A boeing C17 flight crew inadvertently responded and complied with clearances intended for another a...

Narrative:

[While] at FL350 we changed frequency to center 100 miles north of...our intended arrival location. We checked in at FL350 as call sign. We then were instructed to descend to FL240; we read back clearance 'aircraft X descend to FL240.' at this time we descended to FL240; around FL310 we were asked if we were in the descent and responded yes and at that time was issued another descent clearance. We landed at [our destination] uneventful. I was notified today (four weeks later); that we checked on at FL350 and the intended descent was for a [an aircraft with a similar sounding call sign] to which we read back the clearance and descended. ATC did not inform us it was for [another aircraft] nor did they stop us from descending or communicating to us that we had mistakenly thought it was a call to us. We were not given a number to call upon landing. Our crew made the mistake of responding to what we heard was [our call sign] and not confirming it was actually [for other aircraft] who we were unaware was even on frequency. Up until today we had no idea a mishap had even taken place; it was an unfortunate place to be; considering two very similar call signs. Both ATC and our crew is responsible and I think better communication and situational awareness can prevent other similar incidents.

Original NASA ASRS Text

Title: A Boeing C17 flight crew inadvertently responded and complied with clearances intended for another aircraft with a similar call sign. The flight was not advised at the time and the reporter only learned of the incident approximately a month after it occurred.

Narrative: [While] at FL350 we changed frequency to Center 100 miles north of...our intended arrival location. We checked in at FL350 as call sign. We then were instructed to descend to FL240; we read back clearance 'Aircraft X descend to FL240.' At this time we descended to FL240; around FL310 we were asked if we were in the descent and responded yes and at that time was issued another descent clearance. We landed at [our destination] uneventful. I was notified today (four weeks later); that we checked on at FL350 and the intended descent was for a [an aircraft with a similar sounding call sign] to which we read back the clearance and descended. ATC did not inform us it was for [another aircraft] nor did they stop us from descending or communicating to us that we had mistakenly thought it was a call to us. We were not given a number to call upon landing. Our crew made the mistake of responding to what we heard was [our call sign] and not confirming it was actually [for other aircraft] who we were unaware was even on frequency. Up until today we had no idea a mishap had even taken place; it was an unfortunate place to be; considering two very similar call signs. Both ATC and our crew is responsible and I think better communication and situational awareness can prevent other similar incidents.

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.

Attributes
ACN	1217550
Time
Date	201410
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Globemaster (C-17)
Operating Under FAR Part	Part 91
Flight Phase	Descent
Flight Plan	IFR
Person 1
Function	Captain Instructor Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine Flight Crew Flight Instructor Flight Crew Instrument
Experience	Flight Crew Last 90 Days 150 Flight Crew Total 2500 Flight Crew Type 1100
Events
Anomaly	ATC Issue All Types Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance

A boeing C17 flight crew inadvertently responded and complied with clearances intended for another aircraft with a similar call sign. The flight was not advised at the time and the reporter only learned of the incident approximately a month after it occurred.