Narrative: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 stickshaker 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."
Follow-up / safety actions
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)
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not
display the exact flight path.
Distance from Denver International Airport, CO to Fort Lauderdale International Airport, FL as the crow flies is 2720 km (1700 miles).