Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 134; Flight Crew Total 3256; Flight Crew Type 1485
Troubleshooting; Human-Machine Interface; Situational Awareness; Confusion; Distraction
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Provided Assistance; Flight Crew FLC Overrode Automation; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Became Reoriented
Equipment / Tooling
Indianapolis Center sent a reroute via CPDLC 'proceed direct to IOW. Rest of route unchanged.' IOW was previously a fix further down on our cleared flight plan. We accepted the clearance and loaded to fix via the load prompt on the CPDLC page displayed on the FMC. We quickly noticed that the path to IOW; displayed on the MFD; did not represent the general direction we believed IOW to be. We did not make the turn and instead queried ATC via voice communications and asked for a heading to allow time to analyze the new route. We investigated further and found that the IOW sent and loaded via CPDLC was in fact the identifier IOW for the ILS 07 in Ottawa Ontario (CYOW). We loaded the correct IOW manually and informed ATC of the discrepancy. The flight otherwise continued normally.
Cruising along and CPDLC uplinked clearance to proceed direct IOW. Flying pilot selected the 'load' prompt from CPDLC message; and verified that IOW was then displayed as the top waypoint on page 1 of legs. Which it was. We both verified this and selected both the execute prompt on FMC and the 'accept' prompt on CPDLC; as I was verifying the clearance with ATC on the radio; as I have some mistrust of the system. The aircraft immediately started a right hand turn to what turns out to be the Ottawa Canada ILS DME identifier for RW 07 in Ottawa. We immediately recognized an obvious error in location so just put the MCP into heading select mode and steered a few degrees back to IOW (as in Iowa City; Iowa); which was directly in front of us. There was only a very minor wiggle of course; not even a fraction of a mile. However; now this new IOW fix is in the legs page on top; so we pull up the IOW fix a few legs down; but could get it to overwrite the position 1 fix. We asked for a heading from ATC just to mitigate that threat; and alerted them to the issue of duplicate IOW. Eventually we had to delete Both IOW fixes and reinsert the correct one. Problem resolved. Took a little time to figure out exactly what and where the duplicate IOW fix was. Significant to note; however; is that we are being instructed to ALWAYS use the load prompt from CPDLC to insert new routing when available. However; in this case not only was the wrong fix inserted; but there was no duplicate fix warning page that we normally get when inputting fixes into the box by hand. When IOW is inserted by hand; the box comes up with two options and shows the lat/long coordinates of both; making you select further which one you want. This page did not come up when cpdlc injected IOW into the fmc; and in this case turned out to be incorrect. I think at the exact time of the event; the IOW fix in Canada was slightly shorter distance than Iowa city; so the box defaulted to the closer fix. Perhaps. By the time we figure all this out; we were almost to IOW. ATC was notified of all this; and the aircraft; flight; and passengers were not put in an unsafe condition; because we caught the issue immediately.
B737 flight crew reported receiving a CPDLC that contained a fix for a nearby ILS when the fix needed was an enroute waypoint.  The spelling was the same for each location.