Air carrier flight crew reported they departed an airport after the Tower closed without obtaining approval from Center to depart.
Synopsis
Air carrier flight crew reported they departed an airport after the Tower closed without obtaining approval from Center to depart.
Narrative
At approximately XA40; I received and read back complete IFR flight clearance prior to push-back. The PIC and I then thoroughly briefed the flight plan beginning with clearance instructions. We pushed back at XB06; and realized on push-back the field had reverted to Class E. We continued to taxi for and depart runway 03 making all calls on CTAF. During taxi to Runway 03; we heard; and were in visual and radio contact with an inbound air carrier aircraft. We took the runway as that aircraft called a 4 mile final to Runway 03. On climb out; we performed the obstacle departure procedure (as briefed) and contacted Departure; whereupon we were immediately notified of a possible departure deviation for departure without ATC release.The cause of the event was confusion on multiple fronts. 1) Aircrew called for and received complete clearance prior to mid-day airfield temporary closure. Shortly after receiving clearance; tower closed and the airfield reverted to uncontrolled operations. Aircrew continued to taxi and depart with full clearance; lacking any 'wheels-up'; 'clearance void'; or 'contact departure to activate flight plan' instructions. We contacted Departure agency as soon as possible after takeoff. 2) The Field closure NOTAM was under Section A. 3) FO/Flying Pilot's limited experience flying from uncontrolled airfields with IFR clearance.1. Upon realizing the airfield was closed; the aircrew should probably have contacted ATC to ensure departure clearance. Quarterly training on uncontrolled airfield operations could help to prevent further similar occurrences. 2. Ensure temporary field closure NOTAMS are included in Section B with clear IFR departure procedure instructions; including appropriate ATC frequencies; rather than under Section A. 3. Ensure airport controllers remain cognizant of closures and departure times; and handle clearances accordingly. Please.
Second reporter narrative
While acting as PIC; I operated a flight on an IFR flight plan filed by a company dispatcher.Approximately 25 minutes before our scheduled departure time; my First Officer (FO) obtained our IFR clearance from the ground controller while I gave my company's standard jumpseat briefing to an offline pilot who was to occupy the cockpit jumpseat for the flight. The FO was on headset for this so as to hear the clearance better over the cockpit avionics fans and to not interfere with my jumpseat briefing. Afterward; we went through the clearance together to verify proper inputs to the aircraft's Flight Management System; it was a complete clearance and the FO did not note any clearance void times or 'hold for release' instruction in the clearance.Our company flight release contained an active NOTAM. We both missed that this NOTAM meant a closure of the control tower due to the notice's use of 'SVC TWR'; nonstandard (and non-noted) use of local time rather than UTC/Zulu; and the notice being categorized under Section A on our company flight release; rather than Section B where I would expect to see a tower closure notice. I had never heard a control tower referred to as a 'service tower' before and the window had already passed in the expected UTC/Zulu time. As a result; I was not immediately aware that the tower had closed just before pushback. Nevertheless; it became clear that this was the case after we were unable to contact ground control for pushback clearance on either the Ground Control or Tower frequencies--a fact reinforced by another air carrier flight heard making position reports on the tower/CTAF frequency as it approached the field.We pushed back from the terminal and taxied to the active runway for departure. During the taxi-out; we were in visual and radio contact with a second inbound air carrier flight (the flight previously heard on CTAF landed as we taxied to the runway). That second aircraft reported being on a 4-mile final approach just before we took the runway for takeoff. Though we had been issued an IFR clearance; VMC conditions prevailed and we effectively departed under VFR; though we had our assigned discrete squawk code in the transponder. We contacted the ARTCC as we climbed out of the traffic pattern and joined our flight plan route. The controller reissued the same clearance we were given by the ground controller. Shortly thereafter; a second controller asked why we didn't contact the ARTCC for IFR release. I told him we had not been told to do so when we obtained our clearance.Cause: The cause of the event was confusion created by the temporary daytime closure of the control tower. Contributing factors included: 1) a poorly-worded NOTAM pertaining to the tower closure; the non-standard use of local time rather than UTC/Zulu within the NOTAM; and how the NOTAM was categorized on the company flight release; 2) the timing of the tower closure occurring after we had obtained our IFR clearance but before our departure; 3) the absence of any clearance void time or instruction to contact the ARTCC prior to departure for IFR release in the IFR clearance issued by ground control; despite the issuing controller knowing that the tower would be closing prior to our departure time; and 4) PIC's limited experience departing uncontrolled fields when operating under IFR. Suggestions: In hindsight; contacting the ARTCC prior to takeoff would've been prudent despite our already having received a full IFR clearance. Typically; when departing an uncontrolled field; ARTCCs instruct us to contact them short of the runway; ready for takeoff; to obtain an IFR clearance. Our situation unfolded in a manner conducive to errors. A training module outlining ATC's expectations in such situations; to include discussion of departing uncontrolled fields under VFR; could help avoid this; as would guidance for controllers issuing clearances just prior to scheduled facility closures to instruct pilots to contact ARTCC prior to departure if the tower is closed.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.