Narrative:

Visual approach to unfamiliar airport. Airport environment was in sight but not landing runway. Chain of events started with my concern about the landing runway performance in the [aircraft]. I focused too much on the actual runway then misread/didn't see important information on ILS approach chart to [runway] 24. Briefed highest obstacle south of CCC [VOR]; but missed tower next to centerline. Thought rizer was at 1400 feet; it's 1271 feet. While on left base outside of rizer; realized that we were 2 dots high. Descended to catch glideslope while still on left base. Tower called a low altitude warning. I looked at my chart to check altitude and received a GPWS obstacle warning. Instead of an immediate go-around; I looked out to see where tower [was] relative to our position and extended centerline. Then GPWS 'obstacle; pull up' prompted immediate go around while at 1000 feet. Tower told us to go runway heading and 2000 feet while I was climbing through 2000 feet; cleaning up the aircraft and turning to runway heading. I pulled thrust to idle to prevent flap overspeed but still hit 2700 feet before descending back down to 2000 feet. First officer notified tower of altitude deviation. We were then vectored for another visual approach. Second approach and landing was in moderate turbulence; but completed.all would have been avoided had I studied the approach chart more in depth; then briefed and executed an ILS instead of a visual. I haven't been to islip in a long time and never in visual conditions. I was focused more on the [aircraft's] landing performance in gusty crosswinds. It was poor judgment after a long day. I know to immediately execute a go-around from a GPWS alert; but had a delayed reaction to it.

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Original NASA ASRS Text

Title: Air carrier Captain reported receiving a GPWS obstacle warning on approach to ISP airport.

Narrative: Visual approach to unfamiliar airport. Airport environment was in sight but not landing runway. Chain of events started with my concern about the landing runway performance in the [aircraft]. I focused too much on the actual runway then misread/didn't see important information on ILS approach chart to [Runway] 24. Briefed highest obstacle south of CCC [VOR]; but missed Tower next to centerline. Thought RIZER was at 1400 feet; it's 1271 feet. While on left base outside of RIZER; realized that we were 2 dots high. Descended to catch glideslope while still on left base. Tower called a low altitude warning. I looked at my chart to check altitude and received a GPWS obstacle warning. Instead of an immediate go-around; I looked out to see where Tower [was] relative to our position and extended centerline. Then GPWS 'obstacle; pull up' prompted immediate go around while at 1000 feet. Tower told us to go runway heading and 2000 feet while I was climbing through 2000 feet; cleaning up the aircraft and turning to runway heading. I pulled thrust to idle to prevent flap overspeed but still hit 2700 feet before descending back down to 2000 feet. First Officer notified Tower of altitude deviation. We were then vectored for another visual approach. Second approach and landing was in moderate turbulence; but completed.All would have been avoided had I studied the approach chart more in depth; then briefed and executed an ILS instead of a visual. I haven't been to Islip in a long time and never in visual conditions. I was focused more on the [aircraft's] landing performance in gusty crosswinds. It was poor judgment after a long day. I know to immediately execute a go-around from a GPWS alert; but had a delayed reaction to it.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.