Introduction
The following essay shall address the Northwest Airlines Flight 5 mechanical failure, which occurred on January 4, 1990. Firstly, I will summarize the details of the flight. Secondly, I will discuss the causes of the accident, as well as summarize the investigation into the accident and the conclusions drawn by this investigation. Lastly, I will provide a critical review of the case, discussing the incident itself, the conclusions of the official investigation, in addition to how the incident informed air legislation in the United States.
Summary of the Incident involving Northwest Airlines Flight 5
On January 4, 1990, Northwest Airlines Flight 5, a fourteen-year old Boeing 727-251 aircraft, departed from Miami International Airport with an intended destination of Minneapolis-Saint Paul International Airport. (Weiner, 1990A) Northwest Airlines Flight 5 was a standard passenger flight, carrying 139 and having a crew of 6. (Weiner, 1990A) At 9:10 EST, that is, approximately one hour after the 8:15 EST take off time, pilots heard a large noise emanating from the rear portion of the plane. (Weiner, 1990B) The plane was at this time at an altitude of 35,000 feet, flying approximately over Madison, Florida. (Weiner, 1990A) The large noise was the result of the aircraft having lost its number three (starboard) engine. (Aviation Safety Board, 2014) The pilots, unaware of what the source of the reported noise, continued their flight for fifty minutes, after which they were forced to make an emergency landing at 9:58 EST at Tampa International Airport. (Aviation Safety Board, 2014) The missing engine was recovered on January 5, 1990 in an agricultural area outside of Madison, Florida. (Weiner, 1990B) There were no fatalities or injuries in the incident. (NTSB, 1992)
Investigation
Immediately after the emergency landing at Tampa International Airport, inspectors sought to determine the cause of the incident. Their final conclusions, published in 1992, were that a forward lavatory external seal was absent, most likely the result of flawed installation. (NTSB, 1992) This, in turn, created leakage at the time when the aircraft was pressured. (NTSB, 1992) The investigators concluded that the seal had triggered lavatory fluid to damage the number three engine’s compressor blades. (NTSB, 1992) The reason why the engine detached from the airplane was because of design purposes: the engine, a Pratt & Whitney JT8D-15, was installed in a manner so as to separate from the plane’s fuselage in such instances. (Weiner, 1990B) The official investigation report, MIA90IA047 thus concluded that the “probable cause(s) of this incident” (NTSB, 1992) were “the failure of company service personnel to properly service the airplane forward lavatory.” (NTSB, 1992)
4.0 Review
The incident arguably is significant for two main reasons. Firstly, in so far as the official conclusions of the NTSB are accurate, the cause of the incident was the result of the failure of maintenance personnel to efficiently service the aircraft, in particular, the lavatory. This underscores the importance of aircraft maintenance to air transportation safety: although there were no fatalities or injuries in the incident, the severity of losing the engine, as evidenced by the emergency landing undertaken by the pilot, demonstrates the extent to which human error on the level of plane maintenance can have potentially disastrous results. Changes were accordingly made in Northwest Airlines’ maintenance procedure. (NTSB, 1990) Leaking lavatories were to be flagged in the case when leakage to a lavatory was reported to have occurred five times in a five day period. (NTSB, 1990) After this incident, Northwest changed their policy, so as to flag even a single leakage. (NTSB, 1990) Furthermore, this particular incident was part of an NTSB safety recommendation, dated August 14, 1990, wherein the NTSB recommended direct safety investigations for the ingestion of ice into engines and damage sustained by the airframe as a result of ice. (NTSB, 1990) This proposal was then adopted. (NTSB, 1990) It is important to note, however, that the Northwest flight investigation concluded by the NTSB two years after the incident and no mention of ice is found in the final report, this shows that in relation to this incident the NTSB had altered opinions on cause.
Secondly, the incident was also significant in that no safety measures existed to notify the pilots to the missing engine. Commentators on the incident from the Flight Safety Foundation and the Air Lines Pilot Association stressed that the pilots would be unable to deduce what had occurred from, for example, changes in control forces or cockpit procedures. (Weiner, 1990B) Although the plane itself is deliberately designed to effectively fly on two engines, as well as incorporating in the design automatic separation from the fuselage in the case of emergency, further safety measures could have been incorporated into the design so as to make the pilots aware of what happened.
Conclusion
The above has reviewed the details of the Northwest Airlines Flight 5 Mechanical Failure, as well as providing a summary of the official NTSB investigators’ conclusions regarding the cause of the incident. The incident highlights the importance of airplane maintenance to airplane safety issues. Secondary issues of relevance that surface in this case primarily concern the limitations of the pilots’ knowledge what actually occurred, a limitation engendered by the design of the particular aircraft involved in the incident.
- Aviation Safety Network. (2014). Northwest Airlines Flight 5 Incident Description. Aviation
Safety Network. Retrieved 30 May 2014 at http://aviation-safety.net/notfound - NTSB. (1990). August 14, 1990 Safety Recommendation. Washington, DC: The National
Transportation and Safety Board. Retrieved 30 May 2014 at
www.ntsb.gov - NTSB. (1992). MIA90IA047. Washington, DC: The National Transportation and Safety Board.
Retrieved 30 May 2014 at
http://www.ntsb.gov/aviationquery/brief.aspx?ev_id=20001212X22451&key=1 - Weiner, E. (1990). Jet Lands After an Engine Falls Off. The New York Times. January 5.
Retrieved 30 May 2014 at http://www.nytimes.com/1990/01/05/us/jet-lands-after-
an-engine-drops-off.html - Weiner, E. (1990). Pilots Had Know Way of Knowing Engine Fell Off, Experts Say. The New
York Times. January 5. Retrieved 30 May 2014 at
http://www.nytimes.com/1990/01/06/us/pilots-had-no-way-of-knowing-jet-engine-
fell-off-experts-say.html
