 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
A320 flight crew reports being cleared for the lda prm 28R at sfo and switching to visual when DME appears inoperative. The visual is behind a B747 landing runway 28L. After landing the crew discovers the spacing did not satisfy flight manual requirements for approach and landing on closely spaced runways.
| Attributes | |
| ACN | 833422 |
| Time | |
| Date | 200904 |
| Local Time Of Day | 0601-1200 |
| Place | |
| Locale Reference | SFO.Airport |
| State Reference | CA |
| Environment | |
| Flight Conditions | VMC |
| Aircraft 1 | |
| Make Model Name | A320 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Initial Approach |
| Route In Use | Visual Approach Other Instrument Non Precision |
| Flight Plan | IFR |
| Aircraft 2 | |
| Make Model Name | B747 Undifferentiated or Other Model |
| Flight Phase | Initial Approach |
| Person 1 | |
| Function | Pilot Not Flying First Officer |
| Experience | Flight Crew Last 90 Days 240 Flight Crew Total 6800 Flight Crew Type 300 |
| Person 2 | |
| Function | Captain Pilot Flying |
| Experience | Flight Crew Last 90 Days 150 Flight Crew Total 17300 Flight Crew Type 5330 |
| Events | |
| Anomaly | Deviation - Procedural Published Material / Policy Inflight Event / Encounter Wake Vortex Encounter |
Narrative:
Shortly after being cleared for the lda prm 28R to sfo we noticed that we were not receiving the required lda DME. We advised ATC of this and that we had the proceeding aircraft on the ILS runway 28L and the sfo runways in sight. We were subsequently cleared for the visual approach to runway 28R; to maintain 180 KTS until the bridge and to not pass the aircraft on the ILS approach to runway 28L. We continued to fly the lda prm localizer and glideslope for ground track and altitude guidance to darne. Prior to the bridge when the other aircraft lowered their gear we noticed it was a heavy B747. ATC had not advised us. After darne we maneuvered to intercept the centerline of runway 28R and encountered some wake turbulence on short final. Reviewing the approach later we noted fom which requires 5 miles separation between large aircraft following heavy aircraft to the same runway or parallel runways separated by less than 2500 ft. Runways 28L and 28R are separated by 750 ft. The procedure also requires the pilot to maintain wake turbulence avoidance between darne and runway 28R. What we learned. The A319/320 flight manual says nothing about tuning the lda prm DME manually in the FMGC when conducting an lda with glideslope information. We realized later after reviewing the back course procedures in the FM that this is also necessary for this approach. Second we question how it is physically possible for the pilot to maintain wake turbulence separation inside of darne if ATC spacing of aircraft pairs on the ILS runway 28L and lda prm runway 28R is less than 5 miles outside of darne by normal ATC procedure. 5 mile separation would have been possible for us if ATC had advised us to slow earlier due to heavy aircraft to runway 28L. Our other option was to miss approach when we realized the uncorrectable separation during the approach.
Original NASA ASRS Text
Title: A320 flight crew reports being cleared for the LDA PRM 28R at SFO and switching to visual when DME appears inoperative. The visual is behind a B747 landing Runway 28L. After landing the crew discovers the spacing did not satisfy flight manual requirements for approach and landing on closely spaced runways.
Narrative: Shortly after being cleared for the LDA PRM 28R to SFO we noticed that we were not receiving the required LDA DME. We advised ATC of this and that we had the proceeding aircraft on the ILS Runway 28L and the SFO runways in sight. We were subsequently cleared for the visual approach to Runway 28R; to maintain 180 KTS until the bridge and to not pass the aircraft on the ILS approach to Runway 28L. We continued to fly the LDA PRM localizer and glideslope for ground track and altitude guidance to DARNE. Prior to the bridge when the other aircraft lowered their gear we noticed it was a heavy B747. ATC had not advised us. After DARNE we maneuvered to intercept the centerline of Runway 28R and encountered some wake turbulence on short final. Reviewing the approach later we noted FOM which requires 5 miles separation between large aircraft following heavy aircraft to the same runway or parallel runways separated by less than 2500 FT. Runways 28L and 28R are separated by 750 FT. The procedure also requires the pilot to maintain wake turbulence avoidance between DARNE and Runway 28R. What we learned. The A319/320 flight manual says nothing about tuning the LDA PRM DME manually in the FMGC when conducting an LDA with glideslope information. We realized later after reviewing the back course procedures in the FM that this is also necessary for this approach. Second we question how it is physically possible for the pilot to maintain wake turbulence separation inside of DARNE if ATC spacing of aircraft pairs on the ILS Runway 28L and LDA PRM Runway 28R is less than 5 miles outside of DARNE by normal ATC procedure. 5 mile separation would have been possible for us if ATC had advised us to slow earlier due to heavy aircraft to Runway 28L. Our other option was to miss approach when we realized the uncorrectable separation during the approach.
Data retrieved from NASA's ASRS site as of April 2012 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.