Détails:
Flight 970 experienced a gradual loss of power in both of its engines while in cruise flight at flight level 330. The aural stall warning and stick shaker activated, following which the pilots disengaged the autopilot, turned on the engines ignition, activated the engines anti-ice system, and initiated a descent towards Wichita. The pilots shut down the right engine when its exhaust gas temperature (EGT) increased to about 600 ° Celsius and were able to restart it again on the second attempt at about 17,000 feet. The left engine recovered on its own shortly thereafter. The flight then diverted to the Wichita Mid-Continent Airport where it landed safely.
PROBABLE CAUSE: "The flightcrew's failure to verify the engine instrument indications and powerplant controls while on autopilot with the autothrottles engaged, and their failure to recognize the drop in airspeed which led to an aerodynamic stall associated with the reduction in engine power. Factors were the presence of ice crystals at altitude, and the icing of the engine inlet probes resulting in a false engine pressure ratio indication."
| Statuts: | Accident investigation report completed and information captured |
| Date: | mardi 4 juin 2002 |
| Heure: | 12:38 |
| Type/Sous-type: |  McDonnell Douglas DC-9-82 (MD-82) |
| Compagnie: | Spirit Airlines |
| Immatriculation: | N823NK |
| Numéro de série: | 48020/1045 |
| Année de Fabrication: | |
| Heures de vol: | 53116 |
| Moteurs: | 2 Pratt & Whitney JT8D-219 |
| Equipage: | victimes: 0 / à bord: 6 |
| Passagers: | victimes: 0 / à bord: 105 |
| Total: | victimes: 0 / à bord: 111 |
| Dégats de l'appareil: | Substantiels |
| Conséquences: | Repaired |
| Lieu de l'accident: | 37 km (23.1 milles) W of Wichita, KS ( Etats-Unis d'Amérique)
|
| Phase de vol: | En vol (ENR) |
| Nature: | Transport de Passagers Nat. |
| Aéroport de départ: | Denver International Airport, CO (DEN/KDEN), Etats-Unis d'Amérique |
| Fort Lauderdale International Airport, FL (FLL/KFLL), Etats-Unis d'Amérique | |
| Numéro de vol: | 970 |
Flight 970 experienced a gradual loss of power in both of its engines while in cruise flight at flight level 330. The aural stall warning and stick shaker activated, following which the pilots disengaged the autopilot, turned on the engines ignition, activated the engines anti-ice system, and initiated a descent towards Wichita. The pilots shut down the right engine when its exhaust gas temperature (EGT) increased to about 600 ° Celsius and were able to restart it again on the second attempt at about 17,000 feet. The left engine recovered on its own shortly thereafter. The flight then diverted to the Wichita Mid-Continent Airport where it landed safely.
Probable Cause:
PROBABLE CAUSE: "The flightcrew's failure to verify the engine instrument indications and powerplant controls while on autopilot with the autothrottles engaged, and their failure to recognize the drop in airspeed which led to an aerodynamic stall associated with the reduction in engine power. Factors were the presence of ice crystals at altitude, and the icing of the engine inlet probes resulting in a false engine pressure ratio indication."
Accident investigation:
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Sources:
» NTSBOpérations de secours
On April 29, 2004, the NTSB recommended that the FAA:
Issue a flight standards information bulletin to principal operations inspectors to alert all affected air carrier flight crews about the icing situation encountered by Spirit Airlines flight 970 and to emphasize the need to maintain vigilance for the signs of high altitude icing conditions, the effect these conditions can have on airplane and engine performance, and the need for the appropriate use of the engine anti-ice system. (A-04-34)
Actively pursue research with airplane and engine
manufacturers and other industry personnel to develop an ice detector that would alert pilots of inlet pressure probe icing and require that it be installed on new production turbojet airplanes, as well as retrofitted to existing turbojet airplanes. (A-04-35)
Issue a flight standards information bulletin to principal operations inspectors to alert all affected air carrier flight crews about the icing situation encountered by Spirit Airlines flight 970 and to emphasize the need to maintain vigilance for the signs of high altitude icing conditions, the effect these conditions can have on airplane and engine performance, and the need for the appropriate use of the engine anti-ice system. (A-04-34)
Actively pursue research with airplane and engine
manufacturers and other industry personnel to develop an ice detector that would alert pilots of inlet pressure probe icing and require that it be installed on new production turbojet airplanes, as well as retrofitted to existing turbojet airplanes. (A-04-35)
Photos
Plan
Ce plan montre l'aéroport de départ ainsi que la supposée destination du vol. La ligne fixe reliant les deux aéroports n'est pas le plan de vol exact.
La distance entre Denver International Airport, CO et Fort Lauderdale International Airport, FL est de 2720 km (1700 miles).
La distance entre Denver International Airport, CO et Fort Lauderdale International Airport, FL est de 2720 km (1700 miles).
Les informations ci-dessus ne représentent pas l'opinion de la 'Flight Safety Foundation' ou de 'Aviation Safety Network' sur les causes de l'accident. Ces informations prélimimaires sont basées sur les faits tel qu'ils sont connus à ce jour.
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