Date: 202106
Local time of day: 1201-1800
Location: DAL.Airport, TX
Light: Daylight
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class B DAL
ATC / advisory: Tower DAL
Second aircraft: Commercial Fixed Wing
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Human factors: Workload; Distraction; Situational Awareness; Confusion
Anomaly: Deviation - Altitude Undershoot; Deviation / Discrepancy - Procedural Clearance; Ground Event / Encounter Ground Equipment Issue; Inflight Event / Encounter Unstabilized Approach
Detector: Automation Aircraft Terrain Warning; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Overcame Equipment Problem; Flight Crew Executed Go Around / Missed Approach
Contributing factors: ATC Equipment / Nav Facility / Buildings; Airport; Procedure
Primary problem: ATC Equipment / Nav Facility / Buildings

Narrative: I set up for a visual approach with an ILS back-up to Runway 13L at DAL.  We were in good shape from a speed and altitude standpoint at NNATE.  I was hand flying.  I was distracted by the localizer guidance which showed me well right of course when I was actually slightly left.  I mentioned that to the Pilot Monitoring.  While troubleshooting the lateral guidance; I got behind the jet for getting flaps 15 and gear down and we ended up high.  As I regained my crosscheck; I subconsciously followed vertical guidance; which now was taking me erroneously higher. I called for flaps 30; and realized we were now 800 feet. The Pilot Monitoring called out the PAPIs (Precision Approach Indicators); which showed all white; but the glideslope guidance was taking me higher.  I called for a go-around.  My go-around was sloppy; but the Pilot Monitoring brought his A game; so it was manageable. On the second approach; a visual approach backed up by the ILS 13L; both lateral and vertical guidance were erroneous.  I had to fight the tendency to cue on the vertical guidance; which again was taking me high. The Pilot Monitoring turned off both flight directors. On short final; we got an audio glideslope alert. The glideslope raw data showed me way low. The PAPIs were three white and one red.  We should have also turned away from the ILS on the NAV tuning panel. On both approaches; an Aircraft Y was parked right at the hold short line in front of the glideslope antenna.  I suspect we will see more aircraft stopped at the hold short line with the runway closure at DAL; and so we will see more ILS interference.  I have seen similar ILS behavior at other airports with an aircraft stopped at the hold short line.  We did not write up the aircraft.  An ILS test was completed and passed prior to the flight. NOTAM (or other reminder) that the 13L ILS may be unreliable with aircraft in the ILS critical area. More training on go-arounds.




Synopsis: An Air Carrier pilot reported they received erroneous glideslope and lateral guidance from the ILS while an aircraft was holding in the ILS critical area. The reporter stated this will become a recurring issue due to a runway closure at the airport.