空速不可靠.ppt

* * UNRELIABLE AIRSPEED INDICATION Sequence Causes原因 Consequences结果 Recognition of unreliable airspeed空速不可靠的识别 Procedures程序 Causes ? Heavy rain 大雨 ? Severe icing (blocked pitot) 严重结冰 ? Loss of heating 失去加温 Volcanic ash, insects, dusts, 。。 Consequences ? IAS fluctuates or exhibits a gradual or step decrease to very low values ? Large IAS fluctuations or drop, affecting all airspeed indications, observed for a few seconds and repeating over several minutes ? A/THR or AP/FD responds to the IAS upset ? Engine parameters/indications may be affected ? AP/FD may disconnect ? FMS may be temporarily lost ? Altitude indication may fluctuate ? FPV is affected if static ports are blocked (as FPV is based on the Inertial / Baro V/S and GS) Consequences CAUTION: ? No immediate detectable effect if in level flight and at constant airspeed ? Overspeed warning may be activated in climb ? Effects are similar to severe icing, but last as long as icing conditions exist ? In-flight, when pitot or static ports are blocked: IAS decreases when altitude increases IAS increases when altitude decreases Recognition of unreliable airspeed ? Detecting an unreliable IAS presents some traps: All indications may be consistent but equally unreliable, Indications may differ but attempting to assess the correct indication may be hazardous ? The following aspects are important contributors to a timely detection: Instrument scanning Flight crew awareness of IAS / pitch / thrust / climb rate typical characteristics Recognition of unreliable airspeed No single set of cues can be defined, but the following observations are an obvious attention getter: Abnormally large IAS fluctuations Unusual “CAPT - F/O” or “IAS - target speed” differences Unanticipated IAS / aerodynamic noise relationship IAS increasing with large nose-up pitch attitude IAS decreasing with large nose-down pitch attitude Abnormal A/THR or AP/FD behavior IASrelatedcues Recognition of unreliable airspeed Constant i