Air carrier flight crew reported the Jeppesen 10-7 pages listing the operating hours for GSP Tower were incorrect; which resulted in the flight crew taxiing without a clearance from Tower.
Synopsis
Air carrier flight crew reported the Jeppesen 10-7 pages listing the operating hours for GSP Tower were incorrect; which resulted in the flight crew taxiing without a clearance from Tower.
Narrative
During the briefing; we noted on the 10-7 Jepp page that the GSP Tower was not open 24 hours. However; the chart listed the operating hours were between 11:00Z and 0445Z; with a note that daylight savings time is observed. We also heard an earlier departure receiving their IFR clearance from Atlanta Center; which is also detailed on the 10-7. GSP also uses a UNICOM frequency. As we were leaving before 11:00Z and the chart stated the Tower opened at 11:00Z; we made announcements on UNICOM frequency for GSP 'Greer Traffic' during taxi. Exiting the Ramp; we contacted Atlanta Center to obtain our clearance to ZZZ. Atlanta told us to contact Greer Departure who subsequently instructed us to contact Greer Ground.Ground queried if we were taxiing on L toward Runway 4 and we confirmed we were. They then provided clearance to ZZZ [Airport] and taxi instructions to continue. They then informed us the Tower opened at 1000Z and that our chart was incorrect. We departed and continued to ZZZ with no further issues. I then called ATC in GSP to apologize and explain the situation. He was appreciative of the phone call and requested we update the 10-7 for proper hours of operation. I am following up with the company to advise them of the error on the page. I also debriefed the event with the First Officer at the conclusion of the flight.Suggestions: Ensure that 10-7 charts list proper hours of operation for ATC. Had the CTAF and Tower shared the same frequency we would have been heard by ATC as we made our position reports on the CTAF frequency.
Second reporter narrative
During our departure briefing we reviewed the company notes; and began our taxi under the rules associated with non-towered operations with the understanding that the Tower did not open until XH:00; as noted on the 10-7 page. On our way to the runway we attempted to pick up our clearance via Center who then directed us back to Tower. At this time we realized that Tower had opened and we quickly worked with them to resume normal towered operations. Following the flight the Captain called the Tower and discussed the incident productively. We also debriefed the incident as a crew and agreed to send an email to the Company. We found the verbiage on the 10-7 to be misleading as it states that the Tower opens at XH:00 (which is not affected by daylight savings) and then said that daylight savings is observed. We were taxiing at XG:00; so according to the 10-7 the Tower was not open. Converting to local time additionally indicates that the Tower should open at XC:00 local time and XD:00 during daylight savings. We were taxiing at XC:00 local time during daylight savings.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.