Helicopter crash debris at a storage facility. (click on the image to view the WJLA news video)

Three died when a midair collision happened between a fixed-wing arrival and a helicopter, in the traffic pattern at the controlled airport in Frederick, Maryland [KFDK]. The fixed-wing aircraft was a Cirrus; it had departed in the morning and was just finishing a three-hour flight, returning from Cleveland, TN.

At the time, three helicopters were training in a lower flight pattern, underneath the fixed-wing arrival traffic pattern. The helicopters apparently are part of a training program at Advanced Helicopter Concepts, and are based near the south end of the airport. One of them, a Robinson R44 helicopter, collided with the Cirrus. Just seconds before, the controller had reported the Cirrus in sight and told him to maintain his altitude, with the apparent intent being to keep the Cirrus a few hundred feet above the helicopters. It appears that the Cirrus was just establishing midfield on the left downwind leg to Runway 30, while the helicopter was midfield downwind for a grass practice area, when the collision occurred.

Here is a copy of the satellite image for KFDK. The collision happened near the added orange circle, as the two aircraft crashed at the left red square (helicopter) and right red square (Cirrus). The Cirrus was on a left downwind, setting up to land on Runway 30 (the shorter runway, from the right edge to the top-middle of this aerial). A closer look shows the helicopter crash location at the storage lot (small red circle) and the Cirrus crash location in trees just southeast of the large building (larger yellow circle).
Weather was likely not a factor. As indicated by the METAR data copied below, clouds were high (above 4,000-feet all day), visibility was always at least ten miles, and the temperature and dew point was always comfortable. The most notable weather detail were relatively strong — but also fairly steady — winds out of the north-northwest.

As is clear from the ATC archive at LiveATC.net, this accident happened while the tower controller was using Runway 30. [CAUTION: this archived ATC recording includes screams just after the impact.] [Transcript copy (by aiREFORM)] Based on ATC transmissions, the flights were likely 700- to 1,000-feet above the ground when they collided. The Cirrus’ parachute system deployed, and almost certainly saved the lives of the two on that aircraft.

One thing not yet clear is how ATC at Frederick manages their flight patterns for helicopter training. The flight patterns for helicopters and fixed-wing aircraft can conflict dangerously. So, the management at each air traffic control tower has to sit down with airport operators and devise workable plans, to help ‘de-conflict’ the traffic flows. These traffic flow plans are then made official (and signed by the parties, such as the helicopter training company) as letters of agreement or memoranda of understanding. At airports with helicopter training programs, the best strategy is to keep the helicopters flying in one area, and keep all the fixed-wing airplanes away. But, more commonly, there is a need to stuff the helicopter training pattern in underneath the fixed-wing pattern. In any case, the controllers need to be especially vigilant to protect those higher risk areas where the different patterns cross.

Here are some links:

• Transcript of tower communications from Frederick Municipal Airport at time of crash — article by Danielle Gaines at The Frederick News-Post. (10/23/2014 )
• Three dead in helicopter-small plane collision at Maryland airport — article with video, by Mayra Cuevas, at CNN.com. (10/23/2014 )
• Discussion at airlinepilotforums.com — includes list of names of the deceased. (10/23/2014)
• Airport Diagram — jpeg, showing location of Advanced Helicopter Concepts hangar.
• A similar midair in San Jose, with no fatalities (and covered up by FAA) — this one was covered up, and never reported to NTSB. The Cessna climbed up into the helicopter, and its propeller impacted the bottom of the helicopter (the skids). Both aircraft were able to safely return and land. Two controllers within the tower spoke up, but could not get their supervisor and manager to fulfill their reporting requirements.