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NTSB Accident No. ERA10FA246NTSB Accident No. ERA10FA246

By David Jack Kenny

Contrary to what VFR-only pilots might believe, getting the instrument rating tends to complicate rather than simplify flight planning and decision-making—at least until you’re very, very good and flying very capable equipment. Conditions that would have called for an automatic scrub now require considering factors like the risk of embedded thunderstorms, fuel requirements should a missed approach and subsequent diversion require another miss at the alternate … and, of course, the potential for accumulating ice.  In most of this country for much of the year, that possibility exists whenever you’re in the clouds.

Likewise, providing an aircraft with de-icing capability can introduce new ambiguities. In an unprotected airplane, anything more than a trace of ice is cause for immediate action, including declaring an emergency if that’s what it takes to get out. In a better-equipped aircraft, the urgency of the situation depends on a number of things: whether the systems are certified for flight in known icing conditions or merely “hazard protection” intended to buy a little extra time, the pilot’s familiarity with that hardware and accompanying procedures (such as minimum airspeeds in icing conditions), and the severity of the icing itself. Any on-board ice protection can be overwhelmed by sufficiently rapid accumulation. Pilots flying known ice-certified airplanes have sometimes forgotten that—and also that even when ice is only moderate, this equipment just buys them greater flexibility in deciding how to get out, not the ability to linger there at leisure.

Just before 9 a.m. Eastern on April 27, 2010, the owner of a normally aspirated Beech 58 Baron called Flight Service to file two IFR flight plans: the first from Frederick, Maryland, to Olive Branch, Mississippi, departing in about an hour, and the second for a return flight planned for 6 p.m. Central time. He filed the same pre-stored route in both directions with a requested altitude of 8,000 feet msl on the way down and 9,000 feet msl coming home. The transcript of his briefing indicates that he called from his car en route to the airport.

That was unfortunate in two ways:  Aside from the immediate risk posed by distracted driving, it probably did nothing to improve his ability to follow his weather briefing. It contained information worth following, including a convective outlook, an airmet Zulu for moderate icing with a forecast freezing level of 6,000 feet msl, and an airmet Tango for moderate turbulence below 8,000 feet msl.  Widespread IFR conditions were forecast over the mountains, and just over an hour earlier the pilot of a Cessna 421 had reported moderate rime ice at 9,000 feet msl over eastern Kentucky.

The Baron took off about 10:20 a.m. Easetern, and for nearly two hours its communications with air traffic control were routine.  At 12:16 p.m., as it crossed over the over the southeastern corner of Kentucky, the pilot checked in with the Indianapolis ARTCC and reported descending through 11,500 feet for 10,000 feet msl. The controller advised that they’d received “a few reports of light rime ice” between 7,000 feet msl and 11,000 feet msl, adding, “If you need to move for something, just let me know.”  The pilot replied that they’d picked up light rime ice on the climb to 12,000 feet msl, which had continued to accumulate after they’d levelled off.  Since they were “starting to lose some airspeed … I think we’ll try and get down to seven.”  The controller cleared him for a descent at pilot’s discretion to 7,000 feet msl.

At 12:24 p.m., just after levelling off, the Baron’s pilot requested “lower, losing airspeed.”  The controller promptly cleared him to descend and maintain 5,000 feet msl and asked that he advise whether he could maintain level flight at that altitude. The Baron responded “Wilco”—followed 40 seconds later by “Just went down like an absolute rock—don’t know what happened—we’re level at…”  The controller couldn’t make out the altitude, but a passing airplane reported hearing “two thousand five hundred.”  Further attempts to contact the Baron, both directly and by relay, were unsuccessful.

The Civil Air Patrol was notified of a possible downed aircraft and initiated a search. They found the wreckage just before 5:30 p.m. in a remote section of the Daniel Boone National Forest. It took rescuers two more hours to reach the site and find the remains of the 1,500-hour commercial pilot and his passenger. The angle of impact was so steep that the Hartzell Propeller representative who assisted the investigation couldn’t tell how much power the engines were producing at impact, only that both were turning. The throttle, prop, and mixture levers were all full forward, and sections of the various de-icing boots remained inflated. Subsequent analysis of radar track data showed a steep descending right turn that lost 3,100 feet in one minute before a brief climb; the last return showed an altitude of 3,200 feet msl. The elevation of the accident site was 1,614 feet.

The NTSB’s probable cause report describes the airplane as having been certified for flight into known icing conditions, but nevertheless attributed the accident to “the pilot’s improper in-flight planning/decision, his continued flight into adverse weather (icing conditions), and failure to maintain an adequate airspeed during the emergency descent.” Inability to maintain airspeed is definitive evidence that an airplane’s accumulated a dangerous amount of ice, making it seem plain that the emergency resulted from not having treated that ongoing accumulation with the urgency it deserved.