B737 flight crew reported flying off course due to similar sounding fixes.

Attributes
ACN	1517692
Time
Date	201802
Local Time Of Day	1201-1800
Place
Locale Reference	MIA.Airport
State Reference	FL
Environment
Light	Daylight
Aircraft 1
Make Model Name	Large Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Climb
Route In Use	SID VALLY2
Flight Plan	IFR
Person 1
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	ATC Issue All Types Deviation - Procedural Clearance Deviation - Track / Heading All Types

Narrative:

Departing runway 8R miami; captain flying we were assigned heading 090. ATC then cleared us to shalw which I thought was seelo which was another fix on our flight plan. Captain was hand flying so I inputted the fix and confirmed with him. ATC then asked us to fly back to heading 090 and restated direct shalw which we no longer saw in the mcdu. So ATC gave us direct vally which I selected but it was actually the abvally so the plane turned left again. We caught the mistake as ATC told us to turn back to 090. We were handed off to mia center and were given direct another fix back on course. This event occurred due to two similar sounding fixes.

Original NASA ASRS Text

Title: B737 flight crew reported flying off course due to similar sounding fixes.

Narrative: Departing Runway 8R Miami; Captain flying we were assigned heading 090. ATC then cleared us to SHALW which I thought was SEELO which was another fix on our flight plan. Captain was hand flying so I inputted the fix and confirmed with him. ATC then asked us to fly back to heading 090 and restated direct SHALW which we no longer saw in the MCDU. So ATC gave us direct VALLY which I selected but it was actually the ABVALLY so the plane turned left again. We caught the mistake as ATC told us to turn back to 090. We were handed off to MIA Center and were given direct another fix back on course. This event occurred due to two similar sounding fixes.

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.