Aerospatiale SA365N1 accident at Camp Springs, Maryland, 27 Sept 2008 (N92MD)

Accident narrative

On September 27, 2008, about 2358 eastern daylight time, an Aerospatiale SA365N1 helicopter, registration N92MD, operated by the Maryland State Police (MSP) as a public medical evacuation flight, crashed during an instrument landing system (ILS) approach to Andrews Air Force Base (ADW) in Camp Springs, Maryland. The helicopter, operating as Trooper 2, impacted terrain in Walker Mill Regional Park in District Heights, Maryland, about 3.2 miles north of the runway 19R threshold. The commercial pilot, a flight paramedic, a field provider, and one patient were killed. A second patient survived with serious injuries.

### The flight

Trooper 2 was dispatched to transport two automobile accident patients from a landing zone at Wade Elementary School in Waldorf, Maryland, to Prince George's Hospital Center (PGH) in Cheverly, Maryland. The pilot, 59, had 5,225.1 total flight hours, including 2,770 hours in the accident make and model.

The MSP System Communications Center (SYSCOM) duty officer notified the pilot of the flight request at 2302. The pilot expressed doubt about the weather, noting an 800-foot cloud ceiling at College Park, and stated, "I don't know if we can get to the hospital." The duty officer replied that it was up to the pilot. After hearing that another medevac helicopter had just completed a flight in the area, the pilot stated, "if they can do it we can do it... we're going to try it."

Trooper 2 departed ADW at 2310, arrived at the Waldorf landing zone about 2319, and departed with the patients and field provider at 2337.

### The accident sequence

At 2344, the pilot reported to the Ronald Reagan Washington National Airport (DCA) tower controller that the flight had run into "some heavy stuff" and that if he did not see a hole, he would fly under instrument flight rules (IFR) back to ADW. At 2347, about 0.25 miles east of PGH, the pilot advised DCA that "it's solid up here" and requested to climb to 2,000 feet for an approach at ADW.

The pilot contacted Potomac Consolidated Terminal Radar Approach Control (PCT). After an initial lack of response and some confusion regarding the pilot's request, the PCT controller began vectoring Trooper 2 for the ILS runway 19R approach at ADW. At 2351, the PCT controller advised the pilot that the weather at ADW was an 1,800-foot broken ceiling and 7 miles visibility.

At 2355, Trooper 2 contacted the ADW tower, reporting established on the localizer for runway 19R. At 2356:45, the pilot reported, "I'm not picking up the glideslope." The ADW controller replied that her panel showed green but she did not know if it was working. The pilot then requested an airport surveillance radar (ASR) approach, but the controller replied she was not current to provide that service.

Radar and automatic dependent surveillance-broadcast (ADS-B) data indicated that the helicopter had been maintaining a descent consistent with the glideslope. However, at 2357:32, at an altitude of about 1,450 feet mean sea level (msl) and 4 miles north of the runway, the helicopter's descent rate increased rapidly from about 500 feet per minute to greater than 2,000 feet per minute, deviating below the glideslope. The rapid descent continued through the localizer minimum descent altitude (MDA) of 680 feet msl. The last radar target was recorded at 2357:50 at 800 feet msl, and the last ADS-B target at 2358:04 at 325 feet msl.

### Search and rescue

The ADW controller noticed the loss of radar contact and initiated emergency notifications. However, the SYSCOM duty officer logged Trooper 2 as landed at ADW at 0002 and silenced the ADS-B loss-of-signal alert. The Board concluded that the duty officer lost situational awareness and assumed the aircraft had landed safely. He did not realize the helicopter was missing until contacted by an MSP barrack 16 minutes later.

Search efforts were further delayed when SYSCOM provided the helicopter's last coordinates in degrees, minutes, and seconds, which county dispatchers mistakenly entered into mapping software as decimal degrees, directing searchers to a location 30 miles away. The wreckage was eventually located at 0158 by another MSP pilot and medic who drove to the area.

### What the investigation found

The helicopter struck an 80-foot tree in a level, descending attitude. All components were accounted for, and investigators found no evidence of preimpact mechanical failures or malfunctions of the airframe, systems, or engines. The radar altimeter bug was set to 300 feet. Testing of the navigation receivers revealed no discrepancies that would have prevented them from capturing the glideslope. The Board concluded that no evidence suggested the glideslope was not functioning properly, though it could not determine why the pilot believed he was not receiving a valid signal.

The investigation found that the weather information provided to the pilot by the PCT controller was almost five hours old. Current ADW weather included a broken ceiling at 500 feet and 4 miles visibility in mist. A Department of Defense communications failure had prevented current ADW observations from reaching the weather tool used by MSP pilots. The Board concluded that the outdated weather report likely led the pilot to expect he could descend below the clouds and establish visual contact with the ground well above the MDA.

The Board concluded that factors such as the outdated weather report, his familiarity with ADW, and the desire to reduce his workload by returning to visual conditions may have encouraged the pilot to intentionally deviate below the glideslope and attempt to "duck under" the cloud ceiling. The pilot failed to adhere to instrument approach procedures when he did not arrest the descent at the MDA.

The investigation noted several air traffic control deficiencies. The PCT controller failed to provide current weather, was unresponsive, provided poor radar vectoring, and failed to issue an IFR transponder code (though postaccident analysis determined a minimum safe altitude warning would not have alerted regardless). The ADW controller was not current to provide the requested ASR approach. The Board concluded these deficiencies distracted the pilot and increased his workload.

The pilot's instrument experience was also examined. In the two years before the accident, he had completed 25 instrument approaches, but only four were nonprecision approaches, and none were the localizer approach to runway 19R. MSP had recently reduced its instrument training requirements. The Board concluded that the pilot was not proficient in instrument flight, and that the MSP's training changes did not promote proficiency.

Additionally, the pilot had been awake for about 16 hours, and the accident occurred near his normal bedtime. He also exhibited risk factors for obstructive sleep apnea, including obesity and loud snoring. The Board concluded that the pilot was likely less than fully alert, and fatigue may have contributed to his deficient decision-making.

The helicopter was not equipped with a terrain awareness and warning system (TAWS), nor was it required to be. A simulation indicated that a TAWS would have provided aural terrain warnings 7, 4, and 2 seconds before impact, which the Board noted likely would have caused the pilot to attempt to arrest his descent.

### Probable cause

The National Transportation Safety Board determined that the probable cause of this accident was the pilot's attempt to regain visual conditions by performing a rapid descent and his failure to arrest the descent at the minimum descent altitude during a nonprecision approach.

Contributing to the accident were (1) the pilot's limited recent instrument flight experience, (2) the lack of adherence to effective risk management procedures by the Maryland State Police, (3) the pilot's inadequate assessment of the weather, which led to his decision to accept the flight, (4) the failure of the Potomac Consolidated Terminal Radar Approach Control (PCT) controller to provide the current Andrews Air Force Base weather observation to the pilot, and (5) the increased workload on the pilot due to inadequate Federal Aviation Administration air traffic control handling by the Ronald Reagan National Airport Tower and PCT controllers.