Originally Posted by
Auxtank
FOR 737 NG
Condition: AIRSPEED UNRELIABLE
The pitch attitude is not consistent with the phase of flight, altitude, thrust and weight, or noise or low frequency buffeting is experienced. Objective: To establish the normal pitch attitude and thrust setting for the phase of flight.
1 Adjust the airplane attitude and thrust. Maintain airplane control.
- PROBE HEAT switches . . . . . . . . . . . . . Check ON
- Cross check the MACH/AIRSPEED indicators.
- Cross check the IRS and FMC ground speed and winds to determine airspeed accuracy if indicated airspeed is questionable.
Note: Erroneous or unreliable airspeed indications may be caused by blocked or frozen pitot-static system(s), or a severely damaged or missing radome
2. Attitude and thrust information is located in the Performance Inflight section.
Additional Information
The flight path vector is based on inertial sources and may be used as a reference in maintaining proper path control
10.1
737 Flight Crew Operations Manual
FillieghHtiIgnhsltirguhmtents, Displays
Airspeed Unreliable
Condition: Airspeed or Mach indications are suspected to be unreliable. (Items which might indicate unreliable airspeed are listed in the Additional Information section.)
Objective: Toidentifyareliableairspeedindication,if possible, or to continue the flight using the Flight With Unreliable Airspeed table in the Performance Inflight chapter.
1 Autopilot(ifengaged).............Disengage 2 Autothrottle(ifengaged)...........Disengage 3 F/Dswitches(both) .................. OFF 4 Setthefollowinggearuppitchattitudeandthrust:
Flapsextended .......... 10°and80%N1 Flapsup ................4°and75%N1
-----------------------
5 PROBEHEATswitches.............CheckON
6 Thefollowingarereliable:
Attitude
N1
Ground speed Radio altitude
7 Refer to the Flight With Unreliable Airspeed table in the Performance Inflight chapter and set the pitch attitude and thrust setting for the current airplane configuration and phase of flight.
▼ Continued on next page ▼
Note: Stick shaker, overspeed warning and AIRSPEED LOW (as installed) alerts may sound erroneously or simultaneously.
Note: The Flight Path Vector and Pitch Limit Indicator may be unreliable.