Accident Sequence
A helicopter engaged in a water sampling mission in the Florida Everglades experienced an accident during takeoff. According to the pilots, the aircraft was departing from a level site covered with 4 to 6 inches of water and moderately covered with mangrove vegetation. During the transition to forward flight, the helicopter's wire strike protection guide made contact with a mangrove branch. This contact caused the nose to pitch down, and the helicopter subsequently rolled to the right, resulting in a rotor blade striking the ground.
Flight Following and Communication
The National Park Service (NPS) was providing flight following services for the mission, with the pilot required to report every 15 minutes. At the time of the accident, there were 7 minutes remaining until the next scheduled report. Unbeknownst to the pilot, the flight following dispatcher had closed after the last report, and the pilot was not notified of this change.
Emergency Locator Transmitter Failure
The helicopter's emergency locator transmitter (ELT) did not activate after the crash. Consequently, no one was immediately aware of the accident. Approximately 5 hours after the flight was expected to report, a ground crew member became concerned upon not hearing from the flight. This crew member contacted NPS personnel and expressed their concern. The occupants remained with the wreckage until around 1845, when they were rescued by a Coast Guard helicopter.
ELT Examination
A subsequent examination and functional test of the ELT revealed that the 'ON-OFF-ARM' switch was not functioning properly. Disassembly of the ELT did not expose the interior of the switch, and no determination could be made regarding the reason for the malfunction.