2023-07 · NASA ASRS report 2019514
A Tower Local Controller and Ground Controller reported an aircraft taxied across a runway without a clearance the same time as another aircraft was departing.
I was working Ground Control 1 and Ground Control 3 combined at the time of the event. Aircraft X called me on the south route; en route to Company aviation. I instructed Aircraft X to turn right on taxiway 1 and taxi via [Taxiway] 1; [Taxiway] 2 onto [Taxiway] 3 and hold short of [Taxiway] 4. Aircraft X read back the instructions correctly. I went on to talk to other aircraft and take flight strips to the north Ground Controller. I continued to taxi aircraft out and update data tags on the ASDE-X that keep dropping off. Local 1 was departing Aircraft Y at the time. After Aircraft Y rotated; the local team and I observed Aircraft X data tag reappear on taxiway in between Runway XXL and Runway XXR. I instructed Aircraft X to hold position and contact Tower. At no time did I observe a data tag crossing the runway and no safety logic alarm went off. The ASDE-X has been dropping data tags and does not show primary targets. This has been an issue since about Day 0. A lot of extra time is spent re-typing in call signs and gate numbers of aircraft after they drop off. The weather here in the summer months produce foggy conditions and at times; the runway exits are obscured. Aircraft X is a smaller white jet that can blend into the foggy background at the departure end. The ASDE-X is a vital piece of safety equipment that needs to be working fully; 100% of the time.
Aircraft X had landed the north complex Runway YYR and was taxiing to parking with Ground Control 1. I had put Aircraft Y into position and had coordinated a south flow departure. I was doing my final scan of the runway and the ASDE-X as I was issuing the take-off clearance with the new departure instructions. Aircraft Y started the take-off roll. I then crossed Aircraft Z at taxiway and Aircraft A at another taxiway after the departure had gone past the respective taxiways. I then talked to Aircraft B exiting the runway and had them hold short. At this time; Local Controller 2 coordinated with me for 2 crossovers aircraft which were approved. I looked for the departure to verify the turn; but could not see the aircraft due to the cloud layer. I then looked at the radar to reissue the turn and confirm. That is when I noticed Aircraft X tag appeared on the taxiway in between Runway XXR/L. I looked out and confirmed visually that there was now an aircraft at that location. The Aircraft X was painted white and being a small aircraft a mile away from the Tower; it did blend in with the white cloud layer at the west end of the airport.Looking back on the replay; Aircraft Y had been cleared for take-off when Aircraft X was still on taxiway. Aircraft X was on Ground Control 1 frequency the entire time. The instructions for Aircraft X were 'taxi 1-2-3 hold short of 4'. Aircraft X tag had dropped off of the ASDE-X due to it being in limited multilateration (MLAT) mode. It was not the only tag that had dropped as I had multiple tags also drop off throughout the day. Because the Aircraft X tag had dropped off; the ASDE-X did not alarm. According to replay; Aircraft Y was passing taxiway when Aircraft X had entered Runway XXR. Aircraft X had vacated the Runway XXR when Aircraft Y had passed [Taxiway] 1. The ASDE-X has been in the limited MLAT mode since at least Day 0 waiting to be fixed this entire time with still no fix date set. The ASDE-X never should be out of service for this long even in limited mode. All GA and Cargo aircraft should land on Runway XXL. This will eliminate 3 runway's that they have to cross when the land on the north side Runway YYR.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.
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