A B757 crew and dispatcher report a transponder dead zone at the intersection of Taxiway A10 and Alpha . The transponder failure alert disappeared when climbing out of 500' after takeoff.
Synopsis
A B757 crew and dispatcher report a transponder dead zone at the intersection of Taxiway A10 and Alpha . The transponder failure alert disappeared when climbing out of 500' after takeoff.
Narrative
On taxi-out (taxiway A10/A intersection) we received the EICAS message 'ATC Fault' and confirmed it with the ATC Fail Light on the IFF Mode Control Panel; as well as the 'TCAS Fail' message on the HSI. The manual refers to it as a 'pilot awareness item' We recycled; and it did not clear. We ran the TCAS test; and it failed. We asked tower if they had a positive transponder from us. They replied that they did not; but their ground capability was very limited. We then called Dispatch and Maintenance. Dispatch reported TWO other incidents from B757 aircraft at same location. Dispatch reported once airborne; the transponders worked normally. We made the decision to takeoff; and sure enough; at 500 FT AGL; the transponder error messages cleared and everything came back to normal. The transponder remained working throughout the entire flight. There is much construction at SMF; this may be causing a 'dead zone' for our 757 transponders. Suggest a NOTAM to alleviate this problem; as it cost us time; wasted valuable gas; and resulted in additional aircraft movement on the airfield to stay clear of runways and other aircraft.
Second reporter narrative
During taxi; in vicinity of taxiway A10; crew received ECAM message (ATC FAULT). Transponder was operating normally. Per Captain the situation occurred on 12/15 as well; in same position on airport. Report from another flight departing SMF; on taxi out the same situation occurred in the same area. There seems to be a dead spot in transponder coverage near A10. This may cause incorrect deferral of transponder if dead spot not noted for flight crews; dispatchers; and maintenance controllers.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.