A VFR cpr mdt caused a TCASII alert in an IFR air carrier medium large transport.

Attributes
ACN	256078
Time
Date	199311
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : mmun
State Reference	FO
Altitude	msl bound lower : 1500 msl bound upper : 14000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : corporate
Make Model Name	Medium Transport
Flight Phase	descent other
Route In Use	enroute airway : mmun
Flight Plan	VFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 50 flight time total : 6700 flight time type : 1800
ASRS Report	256078
Person 2
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	conflict : airborne less severe other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	none taken : anomaly accepted
Consequence	Other
Miss Distance	horizontal : 6000 vertical : 500
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Our cpr mdt was descending on airway to mmun (cancun). PIC requested a VFR descent along the cancun beach to see our company's construction project. Level at 14000 ft MSL, cancun approach issued traffic, an air carrier medium large transport at 11000 ft level, and cleared us for visual separation and VFR descent along a beach. With the traffic at all times in sight, we descended to 1500 ft. During descent, we heard initial communication contact between medium large transport and cancun approach, about 12-15 mi from airport. Either he was not handed off from merida center to cancun approach, or he forgot to call approach. The air carrier medium large transport got an RA with climb command, and he was not aware of our visual descent. My recommendation is to notify all traffic involved of clrncs so there are no surprises. At no time was there a traffic conflict, however, it must have been unnerving for the pilot of the medium large transport to get a TCASII alert.

Original NASA ASRS Text

Title: A VFR CPR MDT CAUSED A TCASII ALERT IN AN IFR ACR MLG.

Narrative: OUR CPR MDT WAS DSNDING ON AIRWAY TO MMUN (CANCUN). PIC REQUESTED A VFR DSCNT ALONG THE CANCUN BEACH TO SEE OUR COMPANY'S CONSTRUCTION PROJECT. LEVEL AT 14000 FT MSL, CANCUN APCH ISSUED TFC, AN ACR MLG AT 11000 FT LEVEL, AND CLRED US FOR VISUAL SEPARATION AND VFR DSCNT ALONG A BEACH. WITH THE TFC AT ALL TIMES IN SIGHT, WE DSNDED TO 1500 FT. DURING DSCNT, WE HEARD INITIAL COM CONTACT BTWN MLG AND CANCUN APCH, ABOUT 12-15 MI FROM ARPT. EITHER HE WAS NOT HANDED OFF FROM MERIDA CTR TO CANCUN APCH, OR HE FORGOT TO CALL APCH. THE ACR MLG GOT AN RA WITH CLB COMMAND, AND HE WAS NOT AWARE OF OUR VISUAL DSCNT. MY RECOMMENDATION IS TO NOTIFY ALL TFC INVOLVED OF CLRNCS SO THERE ARE NO SURPRISES. AT NO TIME WAS THERE A TFC CONFLICT, HOWEVER, IT MUST HAVE BEEN UNNERVING FOR THE PLT OF THE MLG TO GET A TCASII ALERT.

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.