Narrative:

Returning to base from a patient flight. Checked WX before departure. WX reporting MVFR, 1200 ft scattered, 1500 ft broken, better than 5 mi visibility. Leaving eastward, call-up to ZZZ tower was initiated with no response (the same situation has been reported to me by my fellow pilots). Several subsequent attempts were made, again with no reply from tower. Thinking maybe that the tower had closed, I continued transitioning the area. Finally, as I was about to exit the area, the controller called up and asked 'north-number so and so, is that you?' I replied 'yes, I've been trying to call you.' then the controller said 'just because you can't reach us on the normal frequency, doesn't mean you should continue through the airspace.' 'we could have other aircraft out there.' 'you could have tried 121.5.' I agreed, I could have called on the emergency frequency. I don't want to point fingers, but there seems to be periods when the controller is not being attentive. I believe that the radio in a 24 hour facility should be monitored 24 hours. This would prevent future recurrence of the situation.

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Original NASA ASRS Text

Title: AIR AMBULANCE HELI PLT FLEW THROUGH CLASS D AIRSPACE WITHOUT CLRNC DUE TO NOT BEING ANSWERED AFTER SEVERAL ATTEMPTS.

Narrative: RETURNING TO BASE FROM A PATIENT FLT. CHKED WX BEFORE DEP. WX RPTING MVFR, 1200 FT SCATTERED, 1500 FT BROKEN, BETTER THAN 5 MI VISIBILITY. LEAVING EASTWARD, CALL-UP TO ZZZ TWR WAS INITIATED WITH NO RESPONSE (THE SAME SIT HAS BEEN RPTED TO ME BY MY FELLOW PLTS). SEVERAL SUBSEQUENT ATTEMPTS WERE MADE, AGAIN WITH NO REPLY FROM TWR. THINKING MAYBE THAT THE TWR HAD CLOSED, I CONTINUED TRANSITIONING THE AREA. FINALLY, AS I WAS ABOUT TO EXIT THE AREA, THE CTLR CALLED UP AND ASKED 'N-NUMBER SO AND SO, IS THAT YOU?' I REPLIED 'YES, I'VE BEEN TRYING TO CALL YOU.' THEN THE CTLR SAID 'JUST BECAUSE YOU CAN'T REACH US ON THE NORMAL FREQ, DOESN'T MEAN YOU SHOULD CONTINUE THROUGH THE AIRSPACE.' 'WE COULD HAVE OTHER ACFT OUT THERE.' 'YOU COULD HAVE TRIED 121.5.' I AGREED, I COULD HAVE CALLED ON THE EMER FREQ. I DON'T WANT TO POINT FINGERS, BUT THERE SEEMS TO BE PERIODS WHEN THE CTLR IS NOT BEING ATTENTIVE. I BELIEVE THAT THE RADIO IN A 24 HR FACILITY SHOULD BE MONITORED 24 HRS. THIS WOULD PREVENT FUTURE RECURRENCE OF THE SIT.

Data retrieved from NASA's ASRS site as of July 2007 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.