737-600 - 737-900
Non-ILS approaches are normally flown using VNAV or V/S pitch modes or IAN.
Recommended roll modes are provided in the applicable FCOM procedure.
737-300 - 737-500
Note: In order to accomplish non-ILS approaches using VNAV, FMC U7.1 or later is required.
Copyright . The Boeing Company. See title page for details.
5.32 FCT 737 (TM) October 31, 2006
Non - ILS Instrument Approaches - General
Over the past several decades there have been a number of CFIT and unstabilized approach incidents and accidents associated with non-precision (non-ILS) approaches and landings. Many of these could have been prevented by the use of Continuous Descent Final Approach (CDFA) methods. Traditional methods of flying non-ILS approaches involve setting a vertical speed on final approach, leveling off at step-down altitudes (if applicable) and at MDA(H), followed by a transition to a visual final approach segment and landing. These traditional methods involve changing the flight path at low altitudes and are not similar to methods for flying ILS approaches. Further, these traditional methods often require of the crew a higher level of skill, judgment and training than the typical ILS approach.
The following sections describe methods for flying non-ILS CDFA. These methods provide a constant angle approach, which reduces exposure to crew error and CFIT accidents. These methods also make it much easier for the crew to achieve a stabilized approach to a landing once suitable visual reference to the runway environment has been established.
737-300 - 737-500 A typical Instrument Approach using VNAV or V/S, as illustrated, assumes all preparations for the approach; such as review of the approach procedure and setting of minima and radio tuning have been completed. The procedures illustrated focus generally on crew actions and avionics systems information. The flight pattern may be modified to suit local traffic and air traffic requirements.
737-600 - 737-900 A typical Instrument Approach using VNAV, IAN or V/S, as illustrated, assumes all preparations for the approach; such as review of the approach procedure and setting of minima and radio tuning have been completed. The procedures illustrated focus generally on crew actions and avionics systems information. The flight pattern may be modified to suit local traffic and air traffic requirements.
737-300 - 737-500 The following discussions assume a straight-in instrument approach is being flown. A circling approach may be flown following an instrument approach using VNAV or V/S provided the MCP altitude is set in accordance with the circling approach procedure.
737-600 - 737-900 The following discussions assume a straight-in instrument approach is being flown. A circling approach may be flown following an instrument approach using VNAV, IAN or V/S provided the MCP altitude is set in accordance with the circling approach procedure.
Types of Approaches
737-300 - 737-500 VNAV is the preferred method for accomplishing non-ILS approaches that have an appropriate vertical path defined on the FMC LEGS page. The section on Use of VNAV provides several methods for obtaining an appropriate path, to include published glide paths, and where necessary, a pilot constructed path. V/S may be used as an alternate method for accomplishing non-ILS approaches.
737-600 - 737-900 For airplanes not equipped with IAN, VNAV is the preferred method for accomplishing non-ILS approaches that have an appropriate vertical path defined on the FMC LEGS page. The section on Use of VNAV provides several methods for obtaining an appropriate path, to include published glide paths, and where necessary, a pilot constructed path. V/S may be used as an alternate method for accomplishing non-ILS approaches.
737-600 - 737-900 Airplanes with IAN are capable of using the MCP APP switch to fly non-ILS approaches that have an appropriate lateral and vertical path defined on the FMC LEGS page. All IAN approaches provide the functions, indications, and alerting features similar to an ILS approach while following FMC glide path. Although non-ILS approaches using LNAV and VNAV can still be executed, IAN is normally used in place of LNAV and VNAV because of improved approach displays, alerts and standardized procedures.
Use of the Autopilot during Approaches
Automatic flight is the preferred method of flying non-ILS approaches. Automatic flight minimizes flight crew workload and facilitates monitoring the procedure and flight path. During non-ILS approaches, autopilot use allows better course and vertical path tracking accuracy, reduces the probability of inadvertent deviations below path, and is therefore recommended until suitable visual reference is established on final approach.
Manually flying non-ILS approaches in IMC conditions increases workload and does not take advantage of the significant increases in efficiency and protection provided by the automatic systems. However, to maintain flight crew proficiency, pilots may elect to use the flight director without the autopilot when in VMC conditions.
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