Two Center Controllers reported an aircraft transiting their sector flew below minimum safe altitude. Controller directed an immediate climb to the aircraft.

ACN 2090112 2024-02 PA-34-200T Turbo Seneca II Air Traffic Controller Reports

Cruise

What is ASRS?

The Aviation Safety Reporting System is NASA's voluntary, confidential, non- punitive incident-reporting system, established 1976. Pilots, controllers, dispatchers, and maintenance technicians file reports describing safety- relevant events. NASA de-identifies every report before adding it to the public database. Reports are not investigated by NASA, the FAA, or the NTSB — they represent the reporter's perspective.

Pilot narratives

Verbatim from the de-identified NASA record. First-person account by the reporter. NASA strips identifying details (names, company, specific time); anonymization placeholders are ZZZ, X, Y.

Reporter 1

Aircraft X IFR ZZZ to ZZZ1, canceled IFR and requested flight following. Approximately 20 miles later requested to pick up IFR again. I issued clearance "Aircraft X cleared to ZZZ1 via direct ZZZZZ direct ZZZ1 maintain 100." Aircraft X's readback was stepped on but upon reviewing the playback it sounds like her read back "cleared to ZZZ1 via direct." Multiple fighters were recovering the from SUAs (special use airspace) at the time and I neglected to follow up on the readback that was covered. I was alerted to the MSAW alert by the next Controller, I could not discern it from the erroneous alerts caused by the fighter recovery. When I was made aware of the situation I issued a climb to the ZZZ2. "Aircraft X climb and maintain 110 immediately" I then issued a low altitude alert. Suggestions: Get clarification on readback if it is covered.

Reporter 2

Aircraft X was on an IFR flight plan with good route and altitude and cancelled IFR for flight fallowing and turned direct to his destination, the fighters started recovering from the military airspace in different flight configurations and callsigns than they entered the airspace on. I became task saturated on the D-side entering fighter flight plans and getting the R-side beacon codes in a timely manor. During this period Aircraft X asked again for an IFR clearance and was clearly issued his previous route of ZZZZZ direct ZZZ1 at 100 which is good route and altitude, his read back was partially covered by multiple aircraft but it is a familiar flight and route and we also both observed the aircraft turn towards ZZZZZ and moved on to other duties. I was not watching the scope much at all and fixing/entering fighter flight plans when sector 3 called and asked about the aircraft route. I pointed to it on the score and the R-side immediately climbed the aircraft. I’m unaware of when the MSAW started because all the fighter flights were triggering alerts as usual. Comms in this area are not good at 100 and the pilot had to be issued the climb twice before acknowledging. And was issued a low altitude alert. Splitting the sector was not an option given the timing of the bump in traffic, and had it been split ahead of time all this occurred in sector 06 so I don’t believe it would have helped the frequency congestion or traffic load. It was a missed read back and expectation bias given the route filed, altitude, and the flight being a regular one in the area, on this route regularly.

NASA classification — Anomalies

ATC Issue
Deviation / Discrepancy - Procedural
Inflight Event / Encounter

NASA classification — Assessments

Contributing Factors / Situations: Human Factors
Primary Problem: Human Factors

ASRS reports are voluntarily submitted, de-identified by NASA, and represent the reporter's perspective. The presence of reports on a topic cannot be used to infer prevalence in the National Airspace System. The authoritative source is the NASA ASRS Database Online at asrs.arc.nasa.gov ↗.