La mia vita è dove mi spendo, non dove mi ingrasso!
Prima o poi si muore, non c'è scampo, l'importante è morire da vivi. http://web.tiscali.it/windrider/
Prima di pretendere un diritto devi assolvere almeno ad un dovere.
"La corsa di decollo è una metamorfosi, ecco una quantità di metallo che si trasforma in aeroplano per mezzo dell'aria. Ogni corsa di decollo è la nascita di un aeroplano" (Staccando l'ombra da terra - D. Del Giudice)
the aircraft clipped the tops of a number of trees
Alla fine gli è andata di lusso: nessun ferito. Probabilmente con un metro di quota in meno sugli alberi non sarebbero arrivati alla pista.
Deo gratias.
Fran65 ha scritto:...perché parlano di decollo dalla pista 16, e su gugolert si legge 15?
A causa del cambio della posizione dei poli magnetici, gli orientamenti delle piste (che sono magnetici) cambiano. E vicino ai poli cambiano più velocemente. Le immagini di Google Earth hanno quasi 10 anni.
Lele_Patti ha scritto:La buffalo airways non è quella del programma su dmax ???
si, è quella.
Alberto MD80 Fan
«Ogni domanda alla quale si possa dare una risposta ragionevole è lecita.» Konrad Lorenz «Un sogno scaturito da un grande desiderio: la grande voglia di volare e scoprire altri orizzonti verso i quali andare, con la voglia di nuovo. Per me questa è l'avventura.» Angelo D'Arrigo «Non prendete la vita troppo sul serio, comunque vada non ne uscirete vivi.» Robert Oppenheimer
Fran65 ha scritto:...perché parlano di decollo dalla pista 16, e su gugolert si legge 15?
A causa del cambio della posizione dei poli magnetici, gli orientamenti delle piste (che sono magnetici) cambiano. E vicino ai poli cambiano più velocemente.
Mi hanno spostato un'altra volta i poli magnetici? E che cavolo, non si può stare tranquilli un attimo!
Manco una misera telefonata, sempre davanti al fatto compiuto...
"The curve is flattening: we can start lifting restrictions now" = "The parachute has slowed our rate of descent: we can take it off now!" Chesley Burnett "Sully" Sullenberger
Fran65 ha scritto:...perché parlano di decollo dalla pista 16, e su gugolert si legge 15?
A causa del cambio della posizione dei poli magnetici, gli orientamenti delle piste (che sono magnetici) cambiano. E vicino ai poli cambiano più velocemente. Le immagini di Google Earth hanno quasi 10 anni.
ciao
Andrea
Ero convinto che gli orientamenti fossero geografici e non magnetici...
Come mai si sceglie l'orientamento magnetico che non è mai fisso? Per evitare ogni volta la declinazione ed avere un rapporto diretto bussola/pista?
"La vita è troppo breve per bere vini mediocri" - Johann Wolfgang von Goethe
Skip100 ha scritto:
Come mai si sceglie l'orientamento magnetico che non è mai fisso? Per evitare ogni volta la declinazione ed avere un rapporto diretto bussola/pista?
è proprio scegliendo l'orientamento magnetico che farai uso della cosiddetta declinazione magnetica che può essere "W" oppure "E"dipendendo del luogo di sorvolo; ci sono posti dove la dmg (declinazione magnetica) è uguale a zero e altri dove possono raggiungere anche 12° rispetto alla direttrice vera, per fare un esempio.
i database dei liner hanno già incorporati questi valori di dmg, (almeno per il B-737 è così) sicché quando vai ad allineare i giroscopi del sistema inerziale, una volta che sono pronti ed allineati, e con l'aereo fermo in parcheggio, il valore di prua che leggi sul ND (navigation display) è già corretto della dmg di quel posto, quindi leggi il valore di prua magnetica direttamente senza dovere usare le cartine e senza dover far dei calcoli di addizione o di sottrazione della dmg.
Skip100 ha scritto:
Come mai si sceglie l'orientamento magnetico che non è mai fisso? Per evitare ogni volta la declinazione ed avere un rapporto diretto bussola/pista?
è proprio scegliendo l'orientamento magnetico che farai uso della cosiddetta declinazione magnetica che può essere "W" oppure "E"dipendendo del luogo di sorvolo; ci sono posti dove la dmg (declinazione magnetica) è uguale a zero e altri dove possono raggiungere anche 12° rispetto alla direttrice vera, per fare un esempio.
i database dei liner hanno già incorporati questi valori di dmg, (almeno per il B-737 è così) sicché quando vai ad allineare i giroscopi del sistema inerziale, una volta che sono pronti ed allineati, e con l'aereo fermo in parcheggio, il valore di prua che leggi sul ND (navigation display) è già corretto della dmg di quel posto, quindi leggi il valore di prua magnetica direttamente senza dovere usare le cartine e senza dover far dei calcoli di addizione o di sottrazione della dmg.
Aspetta aspetta... non ho capito bene e sto facendo confusione...
Con la bussola normale hai già il nord magnetico e per arrivare al nord geografico devi fare la declinazione ma sui liner hai invere la girobussola giusto? Che ti indica il nord geografico... perchè andare ad inserire i dati delle declinazioni per tornare ad avere il nord magnetico?
"La vita è troppo breve per bere vini mediocri" - Johann Wolfgang von Goethe
la bussola ti dice dove si trova il Nord magnetico, ma non ti calcola la declinazione magnetica per giungere alla tua destinazione.
con la bussola hai l'orientazione magnetica, ma se vai a sorvolare aree dove esistono grosse deviazione magnetiche, devi aggiungere o togliere a seconda se è "W" o "E", per poter arrivare alla tua destinazione senza sgarrare e questo lo devi fare te con gli aeroplanini dell'aviazione generale.
quando ho citato i liners (almeno per i B-737 è così), quando i piloti preparano il cockpit, prima di accendere i motori, agiscono su due selettori del sistema IRS, quelli che allineano i giroscopi ed accelerometri di questo sistema, ci vuole meno tempo alle basse latitudini rispetto a quelle alte, ma comunque una volta allineati, trasmettono questo dato insieme ad altri al FMC, (Flight Management Computer), che a sua volta invia al DU (Display Unit), cioè, al sistema degli schermi il valore di prua magnetica già corretto della dmg del posto dove si trova l'aereo perché il database del B-737 possiede al suo interno i valori di dmg. da qui il pilota legge sul ND il valore della prua magnetica già corretto della dmg.
E' stato pubblicato il final report relativo a questo evento. L'aereo è decollato con un peso superiore al MTOW certificato. Il problema al motore è derivato da un cedimento del cilindro n°1 del motore destro, dovuto a preesistenti rotture per fatica. L'elica non è andata correttamente in bandiera a causa di un problema sulla feathering pump. Sono emerse notevoli criticità da parte dell'operatore.
On Apr 27th 2015 the Canadian TSB released their final report concluding the probably causes of the accident were:
Findings as to causes and contributing factors
- An accurate take-off weight and balance calculation was not completed prior to departure, resulting in an aircraft weight that exceeded its maximum certified take-off weight.
- The right engine number 1 cylinder failed during the take-off sequence due to a pre-existing fatigue crack, resulting in an engine fire.
- After the right propeller’s feathering mechanism was activated, the propeller never achieved a fully feathered condition likely due to a seized bearing in the feathering pump.
- The windmilling right propeller caused an increase in drag which, combined with the overweight condition, contributed to the aircraft’s inability to maintain altitude, and the aircraft collided with terrain short of the runway.
- The operator’s safety management system was ineffective at identifying and correcting unsafe operating practices.
- Transport Canada’s surveillance activities did not identify the operator’s unsafe operating practices related to weight and balance and net take-off flight path calculations. Consequently, these unsafe practices persisted.
Findings as to risk
- If companies do not adhere to operational procedures in their operations manual, there is a risk that the safety of flight cannot be assured.
- If Transport Canada does not adopt a balanced approach that combines inspections for compliance with audits of safety management processes, unsafe operating practices may not be identified, thereby increasing the risk of accidents.
- If cockpit or data recordings are not available to an investigation, this may preclude the identification and communication of safety deficiencies to advance transportation safety.
Other findings
- Current Canadian Aviation Regulations permit a transport category piston-powered aircraft to carry passengers without a flight data recorder or cockpit voice recorder.
The TSB reported that the airline has a walk-in/on demand scheme that permits passengers to show up for boarding without pre-booking a seat. If the passenger count exceeds the capacity of the aircraft a stand by aircraft is being dispatched, on Aug 19th 2013 a stand by aircraft needed to be dispatched.
The accident aircraft was loaded with cargo and 17 passengers, the passengers and their luggage were not weighed at check in. After the aircraft had been loaded, 4 last minute passengers boarded the aircraft along with the luggage.
At the time of departure the operational flight plan had been partially completed without passenger count, cargo weight, the crew never received a cargo manifest.
The aircraft subsequently departed Yellowknife's runway 16 from intersection runway 16/34 with runway 10/28 with a takeoff distance available of 5956 feet.
About 2 minutes after the takeoff clearance was issued tower observed heavy torching and smoke from the right hand engine and called the aircraft reporting the observation but did not receive a reply. The crew was just retracting the landing gear when they observed fire in the right hand engine and initiated the checklist which included to shut the engine down and feather the propeller.
The right propeller moved towards the feathered position but did not reach the feathered position and continued windmilling.
The crew initiated a low altitude, the aircraft reached a maximum height of 180 feet AGL, right hand turn in an attempt to reach runway 10 but struck a stand of trees, about 30 feet in height, about 690 feet southwest of the threshold of runway 10 and impacted ground about 400 feet past the trees. The wreckage trail extended over 330 feet parallel to and south of runway 10.
Landing gear and flaps were found in the retracted position, the ELT did not activate due to the relatively low impact energy.
After the aircraft came to a stand still the flight attendant initiated the evacuation of the aircraft, all 21 passengers exited the aircraft through the left aft door. The flight attendant then returned to the aircraft and moved some galley drawers that were blocking the cockpit door and confirmed the flight crew was safe, all three crew then evacuated the aircraft.
Arriving emergency services, who had been near the threshold of runway 10 due to an unrelated vehicle recovery operation, foamed the aircraft as a precaution.
The TSB reported that the aircraft was not equipped with a flight data recorder or a cockpit voice recorder and was not required to carry those items by Canadian regulations.
The TSB reported that the aircraft is certified for a maximum takeoff weight (MTOW) of 26,200 lbs. The aircraft carried 2707lbs of fuel, 21 passengers along with their cargo and 3 crew, which using standard weights resulted in an estimated takeoff weight of 27,435 lbs, 1235 lbs above MTOW. The TSB cited a study by the Australian TSB who had experimentally determined the aircraft with the left hand (critical) engine shut down and the propeller windmilling would be able to climb at 100fpm at 26,200 lbs, maintain altitude at 28,000 lbs and descend at 90 fpm at 30,000 lbs.
The TSB reported that the right hand engine's #1 cylinder's head and barrel were found separated due to a fracture of the barrel along the threaded joint with the head. A pre-existing fatigue crack was discovered in a thread groove, the cause of the crack could not be determined due to the accident impact damage.
The feathering system of the right hand propeller was designed to move the propeller to 88 degrees of pitch which stops the rotation of the propeller and thus reaches minimum drag. An oil pump driven by an electrical motor supplies oil pressure to the propeller dome which moves the propeller into its feathered position, when the propeller reaches the full stop position the pressure would increase to 600psi at which point the the cut out switch prompts the motor to de-energize. If the pressure of 600psi is not reached the motor and pump continue to operate until they fail. The feathering system is also design to unfeather the propeller. If the feathering system continues to run beyond the feather position, the propeller would move through the feathered position and reach fine pitch again. Douglas had issued a flight operations bulletin following an accident in the Netherlands advising crews that it was possible to interrupt the feathering manually in case the cut off switch did not operate, the accident crew was aware of this bulletin. In the post accident examination During the propeller was found at a blade angle of 46 degrees only which reduced but did not stop the windmilling.
The TSB analysed: "Feathering the propeller of an inoperative engine is critical to the performance of a multi-engine aircraft as it reduces parasite drag by moving the propeller blades towards a coarser pitch angle relative to the flight path of the aircraft. In most cases, the propeller will stop spinning. A non-feathered, or windmilling, propeller will induce a high parasite drag penalty on aircraft performance. In order to maintain airspeed at or above the minimum airspeed of 90 knots indicated airspeed (KIAS), Buffalo 168 (BFL168) sacrificed climb performance and was barely able to maintain a constant altitude. Manoeuvring the aircraft to return to the airport led to a loss of altitude, which ultimately resulted in the collision with terrain. After the right propeller’s feathering mechanism was activated, the propeller never achieved a fully feathered condition due to a system failure. Post-occurrence testing of the propeller feathering system indicated the oil pump motor failed likely due to a seized bearing. Activation of the feathering system results in the pump motor running until sufficient oil pressure develops to trip the pressure-sensitive cut-out switch, set for 600 pounds per square inch (psi), which occurs when full feather position is reached. The compromised bearing likely slowed the motor speed resulting in decreased oil pressure. The pump will continue to run until it fails if the trip pressure is not reached and system operation is not monitored. There is no back-up pump."
The TSB analysed: "Aircraft performance, as indicated in the aircraft flight manual (AFM), is predicated on the weight of the aircraft. In this occurrence, a complete and accurate weight and balance report was not calculated prior to takeoff. As the aircraft’s weight and balance had not been updated since 1990, using actual passenger and cargo weights may not have produced an accurate take-off weight. As such, the crew would not be able to determine accurately the aircraft’s performance capabilities during a normal takeoff. As was determined in the 1994 Australian DC-3 accident report19, aircraft operating above the maximum certified take-off weight (MCTOW) experience a serious degradation in climb performance when experiencing an engine failure with a windmilling propeller."
The TSB thundered:
In this occurrence, the aircraft departed without a completed weight and balance calculation and was later determined to weigh in excess of the MCTOW at the time of departure. The investigation found that it was common to operate in this manner, and that weight and balance forms were normally completed enroute without the benefit of accurate information and without using standard or actual passenger weights as required by the Company Operations Manual (COM). The risks associated with operating the aircraft overweight may not have been fully appreciated by the crews since net take-off performance calculations required by the Canadian Aviation Regulations (CARs) and specified in the COM were not being conducted. As a result, no assessment of obstacle clearance in the event of an engine failure during takeoff had been carried out. Successful adaptations from procedures tend to reinforce that activity. Therefore, previous success in operating the aircraft overweight was likely taken as assurance of future performance without consideration being given to aircraft performance in the event of an emergency. Given that neither the Pro-Active nor the Re-Active Risk Assessment programs identified issues relating to operational control, weight and balance or calculated aircraft performance, and that the practice of adjusting weight and balance calculations to maintain them within limits after departure was well known and accepted by senior management, it was highly unlikely that these unsafe practices would be reported through, or addressed by, the company’s SMS.
There were other indications that the organizational culture at Buffalo Airways was not supportive of a system that required the organization to take a proactive role in identifying hazards and reducing risks. The company’s response to deficiencies identified during TC surveillance activities demonstrated an adversarial relationship between the company and the regulator. The company refuted the regulatory basis of findings, questioned the competence of TC inspectors and initially did not take responsibility for the issues identified. The overall picture that emerged from this investigation is of an organization that met the basic requirements of regulations and then only when pushed by the regulator. An SMS introduced into a culture motivated merely to comply with regulations is unlikely to be effective. The operator’s SMS was ineffective at identifying and correcting unsafe operating practices.
With respect to the regulator, Transport Canada, the TSB analysed: "The current approach to regulatory oversight, which focuses on an operator’s SMS processes almost to the exclusion of verifying compliance with the regulations, is at risk of failing to address unsafe practices and conditions. If TC does not adopt a balanced approach that combines inspections for compliance with audits of safety management processes, unsafe operating practices may not be identified, thereby increasing the risk of accidents."
"La corsa di decollo è una metamorfosi, ecco una quantità di metallo che si trasforma in aeroplano per mezzo dell'aria. Ogni corsa di decollo è la nascita di un aeroplano" (Staccando l'ombra da terra - D. Del Giudice)
There were other indications that the organizational culture at Buffalo Airways was not supportive of a system that required the organization to take a proactive role in identifying hazards and reducing risks. The company’s response to deficiencies identified during TC surveillance activities demonstrated an adversarial relationship between the company and the regulator. The company refuted the regulatory basis of findings, questioned the competence of TC inspectors and initially did not take responsibility for the issues identified. The overall picture that emerged from this investigation is of an organization that met the basic requirements of regulations and then only when pushed by the regulator. An SMS introduced into a culture motivated merely to comply with regulations is unlikely to be effective. The operator’s SMS was ineffective at identifying and correcting unsafe operating practices.
With respect to the regulator, Transport Canada, the TSB analysed: "The current approach to regulatory oversight, which focuses on an operator’s SMS processes almost to the exclusion of verifying compliance with the regulations, is at risk of failing to address unsafe practices and conditions. If TC does not adopt a balanced approach that combines inspections for compliance with audits of safety management processes, unsafe operating practices may not be identified, thereby increasing the risk of accidents."[/i]
«Ogni domanda alla quale si possa dare una risposta ragionevole è lecita.» Konrad Lorenz «Un sogno scaturito da un grande desiderio: la grande voglia di volare e scoprire altri orizzonti verso i quali andare, con la voglia di nuovo. Per me questa è l'avventura.» Angelo D'Arrigo «Non prendete la vita troppo sul serio, comunque vada non ne uscirete vivi.» Robert Oppenheimer
