Helicopter pilot reported an near midair collision with another helicopter as both aircraft returned...

Attributes
ACN	1048773
Time
Date	201211
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Make Model Name	Agusta Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	Landing
Flight Plan	None
Aircraft 2
Make Model Name	Bell Helicopter Textron Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	Descent
Flight Plan	VFR
Person 1
Function	Pilot Flying
Qualification	Flight Crew Instrument Flight Crew Commercial Flight Crew Flight Instructor
Experience	Flight Crew Last 90 Days 40 Flight Crew Total 2580 Flight Crew Type 165
Events
Anomaly	Conflict NMAC
Miss Distance	Horizontal 0 Vertical 200

Narrative:

After completing a hoist rescue mission; three aircraft from a local city fire department were returning to base. One aircraft was cancelled and made a 180 degree turn prior to leaving the area. This aircraft was approximately one mile south and not involved. The other two aircraft involved in the rescue were returning from the incident via the same standard helicopter arrival route for the home base airport. Both aircraft were in contact with each other; however each pilot believed the other aircraft was in a different location than they actually were. The larger faster aircraft overflew the other by approximately 200 vertical feet causing that pilot to initiate a rapid descent. The overflying aircraft crew was unaware of the incident until notified by the other pilot. Both aircraft returned safely to base and a thorough debrief with all members involved was conducted.

Original NASA ASRS Text

Title: Helicopter pilot reported an NMAC with another helicopter as both aircraft returned from a rescue mission via the same standard arrival route to their home base. Both aircraft believed the other was in a different location.

Narrative: After completing a hoist rescue mission; three aircraft from a local city fire department were returning to base. One aircraft was cancelled and made a 180 degree turn prior to leaving the area. This aircraft was approximately one mile south and not involved. The other two aircraft involved in the rescue were returning from the incident via the same standard helicopter arrival route for the home base airport. Both aircraft were in contact with each other; however each pilot believed the other aircraft was in a different location than they actually were. The larger faster aircraft overflew the other by approximately 200 vertical feet causing that pilot to initiate a rapid descent. The overflying aircraft crew was unaware of the incident until notified by the other pilot. Both aircraft returned safely to base and a thorough debrief with all members involved was conducted.

Data retrieved from NASA's ASRS site as of July 2013 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.

Helicopter pilot reported an near midair collision with another helicopter as both aircraft returned from a rescue mission via the same standard arrival route to their home base. Both aircraft believed the other was in a different location.