The U.S. National Transportation Safety Board is responsible for investigating U.S. civil aviation accidents and occasionally makes recommendations for improving safety based on knowledge gained through accident these investigations. This issue of the AirSafe Journal features recommendations that came in the wake of three recent accidents: a November 1995 event where an American Airlines MD80 struck trees on a ridge near a Connecticut airport, the February 1996 crash of a Birgenair operated 757 near the Dominican Republic, and the May 1996 crash of a ValuJet DC9 in Florida.

Contents

• American Airlines MD80 near Windsor Locks, CT
• Birgenair 757-200 near the Dominican Republic
• ValuJet DC9-32 near Miami, FL

Event Description: Shortly before 1 a.m. on 12 November 95, an American Airlines MD80 struck trees on a ridge line about 2.5 miles (4.1 km) from the airport during an instrument approach in darkness and variable wind conditions. Both engines subsequently lost power after ingesting tree limbs and the aircraft was substantially damaged during the landing No passengers or crew member sustained any serious injuries. The crew was using an approved approach procedure that called for a normal descent from minimum descent altitude that begins at a Visual Descent Point (VDP) about 0.3 miles (0.5 km) before the ridge line.

Recommendations:The investigation of this accident is ongoing and no probable cause has been determined. However the NTSB recommends that the FAA do the following:

• Ensure that aircraft using that same instrument approach be made aware of a more appropriate VDP.
• If aircraft are unable to use that descent point, then use appropriate means to ensure that pilots are aware of the obstacle hazards and the appropriate glide slope used on that approach.

Disclaimer:For the full text of this NTSB safety recommendation, refer to NTSB document A-96-31 and A-96-32 published 26 June 1996.

Event Description: On 6 February 1996 at 11:47 p.m. local time, a Birgenair 757-200, a charter from Puerto Plata to Frankfurt, Germany with a scheduled refueling stop in Canada, crashed shortly after takeoff. After climbing through 7,300 feet, the aircraft descended until it crashed into the Atlantic Ocean about five miles off the coast. All 189 people on board were killed and the aircraft was destroyed. The NTSB is participating in the investigation which is being conducted by the Director General of Civil Aviation of the Dominican Republic.

Recommendations: The NTSB made a number of recommendations to the FAA due to the events that occurred during the flight:

• Airspeed Discrepancy: The airspeeds displayed to the captain and first officer were different and that difference was consistent with a blocked pitot tube. The NTSB recommended that the FAA issue an airworthiness directive that would revise the 757 and 767 flight manual to notify pilots that simultaneous activation of the "MACH/SPD TRIM" and "RUDDER RATIO" advisories ,which occurred during the Birgenair flight), is an indication of airspeed discrepancy.
• Add Caution Message: Require that the crew alerting systems of the 757 and 767 models be modified to include a "caution" when an erroneous airspeed indication is detected.
• Modify Operations Manual: Require that the operations manuals of the 757 and 767 models include a detailed emergency procedure addressing the identification and elimination of an erroneous airspeed indication.
• Issue Flight Standards Information Bulletins: Issue two flight standards information bulletins - one to direct principal operations inspectors ensure that operating manuals of 757 and 767 operators include a detailed emergency procedure addressing the identification and elimination of an erroneous airspeed indication, and a second to notify those same inspectors about the circumstances of the accident so that future training emphasizes the importance of recognizing an airspeed indication malfunction during the takeoff roll.
• Training: Ensure that 757 and 767 flight simulator training include an effective scenario to train the student to respond appropriately to the effects of a blocked pitot tube.

Disclaimer:This is only a digest of the NTSB safety recommendations and do not take the place of the original document. For the full text of this NTSB safety recommendation, refer to NTSB document A-96-15 through A-96-20 published 31 May 1996.

Event Description: On 11 May 1996, at about 1415 Eastern Daylight Time, a ValuJet DC9-32 crashed into the Everglades swamp shortly after takeoff from Miami International Airport, Miami, Florida. All 105 passengers and five crew members were killed and the aircraft was destroyed. Before the crash, the flight crew reported to air traffic control that there was smoke in the cockpit and cabin.

The accident is still under investigation and many facts are yet to be determined, but the NTSB has discovered sufficient factual information to raise issues needing immediate attention. Preliminary evidence indicates that five cardboard boxes containing as many as 144 chemical oxygen generators, most with unexpended oxidizer cores, and three wheel/tire assemblies had been loaded in the forward cargo compartment shortly before departure. This compartment was classified as a class D compartment, which had no fire or smoke detection system to alert the crew of a fire within the compartment.

Although the NTSB has not determined the origin of fire, the Board decided that the presence of the chemical oxygen generators in the forward cargo compartment created an extremely dangerous condition. The chemical decomposition reaction of an oxidizer such as sodium chlorate in a confined space will generate heat, and the oxygen resulting form the reaction will sustain and intensify a fire.

Recommendations: Because of this accident and past accidents and incidents involving smoke and fire due to onboard chemical reactions, the NTSB made the following recommendations to the FAA:

• Immediately evaluate the practices and training provided by all air carriers for accepting passenger baggage and freight shipments and for identifying undeclared or unauthorized hazardous materials that are offered for transport.
• Require all air carriers to revise as necessary their practices and training for accepting passenger baggage and freight shipments and for identifying undeclared or unauthorized hazardous materials that are offered for transport.
• Permanently prohibit the transportation of chemical oxygen generators as cargo on board any passenger or cargo aircraft when the generators have passed expiration dates, and the chemical core has not been depleted.
• Prohibit the transportation of oxidizers and oxidizing materials (e.g. nitric acid) in cargo compartments that do not have fire or smoke detection systems.

Disclaimer:This is only a digest of the NTSB safety recommendations and do not take the place of the original document. For the full text of this NTSB safety recommendation, refer to NTSB document A-96-25 through A-96-30 published 31 May 1996.

If you have any comments or questions about this issue of the AirSafe Journal, please contact Todd Curtis.

Disclaimer:Any opinion's expressed in this journal are those of the author's and in no way represents the opinion or official policies of any airline, aircraft manufacturer, aviation organization, or government agency.