Narrative:

We were in route deviating through a line of weather. I believe we changed controllers when the new [controller] cleared us direct to 'sin-dee'. Controller spelled it out for us as 'sierra-india...etc'. I was pilot monitoring (pm). I recorded the fix on paper. As I was writing the captain plugged what was heard as 'cinde' into the FMS. By the time I got done copying the fix he said captain got 'sin-dee' already and asked what was after that. I told captain and we proceeded along not yet catching the correct spelling as 'sinde'. Somehow the captain typed a C. Maybe because the first syllable of 'sierra' sounds like 'cee'. I don't know. Somehow I didn't yet catch it. Usually when you do this the wrong fix is obviously wrong. This time was different.the resulting flight path on the mfd looked very reasonable as it took us around some weather and then to the airport. No big deal; right? That's when ATC asked us where we were going. Said we should have made a left turn. I told controller we were going to 'sin-dee' and as I was saying it I looked and that's when I saw the pilot flying (PF) put in cinde instead of sinde. In the same breath I told ATC I was turning left and asked controller to spell it again. We corrected everything never getting too far off course it. It was a heading error of about 30 degrees. Thankfully ATC was quick to recognize the error before it became a problem. Team work; right? Researching our flight we discovered that cinde is the FAF to a VOR a approach to 3g4 airport in ohio. This was southwest of cvg and reasonable as a route assignment. This is also not in washington center's area so he wouldn't know about it. Two fixes that sound the same are best kept far away from each other. Also; the PF should have the pm who took the clearance put it in the box. However; had PF been the pm and I PF and pm copied the clearance and loaded the box I believe pm still would have said sierra but typed C because that word is so commonly spelled that way and we were tasked with weather and arrival procedures. Again I am really surprised to see two fixes that sound the same so close to each other. Additionally we were over 10 hours of duty at this point and our cognitive responsiveness may not have been as high as it was earlier in the day. Removing any one of these by themselves may or may not have broken the error chain but together they all added up to a mistake. Again; I am greatful for the watchful eye of a controller who fixed the mistake before it became an issue.

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Original NASA ASRS Text

Title: A CE-680 air crew; while enroute; were cleared to fix 'SINDE'. The Captain mistakenly typed the fix as 'CINDE'. The crew began to turn to the wrong fix when they were queried by ATC who also respelled the fix name. The crew entered the correct fix and proceeded as cleared. CINDE is 150 NM northwest of SINDE.

Narrative: We were in route deviating through a line of weather. I believe we changed controllers when the new [controller] cleared us direct to 'Sin-Dee'. Controller spelled it out for us as 'Sierra-India...etc'. I was pilot monitoring (PM). I recorded the fix on paper. As I was writing the Captain plugged what was heard as 'CINDE' into the FMS. By the time I got done copying the fix he said Captain got 'Sin-Dee' already and asked what was after that. I told Captain and we proceeded along not yet catching the correct spelling as 'SINDE'. Somehow the captain typed a C. Maybe because the first syllable of 'Sierra' sounds like 'Cee'. I don't know. Somehow I didn't yet catch it. Usually when you do this the wrong fix is obviously wrong. This time was different.The resulting flight path on the MFD looked very reasonable as it took us around some weather and then to the airport. No big deal; right? That's when ATC asked us where we were going. Said we should have made a left turn. I told Controller we were going to 'Sin-Dee' and as I was saying it I looked and that's when I saw the pilot flying (PF) put in CINDE instead of SINDE. In the same breath I told ATC I was turning left and asked Controller to spell it again. We corrected everything never getting too far off course it. It was a heading error of about 30 degrees. Thankfully ATC was quick to recognize the error before it became a problem. Team work; right? Researching our flight we discovered that CINDE is the FAF to a VOR A approach to 3G4 airport in Ohio. This was southwest of CVG and reasonable as a route assignment. This is also not in Washington center's area so he wouldn't know about it. Two fixes that sound the same are best kept far away from each other. Also; the PF should have the PM who took the clearance put it in the box. However; had PF been the PM and I PF and PM copied the clearance and loaded the box I believe PM still would have said Sierra but typed C because that word is so commonly spelled that way and we were tasked with weather and arrival procedures. Again I am really surprised to see two fixes that sound the same so close to each other. Additionally we were over 10 hours of duty at this point and our cognitive responsiveness may not have been as high as it was earlier in the day. Removing any one of these by themselves may or may not have broken the error chain but together they all added up to a mistake. Again; I am greatful for the watchful eye of a controller who fixed the mistake before it became an issue.

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.