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EASA issues bulletin on the prevention of hazardous low speed at high altitude cruise
16 April 2015

EASA issues bulletin on the prevention of hazardous low speed at high altitude cruise

EASA

The  European Aviation Safety Agency (EASA) issued a safety information bulletin, reminding flight crew of the dangers of low speed at high altitude cruise.

A recently published interim report on a July 2014 accident involving an MD-83 Mali, prompted EASA to issue a bulletin to remind flight crews of some basic flight physics principles to better manage the airplane speed (Mach number) when flying at high altitudes to prevent entry into upset situations such as stall.

Investigators think the MD-83 accident occurred when pressure sensors became obstructed by icing while en route at FL310. Due to the incorrect pressure values, the auto-throttle tried to maintain a lower thrust than was necessary. The aircraft lost speed and developed a tendency to descend.  The autopilot, engaged in altitude hold mode, then attempted to raise the nose in order to maintain altitude.  The aircraft ultimately stalled.

The bulletin concludes that, when in cruise,

– if continuous Mach decrease cannot be stopped after the maximum available thrust has been applied, and
– if the Mach/airspeed indication can be considered reliable,

flight crews should establish the aeroplane in a reasonable descent to recover the initial targeted Mach. Then after a descent has been initiated, appropriate actions to mitigate the risk of air-to-air collision should be taken (ATC advised, TCAS monitoring etc.). Return to the previous cruise altitude should be initiated only after reaching the optimum Mach for climb and only then in coordination with ATC.

Failure of the flight crew to take the decision to descend in due time will result in a stall with significant altitude loss and a potential loss of control of the aeroplane. The initiation of a controlled descent manoeuvre is the correct action to be taken by the flight crew.

More information:

EASA recommends minimum two crew in the cockpit

EASA published a temporary recommendation for airlines to ensure that at least two crew, including at least one qualified pilot, are in the flight crew compartment at all times of the flight.

Airlines should re-assess the safety and security risks associated with a flight crew leaving the cockpit due to operational or physiological needs.

The Agency makes this recommendation based on the information currently available following the dramatic accident of the Germanwings flight 4U9525, and pending the outcome of the technical investigation conducted by the French Bureau d’Enquetes et d’Analyses (BEA). This recommendation may be reviewed in the light of any new information concerning the accident.

EASA

NTSB calls for better ways to find aircraft accident sites and retrieve critical flight data

 

One of the recorders recovered from the sea bed (photo: BEA)

One of the recorders of Air France 447 recovered from the sea bed (photo: BEA)

The U.S. National Transportation Safety Board (NTSB) issued a series of safety recommendations to the Federal Aviation Administration (FAA) calling for improvements in locating downed aircraft and ways to obtain critical flight data faster and without the need for immediate underwater retrieval. The Board also re-emphasized the need for cockpit image recorders on commercial airplanes.

According to the NTSB recent accidents have pointed to the need for improved technologies to locate aircraft wreckage and flight recorders lost in remote locations or over water. In the 2009 crash of Air France Flight 447, it took almost two years and $40 million to find the recorders. Investigators are still searching for Malaysian Airlines Flight 370.
Last October, the NTSB held a forum, Emerging Flight Data and Locator Technology, which explored these issues in detail.

Among the recommendations to the FAA are to equip commercial airplanes with a tamper-resistant method to broadcast to a ground station sufficient information to establish the location where an aircraft terminates flight as a result of an accident within six nautical miles of the point of impact.

The NTSB also called for the FAA to coordinate with other regulatory authorities and the International Civil Aviation Organization (ICAO) to harmonize implementation of several of these recommendations.

The NTSB also repeated recommendations for a crash-protected image recording system that would record the cockpit environment during the last two hours of a flight.

More information:

 

AAIB recommends Jetstream 31 landing gear inspections following accident

The Jetstream came to rest next to the runway (AAIB)

The Jetstream came to rest next to the runway (AAIB)

A recent Jetstream 31 gear failure at Doncaster Airport, U.K., resulted from stress corrosion cracking in the landing gear leg, according to a preliminary report issued by the AAIB. 

The Jetstream 31 took off from Belfast City Airport (BHD) at 17:45 hrs operating a scheduled air service to Doncaster with one passenger and a crew of two pilots on board. The captain was the Pilot Flying (PF) and the co-pilot was the Pilot Monitoring (PM).
The departure, cruise and approach to Doncaster Sheffield Airport were uneventful. The aircraft touched down at 19:36 hrs with an IAS of 102 kt and a peak normal acceleration of 1.3 g, and the commander moved the power levers aft to ground idle followed by reverse. As the aircraft decelerated, the commander moved the power levers forward to ground idle and asked the co-pilot to move the rpm levers to taxi. At an IAS of 65 kt, eight seconds after touchdown, the left wing dropped suddenly, the aircraft began to yaw to the left and the commander was unable to maintain directional control with either the rudder or the nosewheel steering tiller. The aircraft ran off the left side of the runway and stopped on the grass having turned through approximately 90º. The left landing gear had collapsed and the aircraft had come to a halt resting on its belly, right landing gear and left wing.
The captain pulled both feather levers, to ensure that both engines were shut down, and switched the electrics master switch to emergency off. The co-pilot radioed for emergency services.

A review of the previous 82 landings recorded on the FDR has not identified any of concern but it was noted that a peak normal acceleration of 1.72g was recorded during the eighteenth landing prior to the accident. However, this was within the landing gear limit load.
Preliminary findings indicate that the failure was initiated as a result of stress corrosion cracking in the forward yoke pintle at the top of the left landing gear leg.

Incidently, this same aircraft (Jetstream 31 msn 785) suffered a failure of the right hand main landing gear while landing at Isle Of Man-Ronaldsway Airport (IOM), March 8, 2012. It was determined that in that case the landing gear had failed as a result of intergranular corrosion / stress corrosion cracking of the forward yoke pintle.

A preventive measure taken following this accident involved a modification to install a protective washer on the forward face of the yoke pintle. It appears that this washer could rotate out of position, negating the protection. The AAIB issued two safety recommendations to EASA , among others mandating an effective inspection regime for the Jetstream 31 that will detect cracking and prevent failure of the yoke pintle of main landing gear legs.

More information:

 

AAIB: short-circuit likely caused ELT battery fire on Ethiopian Boeing 787-8

ELT case with battery cover-plate removed; tops of battery cells visible (AAIB)

ELT case of ET-AOP with battery cover-plate removed; tops of battery cells visible (AAIB)

An ELT battery fire on an Ethiopian Boeing 787-8 at London-Heathrow Airport was likely caused a short-circuit caused by improperly installed battery wires, leading to a thermal runaway.

The U.K. AAIB published a Special Bulletin containing information on the progress of the investigation into a ground fire on an unoccupied Boeing 787-8, registration ET-AOP, at London Heathrow Airport on 12 July 2013.
Examination of the aircraft’s ELT revealed that the internal battery pack had experienced severe disruption, exhibiting evidence of a very high-energy thermal event, consistent with having experienced a thermal runaway.

All five cell cases had been breached and burnt battery material had been ejected into the battery compartment and outside of the ELT case.

The AAIB reports that the most probable cause of the thermal runaway was a short-circuit caused by improperly installed battery wires, leading to an uncontrolled discharge of the battery. It was established that this condition in isolation should not have caused a battery thermal event, if the battery short-circuit protection features had effectively limited the current to a safe level. In addition, the failure sequence would have required one of the battery cells to deplete more rapidly than the others until it reversed polarity, becoming resistive and absorbing energy from the other four cells as they discharged and ultimately resulting in thermal runaway of the depleted cell. Several tests demonstrated that when a cell failed in this manner, the heat released caused the failure to cascade to the remaining four cells.

Five safety recommendations were issued:

  1. It is recommended that the Federal Aviation Administration develop enhanced certification requirements for the use of lithium-metal batteries in aviation equipment, to take account of current industry knowledge on the design, operational characteristics and failure modes of lithium-metal batteries.
  2. It is recommended that the Federal Aviation Administration require that electrical performance and design-abuse certification tests for lithium-metal batteries are conducted with the battery installed in the parent equipment, to take account of battery thermal performance.
  3. It is recommended that the Federal Aviation Administration work with industry to determine the best methods to force a lithium-metal cell into thermal runaway and develop design-abuse testing that subjects a single cell within a lithium-metal battery to thermal runaway in order to demonstrate the worst possible effects during certification testing.
  4. It is recommended that the Federal Aviation Administration require equipment manufacturers wishing to use lithium-metal batteries to demonstrate (using the design-abuse testing described in Safety Recommendation 2014-022) that the battery and equipment design mitigates all hazardous effects of propagation of a single-cell thermal runaway to other cells and the release of electrolyte, fire or explosive debris.
  5. It is recommended that the Federal Aviation Administration review whether the Technical Standard Order (TSO) process is the most effective means for the certification of lithium-metal batteries installed in aircraft equipment, the actual performance of which can only be verified when demonstrated in the parent equipment and the aircraft installation.

 

More information:

 

NTSB issues recommendations on certification of lithium-ion batteries and emerging technologies

B787 JA829JA at Boston Airport during the battery fire incident (photo: NTSB)

B787 JA829JA at Boston Airport during the battery fire incident (photo: NTSB)

The U.S. National Transportation Safety Board (NTSB) issued five safety recommendations related to the evaluation and certification of lithium-ion batteries for use in aircraft systems, as well as the certification of new technology.

The safety recommendations, all addressed to the Federal Aviation Administration, are derived from the NTSB’s ongoing investigation of the January 7, 2013, fire event that occurred in a lithium-ion battery on a Boeing 787 that was parked at Boston Logan Airport.

Investigators found that the battery involved in the Boston 787 fire event showed evidence not just of an internal thermal runaway but that “unintended electrical interactions occurred among the cells, the battery case, and the electrical interfaces between the battery and the airplane.”
The 12-page safety recommendation letter said that the processes used in 2006 to support the certification of the lithium-ion battery designed for the 787 were inadequate, in part, because there is no standardized thermal runaway test that’s conducted in the environment and conditions that would most accurately reflect how the battery would perform when installed and operated on an in-service airplane.
Further, the NTSB said that because there is no such standardized thermal runaway test, lithium-ion battery designs on airplanes currently in service might not have adequately accounted for the hazards associated with internal short circuiting.
In its examination of the challenges associated with introducing newer technologies into already complex aircraft systems, the NTSB said that including subject matter experts outside of the aviation industry “could further strengthen the aircraft certification process” by ensuring that both the FAA and the aircraft manufacturer have access to the most current research and information related to the developing technology.

To address all of these issues, the NTSB asked the FAA to do the following:

  • Develop an aircraft-level thermal runaway test to demonstrate safety performance in the presence of an internal short circuit failure
  • Require the above test as part of certification of future aircraft designs
  • Re-evaluate internal short circuit risk for lithium-ion batteries now in-service
  • Develop guidance for thermal runaway test methods
  • Include a panel of independent expert consultants early in the certification process for new technologies installed on aircraft

The final report on the January 2013 Boston 787 battery fire investigation is estimated to be completed in the fall.

More information:

NTSB recommends FAA, National Weather Service to improve weather forecast to pilots

Meteorological conditions in the Continental flight 1404 accident in 2008 might have been favorable for MWA

The U.S. National Transportation Safety Board (NTSB) issued nine recommendations addressing the need to provide more comprehensive preflight weather information to pilots. The recommendations were issued to both the U.S. Federal Aviation Administration (FAA) and the U.S. National Weather Service (NWS), who are jointly responsible for providing such information to pilots. 

The recommendations are based on NTSB accident investigations involving aircraft encountering weather conditions, such as adverse surface wind, dense fog, icing, turbulence, and low-level wind shear. Currently, although information on these conditions may exist, it is not always provided to pilots through NWS products during preflight weather forecasts.

Additionally, although the NWS routinely advises pilots of turbulence and weather patterns associated with mountain wave activity (MWA), which can cause unique and adverse flying conditions, there are currently no requirements for the NWS to issue advisories specific to MWA. The NTSB believes notification of the potential for and the existence of MWA allows pilots to prepare for these atmospheric disturbances.

The NTSB also identified the need for improved situation awareness and communication between the center weather service units (CWSUs) and the Aviation Weather Centers. Appreciating the challenges involved in issuing critical weather advisories in a timely manner, the NTSB recognizes the importance of proper coordination and communication between the various NWS components. Therefore, the NTSB is also recommending a protocol be established to enhance communication among meteorologists to ensure mutual situation awareness of critical aviation weather data among meteorologists.

More information:

 

France recommends ground ice detection system following fatal takeoff accident of Premier 1A jet

Radar plots and position of the wreckage (BEA)

Radar plots and position of the wreckage (BEA)

The French accident investigation bureau, BEA, recommends EASA to study the possibilities of ground ice detection systems following the fatal accident involving a Premier 1A corporate jet in March 2013.

The Hawker Beechcraft 390 Premier IA jet, registered VP-CAZ,  was parked overnight on the platform at Annemasse Airport in France. The temperature was -2°C and humidity was 98% with fog or low clouds as the pilot prepared for a 5-minute VFR flight to Genève-Cointrin Airport (GVA). One passenger was seated in the cockpit, another passenger was seated in the passenger cabin.

The pilot started the takeoff from runway 12 at 08:38. Rotation occurred 19 seconds later. Several witnesses reported seeing the airplane with a high nose-up pitch attitude, with a low rate of climb. Three seconds after the rotation the “Bank Angle” warning, indicating excessive bank, and then the stall warning, was recorded several times on the cockpit voice recorder. Several witnesses saw the airplane turn sharply to the right and then to the left.
Fifteen seconds after the rotation, the left main landing gear struck the roof of a house about 500 m from the threshold of runway 30 at Annemasse. The aircraft then collided with the ground. During the impact sequence, all three elements in the landing gear and the left wing were torn away from the rest of the airplane. It then slid along the ground for a distance of about 100 m before hitting a garden shed, a low wall and some trees in the garden of a second house. A post-impact fire erupted. Both occupants seated in the cockpit were killed.

BEA concluded: “The pilot’s insufficient appreciation of the risks associated with ground-ice led him to take off with contamination of the critical airframe surfaces. This contaminant deposit then caused the aerodynamic stall of the aeroplane and the loss of control shortly after lift-off.”

Investigators noted among others that Annemasse Airport was not equipped with anti-icing/de-icing facilities. A recommendation was issued to the regulator DGAC to “define criteria intended to make it mandatory for aerodrome operators to have de-icing/anti-icing facilities at aerodromes.”

Additionaly BEA recommends EASA to “make  changes to the training requirements for pilots so as to include periodic  reminders on the effects of contaminants such as ice on stall and loss of control on takeoff.”

Citing 32 takeoff accidents since 1989, attributed to contaminated wings, BEA also recommends EASA, in coordination with the FAA and the other non-European civil aviation authorities, to “study the technical and regulatory means to put in place in order to install systems for the detection of frozen contaminants on the critical surfaces of aircraft.”

More information:

 

NTSB issues urgent safety recommendation to improve oversight of operator in Alaska

Cessna 208B Grand Caravan N12373 crashed in Alaska in November 2013.

Cessna 208B Grand Caravan N12373 crashed in Alaska in November 2013.

The U.S. National Transportation Safety Board (NTSB) issued an urgent safety recommendation to the Federal Aviation Administration (FAA) regarding the oversight of air operators in Alaska owned by HoTH, Inc., after six recent accidents and one incident.

These operators include Frontier Flying Service; Hageland Aviation Services, Inc.; and Era Aviation, which may do business as Ravn Alaska, Ravn Connect, and Corvus Airlines.

The NTSB issued an urgent safety recommendation to the FAA to conduct a comprehensive audit of the regulatory compliance and operational safety programs in place at HoTH, Inc., operators. The NTSB also issued a second, non-urgent safety recommendation that the FAA conduct a comprehensive audit of its own oversight of these Alaska-based operators. The oversight audit should be conducted by FAA units that are based outside of Alaska, the NTSB recommended.

While the operator and the FAA have made several recent changes designed to improve safety and oversight, the NTSB believes that, due to the breadth of the issues identified during its investigations, today’s recommendations are necessary to ensure the safe operation and effective oversight of the operators owned by HoTH, Inc.

More information:

NTSB issues recommendations to address MD-11 bounced landing susceptibility

Accident sequence of a FedEx MD-11 at Narita, 2012 (JTSB)

Accident sequence of a FedEx MD-11 at Narita, 2012 (JTSB)

The U.S. NTSB issued seven safety recommendations, aimed at providing long term solutions for reducing the risk of MD-11 landing accidents.

The McDonnell Douglas MD-11 airplane was involved in fourteen hard landing accidents since 1994, leading to several safety recommendations. The last recommendations were issued on July 12, 2011, while two accident investigations were still underway. These recommendations addressed the need for improved recurrent training and operational guidance for MD-11 pilots. The NTSB believed that the actions described in those recommendations would provide near-term improvements to reduce the risk of MD-11 landing accidents.
The seven new recommendations are aimed at providing longer term solutions for further reducing the risk of MD-11 landing accidents.

The NTSB reviewed data from multiple MD-11 hard landing accidents and identified factors that might have contributed to the severity of these hard landing accidents, including the following:

  • the MD-11’s high landing speed, which increases the difficulty of a properly timed and executed flare because it must be initiated within a narrow timeframe; 
  • the airplane’s geometry, which places the cockpit far ahead of the center of gravity and the main landing gear, reducing pilot awareness of wheel-ground contact; 
  • the MD-11’s automatic reduction of thrust during the landing flare, which could lead to a delay in adjusting thrust or pitch overcontrol during landings with excessive sink rates; and 
  • the airplane’s use for long-range cargo flights, which reduces the opportunities for pilots to maintain landing proficiency compared with transport-category pilots who do not fly such routes.

The interaction of all of these factors might increase the MD-11’s susceptibility to a late flare, a bounced landing, and improper column inputs by the pilot after a bounce, which could lead to overload of the main gear and the potential for catastrophic structural overload, a hull loss, and injuries and/or fatalities, according to the NTSB.

The NTSB issued the following recommendations to the Federal Aviation Administration (FAA):

  • Work with Boeing to (1) assess the effectiveness of flare cueing systems to assist MD-11 pilots in making timely and appropriate inputs during the landing flare, (2) provide a formal report on the findings of the assessment, and (3) if the assessment shows that flare cueing systems could be useful to MD-11 pilots, provide copies of the report to all US operators of MD-11 airplanes and encourage them to install such a system on these airplanes. (A-14-004)
  • Work with Boeing to (1) assess methods for providing weight-on-wheels cueing to MD-11 pilots to enhance pilot awareness of bounced landings and facilitate proper pilot reaction and effective control inputs when bounced landings occur, (2) provide a formal report on the findings of the assessment, and (3) if the assessment shows that the weight-on-wheels cueing methods could be useful to MD-11 pilots, provide copies of the report to all US operators of MD-11 airplanes and encourage them to provide a means for weight-on-wheels cueing for these airplanes. (A-14-005)
  • Work with Boeing to (1) evaluate the effect of brief power increases on simulated MD-11 landing distances, (2) adjust the values in published MD-11 landing distance tables accordingly, and (3) provide the adjusted values to MD-11 operators. (A-14-006)
  • Reconvene the MD-10/MD-11 flight standardization board to determine whether currency requirements should be strengthened for MD-11 pilots. (A-14-007)

The NTSB issued the following recommendations to the Boeing Company:

  • In collaboration with the Federal Aviation Administration, (1) assess the effectiveness of flare cueing systems to assist MD-11 pilots in making timely and appropriate inputs during the landing flare, (2) provide a formal report on the findings of the assessment, and (3) if the assessment shows that flare cueing systems could be useful to MD-11 pilots, provide copies of the report to all US operators of MD-11 airplanes and encourage them to install such a system on these airplanes. (A-14-008)
  • In collaboration with the Federal Aviation Administration,(1) assess methods for providing weight-on-wheels cueing to MD-11 pilots to enhance pilot awareness of bounced landings and facilitate proper pilot reaction and effective control inputs when bounced landings occur, (2) provide a formal report on the findings of the assessment, and (3) if the assessment shows that the weight-on-wheels cueing methods could be useful to MD-11 pilots, provide copies of the report to all US operators of MD-11 airplanes and encourage them to provide a means for weight-on-wheels cueing on these airplanes. (A-14-009)
  • In collaboration with the Federal Aviation Administration,(1)evaluate the effect of brief power increases on simulated MD-11 landing distances, (2) adjust the values in published MD-11 landing distance tables accordingly, and (3) provide the adjusted values to MD-11 operators. (A-14-010)

More information: