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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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Aircraft cleared to descend below sector MSA, 4900 ft. Flight crew noticed discrepancy on approach plate, then visually saw ridgeline just before receiving a GPWS terrain warning. They climbed and notified ATC, who said their present sector MSA was 4000 ft.
| Attributes | |
| ACN | 332572 |
| Time | |
| Date | 199604 |
| Day | Sat |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | airport : swf |
| State Reference | NY |
| Altitude | msl bound lower : 4000 msl bound upper : 5000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | tracon : n90 |
| Operator | common carrier : air carrier |
| Make Model Name | MD-80 Super 80 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | descent other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| ASRS Report | 332572 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | flight crew : took evasive action |
| Consequence | faa : reviewed incident with flight crew |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | other |
Narrative:
Approximately 20-25 NM nnw of swf we were given a descent to 4000 ft. Heading was between 150-170 degrees going direct to neely LOM for ILS runway 9 to swf. After leveling at 4000 ft, I noticed, and told the captain, that the MSA north of the airport on the ILS runway 9 approach plate was 4900 ft. It was VFR, night and we could see a ridgeline in front of us. As we approached the ridge we got the aural terrain alert and the red GPWS light. The captain immediately climbed to 5000 ft. The warning stopped passing through approximately 4500 ft. As the climb was started the lowest that I saw on the radar altimeter was 1700 ft. I told approach that we had climbed due to the terrain alert and he said that MSA for that area was 4000 ft. I asked him about the 4900 ft MSA on the approach plate and he said that he did not know about that but that the MSA for where we were was 4000 ft but we could stay at 5000 ft for now. We continued and made an uneventful approach and landing at swf. When we noticed that the MSA on our approach plate was higher than our altitude we probably should have questioned approach or climbed.
Original NASA ASRS Text
Title: ACFT CLRED TO DSND BELOW SECTOR MSA, 4900 FT. FLC NOTICED DISCREPANCY ON APCH PLATE, THEN VISUALLY SAW RIDGELINE JUST BEFORE RECEIVING A GPWS TERRAIN WARNING. THEY CLBED AND NOTIFIED ATC, WHO SAID THEIR PRESENT SECTOR MSA WAS 4000 FT.
Narrative: APPROX 20-25 NM NNW OF SWF WE WERE GIVEN A DSCNT TO 4000 FT. HEADING WAS BTWN 150-170 DEGS GOING DIRECT TO NEELY LOM FOR ILS RWY 9 TO SWF. AFTER LEVELING AT 4000 FT, I NOTICED, AND TOLD THE CAPT, THAT THE MSA N OF THE ARPT ON THE ILS RWY 9 APCH PLATE WAS 4900 FT. IT WAS VFR, NIGHT AND WE COULD SEE A RIDGELINE IN FRONT OF US. AS WE APCHED THE RIDGE WE GOT THE AURAL TERRAIN ALERT AND THE RED GPWS LIGHT. THE CAPT IMMEDIATELY CLBED TO 5000 FT. THE WARNING STOPPED PASSING THROUGH APPROX 4500 FT. AS THE CLB WAS STARTED THE LOWEST THAT I SAW ON THE RADAR ALTIMETER WAS 1700 FT. I TOLD APCH THAT WE HAD CLBED DUE TO THE TERRAIN ALERT AND HE SAID THAT MSA FOR THAT AREA WAS 4000 FT. I ASKED HIM ABOUT THE 4900 FT MSA ON THE APCH PLATE AND HE SAID THAT HE DID NOT KNOW ABOUT THAT BUT THAT THE MSA FOR WHERE WE WERE WAS 4000 FT BUT WE COULD STAY AT 5000 FT FOR NOW. WE CONTINUED AND MADE AN UNEVENTFUL APCH AND LNDG AT SWF. WHEN WE NOTICED THAT THE MSA ON OUR APCH PLATE WAS HIGHER THAN OUR ALT WE PROBABLY SHOULD HAVE QUESTIONED APCH OR CLBED.
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.