Air carrier captain reported two flights with similar callsigns departing the same airport around th...

Attributes
ACN	1700915
Time
Date	201911
Local Time Of Day	0001-0600
Place
Locale Reference	SPIM.Airport
State Reference	FO
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	Heavy Transport
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Person 1
Function	Captain Pilot Not Flying
Qualification	Flight Crew Instrument Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 114
Events
Anomaly	Deviation - Procedural Published Material / Policy

Narrative:

Spim to ZZZ cancelled a few days ago; but came home last night. They took off around 15 minutes prior to us. On paper they were aircraft Y; or close to that; but they took off as aircraft X. We were aircraft X. This caused problems all night as we were on the same frequency most of the night. Callsigns this close would cause problems anywhere; but south of the border; the controllers could not grasp that they had to use complete callsigns - add the 'company name' to the other callsigns. Had it not been for the diligence of both crews we would have taken one another's clearances several times in the night. Having two aircraft airborne in close proximity to one another with callsigns that close is unacceptable. This problem should have been foreseeable.

Original NASA ASRS Text

Title: Air carrier Captain reported two flights with similar callsigns departing the same airport around the same time created confusion in communication between controllers and flight crew.

Narrative: SPIM to ZZZ cancelled a few days ago; but came home last night. They took off around 15 minutes prior to us. On paper they were Aircraft Y; or close to that; but they took off as Aircraft X. We were Aircraft X. This caused problems all night as we were on the same frequency most of the night. Callsigns this close would cause problems anywhere; but south of the border; the controllers could not grasp that they had to use complete callsigns - add the 'Company name' to the other callsigns. Had it not been for the diligence of both crews we would have taken one another's clearances several times in the night. Having two aircraft airborne in close proximity to one another with callsigns that close is unacceptable. This problem should have been foreseeable.

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.

Air carrier captain reported two flights with similar callsigns departing the same airport around the same time created confusion in communication between controllers and flight crew.