shouldn't be there and starts to worry what it's doing.
If all non active aircraft are displaying 2000 (as soon as they put the brakes on after a flight, or prior to receiving their squawk for the next flight) then the ground controllers know it's not an active flight.
As I understand it (I might be wrong) the reason for this, is to avoid confusion.
Most large airports use ground radar. If the transponder is turned off with the last code used still being displayed, when it comes back on the ground controller sees a ghost aircraft that shouldn't be there and starts to worry what it's doing.
If all non active aircraft are displaying 2000 (as soon as they put the brakes on after a flight, or prior to receiving their squawk for the next flight) then the ground controllers know it's not an active flight.
Last edited by Cloud Chaser; 23rd Nov 2015 at 13:35.
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Here is some relevant information from the FAA:
TCAS Operations While on the Airport Surface - InFO 11012
Additionally it is a good operating practice to turn TCAS on in the TA-ONLY or TA/RA mode for a short period of time before crossing an active runway to double-check for the presence of any aircraft on short final. NOTE: It takes several seconds to display traffic when switching to TA-Only or TA/RA. The time period varies between different TCAS II equipment manufacturers.
http://www.faa.gov/other_visit/aviat.../InFO11012.pdf
Transponder Use by Aircraft On Airport Movement Areas - SAFO 15006
Operators should ensure that their procedures and manuals clearly state that flightcrews and general aviation (GA) pilots enable transponders to the altitude reporting mode and enable ADS-B Out transmissions (if equipped) any time their aircraft is positioned on any portion of an airport movement area. This includes all defined taxiways and runways on all airports.
http://www.faa.gov/other_visit/aviat.../safo15006.pdf
FAA AIM 4-1-20 Transponder Operation
3. Civil and military transponders should be
turned to the “on” or normal altitude reporting
position prior to moving on the airport surface to
ensure the aircraft is visible to ATC surveillance
systems.
NB: Selecting 1200 (equivalent to 2000) prior to shutdown or else is not mentioned. Separately, on many [new] transponders mode S there is no need to switch it to ALT, or any other mode, as it is done automatically.
TCAS Operations While on the Airport Surface - InFO 11012
Additionally it is a good operating practice to turn TCAS on in the TA-ONLY or TA/RA mode for a short period of time before crossing an active runway to double-check for the presence of any aircraft on short final. NOTE: It takes several seconds to display traffic when switching to TA-Only or TA/RA. The time period varies between different TCAS II equipment manufacturers.
http://www.faa.gov/other_visit/aviat.../InFO11012.pdf
Transponder Use by Aircraft On Airport Movement Areas - SAFO 15006
Operators should ensure that their procedures and manuals clearly state that flightcrews and general aviation (GA) pilots enable transponders to the altitude reporting mode and enable ADS-B Out transmissions (if equipped) any time their aircraft is positioned on any portion of an airport movement area. This includes all defined taxiways and runways on all airports.
http://www.faa.gov/other_visit/aviat.../safo15006.pdf
FAA AIM 4-1-20 Transponder Operation
3. Civil and military transponders should be
turned to the “on” or normal altitude reporting
position prior to moving on the airport surface to
ensure the aircraft is visible to ATC surveillance
systems.
NB: Selecting 1200 (equivalent to 2000) prior to shutdown or else is not mentioned. Separately, on many [new] transponders mode S there is no need to switch it to ALT, or any other mode, as it is done automatically.
