 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
An air carrier widebody transport received an unwarranted low altitude warning from the tower while on a localizer approach.
| Attributes | |
| ACN | 237132 |
| Time | |
| Date | 199303 |
| Day | Fri |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | airport : san |
| State Reference | CA |
| Altitude | agl bound lower : 700 agl bound upper : 2000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | tower : san |
| Operator | common carrier : air carrier |
| Make Model Name | Widebody, Low Wing, 2 Turbojet Eng |
| Navigation In Use | Other Other |
| Flight Phase | descent : approach |
| Route In Use | approach : straight in |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 210 flight time total : 15700 flight time type : 1550 |
| ASRS Report | 237132 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : instrument pilot : flight engineer pilot : commercial pilot : cfi pilot : atp |
| Experience | flight time last 90 days : 210 flight time total : 5500 flight time type : 400 |
| ASRS Report | 237125 |
| Events | |
| Anomaly | other anomaly other other spatial deviation |
| Independent Detector | atc equipment other atc equipment : unspecified |
| Resolutory Action | other other |
| Consequence | faa : reviewed incident with flight crew |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | other |
| Situations | |
| ATC Facility | other physical facility |
Narrative:
The autoplt was engaged (controled by the first officer) and used for the approach as per company SOP. We crossed reebo at 2000 ft with gear down and flaps 30 degrees, speed 160 KTS as requested by approach. MDA is 660 ft so 700 ft was selected in autoplt altitude window. The vertical speed mode was used after reebo with 1200 FPM down selected. Reaching 700 ft MSL the tower called 'low altitude alert, check your altitude.' I responded that we were at MDA, 700 ft. We maintained 700 ft to the vdp and then continued the descent to a landing. Talking to ground control later, we were told that their computer generated a low altitude warning because of our gradient and distance from the airport. We were not below MDA when tower called with their low altitude warning. Either the tower computer parameters need to be changed or a step down altitude needs to be added to the localizer 27 profile inside of reebo.
Original NASA ASRS Text
Title: AN ACR WDB RECEIVED AN UNWARRANTED LOW ALT WARNING FROM THE TWR WHILE ON A LOC APCH.
Narrative: THE AUTOPLT WAS ENGAGED (CTLED BY THE FO) AND USED FOR THE APCH AS PER COMPANY SOP. WE CROSSED REEBO AT 2000 FT WITH GEAR DOWN AND FLAPS 30 DEGS, SPD 160 KTS AS REQUESTED BY APCH. MDA IS 660 FT SO 700 FT WAS SELECTED IN AUTOPLT ALT WINDOW. THE VERT SPD MODE WAS USED AFTER REEBO WITH 1200 FPM DOWN SELECTED. REACHING 700 FT MSL THE TWR CALLED 'LOW ALT ALERT, CHK YOUR ALT.' I RESPONDED THAT WE WERE AT MDA, 700 FT. WE MAINTAINED 700 FT TO THE VDP AND THEN CONTINUED THE DSCNT TO A LNDG. TALKING TO GND CTL LATER, WE WERE TOLD THAT THEIR COMPUTER GENERATED A LOW ALT WARNING BECAUSE OF OUR GRADIENT AND DISTANCE FROM THE ARPT. WE WERE NOT BELOW MDA WHEN TWR CALLED WITH THEIR LOW ALT WARNING. EITHER THE TWR COMPUTER PARAMETERS NEED TO BE CHANGED OR A STEP DOWN ALT NEEDS TO BE ADDED TO THE LOC 27 PROFILE INSIDE OF REEBO.
Data retrieved from NASA's ASRS site as of July 2007 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.