NTSB Identification: WPR11LA172
14 CFR Part 91: General Aviation
Accident occurred Saturday, March 19, 2011 in Whidbey Island, WA
Probable Cause Approval Date: 02/14/2013
Aircraft: BEECH G35, registration: N4211D
Injuries: 1 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The owner/pilot was cruising on a personal flight in visual conditions and was engaged in correlating the indications of two very high frequency omni-range (VOR) cockpit navigation displays. The pilot also had a handheld global positioning system (GPS) unit mounted in the cockpit. During the VOR correlation effort, the pilot noticed on the GPS that he was about to intrude into restricted airspace. (Although this particular airspace is only restricted at certain times, the GPS always depicts the boundaries, regardless of the airspace restriction status.) He initiated a turn to avoid the restricted airspace and monitored the GPS display to ensure that he would clear the restricted area. When he returned his attention to the airplane, he noticed that the bank angle was about 75 degrees, the pitch attitude was about 20 degrees airplane nose down, and the airspeed was about 190 mph, which was in the yellow (caution) range of the airspeed indicator scale. The pilot leveled the wings and initiated a pull-up, during which he heard three or four "thumps" in rapid succession.

After recovery to level flight, the airplane seemed normal, but the pilot's concern about the thumps prompted him to return to his home airport where he landed uneventfully. The pilot estimated that he loaded the airplane to about 2g during the pullout, while a cockpit mounted g-meter registered a maximum loading of about 2.5g. Postflight examination of the airplane revealed that the aft fuselage side skins were wrinkled and that the aft fuselage lower skin was torn. Detailed evaluation of the ruddervator system revealed some minor discrepancies in control surface travel ranges. Damage patterns were consistent with in-flight overload and were not consistent with flutter. Review of airplane certification requirements and the in-flight events indicated that the airplane was in the region of its flight envelope where flight control inputs could result in structural damage. The control surface travel discrepancies did not contribute to the ability of the pilot to induce the observed structural damage.

Because the restricted airspace is not continuously active, notification of its active status is provided via a Notice to Airmen (NOTAM), which is issued 2 hours in advance of the restriction. The airspace status can also be determined on a real-time basis via radio communications with the controlling facility. The pilot had not checked the NOTAMs and was not in communication with the controlling facility, and he was therefore unaware of the airspace status at the time of his near-penetration of the airspace. Because he was unaware of the status of the airspace, he took evasive action to avoid it, although such action was unnecessary because the airspace was not restricted at the time of the flight. Adequate preflight planning would have allowed the pilot to determine the status of the restricted airspace and would have obviated the need for the avoidance maneuver, which ultimately resulted in structural damage to the airplane. In addition, when it became apparent to the pilot that he was about to penetrate the airspace, he prioritized avoidance of the airspace above retaining control of the airplane, which was a reversal of the "aviate, navigate" priority hierarchy necessary for safe operation of any aircraft.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The pilot's failure to prioritize flying over navigation due to his diverted attention, which allowed the airplane to near a restricted area, which, in turn, led the pilot to enter a rapid avoidance maneuver and subsequently lose airplane control. Contributing to the accident was the pilot's failure to adequately prepare for the flight.

Full narrative available

Index for Mar2011 | Index of months