A pitts S1S pilot reported a near miss with a helicopter immediately after takeoff at a CTAF airport...

Narrative:

After performing my run-up at runway 34 I waited for two arrivals. After the second arrival cleared the runway I announced departing runway 34 straight out; entered the runway and started my takeoff roll. Just before I broke ground a helicopter announced crossing the runway and did so about 500 ft down the runway from where I was when the crossing call was made. I descended to cross under the helicopter approximately 3-5 seconds after the crossing call. I would estimate 50 ft altitude clearance with 100 ft lateral clearance. The event was observed by two other pilots. One was a twin turbine commander pilot waiting to depart after me. The other was an rv pilot; the second of the two arrivals. He had stopped on the parallel runway to watch my departure as I was flying a pitts S1S. The rv pilot later said that he estimated 50 ft of vertical clearance and that I was directly under the helicopter. The rv pilot also said that he clearly heard my departure call. Per the rv pilot the helicopter was a robinson R22. Because of the short time from the helicopter's call and the high workload to a pitts type aircraft I was unable to made a radio call. Any sudden turn to avoid at low altitude and low speed would have been undesirable. Given the available space under the helicopters I elected to continue straight ahead and descend. The rotor wash consisted of two very sharp jolts a fraction of a second apart. I believe the cause of the incident was failure on the part of the helicopter pilots to hear my radio call and the failure by the helicopter to look for aircraft using the runway. A contributing factor may have been that we had just switched from runway 16 to runway 34. There had; however; been two arrivals on runway 34 prior to my departure.

Original NASA ASRS Text

Title: A Pitts S1S pilot reported a near miss with a helicopter immediately after takeoff at a CTAF airport. The helicopter pilot either did not hear or did not responded to the reporter's CTAF traffic pattern call and took off at the other end of the runway.

Narrative: After performing my run-up at Runway 34 I waited for two arrivals. After the second arrival cleared the runway I announced departing Runway 34 straight out; entered the runway and started my takeoff roll. Just before I broke ground a helicopter announced crossing the runway and did so about 500 FT down the runway from where I was when the crossing call was made. I descended to cross under the helicopter approximately 3-5 seconds after the crossing call. I would estimate 50 FT altitude clearance with 100 FT lateral clearance. The event was observed by two other pilots. One was a twin turbine Commander pilot waiting to depart after me. The other was an RV pilot; the second of the two arrivals. He had stopped on the parallel runway to watch my departure as I was flying a Pitts S1S. The RV pilot later said that he estimated 50 FT of vertical clearance and that I was directly under the helicopter. The RV pilot also said that he clearly heard my departure call. Per the RV pilot the helicopter was a Robinson R22. Because of the short time from the helicopter's call and the high workload to a Pitts type aircraft I was unable to made a radio call. Any sudden turn to avoid at low altitude and low speed would have been undesirable. Given the available space under the helicopters I elected to continue straight ahead and descend. The rotor wash consisted of two very sharp jolts a fraction of a second apart. I believe the cause of the incident was failure on the part of the helicopter pilots to hear my radio call and the failure by the helicopter to look for aircraft using the runway. A contributing factor may have been that we had just switched from Runway 16 to Runway 34. There had; however; been two arrivals on Runway 34 prior to my departure.

Data retrieved from NASA's ASRS site as of April 2012 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.

Attributes
ACN	855930
Time
Date	200910
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	S-1 All Series
Operating Under FAR Part	Part 91
Flight Phase	Takeoff Initial Climb
Flight Plan	None
Aircraft 2
Make Model Name	Robinson R22
Operating Under FAR Part	Part 91
Flight Phase	Initial Climb Takeoff
Person 1
Function	Single Pilot
Qualification	Flight Crew Flight Instructor Flight Crew Commercial Flight Crew Instrument
Experience	Flight Crew Last 90 Days 15 Flight Crew Total 2021 Flight Crew Type 195
Events
Anomaly	Conflict NMAC Deviation - Procedural Published Material / Policy
Miss Distance	Horizontal 100 Vertical 30

A pitts S1S pilot reported a near miss with a helicopter immediately after takeoff at a CTAF airport. The helicopter pilot either did not hear or did not responded to the reporter's CTAF traffic pattern call and took off at the other end of the runway.