Narrative:

Aircraft X called me near ZZZ1 airport near ZZZ. I radar identified him and validated his mode C; but I do not recall if he had the ATIS. I cleared him into ZZZ class B airspace along the route we normally assign. A little while later he said something like; 'tower we are declaring mayday; we are going down.' I reissued the altimeter and asked what assistance he needed. I got no response and then a little while later he called and reported he was on the ground safely and that they were going to call their maintenance. I tried to get more information from him and ended up getting his location and that the people on board were okay. I got the impression from the pilot that the helicopter was in good enough shape that they may be able to fly it out. I filed this as an accident because I don't know for sure that it won't be classified that way and I don't know what condition the helicopter or the crew are actually in. Immediately after the pilots original call we started scanning to see if we could see him out the window. I made the situation known and we got the crash phone activated and then updated the airport authority fire command that the aircrew said they did not need assistance.

Google
 

Original NASA ASRS Text

Title: Tower describes a situation where he is talking to a helicopter and in lands off the airport in an emergency situation.

Narrative: Aircraft X called me near ZZZ1 airport near ZZZ. I radar Identified him and validated his mode C; but I do not recall if he had the ATIS. I cleared him into ZZZ Class B airspace along the route we normally assign. A little while later he said something like; 'Tower we are declaring mayday; we are going down.' I reissued the altimeter and asked what assistance he needed. I got no response and then a little while later he called and reported he was on the ground safely and that they were going to call their maintenance. I tried to get more information from him and ended up getting his location and that the people on board were okay. I got the impression from the pilot that the helicopter was in good enough shape that they may be able to fly it out. I filed this as an accident because I don't know for sure that it won't be classified that way and I don't know what condition the helicopter or the crew are actually in. Immediately after the pilots original call we started scanning to see if we could see him out the window. I made the situation known and we got the crash phone activated and then updated the airport authority fire command that the aircrew said they did not need assistance.

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.