| Statuts: | Enquête Officielle |
| Date: | 17 SEP 1961 |
| Heure: | 08:57 |
| Type/Sous-type: | Lockheed L-188C Electra |
| Compagnie: | Northwest Orient Airlines |
| Immatriculation: | N137US |
| Numéro de série: | 1142 |
| Année de Fabrication: | 1961 |
| Heures de vol: | 614 |
| Moteurs: | 4 Allison 501-D13 |
| Equipage: | victimes: 5 / à bord: 5 |
| Passagers: | victimes: 32 / à bord: 32 |
| Total: | victimes: 37 / à bord: 37 |
| Dégats de l'appareil: | Perte Totale |
| Conséquences: | Written off (damaged beyond repair) |
| Lieu de l'accident: | ca 1,5 km S of Chicago-O'Hare International Airport, IL (ORD) (Etats-Unis d'Amérique)
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| Phase de vol: | En montée initiale (ICL) |
| Nature: | Transport de Passagers Nat. |
| Aéroport de départ: | Chicago-O'Hare International Airport, IL (ORD/KORD), Etats-Unis d'Amérique |
| Aéroport de destination: | Tampa International Airport, FL (TPA/KTPA), Etats-Unis d'Amérique |
| Numéro de vol: | 706 |
Détails:Lockheed Electra N137US operated on Northwest flight 706 from Milwaukee to Miami (MIA) with intermediate stops at Chicago, Tampa and Fort Lauderdale. After a crew change at Chicago the plane taxied to runway 14R at 08:55 and was cleared for takeoff. Between the 8,000 and the 9,000-foot runway marker the aircraft was observed to commence an apparently coordinated right turn with a slowly increasing rate of bank. When the bank angle was 30 to 45 degrees, the crew made a short, garbled transmission. Immediately thereafter, at a bank angle of 50 to 60 degrees, the aircraft began to lose altitude. The maximum altitude attained in the entire turn was 200 to 300 feet. The right wing struck powerlines adjacent to the Chicago Northwestern Railroad tracks, severing the lines at an angle of about 70 degrees from the horizontal. It then contlnued in a direction of about 271 degrees magnetic and, when in a bank of about 85 degrees and a nose-down attitude of about 10 degrees, the right wing of the aircraft struck the railroad embankment.
Continuing to roll about its longitudinal axis, the aircraft cartwheeled, the nose crarshing into the ground 380 feet beyond the point of first impact, and landed right side up. It then slid tail first another 820 feet. The aircraft disintegrated throughout its path.
PROBABLE CAUSE: "Mechanical failure in the aileron primary control system due to an improper replacement of the aileron boost assembly, resulting in a loss of lateral control of the aircraft at an altitude too low to effect recovery."
Sources:
Photos
Plan
Ce plan montre l'aéroport de départ ainsi que la supposé destination du vol. La ligne fixe reliant les deux aéroports n'est pas le plan de vol exact.
La distance entre Chicago-O'Hare International Airport, IL et Tampa International Airport, FL est de 1620 km (1012 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 tels qui sont connus à ce jour.