N819AC

HISTORY OF FLIGHT

On January 9, 2001, at 1330 Pacific standard time, a Worldwide Aeros 40B airship, N819AC, encountered aircraft (flight) control problems while attempting to land at the Metropolitan Oakland International Airport (OAK), Oakland, California. The airship landed hard, skidded across a taxiway, and struck a parked airplane. After the pilots abandoned the airship, it became airborne and flew about four (4) miles northwest of the airport, where it collided with a sailboat and restaurant. Airship USA, Inc., operated the airship under the provisions of 14 CFR Part 91 as an instructional flight. The airship sustained substantial damage. The certified flight instructor (CFI), and commercial pilot, both with airship ratings, received minor injuries. Visual meteorological conditions prevailed for the flight, and no flight plan had been filed. The flight departed OAK about 2 hours prior to the accident.

According to the flight crew, the airship was readied for flight, then departed about 1130 for a flight to provide touch-and-go takeoffs and landings, and flight experience for the less experienced pilot. On board the airship were two commercially rated pilots; the pilot who occupied the right seat possessed a current sign off in this model airship and acted as the certified flight instructor (CFI) giving flight instruction to the second pilot seated in the left seat. The second pilot, in the left seat, was attempting to gain the necessary experience towards a sign off.

After departure, the pilots requested touch-and-go takeoffs and landings with OAK Air Traffic Control (ATC) Tower (north controller). The controller informed the flight crew that they were too busy to handle their request. The flight crew then departed the area and flew toward the Golden Gate Bridge to conduct air work. However, due to inclement weather, they returned to OAK to conduct touch-and-go takeoffs and landings.

About 8 miles from the airport they encountered a light misting rain. Both pilots noted that the fuel gage (LED) indicator on the annunciator panel had a red indication, and the digital display read OPEN. After a few seconds the LED indicator returned to a normal reading. The pilot receiving instruction and seated in the left seat (the pilot flying - PF) stated they were not worried because it appeared that it was an indicator error, and because they had visually verified full fuel tanks during the preflight inspection. The rain increased in intensity to a moderate rainfall as the airship approached the airport.

According to the CFI's written statement, about the same time as the fuel gauge LED light turned "red," they increased the power to increase their ground speed as they were flying into 15- to 20-knot winds. He and the PF discussed that they would not do a "normal 'weigh-off'" to determine the weight and trim because they were heavy with rain, had no ballast to drop, and could estimate their trim by visually checking the ballonet volume. The CFI then got out of his seat to read the ballonet numbers and reported to the PF that they had "6-7 in the rear and the front was flat." The CFI reported that they "pumped and dumped aft 2 sequences." He then visually checked the ballonets again, and noted they were even, around "3 ½ each." He then suggested that they pump aft on the way to land and lock off the front valves to hold the trim condition.

In the pilot flying (PF) written statement he indicated that they had elected to "lock off" the forward ballonet for landing, thus maintaining the same amount of air in the forward ballonet throughout the landing. While setting up for the approach, the nose dropped. The PF attributed this to the gusty weather conditions that prevailed at the time. He simultaneously noted that the Hull Pressure Indicator (HPI) was low and switched the fan blower to the ON position to add air to the front ballonet. He indicated that the rear ballonet was in the AUTO position. The nose recovered and then dropped again. The PF again noted the HPI reading was low. He recovered using the same procedure as before, and the nose dropped a third time. He informed the CFI that the flight control of the airship did not feel normal. The CFI checked the air pressure system and saw that the rear ballonet valve was open, but the gauge on the annunciator panel indicated that the valve should have been closed. Both pilots visually confirmed that at least one of the aft valves was open and would not respond to air valve control inputs. The CFI attempted to manually close the valve, with no response.

At this point the CFI and PF switched seats so that the CFI had the flight controls and was seated in the left seat. The PF then sat in the right seat and radioed the ground crew that they were having difficulty controlling the airship and were coming into land.

On the first attempt to land, the CFI stated that the airship was too high and came in too fast. The CFI aborted the landing due to the airspeed, excessive height above the ground, and the close proximity to the ground crew. He set up for a second approach, and due to the low nose condition, he added more power and placed the joystick (flight control system) to the full aft position to raise the nose. The CFI stated that he had full aft position on the joystick, and any movement forward resulted in an immediate drop of the nose. He felt, at the time, the flight controls were malfunctioning, but due to the low altitude, high airspeed, deteriorating weather, and the need to get the airship on the ground, he did not have time to accomplish the complete emergency procedure for a flight control malfunction.

The flight crew reported a very hard landing at fast forward airspeed and very heavy nose. The landing gear collapsed and the gondola dug into the ground. The airship then skidded across an adjacent taxiway and struck a parked airplane. At this point both pilots jumped out on opposite sides of the gondola. The CFI pulled the emergency ripcord on his side of the envelope but it failed to open the emergency deflation panel. The pilot receiving instruction initially ran away from the airship because the airship was traveling in his direction. He returned to the airship and unsuccessfully attempted to pull the emergency ripcord; however, he was pulled off of his feet and he let the emergency ripcord go. Both pilots reported an inability of the emergency deflation panels to operate in the wet environment.

The airship took off, unmanned, and reached a peak altitude of 1,600 feet above ground level (agl). The airship traveled for about 4 miles in a northeast direction and struck a marina where the envelope became draped over sailboats and a restaurant.

According to the ground crew, the airship took off, departed the airfield, and was not expected to return for several hours. The crew left the airport for lunch. During lunch the crew chief received a call from the radio watch (crewman left behind to monitor radio communications from the flight crew) that the airship was returning to the field due to weather, but the ground crew could take their time returning to the field. About 5 minutes later the crew chief received another call from the radio watch indicating that the airship wanted the ground crew back to the field as soon as possible to assist with the landing. The crew chief stated that the airship attempted to land on runway 15 and "turn into the crew (a common procedure)." However, the airship was too high and fast. The crew chief could see that the pressure was "very low on the ship due to the way the banners [were] fluttering loosely and the envelope was reacting to the wind." As the airship circled overhead, the crew chief noticed that it "looked like the aft ballonet valves were open." On the first attempt to land, as the airship turned onto the downwind leg, it "suddenly dove down dramatically but recovered at the last minute." The crew chief observed that all four ruddervators were in the "up position." That indicated to him that the nose was "extremely heavy which would explain the aft valves" in the open position, and the "pressure problems" the pilot was referring to.

The crew chief stated that the PF radioed to say they had a very serious situation and could not maintain pressure. The PF indicated that the landing would be "very fast" and that they could only make one approach. On the accident landing, as the airship turned to final, it descended in a stair-step pattern for runway 15. The airship landed "very hard" and away from the ground crew, about 400 yards. The airplane bounced two times before staying on the ground. The nose sunk in the soft dirt, and the airship started to drag/slide across the ground. The airship continued dragging across the ground until it hit the parked Navy P-3 Orion.

The crew chief stated that he next saw the pilot jump out of the gondola and attempt to pull the "helium 'rip lines'." He indicated that the emergency ripcords are the "last defense in avoiding loss of the ship and is an emergency deflation system to prevent the ship from free ballooning, or floating off unmanned." The airship started to float away with the pilots holding onto the emergency ripcords, the pilots let go, and the airship departed the airport environment unmanned. Some of the ground crew went to the accident site, while others stayed with the flight crew to make sure they were okay.

PERSONNEL INFORMATION

A review of Federal Aviation Administration (FAA) airman records revealed that the right seat pilot held a commercial certificate with ratings for airplane single engine, multiengine land and sea, helicopter, glider, and airship. The pilot also held an instrument airplane rating, as well as, a flight instructor certificate with a rating for single engine airplane.

A review of the FAA medical records revealed that the pilot held a second-class medical issued on March 9, 2000, with a limitation "must wear corrective lens...