A 3 ship formation of twin otters came within 3 mi of an airliner near hdf.

Attributes
ACN	454656
Time
Date	199911
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : l65.airport
State Reference	CA
Altitude	msl single value : 13500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : personal
Make Model Name	Twin Otter DHC-6
Operating Under FAR Part	Part 91
Navigation In Use	other
Flight Phase	descent : intermediate altitude
Route In Use	arrival : on vectors
Flight Plan	None
Aircraft 2
Operator	general aviation : personal
Make Model Name	Twin Otter DHC-6
Operating Under FAR Part	Part 91
Navigation In Use	other
Flight Phase	descent : intermediate altitude
Flight Plan	None
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : multi engine pilot : instrument pilot : flight engineer pilot : commercial pilot : cfi pilot : atp
Experience	flight time last 90 days : 100 flight time total : 15000 flight time type : 25
ASRS Report	454656
Person 2
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : private pilot : multi engine
Events
Anomaly	conflict : airborne less severe
Independent Detector	other flight crewa
Resolutory Action	controller : issued advisory flight crew : took precautionary avoidance action
Miss Distance	horizontal : 18000 vertical : 2000
Supplementary
Problem Areas	Airspace Structure Flight Crew Human Performance
Primary Problem	Airspace Structure

Narrative:

After dropping skydivers from 16500 ft MSL, the 3-SHIP formation of DH6's I was leading passed within visual range of an airliner eastbound on V64 approximately 6-8 NM west of the perris (L65) airport. I informed socal approach 'dehavilland xa in the lead, flight of 3 descending to the west (for perris) squawking XXXX.' socal acknowledged with radar contact and altitude verification. Several other radio xmissions were ongoing on frequency 134.0 with other aircraft. Visually spotting airliner traffic ahead eastbound on V64, I started a descending left turn back to the perris airport. Socal approach then issued a TA and requested a right turn northbound to avoid the traffic. The controller also realized that we were already in the left turn to the south, amending his instructions to tighten the turn and rollout northbound. All pilots in the 3-SHIP formation maintained their visual lookout and were not aware of any aircraft causing a traffic conflict for our VFR descent. The rest of the problem is due to ATC saturation, 30-40% of all xmissions are not getting through on the first attempt. Controller workload is so great that normal ATC services are disrupted and delayed. This oversaturation is not the norm, it manifests itself for limited time periods on wkends. LOA's with local skydiving operators help relieve some workload but as capacity increases the current system becomes easily saturated degrading the services provided by ATC.

Original NASA ASRS Text

Title: A 3 SHIP FORMATION OF TWIN OTTERS CAME WITHIN 3 MI OF AN AIRLINER NEAR HDF.

Narrative: AFTER DROPPING SKYDIVERS FROM 16500 FT MSL, THE 3-SHIP FORMATION OF DH6'S I WAS LEADING PASSED WITHIN VISUAL RANGE OF AN AIRLINER EBOUND ON V64 APPROX 6-8 NM W OF THE PERRIS (L65) ARPT. I INFORMED SOCAL APCH 'DEHAVILLAND XA IN THE LEAD, FLT OF 3 DSNDING TO THE W (FOR PERRIS) SQUAWKING XXXX.' SOCAL ACKNOWLEDGED WITH RADAR CONTACT AND ALT VERIFICATION. SEVERAL OTHER RADIO XMISSIONS WERE ONGOING ON FREQ 134.0 WITH OTHER ACFT. VISUALLY SPOTTING AIRLINER TFC AHEAD EBOUND ON V64, I STARTED A DSNDING L TURN BACK TO THE PERRIS ARPT. SOCAL APCH THEN ISSUED A TA AND REQUESTED A R TURN NBOUND TO AVOID THE TFC. THE CTLR ALSO REALIZED THAT WE WERE ALREADY IN THE L TURN TO THE S, AMENDING HIS INSTRUCTIONS TO TIGHTEN THE TURN AND ROLLOUT NBOUND. ALL PLTS IN THE 3-SHIP FORMATION MAINTAINED THEIR VISUAL LOOKOUT AND WERE NOT AWARE OF ANY ACFT CAUSING A TFC CONFLICT FOR OUR VFR DSCNT. THE REST OF THE PROB IS DUE TO ATC SATURATION, 30-40% OF ALL XMISSIONS ARE NOT GETTING THROUGH ON THE FIRST ATTEMPT. CTLR WORKLOAD IS SO GREAT THAT NORMAL ATC SVCS ARE DISRUPTED AND DELAYED. THIS OVERSATURATION IS NOT THE NORM, IT MANIFESTS ITSELF FOR LIMITED TIME PERIODS ON WKENDS. LOA'S WITH LCL SKYDIVING OPERATORS HELP RELIEVE SOME WORKLOAD BUT AS CAPACITY INCREASES THE CURRENT SYS BECOMES EASILY SATURATED DEGRADING THE SVCS PROVIDED BY ATC.

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.