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When ATC held them high and then cleared them for the approach while still descending at a rapid rate; the pilot flying of a B737 elected to use flch and full speed brakes to attempt to get on profile. When utilizing the 'lavs' procedure (lateral nav mode/altitude to which descending/vertical navigation mode/airspeed) to configure avionics for the approach VNAV was selected but; due to the high rate of descent; they had already passed through the last useable crossing restriction and; thus; VNAV would not engage. In VMC at the time; they then disconnected the automation and landed without incident.
| Attributes | |
| ACN | 1182317 |
| Time | |
| Date | 201406 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | MCO.Airport |
| State Reference | FL |
| Environment | |
| Flight Conditions | Mixed |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | B737 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Final Approach |
| Route In Use | Vectors |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Autoflight System |
| Person 1 | |
| Function | First Officer Pilot Not Flying |
| Experience | Flight Crew Last 90 Days 240 Flight Crew Total 12000 Flight Crew Type 3000 |
| Events | |
| Anomaly | Deviation - Procedural Published Material / Policy Inflight Event / Encounter CFTT / CFIT Inflight Event / Encounter Weather / Turbulence |
Narrative:
We were approaching orlando thru an area of multiple thunderstorms. The final approach controller was very busy and you could hear he was a bit tense. We were approaching the inbound localizer course for 17R at 6;000 ft which was 2;000 ft high since we were just outside onner intersection. My copilot was trying to get a request in for lower; but the frequency was congested. As we approached at 6;000 were were getting higher by the minute. We finally were cleared to 4;000 ft. I selected flch 4;000 ft with full speed brakes. Shortly after we were cleared to maintain 4;000 till established on final cleared for the approach. I was in flight level change descending from 6;000 to 4;000 when given the ILS approach clearance maintain 4;000 till established. I wanted to set up lavs to the feather; so we would comply with the next two fixes hammy (3;000 ft) & tuffe (2;200 ft) I selected localizer; altitude to 200; VNAV; speed. The VNAV did not engage. As I was focused on the lavs setup the ac had just descended below 4;000 ft; so VNAV would not engage. We descended to about 3;700 ft and I hand flew the correction and approach. The weather was VFR. We landed without incident. In retrospect using VNAV initially would have been a better choice considering the timing of clearance and aircraft rate of descent. Also flch would have worked also if I continued using it and not changing to VNAV. Changing methods of descent from flch to VNAV in such a time compressed event is not a good idea
Original NASA ASRS Text
Title: When ATC held them high and then cleared them for the approach while still descending at a rapid rate; the pilot flying of a B737 elected to use FLCH and full speed brakes to attempt to get on profile. When utilizing the 'LAVS' procedure (Lateral nav mode/Altitude to which descending/Vertical navigation mode/airSpeed) to configure avionics for the approach VNAV was selected but; due to the high rate of descent; they had already passed through the last useable crossing restriction and; thus; VNAV would not engage. In VMC at the time; they then disconnected the automation and landed without incident.
Narrative: We were approaching Orlando thru an area of multiple thunderstorms. The final Approach Controller was very busy and you could hear he was a bit tense. We were approaching the inbound localizer course for 17R at 6;000 FT which was 2;000 FT high since we were just outside ONNER Intersection. My copilot was trying to get a request in for lower; but the frequency was congested. As we approached at 6;000 were were getting higher by the minute. We finally were cleared to 4;000 ft. I selected FLCH 4;000 FT with full speed brakes. Shortly after we were cleared to maintain 4;000 till established on final cleared for the approach. I was in Flight level change descending from 6;000 to 4;000 when given the ILS approach clearance maintain 4;000 till established. I wanted to set up LAVS to the feather; so we would comply with the next two fixes HAMMY (3;000 FT) & TUFFE (2;200 FT) I selected LOC; Altitude to 200; VNAV; Speed. The VNAV did not engage. As I was focused on the LAVS setup the ac had just descended below 4;000 FT; so VNAV would not engage. We descended to about 3;700 FT and I hand flew the correction and approach. The weather was VFR. We landed without incident. In retrospect Using VNAV initially would have been a better choice considering the timing of clearance and aircraft rate of descent. Also FLCH would have worked also if I continued using it and not changing to VNAV. Changing methods of descent from FLCH to VNAV in such a time compressed event is not a good idea
Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.