Air carrier flight crew reported frequency 127.325 for GGG departure control is not listed as a frequency on their Jepp 10-9 chart and Tower/TRACON operating hours may also be in error. The crew reported they taxied and departed without contacting Tower or Departure Control.
Synopsis
Air carrier flight crew reported frequency 127.325 for GGG departure control is not listed as a frequency on their Jepp 10-9 chart and Tower/TRACON operating hours may also be in error. The crew reported they taxied and departed without contacting Tower or Departure Control.
Narrative
My First Officer and I thought the GGG tower was closed based on the information provided on the Jeppesen Info & WX Communications tab; which states the tower is open XB00Z-XR00Z. We did not realize the Jeppesen information did not factor in Daylight Savings Time changes. Therefore; we did not try to get our IFR Clearance to ZZZ on the Tower/Ground frequencies. We pushed at XA04Z and took off at XA15Z. We tried multiple times on the ground to get our clearance to ZZZ on both VHF Comm 1 and 2 on the published frequencies on the 10-9 Airport Diagram (Departure on 128.75; Center on 126.325).At taxi time I asked the First Officer to make the required radio calls on the published UNICOM frequency of 122.95. I thought that the asterisk (*) next to the Ground and Tower frequencies on the 10-9 meant that our required airport movement awareness callouts should be done on the UNICOM frequency (122.95) when the tower is closed. We made all of the required calls on 122.95 and departed VFR. Upon contacting FTW Center on 126.325 once airborne to get our IFR clearance; they sent us to GGG Departure control on 127.325 (not listed on 10-9). That controller told me we had taken off without clearance when the tower was open (which came as a surprise). Upon landing at ZZZ; I called the tower and spoke with the Tower Supervisor. When I told the Supervisor we made all of our required ground calls on the UNICOM frequency; he informed me he had no idea what frequency I was talking about; which surprised me; since it is published on the 10-9 page for the airport.First cause was the fact that the Jeppesen Comm page states the tower does not open until XB00Z. This led to us incorrectly treating the situation as the tower being closed. The second cause was the confusion regarding the use of the published UNICOM frequency vs the CTAF* (Tower) frequency. My understanding came from the Company Flight Operations Manual (FOM); which states; CTAF is a frequency designated for the purpose of carrying out airport advisories practices while operating to or from an airport without an operating Control Tower. The CTAF may be a UNICOM (emphasis added); FSS; or tower frequency and is identified on the Jeppesen airport diagram and/or approach plate.Update all of the Jeppesen Com Pages to reflect the hours of operation for all airports in the database to LOCAL time. This will eliminate the confusion regarding seasonal adjustments made to hours of operation due to Daylight Savings provided in Zulu time. Add clarification to the FOM regarding the meaning of the asterisk (*) next to Ground/Tower/Departure frequencies; when listed on a Jeppesen 10-9; especially when a UNICOM frequency is also published. Add clarification to the FOM as to when pilots should and should not use the UNICOM frequency for required calls when the Tower is closed; specifically when they are both listed on Jeppesen Airport Diagram 10-9 page. Remove the UNICOM frequency from the GGG Jeppesen Airport Diagram 10-9 page if the airport Ground/Tower personnel do not monitor it. Add 127.325 to the GGG Jeppesen 10-9 Departure Control frequencies if this is also a frequency used.
Second reporter narrative
Flight from GGG to ZZZ.Departed without clearance due to our understanding that the airport was closed as noted on the Jeppesen Info & WX Communications tab; which states the tower is open XB00Z-XR00Z.I attempted to obtain an IFR clearance from Longview Departure (128.75) and Ft. Worth Center (126.325) via 16 radio transmissions.I tried each frequency 2 times on each radio. We then moved the aircraft away from the gate and tried each frequency 2 times on each radio thinking perhaps there was interference from the infrastructure.After getting no response I discussed the situation with the captain to get input on the best course of action. The plan was to make standard CTAF calls on the UNICOM frequency (122.95) and we would get our clearance once airborne. As a new FO; this seemed like a reasonable solution as I have once before departed prior to airport operations and received clearance in flight. Once airborne; we made positive contact with ATC who then advised us of our error.Cause: Confusion about the chart and airport hours. The Jepp chart does not take daylight saving into account.It noted the hours of operation in Zulu time which per our clock (Also in Z) indicated to us that the tower was closed.Suggestions: In hindsight; calling tower or ground even if we believed them to be closed would have prevented this.A better understanding of the time on the chart or a note indicating that this time frame does not account for DST (Daylight Saving Time) would have prevented it.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.