Narrative:

Shift change at EMS operation at ZZZ. Was a request for an emergency flight from xyz to abc. Pilot coming on duty immediately got a copy of WX (see enclosure). Pilot preflted helicopter and launched from home base to xyz. Pilot called xyz radio on frequency north of XXX and asked def for winds at 3 and 6. Pilot did not request WX briefing because he knew what the WX was like (first mistake), because radio would have given NOTAMS concerning frequency change at ZZZ. Pilot had not been to xyz in the last 6 months. He was unaware of NOTAM concerning frequency change. This call was out of the ordinary because another EMS operation in abc usually covered these flts. Pilot called on published frequencys when 7 mi to west with no response frequency. Pilot did not notice other aircraft in area. Pilot landed at hospital, dropped off crew and proceeded back over to ZZZ airport to refuel for lifeguard flight to abc. FBO fuel truck was standing by because of prior phone call set up refueling. On approach pilot noticed fuel truck and another anti-collision light from what appeared to be an aircraft. Pilot changed to frequency and tried contacting. No response. Pilot flew to refuel pad where truck was waiting. Pilot then noticed another 2 aircraft that turned on anti-collision lights. Three national guard aircraft were operating under night vision goggles at airport. Pilot immediately asked refueling attendant if he had heard pilot transmitting on both CTAF and tower frequency. Attendant said he thought they changed frequency to. Pilot talked to officer and told him he was unaware of the frequency change. He said frequencys were changed as per NOTAM back 3 weeks ago. Pilot then received information and passed it along to EMS operation in abc, too. Pilot, upon getting finished with lifeguard flight, immediately put notice of NOTAMS board. Things that could have prevented this: 1) pilot should have asked def radio for WX brief to include NOTAMS since he had not been to xyz in last 6 months. 2) please notify EMS operations of work at xyz so we (if we get called) can be aware of helicopter's operating night vision goggles. 3) pilot admits he entered a control zone west/O establishing communications. This was inadvertent and not deliberate.

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Original NASA ASRS Text

Title: EMS HELICOPTER LANDED AT DEF UNABLE TO CONTACT TWR. UNAWARE THAT TWR FREQ HAD BEEN CHANGED.

Narrative: SHIFT CHANGE AT EMS OPERATION AT ZZZ. WAS A REQUEST FOR AN EMER FLT FROM XYZ TO ABC. PLT COMING ON DUTY IMMEDIATELY GOT A COPY OF WX (SEE ENCLOSURE). PLT PREFLTED HELI AND LAUNCHED FROM HOME BASE TO XYZ. PLT CALLED XYZ RADIO ON FREQ N OF XXX AND ASKED DEF FOR WINDS AT 3 AND 6. PLT DID NOT REQUEST WX BRIEFING BECAUSE HE KNEW WHAT THE WX WAS LIKE (FIRST MISTAKE), BECAUSE RADIO WOULD HAVE GIVEN NOTAMS CONCERNING FREQ CHANGE AT ZZZ. PLT HAD NOT BEEN TO XYZ IN THE LAST 6 MONTHS. HE WAS UNAWARE OF NOTAM CONCERNING FREQ CHANGE. THIS CALL WAS OUT OF THE ORDINARY BECAUSE ANOTHER EMS OPERATION IN ABC USUALLY COVERED THESE FLTS. PLT CALLED ON PUBLISHED FREQS WHEN 7 MI TO W WITH NO RESPONSE FREQ. PLT DID NOT NOTICE OTHER ACFT IN AREA. PLT LANDED AT HOSPITAL, DROPPED OFF CREW AND PROCEEDED BACK OVER TO ZZZ ARPT TO REFUEL FOR LIFEGUARD FLT TO ABC. FBO FUEL TRUCK WAS STANDING BY BECAUSE OF PRIOR PHONE CALL SET UP REFUELING. ON APCH PLT NOTICED FUEL TRUCK AND ANOTHER ANTI-COLLISION LIGHT FROM WHAT APPEARED TO BE AN ACFT. PLT CHANGED TO FREQ AND TRIED CONTACTING. NO RESPONSE. PLT FLEW TO REFUEL PAD WHERE TRUCK WAS WAITING. PLT THEN NOTICED ANOTHER 2 ACFT THAT TURNED ON ANTI-COLLISION LIGHTS. THREE NATL GUARD ACFT WERE OPERATING UNDER NIGHT VISION GOGGLES AT ARPT. PLT IMMEDIATELY ASKED REFUELING ATTENDANT IF HE HAD HEARD PLT XMITTING ON BOTH CTAF AND TWR FREQ. ATTENDANT SAID HE THOUGHT THEY CHANGED FREQ TO. PLT TALKED TO OFFICER AND TOLD HIM HE WAS UNAWARE OF THE FREQ CHANGE. HE SAID FREQS WERE CHANGED AS PER NOTAM BACK 3 WKS AGO. PLT THEN RECEIVED INFO AND PASSED IT ALONG TO EMS OPERATION IN ABC, TOO. PLT, UPON GETTING FINISHED WITH LIFEGUARD FLT, IMMEDIATELY PUT NOTICE OF NOTAMS BOARD. THINGS THAT COULD HAVE PREVENTED THIS: 1) PLT SHOULD HAVE ASKED DEF RADIO FOR WX BRIEF TO INCLUDE NOTAMS SINCE HE HAD NOT BEEN TO XYZ IN LAST 6 MONTHS. 2) PLEASE NOTIFY EMS OPS OF WORK AT XYZ SO WE (IF WE GET CALLED) CAN BE AWARE OF HELI'S OPERATING NIGHT VISION GOGGLES. 3) PLT ADMITS HE ENTERED A CTL ZONE W/O ESTABLISHING COMS. THIS WAS INADVERTENT AND NOT DELIBERATE.

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.